Purpose: We assessed the usefulness of sonographic measurement of abdominal subcutaneous tissue thickness in predicting fetal macrosomia (weight > 4,000 g).
Methods: Abdominal subcutaneous tissue thickness was measured sonographically in 133 term fetuses. All studied fetuses were delivered within 72 hours after the measurements were taken.
Results: One hundred thirteen fetuses were normal size, and 20 were macrosomic. The fetal abdominal subcutaneous tissue thickness ranged between 3 and 18 mm in all fetuses, with a mean measurement of 8.4 +/- 2.7 mm (standard deviation). The mean tissue thickness differed significantly between normal and macrosomic fetuses (7.0 mm versus 12.4 mm, respectively; p < 0.0001). There was a significant positive correlation between the abdominal subcutaneous tissue thickness and the birth weight (r = 0.67, p < 0.0001). The negative predictive value for a range of cut-off points between 8 and 13 mm varied between 84.3% and 100% (for prevalence rates of macrosomia of 5-25%). However, the positive predictive value was less than 50% for cut-off values below 11 mm.
Conclusions: Sonographic measurement of the subcutaneous tissue thickness of the fetal abdomen is useful for ruling out macrosomia.