MRCOG Part 2 Essay 273: Multiple pregnancy

A healthy 33 year old woman attends the antenatal clinic at 12 weeks gestation. She is known to have a dichorionic diamniotic twin pregnancy. (a) She wishes to know whether or not her babies have Down’s syndrome. Discuss your management [10 marks].

I will start by checking what does she know about down's syndrome and what it implies as regard to health of those who have it e.g. this will result in mental retardation and growth retardation and might predispose the child to have some diseases e.g risk of heart anomalies, childhood leukemia.  If she does not have much knowledge I will explain in simple terms explaining what is down's syndrome i.e.when a baby is being made, the information needed to create it comes from his parents in equal parts. this info is written on chromosomes which are tiny bits that each carries a information eg what the colour of the eye will be etc... there are 23 chromosomes from the father and 23 from the mother. these come together to form the complete make up of human being 46 chromosomes which are also known as karyotype. During this process something might go wrong and the baby will get an extra set of chromosome from one of his parents and thus will have a 47 chromosome and this will interfere with his body's proper functioning.

then I will tell her that her age related risk of down 's syndrome is around 1 in 350, but the overall risk for this pregnancy to have one twin with down's syndrome is double that of a single pregancy i.e. 1 in 175, because each twin has its own risk. 

screening for down's syndrome in twin gestation is best performed by use of ultrasound to measure nuchal translucency which measures the maximal thickness between the skin over the neck of the baby till the neck bone. this measure if increased it will point out to increased risk of chromosomal or cardiac abnormalities. It has a high detection rate of 85%, meaning that it will detect 85 babies with down syndrome out of 100 babies with down syndrome, but if the NT is thick this has false positive rate of 20% thus necessitating further test to confirm down's syndrome. Other ultrasound markers of the first trimester scan include looking for the fetal nasal bone and check for tricuspid regurge.

blood test are not reliable in twin gestation as they have low detection rate of down's syndrome in twin gestation. 

So if we measure first the nuchal translucency and it is thick, further testing to confirm can include more invasive testings like amniocentesis which involves introducing a needle into the belly of the mom to get fluid from around the baby. this will test for fetal chromosomes abnormalities such as in the case of down's syndrome. this test has miscarriage rate of 1-2%, it is done at around 15 weeks, and is performed by a maternofetal specialist. Another test called CVS chorionic villus sampling can be performed earlier, usually after 10wks and is done by taking cells from the cells from the placenta (organ which attaches the baby to his mother's womb and through it gets his nutrients and sheds his waste matter). This is also done via a needle inserted through the belly or the neck of the womb. It has the risk of contamination of the sample by the co-twin material in 4% of cases meaning if one of the twins has down's syndrome we might not be sure which twin is it. This test has a 3-4% risk of miscarriage.

there are other new investigation, expensive not not available blood test for the mother that will detect cell free fetal DNA which means we can sample the maternal blood and know if fetus has chromosomal abnormalities.

Patient should be counselled about her decisions in the event of having one or more affected baby, and whether she will want to terminate the pregnancy or carry the pregnancy till term and delivery of both babies.

patient should be supplied with pamphlets to read at home about Down syndrome and about prenatal testing. She should be encourage to ask questions and will be provided with contact numbers in case she needed more clarifications.

 (b) Discuss the additional antenatal interventions that you would recommend to optimize pregnancy outcome [10 marks].

this is a high risk pregnancy , it should be followed in a consultant led antenatal care. Follow up should be every two weeks.  Screening ultrasound including fetal echocardiography should be offerred at around 20wks as twin pregnancies are at higher risk of congenital anomalies especially midline anomalies: cardiac, cleft lip, spine.Ultrasound can detect only 60%of anomalies.

Also there is increased risk of preterm birth and an ultrasound for cervical length of 25mm at 23 weeks will detect 80% of spontaneous preterm deliveries at <30weeks with false positive rate of 11%. home uterine monitoring, cervical cerclage, progesterone supplementation and bed rest have not shown proof of efficency in preventing preterm delivery and has been abandoned.

This pregnancy is at increased risk growth restriction of one of the twins and this should be followed up every 4 weeks by a growth scan starting at 24 weeks, follow up will occur at intervals of two weeks if growth restriction is detected with doppler studies.

this pregnancy is also at risk of developing high blood pressure as in preeclampsia, thus patient should be screened at each visit by taking blood pressure and check for proteinuria by dipsticks. screening for gestational diabetes should be undertaken due to higher risk.

If anticipating a preterm delivery, steroids should be administered in order to benefit the newborns from accelerated lung maturity as this has shown to decrease the incidence of repiratory distress syndrome. Delivery should be planned in a tertiary care center with well equipped NICU especially in the event of a preterm delivery or in the event of maternal complications. They should be cared by a team including neonatologists, obstetrician, perinatologist, paediatric surgeon. specialized nurse.

a)Firstly I will ask what she knows about down syndrome(DS) and will explain  DS is the baby born with mental  retardation  and  with multiple birth defects . Their life span is short and need support throughout their life.This condition  occurs  due to extra chromosome 21. Chromosomes are thread like structures that carry genetic  information  from each parent  and in  a child  23 chromosomes comes from each parent to make a total of 46 in each normal one , If there is extra transfer of 21 chromosome the total will be 47 which is abnormal one and that is linked to DS.

 The risk of DS increases with advance maternal age and the likelihood is more in twin pregnancy.I will tell her that  in her case  there are two separate placenta for each twin so need to calculate separate risk  for each twin .I will discuss the options  of screening test first   and its sensitivity in predicting risks of DS , its false positive rate and that if positive need diagnostic test like biopsy from placenta( CVS) at this gestation age  or extracting fluid around baby(amniocentesis ) later after 15 weeks gestation  .  The best screening test is combined test that include blood test and ultrasound . In ultrasound we measure  thickness of skin fold  at the fetal neck , between skin and spine of the neck .This is highly predictive of DS if increased .This  together with blood test for specific protein like PAPPA and Hormone level BHCG we calculate the risks along with your age which has high predictability(85 out of 100 if test +) and small false positive risks(5 out of 100 if test negative)and if risks exceeds  1:150 then you need to refer to fetal medicine centre for further invasive testing(According to FASP) so that if selctive fetal reduction  is needed then it can be undertaken by the same  specialist  who has an expertise in doing  such procedures.

In Fetal medicine centre the specialist will map the fetuses and then do invasive testing i.e. putting the needle through your tummy or mouth of the cervix and will take some   placental(organ  connection between fetus and mother where exchange of nutrient and waste occurs )  material through special instruments . The risks of fetal loss is higher as compare to singleton pregnancy as double invasive technique  and risk of fetal contamination while drawing the sample is high.I will discuss the physical risks and psychological  implications of selective reduction.

.She can also go for cell free fetal DNA which is new test where fetal information could be drawn from maternal blood samples but   is not widely available and she can also have an option  later  to do  in 2^nd trimester by  maternal  blood screening  but which is not that reliable as combined screening.The options of amniocentesis i.e. drawing fluid from her tummy by needle insertin in the fluid sac around her babies  after 15 weeks gestation should be discussed and that the risks are less as compare to  CVS but still more than singleton pregnancy .

 She should be provided with written information  and leaflets about DS and methods of CVS and amniocentesis  indicating all risks and benefits.She should be supported throughout this process by special counsellor.  

b)Twin pregnancy is a high risk pregnancy  as there is more likelihood of maternal(anemia, preelampsia, APH, PPH, preterm labour and postpartum depression) as well as fetal complication (IUGR, Still birth, prematurity, congenital anomalies). She should be seen under consultant led unit by MDT including specialist obstetrician, specialist midwife, ultrasonographers, perinatal mental health professional , dietician , infant feeding specialist, women’s specialist  physiotherapist.

