Detecting fetal macrosomia with abdominal circumference alone
Henrichs, C.; Magann, E.F.; Brantley, K.L.; Crews, J.Holt.; Sanderson, M.; Chauhan, S.P.
Journal of Reproductive Medicine 48(5): 339-342
2003
ISSN/ISBN: 0024-7758 PMID: 12815906 Document Number: 564226
OBJECTIVE: To determine if abdominal circumference (AC) can identify macrosomia (gtoreq4,000 g) at or beyond 37 weeks. STUDY DESIGN: Prospectively, parturients at term admitted for delivery underwent sonographic mensuration of AC. A receiver-operating characteristic (ROC) curve was constructed to determine if AC can differentiate between normal (birth weight <3,999 g) and macrosomia. A likelihood ratio was calculated. P<.05 was considered significant. RESULTS: The mean gestational age of the 256 subjects was 39.1+-1.5 weeks, and the prevalence of macrosomia was 8.2% (21/256). Inspection of the ROC curve indicated that AC gtoreq350 mm can identify macrosomic fetuses. The area under the ROC curve (0.79+-0.04 for macrosomia) was significantly different than the area under the nondiagnostic line (P<.005). The likelihood ratio for AC to detect macrosomia was 2.9 (95% confidence interval, 2.1-4.0). Based on the proportion of macrosomia in our population, we would require over 1,000,000 newborns for a macrosomia analysis to obtain narrow confidence intervals around a clinically useful likelihood ratio. CONCLUSION: Using the guidelines proposed by the Evidence-Based Medicine Working Group, AC is slightly useful in detecting macrosomia among term parturients.