Suspicion of intrauterine growth restriction: Use of abdominal circumference alone or estimated fetal weight below 10%

Objective. To determine, among patients at risk for intrauterine growth restriction (IUGR), the peripartum outcomes and predictive accuracy for those with normal abdominal circumference (AC) and estimated fetal weight (EFW) for gestational age (GA; group 1) versus those with AC ≤ 10% for GA but EFW>10% (group 2) versus those with AC and EFW ≤ 10% for GA (group 3). Study design. We identified, retrospectively, non-anomalous singleton pregnancies with reliable GA, and delivery within 21 days of the examination who were referred for possible IUGR. Odds ratios (OR) and 95% confidence intervals (CI) were calculated, as were likelihood ratios (LR) for detection of small for gestational age (SGA) (birth weight ≤ 10% for GA; SGA). Results. Among the 169 consecutive patients who met the inclusion criteria, the prevalence of SGA was significantly higher for group 3 (80%) than group 1 (42%; OR 4.26, 95% CI 1.94–9.16) or group 2 (49%; OR 5.49, 95% CI 2.13–13.85). The rate of admission to the neonatal intensive care unit (67%, 34%, and 36% for groups 3, 2, and 1, respectively) and the combined perinatal morbidity (35%, 23%, and 15%) were different for the three groups. The LR for detection of SGA was 1.2 (95% CI 1.0–1.4) for group 2 and 2.8 (95% CI 1.6–4.9) for group 3. Conclusions. Among patients suspected for IUGR, the peripartum outcome is poorest for those with AC and EFW ≤ 10% for GA, than for those with AC ≤ 10% but EFW>10%. The detection of SGA is poor regardless of whether just AC or AC plus EFW are ≤ 10%.