C H A P T E R 11 Antenatal screening of the mother and fetus

1. C H A P T E R 11 Antenatal screening of the mother and fetus

2. Definition of screening : a process of identifying apparently healthy people who may be at an increased risk of a disease or condition, they can then be offered information, further tests and appropriate treatment to reduce their risk and/or any complications arising from the disease or condition.

3. Screening has important ethical differences from clinical practice as the health service is targeting apparently healthy people,

4. Benefits of screening : • 1-offering to help individuals to make better informed choices about their health. • 2-it is important that people have realistic expectations of what a screening programme can deliver.

5. Screening can reduce the risk of developing a condition or its complications but it cannot offer a guarantee of protection. • In any screening programme there is a minimum of false-positive results (wrongly reported as having the condition) and false-negative results (wrongly reported as not having the condition).

6. Psychologists, sociologists and health professionals now generally accept the finding that high-risk women delay attachment to the fetus until they receive reassuring test results. • classically termed this the ‘tentative pregnancy’, in a study of women undergoing amniocentesis.

7. How screening is set up and the midwife's role and responsibilities • All midwives need to have a broad understanding of screening investigations because they are responsible for offering, interpreting and communicating the results. • midwives should work in partnership with women to provide safe, responsive and compassionate care. • This implies that the midwife as a key public health agent should enable women to make decisions about their care based on individual needs.

8. Some midwives specialize in discussing complex testing issues with parents and become antenatal screening coordinators. • Antenatal and Newborn Screening programmes. has the overall responsibility • recommends that dedicated screening coordinators oversee the running of screening programmes

9. -screening for Down syndrome at between 10 weeks + 0 days and 20 weeks+ 0 days states that in 97% of women there must be suffcient information and the woman's correct date of birth, maternal weight, family origin, smoking status and ultrasound dating assessment in millimetres, with associated gestational date and sonographer ID, must be included on the request form. • All professionals undertaking screening must be appropriately trained and confident in discussing the risks and benefits of all screening programmes

10. Documentation ; • In whatever system is practised, good documentation is vital. • The midwife should discuss and offer screening tests, record that the discussion has taken place, that the ofter has been made, that the offer has been either accepted or declined

11. Discussion of options • When offering tests, it is necessary for the midwife to present and discuss the options, so that women can make an informed choice that best suits their circumstances and preferences. • Midwives are required to discuss options for testing in a manner that enables shared decision-making . • This means providing the opportunity to discuss choices with a trained professional who is impartial and supportive as the women make decisions along the screening and diagnostic pathway.

12. Pr inciple s f o r o bt a ining inf o r m e d co nse nt • Purpose of the procedure/test • All risks and benefits to be reasonably expected • Details of all possible future treatments • Disclosure of all available options (this may include tests that are offered by private providers • The option of refusing any tests • The offer to answer any queries

13. The woman should understand that screening is optional, and understand the risks and benefits of not undergoing screening. • the choice of continuing or terminating a pregnancy for serious fetal abnormalities

14. -Women who decline first trimester screening should know that they can take up second trimester screening for Down's syndrome if they change their mind and that they can undergo second trimester screening for fetal anomaly at 18+0 to 20+6 weeks. • - • Women who decline initial screening for infections can and should be offered screening later in the pregnancy. • Importantly, only the woman has the right to consent to or decline the screening tests. • A partner or family member has no right to consent or decline on her behalf. Women can withdraw consent for testing at any time. This decision should be recorded.

15. The process of consent • requires adequate time. • to ensure that the woman has had the time she needs • has been enough time to ask questions, that she feels comfortable • -The amount of information needed will vary between women.

16. Ge ne r a l pr inciple s whe n pr o v iding inf o r m a t io n • Be clear: explain everything in terms that are not medical or complex • – be simple, concise and to the point. • Give important information first. • Group pieces of information into logical categories, such as treatment, prognosis and ways to cope. • Information may be recalled more easily if it has been presented in several forms. • For example, leaflets can be helpful.

17. Offer to answer any queries. Give contact numbers, in case people think of questions at a later date. • Do not make assumptions about information requirements on the basis of social class, profession, age or ethnic group. • Summarize, check understanding and repeat the information. Ask whether there is anything that remains unclear.

18. Screening for down syndrome: • The national screening programme for Down syndrome in the UK comprises the offer of one of two tests • The gestational age window for a combined test starts from 10+0 weeks to 14+1 weeks in pregnancy. • The combined test comprises measurement of the crown–rump length (CRL) to estimate fetal gestational age (dating scan), measurement of the nuchal translucency (NT) space at the back of the fetal neck and maternal blood to measure the serum markers of pregnancy-associated plasmaprotein A (PAPP-A) and human chorionic gonadotrophin hormone (hCG).

19. The quadruple test window starts from 14+2 weeks to 20+0 weeks. A maternal blood sample is required for the analysis of hCG, alpha-fetoprotein (aFP), unconjugated oestriol (uE3) and inhibin-A.

