Pregnancy loss rate following routine genetic amniocentesis at Wellington Hospital.

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

Methods: 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.

Results: 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).

Conclusions: 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.