If she is uncomplicated  pregnancy , I will offer at least  eight   appointment  with at least 2 with specialist obstetrician. At each appointment  blood pressure and urine analyses to be checked as high risks for Preeclampsia. I will give her advice about lifestyle (Stopping smoking and alcohol if she is taking)  and dietician will provide information  about diet .They are at increase risks of anemia so  at booking ,20-24 weeks and at 28 weeks her FBC and red cell Antibody to be checked  to know the need of iron supplement  to know her red cell AB status  .

 Her  appointment to be merge with the scan schedule  so as to avoid her visits. Anomaly scan to be done between 18-21 weeks + 6 days  and minimum 45 minutes to be devoted . Growth scan to be done 3-4 weekly from 20-34 weeks   and discordant growth to be detected by checking at lest 2 growth parameters with a difference of 25% and time spent should be 30 minutes.If any discordant growth or congenital anomalies then she should be referred to fetal medicine centre.

She is at high risks of preterm labour so should be advised about benefits of corticosteroid . Use of cervical screening and  fetal  fibronectin  is assessing risk is not recommended. Use of home monitoring of contractions , bed rest , Im or vagina progesterone, cervical cerclage and tocolysis  are  not recommended. Use of single or multiple untargeted(routine) steroid not recommended.

I will discuss timing and mode of delivery at 28 weeks  gestation and offer her birth at 37 weeks gestation as risk of still birth increases  at 38 weeks in multiple pregnancy. If the woman denies then her follow up should be weekly for appointment and scan  for BPS(biophysical score) weekly  and growth scan 2 weekly.

A healthy 33 year old woman attends the antenatal clinic at 12 weeks gestation. She is known to have a dichorionic diamniotic twin pregnancy. (a) She wishes to know whether or not her babies have Down’s syndrome. Discuss your management [10 marks]. (b) Discuss the additional antenatal interventions that you would recommend to optimize pregnancy outcome [10 marks].

1. rountine down syndrome screening should be offered to all antenatal women.she should receive pre test counselling about the benfeits and risk associated with it. she may need to go for termination of pregnancy , if she is not considering termination of pregnancy for down syndrome, she may choose not to go for screening tests.  her age related risk is 1/350 , which means at this age 1 in 350 women will have down syndrome fetus. 

she should be offered nuchal translucency mesurement with PAPPA  and HCG. PREGNANCY ASSOCIATED plasma protein will be lower and hcg will be higher value in down syndrome pregnancies. 

nuchal translucency is measurement of tissue fluid , made at 11-13+6wks. there is no strict cut off value . as down syndrome fetuses have delay in  lymphatic maturation , so more fliud, more value of nuchal translucency.it has associations with cardiac anomalies and chromosomal anomalies. detection rate is 72% with 5% false +ve rate.

threshould for invasive screening is 1/150. if after combined screening with NT and HCG + PAPPA  , her risk is 1/150 , she will be offered CVS / amniocentesis DEPENDING UPON GESTATIONAL AGE.invasive screenings are diagnostic . need specialist with expertise in selective termination of pregnancy if needed. risk of miscarriage is 1-2% , that may be higher  in twin pregnancy.

she should be given written information leaflets about down syndrome screening and invasive screening. 

2. she should be booked in consultant led unit with appropriate neonatal facilities available. ideally she should be seen in specialized dedicated multiple preg units with specialized midwifery support and expert health care professionals. 

advice about folic acid supplementation , vit D supplementation should be give. she should be offered 5mg folic acid and 10mg vit D. ADVICE about immunization should be given. if she is smoker , advice about quitting smoking should be a part of consultation.  advice about life stlye modification should be given. she should not use over the counter drugs. ask for domestic abuse and be alert for signs of domestic abuse.

advice about recreational drugs if she is using. assess risk for pre eclampsia . assess risk for VTE. she should be given dietary advice. weight management is important issue nowadays.

advice against high impact excercises . she should have anomaly scan done at 21-22wks. twins are at high risk of congenital anomalies. 

growth scans from 24wks should be done every 4wks . this will help in detection of FGR . 

gestational diabetes screening should be offered. if she has risk factors like previous macrosomic baby , previous gestational diabetes, previous stillbirth , she may be offered early screening at 16wks. 

there is some debate about cervical assessment in multiple pregnancies. she may be offered cervical assessment using TVS at 24wks.if cervical length less than 25mm , it is powerful predictor of preterm delivery before 32wks. there is no proven benfits of treatments and strategies like cervical cerclage, progesterone , bed rest and tocolytics in preventing preterm birth , hence cervical assessment in twin pregnancies  may not be of clinical significance.

inform about corticosteriods value in preterm birth , its benefits .

discuss about risks associated with labour and delivery.may need caesarian section. she may need operative delivery. there is risk of single twin death . mangement and decisions may be complex .

inform about postnatal care , parenting skills and mamnaging twin in postpartum period. she will need social /partner support.

vigilant monitoring for detecting  pre eclampsia should be the routine part of multiple pregnancies. 

delivery plan should be made at 36wks, documented in notes. offer elective birth at 37wks.

We would discuss the difficulties of prenatal diagnosis associated with twin pregnancy. Serum screening for aneuploidy in twins has a poor detection rate because the level of serum markers is double the level expected in a singleton pregnancy.In dichorionic pregnancy it can be even more complex where one twin is chromosomally normal.The normal twins’ biochemistry masks the abnormal result,reducing the sensitivity of the test.  We offer measurement of nuchal translucency as a screening tool for Downs syndrome in twins which is a measurement of the thickness of the back of the fetal neck.This is done between 10-14 weeks of gestation and it is noninvasive. The sensitivity of NT in detecting downs is similar to that of singletons,which is approximately 85%,with false positive rate more than 6%(false positive rate is higher in twins than singletons). False positive rate means that the baby does not have Downs syndrome but the test shows it does and we will only know this if we perform diagnostic tests on the baby. If the test shows positive or if the patient wishes to know then a diagnostic tests can be done: chorionic villus sampling (sample from the placenta) done between 11-14 weeks or amniocentesis(sample from fluid around the baby) from 15 weeks onwards. It is adviced by RCOG that these procedures be done at a tertiary centre in twins,we would therefore refer the patient to a fetal medicine centre.They are done under ultrasound guidance.The person that performs the CVS or amniocentesis should also be experienced enough to carry out selective fetocite of the abnormal twin,if desired.There is a 5-10% risk of loss of a healthy dichorionic twin if selective fetocite of an abnormal twin is performed in the second trimester. I would  also offer written info and leaflets regarding the above procedures ,the reason for offering(mentioned above) and the type of the procedure. I would advice the risk of miscarriage for amniocentesis is 1% above the background risk and CVS 1-2%. I will also explain the time it takes for the results to come back,the type of cytogenetic tests being done and the method of communicating the results to the patient. Patient will need Anti-D if rhesus negative. We would also need a infection screen status before the procedures carried out.

(b) In order to optimise this patients pregnancy outcome we need to identify the maternal and fetal risks in twin pregnancy and monitor those closely antenatally in consultant led antenatal clinics throughout pregnancy and for delivery she would be on consultant led unit with experienced staff on multiple pregnancies.

