Detecting fetal macrosomia with abdominal circumference alone.
OBJECTIVE
To determine if abdominal circumference (AC) can identify macrosomia (> or = 4,000 g) at or beyond 37 weeks.


METHODS
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 > or = 350 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.


CONCLUSIONS
Using the guidelines proposed by the Evidence-Based Medicine Working Group, AC is slightly useful in detecting macrosomia among term parturients.
Henrichs
Christine
C
Division of Maternal-Fetal Medicine, Spartanburg Regional Medical Center, Spartanburg, South Carolina, USA.
Magann
Everett F
EF
Brantley
Kara L
KL
Crews
J Holt
JH
Sanderson
Maureen
M
Chauhan
Suneet P
SP
D000005:Abdomen / Q000033:anatomy & histology*; D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D005260:Female; D005320:Fetal Macrosomia / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal