Intrauterine growth restriction and oligohydramnios among high-risk patients.

The purposes of this study were (1) to determine the prevalence of oligohydramnios (amniotic fluid index < 5.0 cm) among fetuses with intrauterine growth restriction (IUGR) and newborns identified as small for gestational age (SGA), and (2) among fetuses with IUGR, to determine the predictive accuracy of amniotic fluid index (AFI) < or = versus > 5.0 cm for adverse peripartum outcomes. This was a retrospective review of high-risk pregnancy that had reliable gestational age (GA) and needed weekly biophysical profile (BPP). Along with 95% confidence intervals (CIs), we calculated the likelihood ratios (LRs) and used guidelines promulgated by Evidence-Based Medicine Working Group. Among the 1859 singletons undergoing BPP, IUGR (estimated fetal weight < 10% for GA) was suspected in 22% (n = 410) and the prevalence of oligohydramnios was 6% (95% CI, 4 to 8%). SGA (birthweight < or = 10%) occurred among 28% (n = 517) of newborns and oligohydramnios was noted in 6% (95% CI, 4 to 8%). Among fetuses with IUGR, the LR of oligohydramnios to predict cesarean delivery for nonreassuring fetal heart tracing was 2.0 (range, 0.8 to 5.0); for newborns small for gestational age, 1.9 (range, 1.2 to 3.1), and for neonatal intensive care unit admission, 1.4 (range, 0.6 to 2.3) More than 90% of patients with IUGR or SGA have AFI > 5.0 cm, and oligohydramnios with IUGR is a poor predictor of peripartum complications.

Sonographic estimate of birth weight among high-risk patients: feasibility and factors influencing accuracy.

OBJECTIVE: This study was undertaken to determine the feasibility of detecting abnormal fetal growth among patients undergoing biophysical profile (BPP) and to identify the factors those influence the accuracy. STUDY DESIGN: Retrospectively singletons with reliable gestational age (GA) having a BPP were identified. Fetal growth restriction (FGR) and large-for-gestational age (LGA) were based on estimated or actual birth weight 10% or less or 90% or greater for GA, respectively. Likelihood ratio (LR), odds ratio (OR) and 95% CIs were calculated and multivariate predictive models used. RESULTS: Among the 1934 consecutive patients that met the inclusion criteria, the LR of detecting FGR was 10.9 and of LGA, 17.4. Multivariate analysis indicates that accurate classification of fetal growth is significantly better with hydramnios (OR 1.78, 95% CI 2.68), if the GA is less than 32 weeks (OR 3.71, 95% CI 1.50-9.16) or GA is between 32.1 and 36.9 weeks (OR 1.43, 95% CI 1.05-1.96). CONCLUSION: It is feasible to accurately identify abnormal growth among high-risk patients and to delineate factors that influence the correct classification of fetal growth.

Detecting fetal growth restriction or discordant growth in twin gestations stratified by placental chorionicity.

OBJECTIVE: To use recommendations made by the Evidence-Based Medicine Working Group to determine the accuracy of sonographically estimated fetal weight to diagnose fetal growth restriction (FGR) (estimated or actual birth weight < 10% for gestational age [GA]) or discordancy in dichorionic and monochiorionic twin gestations. STUDY DESIGN: The inclusion criteria for this retrospective analysis were nonanomalous twins, reliable GA and sonographic estimate of fetal weight within 21 days of live births of both fetuses beyond 26 weeks. For likelihood ratio (LR) and odds ratio (OR), 95% confidence intervals (CIs) were calculated. RESULTS: Over 52 months, 126 twin gestations met the inclusion criteria; 29% were monochorionic and 71% dichorionic. The incidence of FGR in 1 of monochorionic twin fetuses (46%) was twice as high as in dichorionic (26%; OR 2.01; 95% CI 1.00, 4.03), but the rates of discordance > or = 20% were similar (21% vs. 18%, respectively; OR 1.26; 95% CI 0.64, 2.47). The LR (95% CI) of detecting discordant growth > or = 20% was 6.1 (2.5, 15.1) for dichorionic twins and 6.0 (1.8, 20.0) for monochorionic. The LR of identifying FGR in twin A and B in dichorionic twins was 6.3 (2.0, 19.7) and 8.7 (2.9, 26.9), respectively; the corresponding LR for monochorionic twins was 14.5 (1.9, 112.3) and 18.7 (2.6, 135.1). To determine the number of twins required for a tight confidence interval around an LR of 10, post hoc sample size calculations indicated: (1) regardless of chorionicity, attaining LR > 10 is not feasible; (2) in dichorionic twins, detection of FGR with twin A or B is not possible; and (3) about 500 monochorionic pregnancies are necessary to ensure that estimated fetal weight can accurately identify FGR. CONCLUSION: Using guidelines proposed by the Evidence-Based Medicine Working Group, at present it may not befeasible to identify aberrant growth in twins.