Why do parents prefer to know the fetal sex as part of invasive prenatal testing?

Objectives. The aim of this study was to determine whether prospective parents, primarily referred for prenatal diagnosis to exclude Down syndrome, prefer to know the fetal sex as part of invasive testing. Methods. In this prospective study 400 pregnant women undergoing amniocentesis were invited to answer a questionnaire, including information about demographic factors, current pregnancy, and previous children. In two open-ended questions they were asked why they wanted to know the fetal sex after amniocentesis or ultrasound investigation. Scores were given for reasons that could have played a role in the wish whether or not to know the sex of their unborn child. Results. A total of 210 (52.5%) questionnaires were completed. Overall, 69.0% was interested to know the fetal sex as part of the diagnostic test result. The most important reasons were curiosity (77.8%), “just want to know” (68.0%), and “because it is possible” (66.8%). The overall knowledge of sex chromosomal disorders appeared low and did not seem to affect the parent's wish to know the fetal sex. Almost all women (96.6%) planned to have a 20-week ultrasound scan and 96.2% thought the scan to be reliable in detecting the fetal sex. A minority (28%) was willing to learn the fetal sex by ultrasound examination, whereas 65% preferred to learn the fetal sex only after the amniocentesis. Conclusion. Personal values affect the parental desire to know or not to know the fetal sex. This does not appear to be affected by invasive prenatal testing and/or genetic knowledge of sex chromosomal disorders.

Detection of chromosome aneuploidies in chorionic villus samples by multiplex ligation-dependent probe amplification

The objective of this study was to examine the suitability of multiplex ligation-dependent probe amplification (MLPA) in chorionic villus samples as a replacement for traditional karyotyping for the detection of (an)euploidies of chromosomes 21, 18, 13, X, and Y. Chorionic villus samples were diagnosed by traditional karyotyping using short-term cultures (STC) and long-term cultures (LTC), and by MLPA using kit P095. DNA was extracted after digestion of whole villi with proteinase K and/or trypsin and collagenase. Different cell-dissociation procedures were tested to obtain MLPA results representative of the cytotrophoblast layer and the mesenchymal core. Over 95% of the MLPA results were in concordance with the traditional karyotyping of STC and LTC. Traditional karyotyping revealed seven mosaics. After digestion of whole villi with proteinase K, only abnormal cell lines confined to the STC gave rise to abnormal MLPA results. In one sample, the complete discrepancy between STC and LTC was resolved after enzymatic dissociation of cells from the cytotrophoblast layer and the mesenchymal core. MLPA in chorionic villus samples was found to be a reliable test for the detection of (an)euploidies of chromosomes 21, 18, 13, X, and Y. Whole villi digestion with proteinase K resulted in the over-representation of cytotrophoblasts in the DNA pool. To obtain MLPA results representative for STC and LTC, enzymatic dissociation of cells from the cytotrophoblast layer and mesenchymal core is required.

[Alpha-foetoprotein assessment in amniotic fluid for the detection of neural tube defects: limited added value beyond week 20 ultrasound; retrospective study]

OBJECTIVE

To evaluate the diagnostic additional value of routine alpha-foetoprotein (AFP) assessment in amniotic fluid for the detection of neural tube defects (NTDs), compared with week 20 ultrasonographic examination.

DESIGN

Retrospective.

METHOD

We retrospectively determined AFP concentrations in amniotic fluid obtained from 7981 women who had undergone amniocentesis for karyotyping and AFP assessment. An AFP concentration greater than 2.5 times the median was considered abnormal. Women were categorised into 4 groups based on the indication for invasive prenatal diagnostic assessment: advanced maternal age (group I; n = 6179), increased risk of foetal NTDs (group II; n = 258), ultrasonographically confirmed foetal NTDs (group III; n = 55) or other indications (group IV; n = 1489).

RESULTS

In group I, 18 of 6179 samples had increased AFP levels (0.3%), 2 of which were associated with NTDs. In group II, 2 of 258 samples had increased AFP levels (0.8%); both were associated with NTDs. Increased AFP levels were found in 44 of 55 samples from group III (80%), and 223 of 1489 samples from group IV (15.0%).

CONCLUSION

Routine assessment of AFP in amniotic fluid based on advanced maternal age provides little additional value in the detection of NTDs beyond that of week 20 ultrasound.