The maternal risks are Pre-eclampsia,pregnancy induced hypertension and gestational diabetes mellitus. We would therefore organise regular and frequent BP and urinalysis check every 3 -4 weeks initially and every 2 weeks in 3^rd trimester.We would also educate patient regarding symptoms of headache,visual disturbances or epigastric pain. We would organise glucose tolerance test at 26-28 weeks or 16-18 weeks if history of gestational DM and repeat again at 28 weeks if initial test is normal. For fetal surveillance we would organise serial growth scans starting from 24 weeks every 4 weeks unless there is a suspicion of IUGR,then we would repeat it every 2 weeks with umbilical artery dopplers. I would advice patient regarding the risks of preterm labour (5 fold higher) in twins. There is no clinical method of predicting preterm labour. There is no indication of performing either fetal fibronectin electively or cervical length measurement  in low risk twin pregnancies. There is no indication of electively giving corticosteroids in twins unless there are clinical indications of threatened labour or preterm delivery (prior to 35 weeks).I would also discuss the increased risk of operative vaginal delivery and postpartum haemorrhage. We would use oxytocin 10u in 500ml N/Saline as infusion as well as the bolus (10u) as a preventative measure –active 3^rd stage of labour. We would advice that around 34-36 weeks we will decide on the mode and time of delivery which is usually around 38-39 weeks of gestation to reduce the risk of placental insufficiency and stillbirth which is higher in twins. We also discuss the mode of delivery, vaginal delivery if presenting twin is cephalic. In labour,we would advice continuous fetal monitoring and epidural anaesthesia.

sorry failed to mention in (b) anomaly scan with a detailed 4 chamber view of the heart as twins have a higher risk of structural anomalies.This is done by an experienced sonographer or fetal medicine .

a)

I will enquire about patient understanding about role of screening test which allows identification of high risk group for diagnostic take (more expensive, invasive and high complication rate). I will explain to her that risk of Down syndrome in multiple pregnancies is 3% higher as compared to singleton pregnancy. I will further explain that serum screening for aneuploidy has poor detection rate in twin pregnancy.  I will offer her screening by measurement of nuchal translucency (skin fold at nape of neck) between 12 to 13 weeks. It has detection rate similar to singleton pregnancy (85%) but high false positive rate (20%). The other alternative is anomaly scan at 18 to 21 weeks of gestation. Duodenal atresia, atrioventricular septal defect etc. are typical anomalies associated with Down syndrome. It can detect upto 60% of Down syndrome but in >40% no anomalies are detected.

If women falls in high risk offer diagnostic test including CVS at 11-14 weeks and amniocentesis after 16 weeks. I will explain nature of procedure (done under ultrasound guidance), risk of procedure including ~ 1% risk of miscarriage and rhesus isoimmunisation. FISH provides result within 48-72 hours with confirmation karyotype result available by 2-3 weeks later. CVS/amniocentesis in multiple pregnancies should be done by someone who has expertise to perform selective termination of pregnancy if required. Normal result is reassuring. If Down syndrome confirmed, ensure that she understand long term implication of having Down syndrome baby. Discuss about her attitude towards affected baby, she may wish to continue pregnancy, selective or whole pregnancy termination. Discuss options of TOP if keen. Provide written information leaflet and support group details.

b)

Manage in consultant led unit as it is high risk pregnancy.

I will explain her maternal and fetal risk. Maternal risk including aggravated symptoms of nausea and vomiting in pregnancy, risk of preeclampsia/eclampsia, gestational diabetes mellitus, anaemia, polyhydramnios, PPH, postnatal depression. Fetal risk includes risk of congenital anomaly, IUGR, polyhydramnoios, IUD, premature delivery, fetal distress, operative delivery etc.

Continue Folic acid as it reduces risk of NTD. Start iron supplementation if laboratory evidence of anaemia.  I will arrange for anomaly scan at 18- 22 weeks along with cardiac scan as high risk of congenital anamoly.I will do OGTT at 24-28 weeks as high risk of GDM or earlier if high risk, repeat FBC and atypical antibodies at 28 weeks.  Her BP and urinalysis for proteinuria should be checked at each visit as high risk of developing PIH or preeclampsia. I will do serial growth scan for fetal growth and amount of liquor (risk of IUGR/hydramnois).Advise her to contact early if contraction pain or vaginal loss as high risk of going into premature labour. Discuss mode and timing delivery with patient by 36 weeks and clearly documented in her notes. Offer induction of labour or caesarean section at 37+0 weeks of gestation. Vaginal delivery if 1^sttwin is cephalic, recommend caesarean section if 1^sttwins non vertex presentation. Explain the need for continuous fetal monitoring during labour.

 Ensure anaesthetist review as epidural analgesia is recommended during deliver especially if 2^ndtwin is non-cephalic anticipating need for potential manoeuvre for delivery. Offer corticosteroid cover if elective caesarean section before 39+0 weeks of gestation to reduce risk of respiration morbidity.

I will first talk to her and find out if she understands what ‘Downs syndrome ‘is.If not ,I will explain to her that a chromosome is a thin strand which carries the genes deciding various characteristics and  fetus inherits 23 pairs of chromosomes equal contribution from mother and father.When there is an extra chromosome in the 21^st pair it is 21TRISOMY or DOWNS.Affected babies will have mental retardation,structural anamolies,with a maximum life expectancy of 50-55years and will need to be specially cared for in their life. She has an age related risk of downs 1:350 and also in dichorionic twins risk per twin equals that of a singleton,so risk for this pregnancy is twice that of a singleton pregnancy for the same age.As she is at 12 weeks,screening tests can be offered as a first part of a 2step screening program designed by the NHS.I will explain a screening test does not give a definite diagnosis,also  there is no risk of miscarriage.ACombined test is appropriate now as she is 12 weeks.For this a fetal medicine trained sonologist will measure the fluid in the nape of the fetal neck called “nuchal Trnsluscency” .Pregnancy associated plasma protein –A(PAPP-A) is a substance measured in mothers blood , increased in downs,and a programmed software calculates the risk for downs for her taking into account her age and gestational age(ideal time is when CRL Is 39-84mm).If the cut off is lower than the national recommended cutoff 1:150,then downs is ruled out but if higher ,she should be referred ta fetal medicine centre for further invasive testing.NT alone using a cut off>3.5mm has a20% false positive while that of combined test is 6.1% at a 85%detection rate..Nasal bone is a soft marker on scan,when absent suggests downs but should be interpreted with other screening results.Chorion villus sampling is an invasive test done at 12 weeks,where using usg guidance,a bit of the conceptus is taken for genetic testing,miscarriage risk being1 to2% sampling error1to5%.Amniocentesis is aspirating some fluid from around the fetus using ultrasound guidance,at15to18weeks,miscarriage risk 1%.These results take two weeks but if PCR(polymerase chain reaction)is done it comes in 2to3 days. I will also tell about CELL FREE FETAL DNA from mothers blood ,a noninvasive prenatal diagnosis,not widely available.If  screen positive she should know the options are selective foeticide of affected twin (may kill the normal twin in 5to 10%) or non-interference . I will provide details of support groups like www.arc.org.uk,www.CAFAMILY.org.uk, www.downs-syndrome.org.uk and FASP NHS Website.

             She should be antenatally managed in a dedicated multiple pregnancy clinic comprising of a consultant obstetrician,specialist midwife,a fetalmedicine specialst,a trained sonologist,a dietician and a specilalist physiotherapist. Because of twins she is at increased risk of complications namely,hyperemesis,anemia due to increased demand of iron or poor intake,preeclampsia 5times more,gestational diabetes mellitus,poly or oligohydramnios and increased operative interference. Complications for the foetuses ara increased risk of aneuploidy,congenital anamolies three times more,intrauterine growth restriction,fetal asphyxia,prematurity,increased operative interference and hence more morbidity,mortality. Most of these are preventable.She should be given an optimum dietary advice by dietician her rubella,hep B,HIV status must be checked.A full blood count to identify need for iron supplementation and blood grouping and typing including atypical antibodies to be done.Ultrasound at 12 to 13+6 weeks to be done for viability,number of foetuses,chorionicity and aneuploidy screen.Scan for structural anamolies is to be done at 18 to 20+6weeks,fetal echo at24 weeks.A full blood count to be repeated at 28 weeks.Antenatal visits must be minimum 8,atleast 2  to be seen by consultant.Blood pressure check,urine analysis to be done at every visit .Growth scans are to be done every 4 weeks till 32 weeks then every 2-4 weeks.There is no role for routine cervical length screening to predict preterm labour ,prophylactic cerclage, bed rest,progestogen therapy, home uterine activity monitoring or prophylactic steroids in all cases. The womans/family’s needs towards twin pregnancy must be identified and addressed.Discussion regarding time ,place and mode of delivery done at 34weeks. In view of increased risk of stillbirths in late pregnancy,a planned delivery by induction at 37 to38 weeks is recommended,but if she denies then followed up with weekly Biophysical profile and 2 weekly growth scans. She should be offered counselling by a neonatologist explaining fetal risks and need for probable NICU care.Contact details of support groups like www.tamba.org.uk, www.twinsclub.co.uk are to be given.Advice regarding postnatal care(hospital or community based),breast feeding and contraceptive advice given .Appropriate patient information leaflets are to be given.

A)

Explain that her maternal age related risk of having a singleton fetus affected by Down"s syndrome is about 1/1000 and that this risk is higher in dichorionic twins. Explain that screening is her choice and is not compulsory. Eplain that screening is not diagnostic and that results maybe falsely positive or falsely negative. Explain that if screened positive for Down's syndrome invasive diagnostic tests may be done. Discuss her options for screening which include first trimester screening. This includes Nuchal Transluscency (NT) measurement which, if elevated, has a detection rate of 85% for a false positive rate of 20%. Another first trimester screening test is the combined test wich is a composite of NT measurement, serum hCG and PAPP-A levels. The combined test has a detection rate of 85% for a false positive rate of 5% in singleton pregnancies. Explain that the combined test has a higher false positive rate in Twin gestations than in singletons. Explain that second trimester screening also has a higher false positive rate for twins than for singletons. These include the Double test(maternal serum alpha feto protein and  hCG lecvels) which has a detection rate of 60%, the triple test ( alpha feto protein, hCG, unconjugated Estradiol) which has a detection rate of 70%, and the quadruple test which has a detection rate of 76% for singletons. Offer the Integrated test which is a composite of the combined and quadruple tests. Expalin that it carries a 94% detection rate for a 1% false positive rate for singletons and that the false positive rate is higher for twins. Regarding invasive diagnostic testing, explain this is done by CVS at 11-13weks 6days or amniocentesis after 15weeks. Expalin the nature of the procedures and that maternal risks include bowel perforation, infection, pain, failed procedure requiring a repeat. Fetal risks include miscarriage, fetal injury and maternal isoimmunisation. Explain that risk of miscarriage is higher with Twins than with singletons. Risk of miscarriage with twins undergoing amniocentesis is 1.8% above the backround risk. Explain that CVS with dichorionic twins is controversial as Inter-placental contamination increases the risk of false positive and false positive results. Counsel her taht advantages of establishing a diagnosis include preparation emotionally and financially for a Down's syndrome affected baby, targeted anomaly screening, in-utero treatment if needed, and enabling fetal reduction if required. Explain that fetal reduction may have maternal physical or psychological morbidity. Offer her written information and follow up consultations. Explain that screening tests maybe expensive and that the Integrated test is most Cost effective. Explain that the NHS may not totally subsidise cost of screening and invasive testing.

B) Recognise that twin pregnancies are associated with increased maternal morbidity/mortality and perinatal morbidity/mortality. Adopt a multi-disciplinary team approach by involving a specialist obstetrician, specialist mid wife and ultrasonographers experienced with twin pregnancies. Reffer if needed to a perinatal mental health professional, infant feeding nurse and dietician. Ensure accurate dating and detirmination of chorionicity by a first trimester ultrasound scan with asignment of nomenclautre to the babies. Perform an anomaly scan at 20weeks with measurement of fetal growth parameters at this scan. Perform an fetal cardiac ultrasound at 22-24 weeks. Perform serial fetal growth scans from 20 weeks no morethan 28 days apart. Discordance of more than 25% in fetal growth parameters between the fetuses suggests growth restriction and is an indicatiion for referral to a tertiary level fetal medicine center. Schedule frequent visits to the antenatal clinic with regular assessment by the consultant obstetrician (at least twice). Schedule a visit with an anaesthesist to discuss anaesthesia at delivery. Monitor for pre-eclampsia by checking her BP and urine dipsticks for proteinuria at each visit. Advise her about signs of preterm labour and to return to hospital if signs of labour occur for assessment. Recognise pre-disposition to Anaemia in multiple gestations and perform a CBC at 24weeks. if anaemic (Hb<11.0g/dl) offer iron or folic acid supplimentation and repeat the CBC at 28weeks. Discuss her delivery plan and document this in early third trimester. Because of the increased perinatal mortality associated with dichorionic twin after 37 weeks, offer elective delivery after 37weeks. If this is declined she should be seen by a specialist obstetrician every week with weekly Bio- physical profiles and fiortnightly fetal growth scans. Offer written information  in thte form of brochures and 24 hour hospital contact numbers.

a)

i will inform her by senstive way that the risk of down syndrome is increased in multiple pregnancy.she needs to make u/s and blood test which is called combined test.u/s to measure  the space between fetal cervical spine and the skin which increased in the down syndrome.measure Pregnancy associated plasma protein and B-hcg.the calculated risk will be made as regarding her age and for each fetus.if the calculated risk is denote down syndrome,she should know that there are high false positive rate result.i will inform her about selective termination.if she refused it so i will advice her not to perform invasive tests.if she agrees for selective termination ,i will inform her that she should be refered to fetomaternal medicine unit .invasive tests will be in the form of CVS or amnoicentesis after 15 wks, to know which fetus is affected.proceure will be explained to her by simple language as well as risk associated with it.she should know that risk of miscarriage is increased in twin pregnancy.she should be informed that fetomaternal specialist who will perform CVS is the same person who will do selective termination. finally she will have written information and leaflets about down syndrome , CVS and amnoicentesis.

B)

she should be followed by MDT consist of specialist obstetricin with expirence in multipale pregnancy,specialist midwife ,pediatricin and dietation.

The women should have information about increase risk of complications for her and to her fetus.she will suffer from  increase symptoms of pregnancy in the form of nausea ,vomiting and dyspnea.

she should have information about nutrition during pregnancy and required weight gain during pregnancy .

she should know that there is increased risk of preeclamsia . she should recieve aspirin 75mg from 12 wk of gestion if this her first pregnancy.the previous pregnancy >10years or her BMI>35.

she should be informed of the risk of preterm labour and the need of targeted corticosteroids for fetal lung matuartion,also should Know that there are no need for multiple courses of it.

rotine cervical length measurment and routine crticosteroids are not recommended.

follow up wil be every 4 wk from 16 wks of gestation and at each visit measurment of blood pressure and protine in urine will be done.

as the risk of anemia increase in multiple pregnancy increase so FBC will be done on the 20,24wk then as routine at28wk.prescription of folic acid oriron as required

she should know increase risk of  growth restrction and congental malformation associated with twin pregnanct.So,growth scan will be from 20wk and every 4 wks.detalied anomely scan will be also  on 20wk but she should know that the time for anomely scan is 45min and for groth scan 30 mins.

