The following is a summary of “Amniocentesis in pregnancies at or beyond 24 weeks: An international multicenter study,” published in the June 2024 issue of Obstetrics & Gynaecology by ZEMET et al.

Amniocentesis, a pivotal prenatal diagnostic procedure typically performed between 15 and 22 weeks of gestation, is occasionally undertaken later in pregnancy. While extensive data exist on its safety and diagnostic accuracy before 24 weeks, comprehensive insights into late amniocentesis still need to be improved.

This study aimed to assess the indications, diagnostic efficacy, safety profile, and maternal-fetal outcomes associated with amniocentesis conducted at or beyond 24 weeks of gestation.

The researchers conducted a retrospective cohort study across nine international referral centers from 2011 to 2022. The analysis encompassed singleton or twin pregnancies where amniocentesis was performed between 24 weeks and 36 weeks 6 days, excluding cases involving other invasive procedures or obstetric indications. The study group scrutinized indications for late amniocentesis, genetic testing modalities employed, diagnostic outcomes, pregnancy sequelae, and post-procedural complications.

Among 752 pregnancies included, late amniocentesis was primarily conducted for prenatal diagnosis of structural anomalies (91.6%), with additional indications including suspected fetal infection (2.3%) and high-risk findings from cell-free DNA screening (1.9%). The median gestational age at the procedure was 28 weeks 5 days, with genetic test results disclosed before birth or pregnancy termination in 98.3% of cases. The diagnostic yield was 22.9%, notably higher (36.4%) for fetuses with multisystem anomalies compared to those with single-system anomalies (15.3%). Diagnostic efficacy varied across affected organ systems, with the highest yields observed for musculoskeletal anomalies (36.7%) and hydrops fetalis (36.4%). Predominant genetic diagnoses included aneuploidies (46.8%), copy number variants (26.3%), and monogenic disorders (22.2%). The median gestational age at delivery was 38 weeks 3 days, with an average interval of 59 days between procedure and delivery. The overall complication rate within two weeks post-procedure was 1.2%, and no significant disparity in preterm delivery rates was noted between gestational age groups (24-28 weeks versus 28-32 weeks).

Late amniocentesis, performed at or after 24 weeks gestation, particularly in pregnancies complicated by multiple congenital anomalies, demonstrates high diagnostic utility and minimal procedural risk. It facilitates comprehensive prenatal diagnosis, enabling informed decision-making and optimal perinatal management strategies. This study underscores the clinical benefits of late amniocentesis in providing critical diagnostic information before delivery, enhancing prenatal counseling, and guiding tailored neonatal care plans.

Source: sciencedirect.com/science/article/abs/pii/S0002937824006938