Fear of Pregnancy Loss and Fetal Karyotyping: A Place for Third-Trimester Amniocentesis?

Abstract

Objective: To assess the complications of third-trimester amniocentesis for fetal karyotyping in women unwilling to accept the fetal loss risks of second-trimester amniocentesis. Methods: Retrospective study of singleton pregnancies that underwent a third-trimester amniocentesis for karyotyping. 150 complete charts between 1998 and 2005 were reviewed. Results: The indications were: isolated abnormal second-trimester biochemical markers (n = 57), isolated maternal age >38 years (n = 46), integrated risk (maternal age, first-trimester nuchal translucency, second-trimester maternal serum markers) >1/250 (n = 22), history of chromosomal abnormality (n = 17) or maternal choice (n = 8). The median maternal age and gestational age at sampling were: 40 years (23–48), 32.4 weeks (29.7–37.1). Median interval between amniocentesis, definitive result of amniocentesis, and delivery were 14 days (7–42), and 49 days (10–67) respectively. There were no abnormal karyotypes and no termination of pregnancy. Six women out of 150 (4%) had spontaneous labor before 36 weeks (2% after 36 weeks). Conclusion: The risk of spontaneous labor before 37 weeks after late amniocentesis is 4% (2% before 36 weeks). This technique provides a late but safe reassurance to women who are unwilling to accept the risks of earlier fetal karyotyping. This is of interest to countries such as France where legislation permits late termination of pregnancy.

Proportion of Parents Agreeing to Delay Fetal Karyotyping until the Third Trimester of Pregnancy in Cases with an Indication

“…These results therefore confirm results from earlier studies [5,6]. On the other hand, a high rate of prematurity before 37 WA, of the order of 10%, was observed in all the groups in our study.…”

“…While the feasibility of performing amniocentesis in the third trimester of pregnancy has already been described in previous research, couples’ agreement to delay fetal karyotyping until this later stage has never been reported [5,6]. …”

“…As the risk of delivery before obtaining conventional karyotyping may exist for patients in group 3, couples were informed that a rapid interphase FISH technique targeting the main aneuploidies (aneuploidies affecting chromosomes 13, 18, 21, X and Y) would be applied to some of the uncultured amniocytes [5,8,9]. The rest of the amniocytes were cultivated, and conventional karyotyping was carried out.…”

“…More recently, some authors have reported that when amniocentesis is delayed until the third trimester of pregnancy, the fetal chromosomal formula can be obtained with only a slight obstetrical risk [5,6]. This suggests that patients can defer fetal karyotyping until the third trimester of pregnancy.…”

Évaluation de la pratique de l’amniocentèse sur le réseau sud-ouest francilien pendant l’année 2003

“…À ce terme en effet, le risque de fausse couche laisse place au risque de rupture prématurée des membranes et d'accouchement prématuré. Ces risques sont par ailleurs très faibles [13][14][15]. De plus, nous avons constaté que le taux de fausse couche est inversement proportionnel au nombre d'amniocentèses réalisées par an, par chaque centre, et donc probablement par opérateur.…”