Detection of fetal growth restriction in patients with chronic hypertension: is it feasible?

Objective: To determine the utility of sonographic estimated fetal weight (EFW) in diagnosingintrauterine growth restriction (IUGR, birth weight <10% for gestational age) in patients withchronic hypertension.Methods: All pregnant patients with hypertension delivered during a 5-year period at three centerswere identified retrospectively. Patients with gestational hypertension, pre-eclampsia, diabetesmellitus, fetal anomalies and absence of a sonographic examination within 3 weeks of deliverywere excluded. Likelihood ratio (LR) and guidelines established by the Evidence-Based MedicineWorking Group were used to determine whether sonographic EFW is a reliable diagnostic testto detect IUGR.Results: At the three centers, there were 264 patients with chronic hypertension (122, 77 and 65at centers I, II and III, respectively). The incidence of IUGR ranged from 13% to 27% but wassimilar at the three locations (p = 0.064). The LR (with 95% confidence interval (CI)) of detectingIUGR was 4.4 (95% CI 2.5, 7.7), 2.3 (95% CI 1.4, 3.7) and 6.1 (95% CI 2.7, 13.7) at centers I, IIand III, respectively. Based on the proportions of abnormal growth, we required 253 and 71 newbornswith fetal growth restriction at centers I and II, respectively, to have narrow confidence intervalsaround the clinically important LR of 10. The extremely low incidence of IUGR at center III(13%) precluded the estimation of required sample size.Conclusion: Use of Evidence-Based Medicine Working Group guidelines indicates that sonographicEFW is slightly to moderately useful in detecting fetal growth restriction in patients withchronic hypertension.