Genetic amniocentesis complications: is the incidence overrated?

To estimate the complication rate of 2nd-trimester amniocentesis and to determine the associated risk factors.

A retrospective chart review of genetic amniocenteses performed at a single tertiary care institution, from 1996 to 1998, was done. The variables studied included gestational age, indication for amniocentesis, number and site of needle punctures, and amniotic fluid color. Complications included fetal loss, rupture of membranes, and bleeding.

Out of the 1,347 procedures analyzed, the most common indications were advanced maternal age (72.3%) and abnormal triple screen (20.3%). Transplacental genetic amniocenteses totaled 234 (17.4%). Clear fluid was observed in 98.2% of the patients. Twenty-two complications (1.6%) were observed: fetal loss (0.22%), bleeding (0.59%), and rupture of membranes (0.82%). An abnormal karyotype was detected in 34 (2.5%) fetuses. In separate univariate logistic regression analyses, complications were significantly associated with gestational age [odds ratio OR = 1.19; 95% confidence interval CI = (1.08, 1.32); p = 0.001], number of punctures [OR = 8.2; 95% CI = (1.76, 37.97); p = 0.007], and ultrasound anomalies [OR = 5.82; 95% CI = (1.65, 20.58); p = 0.006]. Gestational age and number of punctures remained significant in multivariate logistic regression analysis.

Genetic amniocentesis performed at a tertiary care institution is rather safe, and the fetal loss rate of 0.22% is significantly lower (p < 0.001) than the previously published incidence of 1/200. The risk of complications is significantly and independently associated with advanced gestational age and number of punctures.