The mode and time of delivery should be explained to her.she should be offered elective delivery at 37wk and if declined she should have weekly appointement with u/s and to offer again at 39-40 wk.

she should know that  elective ceaserean section  will be the mode of the delivery if the first twin is breech.

she and her partener should recive  support and  information about how to parent a twin.

her mental health and wellbing should be checked antenatal and postnatal especially if she has congental malformation.

she should also reicive  advice about how to lactate twin.

Twin pregnancy

a) The reason for her request is explored in a sensitive manner. She is told that her age related risk is about 1 in 350 at term . Previous history of baby with down’s syndrome is asked for. In case of previous down syndrome baby due to non dysjunction of chromosome recurrence risk is 1% plus age related background risk. If due to translocation refer for genetic counselling and karyotype by FISH of both partners .21/21 translocation means risk is 100%. 14/21 translocation means risk is 15%.

She is offered combined screen as per recommendation by NHS Fetal anomaly screen programme. This involves scan by 13+6 weeks for measurement of nuchal translucency (NT) and blood test for PAPP-A and B-HCG hormones. The cut off for high risk is 1in 150 as per latest criteria. This test has 90 % detection rate with 2% screen positive. Explain that if NT not available or not done second trimester screen by Triple screen or Quadruple screen serum testing can be done but detection rate is 75% . If she wants diagnostic test then she is offered Chorionic villous sampling by 14 weeks which is an invasive test with 1% risk of miscarriage..Amniocentesis can be done after 14 weeks if screen is high risk or she wants a confirmationto rule out Down syndrome, explaining the 0.5% risk of miscarriage. She is informed that risk is calculated per baby in dichorionic twins, so if one baby is screen positive and invasive testing is done the normal baby may also be at risk of miscarriage.

There may be more chance of false positive screen , more need invasive monitoring like CVS ,Amniocentesis and associated complications. She is reassured that the outcome is mostly good and what it means if the baby has down syndrome and she does not want to terminate pregnancy . She is given support group like down syndrome .uk ,CA comtact a family contact number.

b) Antenatal care involves special mulitple pregnancy core team with obstetrician, experienced midwife, nutritonist , sonologist with input from enhanced team of perinatal mental health specialist , fetal medicine unit as and when required.

Maternal risk of anemia is increased and full blood count is done at 20-22 weeks to detect if there is need for early iron supplementation. The risk of preeclampsia is increased so low dose aspirin 75 mg is started from 12 weeks if first pregnancy, BMI>35, family history preeclampsia or previous pregnancy >10 years. Blood pressure and urine for protein is checked at every visit for early detection.. Counselling given for nutrition and diet intake . She, her partner ,family are given support and advice about coping with twin pregnancy , need for frequent visits and scans. She is given written information about need for additonal antenatal care.

Fetal monitoring is individualised . Anomaly scan is done at 20-22 weeks with fetal echo at fetal medicine unit. Serial growth scans done at 24,28 ,32 36 weeks and in between as per growth . In case of complications like discordant growth of twins, growth restriction , death of one twin she should be referred to specialist fetal medicine centre for assessment.

Clear written plan of labour by multiple pregnancy team done by 36 weeks in dichorionic twins in the absence of complications.

There is no role of untargeted steroids for lung maturity in absence of preterm labour, prophylactic cervical cerlage , progesterone supplementation. Delivery can be planned after 37 weeks. If she does not get into labour by 38 weeks and induction can be offered and fetal monitoring offered if induction declined.

Her age related risk of having a Down's syndrome baby is around 1in 200 at term. I will ask if her partner is having down's syndrome or affected with chromosomal trans locations which would increase the risk of having a Down's baby. I will ask her if any of her previous children are having Down's syndrome due to non disjunction as this would increase the risk about 0.5-1% above the background age related risk. If due to translocation, genetic counselling is arranged. 

I would explain her about the range of screening tests for assessment of risk of having Down's syndrome. If she prefers to have screening test in the first trimester I would offer combined test (Nuchal translucency , B- HCG and PAPPA ) which has the advantage that it is one point test done between 11-13 weeks with 85% detection rate and 6.1% false positive rate. The integrated test consists of NT, PAPPA at 11- 13 weeks and AFP, HCG, uE3 and inhibin A at 14-20 weeks which has 85% detection rate and 1.2% false positive rate. This is considered to be most effective screening test.  

 I will inform her that serum screening for aneuploidy has poor detection rate in twins. But the sensitivity of nuchal translucency in detecting Down's syndrome is similar to that for singletons. However false positive rate of nuchal translucency is higher in twins.

I will explain her that the screening test does not give a definite diagnosis which is possible either by chorionic villus sampling or an amniocentesis. 

I would ensure that she knows about the spectrum of Down's syndrome abnormalities which include miscarriage, structural abnormalities like congenital cardiac defects ( AV canal) , duodenal atresia and congenital cataract. There will be learning disabilities and long term risk of thyroid disorder, leukaemia , Alzheimer's disease and epilepsy. Life expectancy is between 50 and 55 years. So long time care is required. I would explore her attitude towards having one or both babies affected by Down's syndrome.

CVS is performed between 10-13 weeks and involves aspiration of placental tissue using trans abdominal or trans - cervical route with a risk of miscarriage rate of 2-3% above the background. However the procedure related miscarriage rate after amniocentesis or CVS is not increased in twin pregnancy compared to singletons. 

I will explain her  that  CVS allows an earlier diagnosis to be made.

 Amniocentesis is best performed after completed 14 weeks and involves trans-abdominally aspirating sample of the amniotic fluid and risk of miscarriage is about 1% above the background. The use of methylene blue as a marker during amniocentesis is associated with fetal intestinal atresia and is contraindicated. Direct ultrasound guidance obviates the need for dyes, though indigocarmine may be used. The procedure should be undertaken in a tertiary centre.  

Information should be supported with written leaflets. 

I will inform her that the results will be available after 72 hours using FISH technique. Details of the results and further management options should be discussed by involving fetal medicine specialist.  

Normal karyotyping is reassuring . 

If single foetus is found to be affected by Down's syndrome, the options would be selective foeticide which has 5-10%  risk of loss of healthy dichorionic twin. Elective delayed feticide at 32 weeksof gestation, avoids procedure-related loss of the healthy co-twin for dichorionic twins. The other option is expectant management if the couple are prepared for the birth of a disabled child. 

 If both the foetuses are found to have Down's syndrome the options would be termination of pregnancy or continuation of the pregnancy after considering maternal wishes. Either decision should be supported in a sympathetic manner and arrangements made according to the option chosen.  

B) Discuss the additional antenatal interventions that you would recommend to optimize pregnancy outcome [10 marks].

Antenatal care should be provided by multidisciplinary team comprising of Obstetrician, specialist midwife, radiologist with input from fetal medicine specialist when required. 

Frequent antenatal visits are required as twin pregnancy is associated with increased risk of  hypertension, hydramnios, and preterm delivery.