20. -CVS can be performed from 11 weeks of pregnancy. • - the procedure is carried out transabdominally ,a transcervical (TC) route is needed. • -complication of CVS : • 1-miscarriage rate 2–3% • 2-procedure-related loss rate is closer to 1% (though TC sampling risks are higher). • result is at 1–2 days.

21. If this result shows no evidence of an extra chromosome 21 it can be taken as 99.9% certain that the fetus does not have trisomy 21. • 3-placental mosaicism • the culture result is available at 14–21 days. • Amniocentesis can be performed after 15 weeks • . The procedure-related loss rate 0.5%.

22. Rapid testing using PCR for trisomy 21 need 2–3 days • A diagnosis of Down syndrome by using CVS or amniocentesis, but it cannot give certainty • 1-the severity of the disorder • 2- the quality of life of a particular individual. • 3- Responses to a diagnosis will vary, according to • - cultural, • -social, • -moral • -religious beliefs.

23. Screening for haemoglobinopathies • -linked with the newborn bloodspot screening programme, • - tests for sickle cell disease and thalassaemia. • -for families with genetic disorders • -Haemoglobinopathies are inherited disorders of hemoglobin and are more prevalent in certain racial groups.

24. all pregnant women test for electrophoresis screening for haemoglobin and thalassaemia trait). • -If the mother is found to be a haemoglobinopathy carrier, partner testing is then recommended and should be offered soon after the result is available. • - Genetic ancestry is also important when interpreting screening results. • -It is important to establish maternal iron levels when carrier status for thalassaemia is suspected.(e.g. alpha thalassaemia).

25. Most haemoglobinopathies are recessively inherited, so the fetus would have a 1 in 4 chance of inheriting the disorder and a 1 in 2 chance of being a carrier.

26. Ultrasonography for fetal screening • -a diagnostic imaging tool since the 1950s • -all pregnant women should be offered two routine ultrasound scans. • 1-an early pregnancy scan (usually timed to be able to perform the NT measurement • 2- an 18–20 week fetal anomaly screening scan.

27. Action of Ultrasound • -works by transmitting sound at a very high frequency, via a probe, in a narrow beam. • -When the sound waves enter the body and encounter a structure, some of that sound is reflected back. • -fluid does not reflect sound and appears as a black image. • -bone reflects a considerable amount of sound and appears as white or echogenic.مولد للصدى • -Many structures appear as different shades of grey. • - pictures are transmitted in ‘real time’, which enables fetal movements to be seen

28. Safety aspect of ultra-sound • -levels of exposure to ultrasound have increased in pregnancy. Although the technology is considered safe, • -it should be used with respect and only when there is good indication, • - care should be taken to limit Ultrasound is a diagnostic tool • -u\s depends on the expertise of the operator and the quality of the machine. -As abnormalities may be missed or incorrectly diagnosed if the operator is inexperienced or inadequately trained

29. The midwife's role concerning ultrasound scans • -mothers should be fully informed about the purpose of the scan. • -Information should be given • -Because of the pleasurable aspect of seeing the fetus, mothers undertake without prior discussion and consideration of potential consequences.

30. De t e ct io n r a t e s f o r co m m o nly a sse sse d f e t a l a bno r m a lit ie s • Anencephaly98% • Open spina bifida90% • Cleft lip75% • Diaphragmatic hernia60% • Gastroschisis98% • Exomphalos( umbilical hernia )80% • Serious cardiac abnormalities50% • Bilateral renal agenesis84% • Lethal skeletal dysplasia (defect ) bone tissue )60% • Edw ards' syndrome (trisomy 18)95% • Patau's syndrome (trisomy 13)95%

31. Ultrasound in 1st trimester: • The purpose of this is to establish: • 1• that the pregnancy is viable and intrauterine (not ectopic) • 2• to measure the NT if the gestation is appropriate and screening for Down syndrome • 3• to accurately define the gestational age • 4.to determine fetal number (and chorionicity or amnionicity in multiple pregnancies) • 5• to detect gross fetal abnormalities, such as anencephaly (absence of the cranial vault).

32. -Early ultrasound scanning is beneficial, in reducing the need to induce labour for post maturity • -A gestation sac can usually be visualized from 5 weeks' • gestation and a small embryo from 6 weeks. Until 13 weeks • - gestational age can be • accurately assessed by CRL measurement (the length of the fetus from the top of the

33. head to the end of the sacrum). -Care must be taken to ensure that the fetus is not flexed at the time of measurement. - Mothers are asked to be a full bladder, this aids visualization of the uterus at an early gestation.

34. Dealing with increased nuchal translucency • -A nuchal translucency of >3.5 mm occurs in about 1% of pregnancies • -Increased NT is associated with a risk • of chromosomal abnormalities & other structural abnormality (mainly cardiac)

35. Second trimester ultrasound scans • After 13+6 weeks of pregnancy, gestational age is primarily assessed using the head circumference (HC).

