Oligohydramnios: clinical associations and predictive value for intrauterine growth retardation.

Intrauterine growth retardation (IUGR) is difficult to diagnose before birth. Sonographically diagnosed oligohydramnios has been reported to be highly sensitive and reliable in detecting IUGR in carefully prescreened patients. To evaluate the clinical associations of oligohydramnios and its usefulness as a method of antenatal screening for IUGR on a large obstetric service, the consecutive ultrasound examinations of 2,453 viable singleton pregnancies with intact membranes were surveyed. The 96 (3.9%) pregnancies found to be complicated by oligohydramnios were compared with 96 with the same biparietal diameters, but with normal volumes of amniotic fluid. Mothers with oligohydramnios were younger, of lower parity, and at increased clinical risk for IUGR. Of 96 infants from oligohydramnios-complicated pregnancies, 38 (40%) were small for gestational age (SGA), compared with eight (8%) infants from pregnancies without oligohydramnios. Of 46 SGA births, 38 (83%) were preceded by sonographically diagnosed oligohydramnios (p less than 0.0001). IUGR associated with oligohydramnios tended to occur in young hypertensive gravid women, whereas non-oligohydramnios-associated IUGR tended to occur in gravid women with low prepregnancy weight. With correction for the incidences of oligohydramnios and IUGR in the unselected population, it is shown that four in 10 cases of oligohydramnios would result in SGA births (40% predictive value of an abnormal test), but that only 16% of SGA births would be preceded by sonographically diagnosed oligohydramnios. Eighty-four percent of the cases would be missed. These results suggest that, although the presence of oligohydramnios should increase the clinician's index of suspicion for IUGR, routine sonographic screening to detect oligohydramnios is not warranted.