Pregnancy symptoms like tiredness, nausea and vomiting are more with multiple pregnancy, sometimes admission  may be  required to provide appropriate supportive management.  

As she is at risk of developing anaemia , she requires iron supplementation during antenatal period.

Multiple pregnancy is a risk factor for the development of preeclampsia. Screening for preeclampsia should be undertaken at each antenatal visit by measuring BP and urinalysis for protein. In the presence of other risk factors like nulliparity or BMI more than 35kg/m2,  Asprin 75mg//day from 12 weeks till delivery.

Screening for gestational diabetes by oral GTT is required.

Growth scans are required every 2-4 weeks from 24 weeks onwards as there is increased risk of growth restriction, hydramnios, and feral death in utero. 

The risk of preterm delivery is 5 times higher in twins. Although presence of feral fibronectin on a cervical swab at 28 weeks gestation predictive of preterm delivery , there is no clinically applicable method of predicting prematurity.

Admission for bed rest may be associated with an increased risk of pre-term delivery so avoided.

If complications arise, like hydramnios and death of a co twin, referral to tertiary centre is arranged for further management.  

a) I will asceratin how much knowledge the woman has about Down’s syndrome and explain to her that it is the most common chromosomal abnormality at birth with an incidence of around 1 in 1000. I will explain that the baby has an extra copy of chromosome 21 and this causes learning difficulties, which are often profound, but the majority of children learn to meet most developmental milestones, albeit later than other children. I will also explain that as well as delayed neurodevelopment, there can be long term societal, economic and personal issue’s associated with Down’s syndrome in adults. There is also an increased risk of congenital malformations (particularly cardiac and gastrointestinal anomalies) as well as increased incidence of thyroid disorders. Once the woman understands all the information and has no further questions she can make an informed decision regarding screening and invasive testing for the condition.

I will explain to her that it is her decision whether she wants to proceed with screening and as she is early enough we can perform combined testing which includes nuchal translucency on scan, and blood tests for beta-human chorionic gonadotrophin and pregnancy associated plasma protein A which can be used to screen for Down’s syndrome between 11 and 13+6 weeks gestation when the crown rump length is 45-84mm. A healthcare professional with experience caring for women with twin pregnancies should offer information and counselling to women before and after every screening test. I will advise that the risk of chromosomal and structural abnormalities is higher in twin pregnancies and therefore the likelihood of being offered invasive testing is higher however the clinical benefits of screening include correct identification of the abnormality which will allow the woman to make decisions regarding termination of pregnancy, selective termination of pregnancy, or to be prepared for the outcome after birth. Nuchal translucency has a false positive rate of 3.5-5% which means that out of ever 100 babies screened, 3-5 children will be diagnosed as having Down’s syndrome when they do not, and a false negative rate of 2% which means that out of every 100 cases of Down’s syndrome the diagnosis will be missed in 2 children. Potential harm can arise from false positives including undergoing unnecessary invasive testing with the associated risk of pregnancy loss as well as anxiety for the mother. The risk of pregnancy loss is higher for twin pregnancies (1.8%) as two fetuses are put at unnecessary risks. There is also an added risk of miscarriage of the healthy co-twin if the woman chooses selective embryo reduction to manage the pregnancy. False negatives are also harmful and lead to inappropriate reassurance.

I will also discuss invasive testing as she may wish to have this done following the screening tests or without undergoing the screening tests as she says she wishes to know whether her babies have Down’s syndrome and this would be as accurate as we can be, although it is not 100%. Chorionic villous sampling (CVS) has a false positive rate of 1-2% and a false negative rate of 2%, amniocentesis has a false positive rate of 0.1-0.6% and a false negative rate of 0.6%. Nothing can tell her with 100% certainty whether her babies have Down’s syndrome. In cases of multiple pregnancy a CVS or amniocentesis is performed by a specialist who has the expertise to perform a subsequent selective termination of pregnancy if required. It is important to assign and clearly document nomenclature to fetuses (for example left and right or upper and lower) to ensure consistency throughout the pregnancy. Nomenclature assigned antenatally does not necessarily correspond to order at birth. Miscarriage is higher in twins than in singleton pregnancies. The role of CVS in dichorionic placentas remain controversial because of the relatively high risk of cross contamination of chorionic tissue which may lead to false positive or false negative result. This risk may be minimised if two separate needles are used.

I will provide evidence based written information to assist her in the decision making process.

b) She will be managed by a multidisciplinary team consisting of specialist obstetricians, specialist midwives and ultrasonographers, all of whom have experience and knowledge of managing twin pregnancy. There will also be an enhanced team for referral including perinatal mental health professionals, women’s health physiotherapists, infant feeding specialists and dieticians who also have experience and knowledge in managing twin pregnancy. We will coordinate care to minimise number of hospital visits and she will have at least 8 appointments in her pregnancy at booking (11-13+6), 20, 24, 28, 32 and 36 weeks with anomaly scan at 20 weeks and growth scans following this, she will also have two appointments at 16 and 34 weeks without scans.  Out of these appointments she will have at least two of these appointments with the specialist obstetrician. The team will offer information and emotional support on antenatal and postnatal mental health and wellbeing, antenatal nutrition, timing and possible mode of delivery, breastfeeding and parenting. She will get information about the increased risks in twin pregnancy including raised blood pressure, intrauterine growth restriction, preterm labour, anaemia, haemorrhage, operative delivery and postnatal illness. If she has any risk factors she will be commenced on low dose aspirin for the duration of her pregnancy, these include if she is >40, first pregnancy, BMI>35, pregnancy interval >10 years or family or personal history of pre-eclampsia. I will also discuss the symptoms and signs of preterm labour and the potential need for corticosteroids, as 60% of twin pregnancies spontaneously labour <37/40. I will advise that there is an increased risk of admission to special care baby unit particularly if her babies are born at less than 35/40. We will perform a full blood count (FBC) at between 20-24 weeks of gestation to identify those women who need early iron supplementation as well as the routine FBC at 28 weeks. If her pregnancy is uncomplicated we will plan to deliver between 37-38 weeks of gestation.

I would enquire whether any special reason for this request, personal or family history, any other factors affecting the risk of having baby with Down syndrome or affecting screening markers.

The information about screening and diagnostic tests should be provided, and supported by written information in order to allow woman to make a right choice.

The condition should be explained as balanced and accurate information.

Woman should be explained that screening tests such as combined test which includes measuring PAPP-A (special protein, pregnancy associated protein produced by placenta  , Ultrasound scanning measuring nuchal translucency – the size of nuchal pad at the nape of the fetal neck ) and serum B HCG. Screening gives a risk, this risk is estimated separately for each baby (the risk is around 1 in 700-800 pregnancies). Combined test  gives around 85% detection rate with False positive result up to 6.5% though it is higher in multiple pregnancies. Nuchal translucency alone could be used, though the false positive rate is up to 20%.

If woman wants to know for definite that her babies have or don’t have Down’s syndrome, CVS or amniocentesis could be offered. She should be counseled on the risk of miscarriage as these are invasive tests. Transabdominal CVS and amniocentesis have comparable miscarriage rate, higher those in singleton pregnancies, risk of 3%. The CVS could be performed at this gestation and amniocentesis from 14 weeks, ideally between 15-18 weeks. Fetal blood sampling performed after 16 weeks gestation but required more skilled operator  and may be required  if there is mosaic result or culture failure following CVS or amniocentesis. Risks should be clearly explained.

