Clinical features of polyhydramnios associated with fetal anomalies

The purpose of this study was to examine the clinical features of pregnancy complicated by polyhydramnios associated with fetal anomalies. Sixty-nine patients with a singleton pregnancy complicated by polyhydramnios were retrospectively analyzed. Based on prenatal ultrasonographic findings, 13 cases were considered to have idiopathic polyhydramnios and the remaining 56 cases were associated with fetal anomalies. Between these two groups, no significant difference was found in the gestational weeks when polyhydramnios developed. However, significant difference was noted in the maximum amniotic fluid index (AFI) values during the pregnancy period; 25.4 +/- 2.7 cm in the former, and 30.6 +/- 8.9 cm in the latter (P = 0.0004). In all of 13 cases with idiopathic polyhydramnios, AFI values remained less than 30 cm until delivery. Twenty-two patients (39%) with fetal anomalies required a prenatal treatment such as amnioreduction and tocolysis, whereas only one patient (7.7%) with idiopathic polyhydramnios needed tocolysis therapy (P = 0.03). There was a significant risk of premature delivery with fetal anomalies (35.6 +/- 3.9 weeks' gestation vs. 38.8 +/- 1.5 weeks' gestation, P = 0.004) because of refractory polyhydramnios, rupture of membranes, non-reassuring fetal status, and intrauterine fetal death, and although most infants with idiopathic polyhydramnios were appropriate-for-dates, many of the infants with congenital anomalies were small-for-dates. Significant risk of fetal anomalies should be considered in pregnant women with severe polyhydramnios (AFI > or = 30 cm), an increased trend of amniotic fluid during the pregnancy period, polyhydramnios requiring a prenatal treatment, or fetal growth restriction. On the other hand, based on our experience, a fetus without these conditions seems to have a low risk of congenital anomalies even if polyhydramnios is noted.