Late amniocentesis: better late than never? A single referral centre experience

Abstract

Introduction: Several congenital abnormalities present late in pregnancy necessitating invasive testing to rule out genetic/infectious causes at late gestation. Not many studies have described the indications/safety of a late gestation amniocentesis.

Methods: All records of amniocentesis performed beyond 24 weeks were reviewed and evaluated for indications, positive yield and complications.

Results: About 187 women had an amniocentesis after 24 weeks for various indications with CNS abnormalities being the commonest. The total yield of positive findings was 14.60% (22/150; excluding 2 VOUS). CNS, multiple system involvement and skeletal system anormalities yielded maximum results. About 32.05% abnormalities could have potentially been detected at the time of a routine anomaly scan. Amongst all the deliveries, 2.1% delivered spontaneously within a week of the procedure and about 5.4% delivered spontaneously within a month of the procedure.

Conclusion: The study emphasises the need for additional accreditation (FMF, ISUOG) of sonographers to ensure the detection of anomalies at the routine 18-20 weeks scan. Inspite of a normal mid-trimester scan, central nervous system and gastrointestinal abnormalities presented more commonly after 24 weeks. The high positive yield in our study highlights the importance of testing even in late pregnancy beyond the legal age of termination. The test could clearly stratify the pregnancies with a poor outcome whilst reassuring the others. The procedure itself did not lead to a neonatal death due to prematurity.

Keywords: Amniocentesis; Preterm delivery risks; Third trimester.