Woman should be explained that majority of the patients won’t have Down’s syndrome baby. However, if one baby has Down syndrome or two which is very  rare , options of adoption, termination or decision continue with pregnancy will be discussed by fetal medicine specialist.

 Counseling and support will be provided and intrapartum interventions will be discussed.

Woman should have written information and telephone number  to contact when she leaves clinic if questions arise in the future.

 2) Nutritional information and lifestyle advice should be provided.

 Aspirin 75 mg should be prescribed from 12 weeks until delivery if at least on additional risk factor for hypertension is present such as: first pregnancy , pregnancy interval more than 10 years, BMI more than 35 kg/m2, family history of preeclamsia.

Special multidisciplinary team provides care in pregnancy: specialist midwives, ultrasosnographers, specialist obstetricians with experience and knowledge of managing twin pregnancies. Referral if needs to be is made to enhanced teams: mental health, physiotherapist, dietician etc. Information and support should be readily available.

Full blood count performed at 20-24 weeks apart from routine 28 weeks in order to optimize iron and folic acid supplementation during the pregnancy.

Monitoring for fetal growth restriction should be performed from 20 weeks with intervals of less than 28 weeks. After 20 weeks scan for anomaly, appointments are given at 24, 28, 32 and 36 weeks in uncomplicated DD twin pregnancy. Difference in size at least 2 parameters  > or = 25 % is clinically important requires referral to specialist obstetrician in fetal medicine.

In twin pregnancies fundal height and umbilical artery doppler to monitor IUGR are not recommended.

Woman should be explained about the risk of preterm birth and ask to attend the hospital in case of uterine activity, so that steroids could be given if in threatened labour to reduce risk of neonatal respiratory morbidity.

Routine use of steroids, cervical length +/_ fibronectin , bed rest vaginal progestogens , cervical cerlage are not recommended.

Timing of birth is 37 weeks in uncomplicated DD twin pregnancies seems not associated with adverse neonatal outcome, though the majority would deliver before 37 weeks and timing for delivery should be discussed at 28 weeks.

 At 34 weeks the mode of delivery discussed. If birth is declined at 37 weeks – weekly appointments for biophysical profile and 2 weekly for growth scans as antenatal mortality is increased  after 37 weeks.

Antenatal care should aim to minimize hospital visits and provide continuity of care as much as possible.

The notes should provide clear information on chorionicity, plan of care, mode of delivery and USS report with assigning nomenclature to the babies in order to facilitate clear communication between professionals.

a)      The reasons for her request is sensitively explored,whether it is due to previously affected baby or  information through friends.Her knowledge about Down syndrome is assessed.She is informed that it is genetically affected condition with one extra chromosome in 21^stpair  out of 23 pairs of chromosomes in normal human being.She should also informed that several tests are available for screening   Down  syndrome  with 85% detection with different false positive rate.

            Pre test coucelling for combined test is provided  that USG is done to  measure fluid collection below the skin at the level of neck for both the babies  and a blood test to measure serum beta HCG and  PAPP-A . She is also councelled sensitively  that the screening tests are not a confimatory tests. She is informed that her age related risk at birth is 1:350. if her screening test  cut off value is 1:150 ,she is high risk for Down syndrome based on NHS Foetal aneuploidy  screening programme.Invasive test is done like CVS between 10-14 weeks or Amniocentesis between 15-20weeks to assess  fetal karyotype for DS  with risk of miscarriage

     If she wants only confirmative test to rule out DS,she is offered CVS  with  risk of miscarriage rate of 1-2%.Explain that CVS sould  be taken from both babies with slightly increased miscarriage rate due to DCDA twins. FISH is done the results with in four days to reduce woman’s anxiety and  for final result she has to wait for 2 weeks.If DS positive woman is referred to fetal medicine specialist in tertiary care centre  for selective foeticide.If she wants to continue psychological support for the woman and family and provide support group detail arc.org.uk/CAFAMILY.org.uk.

  b)      Antenatal care of multiple pregnancy in dedicated multiple pregnancy clinic with core team includes  spcialist obstetrician,specialist midwife, sonographer involved in care of multiple pregnancy with  enhanced team includes perinatal mental health specialist, dietitian , infant feeding specialists,and women’s physiotherapist for referral if necessary.She has DCDA twins , 8 AN visits planned at the time of booking and fetal aneuploidy screening visit 11-14 weeks.Dietary advice lifestyle modification, folic acid  intakeadviced. FBC, blood grouping and Rh status,infective screening like HIV status,Hepatitis B,syphilis,Rubella susceptibility is done.Urine test is done for proteinuria and screen for asymptomatic  bacteriuria.Iron supplementation started if her haemoglobin less than 11g/100ml due to high risk of anaemia in twins.Fetal anomaly scan at 20-22weeks and fetal  ECHO due to 3 fold inceased  risk of fetal anomaly in twins compared to singleton.

            Regular AN  visit at 24,28,32 ,34 and 36 weeks for USG to assess interval growth and to look for discordant growth based on fetal biometry ,not based on fetal Doppler or discordant weightand to assess  co twin death and IUGR.If woman is diagnosed with co twin death,or IUGR she is referred to foetal medicine centre. Aspirin 75mgs started from 12 weeks  If she is primigravida, last delivery 10years back,age >40 years,BMI>35Kg/m2 to reduce risk of PE. Every visit check her BP, urine test for proteinuria and assess her mental status,advice her AN classes to cope up  to manage two babies.No role for fetal fibrinectin ,home uterine contraction monitoring,cervix encerclage, intravaginal progesterone, or tocolytic for prediction and prevention of preterm labour. Targeted steroids if  she goes in for PTL.Plan of care for delivery is done by a consultant  obstetrician at 34 weeks of GA with woman. Induction of labour at 37-38weeks if she doesn’t go into spontaneous labour or no maternal /fetal complications.If she declines IOL regular AN visit every week with specialist for scan and BPP after explaining the risk of stillbirth.

A}Tell the patient about Downs syndrome. the incidence about Downs at her age is 1:1000 .Explain that it is due to chromosomal abnormality. it increases in twins and triplets than singleton pregnancy. A downs syndrome baby has structural defects such as septal defect, duodenal atresia. soft tissue marker such as choroid plexus cyst, echogenic bowel . neurodevelopmental defect such as difficult in learning. care through out his life. Combined test is used in the first trimester to detect downs syndrome. it is a screening test including NT, and biochemical test such as  BHCG and Pregnancy associated plasma proteins. For the accuracy of the test we need to know the excat gestational age .it is done between 11-13 weeks of gestation.NT is detected by an expert sonologist at the time of booking scan. Anamoly scan is done by 20 weeks to detect the structural anamoly and soft tissue markers. absence of this findings does not rule out Downs syndrome. This test has sensitivity of about 85% and false positive rate of 5%. after this there is Diagnostic test which is invasive test such as CVS , Amniocentesis, Fetal blood sampling . These test are done to detect karyotype . a normal karyotype may be reassuring. The patient needs adequate counselling before and after the procedure. explain the risk and benefits about induvisual procedure as the patient may have anxiety before and after the procedure . CVS is done by an expert in this procedure between 11-13 weeks of gestation . There is risk of miscarriage about 1-2% . Amniocentesis can be done after 15weeks by an expert in this procedure . the risk of miscarriage is 0.5-1%. Fetal blood sampling can be done at 16-18 weeks. This procedure is also not without risk.  These procedures can be done by abdominal or vaginal route .there is other procedure called ffdna for karyotype but not easily available in all places  . the expert who does the procedure must take induvisual sample for each twin and lable them seperately.

