Pregnancy loss rate following routine genetic amniocentesis at Wellington Hospital

To determine the institutional pregnancy loss rate following second-trimester genetic amniocentesis.

Data from 293 consecutive women who had routine genetic amniocentesis at Wellington Hospital from 1 January to 31 December 2001 were collected. The primary outcome measure was pregnancy loss rate up to 6-weeks post-procedure. Secondary outcomes were pregnancy loss after 6 weeks and culture failure.

Complete information on the pregnancy outcome was obtained for 269 of 293 pregnancies (92%); corresponding to 275 procedures, including two twin pregnancies and four repeat amniocentesis for culture failure (1.3%). There were two miscarriages within 6 weeks of amniocentesis; giving a pregnancy loss rate of 2/269 pregnancies (0.74 %), or 2/275 amniocentesis procedures (0.73%). Of these pregnancies, one fetus had 'trisomy 21'-giving a corrected pregnancy loss rate within 6 weeks of amniocentesis of 1/269 (0.37%) pregnancies or 1/275 (0.36%) amniocentesis procedures. The pregnancies lost after 6 weeks of amniocentesis was three in 269 pregnancies (1.1%); including one neonatal death at 31 weeks due to a lethal congenital anomaly, and two fetal deaths in utero (one at 23 weeks with a non-lethal congenital anomaly and a normal karyotype, and the other at 27 weeks from toxoplasmosis).

The pregnancy loss rate from amniocentesis and the culture failure rate in Wellington Hospital (using modern techniques) are similar to rates found in recently published studies.