Is routine AFP screening in pregnancy reassuring?

Update and Review: Maternal Serum Screening

Maternal serum levels of alpha fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) can be used to screen pregnancies for neural tube defects, Down syndrome, Trisomy 18, and pregnancy complications. This article summarizes the most recent information regarding maternal serum screening, including genetic counseling issues.

Maternal serum screening and psychosocial attachment to pregnancy

OBJECTIVE

The purpose of this study was to examine whether maternal serum screening (MSS) is associated with lower maternal attachment to pregnancy.

METHODS

One hundred one pregnant women identified as at risk for fetal anomaly due to advanced maternal age completed a survey targeting their decisions regarding prenatal testing and their psychological attachment to their pregnancy. Of these women, 38 opted for no prenatal testing, 32 underwent MSS, and 31 had amniocentesis in their current pregnancy.

RESULTS

The results indicate that, throughout their pregnancy, the women who underwent MSS reported lower bonding levels as compared with those who chose either amniocentesis or no testing procedures.

CONCLUSION

The results suggest that MSS may disrupt the developmental trajectory of the maternal-fetal bond even after favorable results are known. This may be due in part to the fact that the probabilistic nature of MSS results creates feelings of confusion rather than reassurance for many women following receipt of favorable results.

Genetic susceptibility testing from a stress and coping perspective

Four theories of health behavior and of stress and coping are reviewed for their ability to illuminate interest in uptake and outcomes of genetic testing for adult-onset diseases. These theories are the Health Belief Model, the Theory of Planned Behavior (TPB), the Common Sense Model of Self-regulation (CSM), and the Transactional Model of Stress and Coping (TMSC). Basic concepts of each theory are discussed, followed by evidence from the literature supporting the relevance of these concepts to the understanding of genetic testing for four adult-onset diseases: Huntington's disease, Alzheimer's disease, hereditary breast/ovarian cancer, and hereditary colorectal cancer. Emphasis is placed on the finding that a decision to undergo genetic testing may be considered as a way to cope with both the cognitive and affective concerns that arise from living at increased risk of developing a disease in the future. The potential value of genetic testing for reducing uncertainty about and gaining a sense of control over one's risk of developing a chronic disease is highlighted. We argue that theories which focus on stress and coping provide a useful framework for future studies of genetic testing decisions for adult-onset disease risk.

Does prenatal screening influence anxiety levels of pregnant women? A longitudinal randomised controlled trial

OBJECTIVES

Questions addressed are: (1) Does offering prenatal screening increase anxiety? (2) Does receiving a negative screening result make women less anxious and does a positive screening result make women more anxious? (3) What are the long-term consequences on anxiety of offering screening and receiving a screening result?

METHODS

Women were offered prenatal screening or no screening in a randomised controlled trial. State anxiety (STAI) and child-related anxiety (PRAQ-R) were measured. Questionnaires were filled in before prenatal screening was offered (T1), after the offer (T2), after the test result (T3), and in the third trimester of pregnancy (T4).

RESULTS

Child-related anxiety levels were higher in women who chose to be screened compared to women who declined screening. Offering prenatal screening did not lead to increased anxiety levels. General anxiety increased in positively screened women, but decreased later in pregnancy. Women who were negatively screened or declined screening scored lower than the control group.

CONCLUSION

For most women, offering prenatal screening and receiving the test result do not adversely affect anxiety. Giving pregnant women a choice to have prenatal screening done seems to have a small favourable effect on general feelings of anxiety.

Distress associated with prenatal screening for fetal abnormality

A theoretically-based, multivariate approach was used to identify factors associated with emotional distress for pregnant women undergoing maternal serum alpha fetoprotein (MSAFP or AFP) testing, used to detect abnormalities of the fetal brain and spinal cord. Participants were those who received normal results (N = 87). Study results supported the hypothesis that different factors would predict distress before and after testing. Satisfaction with information about testing predicted lower emotional distress early in the testing process; concerns about the child having other medical conditions and low-dispositional optimism predicted distress later. Study findings indicate that even in women who receive normal test results, AFP testing is associated with a modest degree of emotional disturbance which declines, but does not completely abate, after testing.

