Antibiotic prophylaxis before second-trimester genetic amniocentesis (APGA): a single-centre open randomised...

To compare procedure-related pregnancy loss after second-trimester genetic amniocentesis in women given an antibiotic prophylaxis and controls.

Prospective, open randomised controlled single-centre study between January 1999 and December 2005 at Artemisia Fetal Maternal Medical Centre. A follow-up within 4 weeks after the procedure was done.Of 36,347 eligible women, 1424 refused to participate and 34,923 were enrolled and randomised with unequal chance of selection, 21,991 were assigned to treatment group and 12,932 were assigned to the control group, and did not receive any placebo. Oral azithromycin, 500 mg per day, was administered 3 days before amniocentesis. The primary endpoint was the procedure-related pregnancy loss. The secondary endpoint was the rate of preterm premature rupture of membranes.

The rate of abortion related to the amniocentesis was 7/21 219 women (0.03%, 95% CI 0.009-0.057) in the intervention group, and 36/12 529 (0.28%, 0.28-0.30) in controls (p = 0.0019). The rate of preterm premature rupture of membranes was 14/21 219 (0.06%, 0.031-0.101) in the intervention group, and 140/12 529 (1.12%, 0.94-1.30) in the control group (p = 0.001).

Antibiotic prophylaxis before second-trimester amniocentesis reduced the risk of abortion and of rupture of the membranes.