36. The detailed fetal anomaly screening scan • -performed at 18–20+6 weeks of pregnancy. • The purpose of this scan is • @to reassure the mother that the fetus has no obvious structural anomalies that fall into • the following categories: • • anomalies that are incompatible with life; • • anomalies that are associated with significant morbidity and long-term disability; • • anomalies that may benefit from intrauterine therapy; • • anomalies that may require postnatal treatment or investigation.

37. @show fetal position, multiple pregnancy, fibroids or maternal obesity may mean that a • second scan before 23 weeks is offered. • @ Some structural problems do not have • sonographic signs that would be visible at this gestation or even at all. • Anal atresia does • not have a clear appearance on ultrasound; hydrocephalus and other bowel obstructions • may not appear until later in pregnancy.

38. 18+0 to 20+6 weeks fetal anomaly ultrasound scan base menu • -Spine, vertebrae and skin covering in transverse and longitudinal sections. • • Head and neck: Head shape and internal structures cerebellum,ventricular size at atrium). Nuchal fold. Face and lips. • • Thorax: Four-chamber view of heart, cardiac outflow tracts, lungs. • • Abdominal shape and content – at level of the stomach with small portion ofintrahepatic vein, abdominal wall, renal pelves, bladder.

39. • Limbs: Arms – three bones and hand (metacarpals). Legs – three bones and foot • (metatarsals). • • Placental location and amniotic fluid. • -Some features on ultrasound may be seen that increase the risk of another problem such as Down syndrome. • -An increased skin fold measurement of >6 mm at the level of • the nuchal fold (an associated increase in the risk for Down syndrome of at least 10-fold. • -Mild cerebral ventriculomegaly should be noted as there is again an increased risk of chromosomal • abnormalities of about 10%.

40. what is gastroschisis • an abdominal wall defect, adjacent to the umbilicus, allowing the intestines and other abdominal organs to • protrude outside the body),

41. New and emerging technologies • Fetal imaging techniques • u\s • neurological scanning • Magnetic resonance imaging (MRI) has also been applied in the examination of the fetus This technique has not been widely applied because ultrasound can give similar diagnostic information at a lower cost.

42. -MRI has been effective when examining the brain. may provide additional information and change the counselling and management for a significant number of pregnancies where brain abnormalities are suspected • -MRI offers to postmortem • following termination or perinatal death.

43. Free fetal DNA • identifies free fetal DNA in thematernal circulation. • to identify fetal sex, blood group and some genetic disorders. • - testing for Down syndrome

44. Screening for maternal conditions • 1-Infectious diseases • all pregnant women are screened for: • • HIV • • syphilis • • hepatitis B (HBV) • .rubella. • Rubella screening cannot reduce the risk if • a mother develops the illness but allows immunization in the future to reduce risk.

45. Hepatitis B (HB) • -Adequate immunization programmes for infants at risk of vertical transmission of HBV can reduce infant infection rates by 90% and improvements in maternal health • -Referral to a specialist is required for women who are found to be hepatitis B positive. • -Establishing the neonatal and maternal risk will be determined by testing of antibody and antigen status and viral DNA levels. • -Occasionally hepatitis B can reactivate in pregnancy and knowledge of status can aid management of the pregnant mother.

46. Syphilis • -Syphilis is a rare infection • -Treatment of syphilis can prevent • 1-pregnancy loss • 2- congenital syphilis • 3- long-term problems for the mother. • - A positive screening result does not distinguish • between syphilis and other treponemal infections

47. Rubella • Screening to avoid of potentially infected individuals during • pregnancy and to offer postnatal vaccination. • For the above infections, testing in early pregnancy is recommended. • the midwife should discuss the following • • The infections that are screened for, their routes of transmission and the implications of a positive test. • •

48. -in labour can be urgently screened. • -Women with a positive result for syphilis, HIV or HBV should be seen and counselled • as soon as possible and within 10 days • - Appropriate referrals should then be made to ensure that the correct care pathway is inducted. • -Screening for infectious diseases in pregnancy can be cultural and social stigma • -The midwife needs to have enough knowledge to understand • the disease, the process following a positive test and the ability to answer questions or direct women to the answers.

49. New screening • -Group B Streptococcus • -(GBS). GBS is carried in the genital tract and gut of many healthy people • -occur after premature or prolonged rupture of the membranes. • -babies are affected by GBS disease, a disease, that can cause severe problemsincluding • meningitis • and death. • -screening is offered by vaginal swabs at 35–37 weeks.

50. Mid-stream urine testing • -Screening for asymptomatic bacteriuria will lead to pyelonephritis. • -Pyelonephritis can be life-threatening • - lead to miscarriage and premature labour. • Treatment is appropriately antibiotics.