Effect of indomethacin on individual amniotic fluid indices in multiple gestations.

To determine the effect of indomethacin on the amniotic fluid index of individual fetuses in multiple gestations, we evaluated seven sets of twins and two sets of triplets in preterm labor (eight cases) or with polyhydramnios (one case). The dose of oral indomethacin was either 25 mg every 12 hours or 25 mg every 6 hours. The amniotic fluid volume of individual amniotic sacs was estimated serially by the amniotic fluid index. When an oral dose of indomethacin of 25 mg every 6 hours was used, oligohydramnios eventually occurred in five of eight amniotic sacs and a subjective decrease in amniotic fluid occurred in one sac. Oligohydramnios was detected in only one of 13 amniotic sacs when the dose of indomethacin was 25 mg every 12 hours. The amniotic fluid volume returned to normal in these seven amniotic sacs within 4 days of discontinuing indomethacin. We conclude that maternal indomethacin therapy has a variable effect on the individual amniotic fluid volumes in multiple gestations.