Psychological responses to prenatal NTS counseling and the uptake of invasive testing in women of advanced maternal age

This study examines women's psychological responses to prenatal group genetic counseling, and to subsequent individualized risk counseling. All women (N=123) aged 35 and older underwent nuchal translucency screening (NTS), a prenatal ultrasound screening test. After group counseling, decisional conflict decreased significantly among those reporting at baseline having made a decision about invasive testing (t(222)=2.0, P=0.014) and for those who were uncertain (t(222)=5.74, P <0.0005). After receiving NT-adjusted risks, decisional conflict decreased further for those uncertain about testing at baseline (t(222)=4.64, P <0.0005). There was no change in risk perception and anxiety after group counseling. After NT-adjusted risks were communicated, risk perception decreased significantly (t(230)=5.02, P <0.0005), as did anxiety (t(115)=7.91, P <0.005). Despite reassuring NTS results, the uptake rate for prenatal invasive testing was 78.4%. Risk perception, anxiety, and decisional conflict decreased after individual counseling for reassuring NTS results, but the uptake of invasive testing remained high.

Antenatal screening for Down's syndrome

BACKGROUND

In 1968 the first antenatal diagnosis of Down's syndrome was made and screening on the basis of selecting women of advanced maternal age for amniocentesis was gradually introduced into medical practice. In 1983 it was shown that low maternal serum alpha fetoprotein (AFP) was associated with Down's syndrome. Later, raised maternal serum human chorionic gonadotrophin (hCG), and low unconjugated oestriol (uE3) were found to be markers of Down's syndrome. In 1988 the three biochemical markers were used together with maternal age as a method of screening, and this has been widely adopted. PRINCIPLES OF ANTENATAL SCREENING FOR DOWN'S SYNDROME: Methods of screening need to be fully evaluated before being introduced into routine clinical practice. This included choosing markers for which there is sufficient scientific evidence of efficacy, quantifying performance in terms of detection and false positive rates, and establishing methods of monitoring performance. Screening needs to be provided as an integrated service, coordinating and managing the separate aspects of the screening process. SERUM MARKERS AT 15-22 WEEKS OF PREGNANCY: A large number of serum markers have been found to be associated with Down's syndrome between 15 and 22 weeks of pregnancy. The principal markers are AFP, hCG or its individual subunits (free alpha- and free beta-hCG), uE3, and inhibin A. Screening performance varies according to the choice of markers used and whether ultrasound is used to estimate gestational age (table 1). When an ultrasound scan is used to estimate gestational age the detection rate for a 5% false positive rate is estimated to be 59% using the double test (AFP and hCG), 69% using the triple test (AFP, hCG, uE3), and 76% using the quadruple test (AFP, hCG, uE3, inhibin A), all in combination with maternal age. Other factors that can usefully be taken into account in screening are maternal weight, the presence of insulin dependent diabetes mellitus, multiple pregnancy, ethnic origin, previous Down's syndrome pregnancy, and whether the test is the first one in a pregnancy or a repeat. Factors such as parity and smoking are associated with one or more of the serum markers, but the effect is too small to justify adjusting for these factors in interpreting a screening test.

URINARY MARKERS AND FETAL CELLS IN MATERNAL BLOOD

Urinary beta-core hCG has been investigated in a number of studies and shown to be raised in pregnancies with Down's syndrome. This area is currently the subject of active research and the use of urine in future screening programmes may be a practical possibility. Other urinary markers, such as total oestriol and free beta-hCG may also be of value. Fetal cells can be identified in the maternal circulation and techniques such as fluorescent in situ hybridisation can be used to identify aneuploidies, including Down's syndrome and trisomy 18. This approach may, in the future, be of value in screening or diagnosis. Currently, the techniques available do not have the performance, simplicity, or economy needed to replace existing methods.

DEMONSTRATION PROJECTS

Demonstration projects are valuable in determining the feasibility of screening and in refining the practical application of screening. They are of less value in determining the performance of different screening methods. Several demonstration projects have been conducted using the triple and double tests. In general, the uptake of screening was about 80%. The screen positive rates were about 5-6%. About 80% of women with positive screening results had an invasive diagnostic test, and of those found to have a pregnancy with Down's syndrome, about 90% chose to have a termination of pregnancy. ULTRASOUND MARKERS AT 15-22 WEEKS OF PREGNANCY: There are a number of ultrasound markers of Down's syndrome at 15-22 weeks, including nuchal fold thickness, cardiac abnormalities, duodenal atresia, femur length, humerus length, pyelectasis, and hyperechogenic bowel. (ABSTRA