Fish test is done for karyotype and the results are available in 48-72 hrs. Confirmation can be done after 3 weeks. Maternal age , screening test , biochemical test can detect upto 60 % of the Downs syndrome. 40% are false positive rate. the rate of recurrence is high if previous downs baby. If the test is positive take the mothers wishes into concideration whether to terminate the pregnancy or continue or go for adoption. provide information leaflet and contact details of support group .
B] DCDA twin is confirmed by early booking USG by an expert sonologist at about 10 weeks of gestation age . if there is no expert available refer the patient to higher centre. keep this scan report as as a referance for follow up . early scan not only confirmes viabiliy, but also detects chorionicity and NT. This patient needs multidisciplinary core team involving consultant obstretician, sonologist and specialist midwife. an enhancement team including perinatal mental health, women physiotherapist,dietician, breast feeding and child care support group. Advice the patient about diet, 5mg folic acid, aspirin from early pregnancy. tell her to avoid alcohol, smoking, and recreational drugs.The maternal risk associated with DCDA twins are anemia, pre eclampsia, preterm delivery, operative delivery, PPH, maternal morbidity. The fetal risk are Miscarriage, FGR, Preterm delivery, TTTS if they are sharing single placenta, stillbirth.This patient should be under consultant led unit . She should have about 9 anc visits,in which 2 is by consultant. Her anc should be near the home and combined with USG screening. The mother should have FBS done at 22-24 weeks and at 28weeks to detect anemia and supplement with iron if needed. her BP and urine analysis should be done at each visit for early detection of preeclampsia. Anamoly scan is done at 20-22 weeks and cardiac echo at 24 weeks. the expert who does this usg, should scan induvisual twin and label them.IF they are sharing a single placenta ther is risk of TTTS so it should be detected between 16-24 weeks. tell the mother to report immediately if she finds sudden increase in abdominal girth or respiratory distress. regular monitoring is needed to detect FGR ,use atleast two parametres of usg to detect FGR. USG in done every 3-4 weeks till 24 weeks then every 2 weeks . There is risk of preterm delivery  .assesment of cervical length, fibronectin, progesterone supplement and bed rest is not helpful.prophylactic ,repeated doses of corticosteroides is not needed.discuss and plan delivery at 36 weeks . deliver after 37 weeks under cover of corticosteroides. take mothers wishes into consideration . if she does not want early delivery or if there is death of one twin weekly monitoring is needed until the patient delivers. anticipate vaginal delivery, cs for obstretic reason and breech presentation.active management of third stage. encourage breast feeding. post natal psychological councelling as risk of post partum deppression.provide information leaflet and contact detail of support group

A)

       Down syndrome screening should be undertaken with special consideration and sensitivity. I would counsel the pregnant lady about different options for down screening. Maternal serum screening has poor detection rate; with sensitivity similar to singleton pregnancy but high positive results. I would offer her combined maternal serum beta human chorionic gonadotropins; plasma associated placental protein and USS of nucheal translucency. I would counsel her about the possibility of needing further diagnostic invasive tests, amniocentesis and chorionic villous sampling, which is associated with higher risk of miscarriage with multiple pregnancy. There is risk of having one fetus with Down syndrome so; I would counsel her about different options like termination of pregnancy, selective termination of pregnancy, or continuing pregnancy.

B)

     Multiple pregnancies are considered high risk, so the management should be consultant led through MDT consisting of specialist obstetrician, midwife, ultrasonographer, and dietitian as needed. Eight antenatal care appointments should be offered, two at least with specialist obstetrician. Routine nutritional supplements and life style advice should be offered. Twin pregnancy is associated with high risk of anemia, so FBC and red cell antibody screening should be offered at 20-24 weeks and repeated at 28 weeks as in routine antenatal care. I would counsel her about the benefits of targeted corticosteroids to minimize risks associated with preterm labour. Detailed anomaly scan should be offered at 20 weeks. Serial growth scans should be offered at 24, 28, 32, and 36 weeks. Delivery plan should be discussed at 28 including mode and timing of delivery. Determination of presentation of leading twin should be assessed at 34 weeks would offer her induction of labour at 37w+0 after counseling about possible risks of continuing pregnancy after 38 w, as there is increased risks of fetal death, without increased adverse fetal outcome.

A-

I would inform the patient that it is aroutine practice to offer Down syndrome screening to all pregnant women . After discussion about the syndrome and its screening and diagnosis pathway , she will be allowed enough time to consider the decision whether or not to accept screening .

Information about Down syndrome should be given to the patient including the physical features of Down syndrome such as short stature and facial characteristics . Also , there is learning difficulties and increased risk of cardiac disease and reduced hearing and vision associated with Down syndrome .

The concept and pathway of screening and diagnosis of Down syndrome should be discussed with the patient .screening tell us the chance of the baby having Down syndrome . As the patient is 12 weeks gestation , the test to be offered is the combined test . It include obtaining a blood sample for measurement of 2 substances called human chorionic gonadotrophins ( hCG) and pregnancy -associated plasma protein A ( PAPP-A) .and ultrasound for measurement of nuchal translucency of each fetus which is the amount of fluid under the skin at the back of the babys neck . 

If the test result is lower than the recommended national cut-off , no further investigations are required . this result does not mean that there is no risk , but , it means that it is unlikely that any one of the 2 fetuses have down syndrome .

If the test result is higher than the recommended national cut-off , the result is called higher risk and a diagnostic test is offered . diagnostic test will give a definite diagnosis of the condition . the patient has the right to refuse the diagnostic test . there are 2 diagnostic tests available : chorionic villous sampling ( CVS ) nd amniocentesis .they should be performed by a specialist who has the expertise to perform a selective termination of pregnancy if required .

In CVS , under ultrasound guidance , a tiny piece of tissue from the placenta will be obtained either transabdominally or transvaginally . about 2% of CVS samples do not produce a result . CVS is usually performed between 11 and 13 weeks .

amniocentesis is usually performed between 15 and 18 weeks gestation . It include using a fine needle to remove a small sample of amniotic fluid around the fetus , under ultrasound guidance . about 1% of samples does not produce a result . risk of miscarriage with amniocentesis is 1%.

management options , if one or both twins are affected should be discussed with the patient . continuation of pregnancy is an option . in this case the patient may choose not to have screening from the start .termination of the whole pregnancy is another option . a third option ,if only one fetus is affected , is selective termination of the life of the affected twin ( selective fetecide ) . In Dichorionic twin pregnancy , this can be achieved by injection of KCL into the heart of the affected twin 

the patient should be given information leaflet and informations about support groups and allowed enough time to consider her options 

(B) 

Anomaly scan should be offered at 20 weeks gestation to screen for congenital anomalies as there is increased risk of fetal malformations with twin pregnancy. monthly ultrasound scans for monitoring of fetal growth from 24 weeks because there is increased risk of fetal growth restriction . there should be frequent antenatal visits for early detection of maternal complications as the risk of gestational diabetes and pre-eclampsia is increased with twin pregnancy . Iron supplementations should be given routinely to women with twin pregnancy as the is increased risk of iron deficiency anaemia due to increased fetal demands .corticosteroids should be given in the the third trimester to enhance fetal lung maturation as there is increased risk of preterm birth . delivery should be arranged with a unit with adequate neonatal facilities . If remained undelivered , it is a common practice to offer induction of labour at 37 weeks , as there is increased risk of antepartum stillbirth with twins , although , there is insuffient available data to recommend this practice in otherwise uncomplicated twin pregnancy