Complications of third-trimester amniocentesis using continuous ultrasound guidance.

Objective: The objective of the study was to estimate the risks of third-trimester amniocentesis with continuous ultrasound guidance.

Methods: Cohort study. We reviewed the medical records of women who had an amniocentesis with continuous ultrasound guidance after 30 weeks' gestation at a single institution from January 1991 through December 1994. For procedures performed from January 1991 to February 1994, we obtained information from a chart review. From March 1994 to December 1994, we collected data prospectively. The primary outcome was whether or not there were any complications within 48 hours of the procedure. We also sought to determine any risk factors associated with complications.

Results: Complete records and data were available for 562 amniocenteses during the study period. The mean gestational age at the time of amniocentesis was 34.9 weeks. Of the 562 procedures, five (0.8%) were unsuccessful and 50 (9%) required more than one needle stick. The complication rate was 0.7% (95% confidence level (CI) = 0.02%, 1.9%). These included spontaneous labor in a preterm gestation (1), premature rupture of the membranes (1), placental abruption (1), and fetal-maternal hemorrhage (1). No patient required an emergency cesarean delivery and none suffered a perinatal death (95% CI 0, 0.8%). Complications were not associated with the number of needle sticks, the presence of bloody amniotic fluid, or the level of operator experience.

Conclusions: Third-trimester amniocentesis performed with continuous ultrasound guidance has a high success rate and low risk for complications.