Ultrasound screening for fetal aneuploidy using soft markers in the overweight and obese gravida

To determine the completion rate of ultrasound surveys for aneuploidy markers by maternal body mass index (BMI).

A retrospective review of ultrasounds on midtrimester singleton pregnancies was performed. Subjects were grouped as normal, overweight (BMI 25-29.9 kg/m(2)), and obese: class I (30-34.9 kg/m(2)), class II (35-39.9 kg/m(2)), and class III (>or= 40 kg/m(2)). Examinations with visualization of at least seven of eight markers were considered complete.

Of 14 353 ultrasounds reviewed, 5690 patients were eligible: 43% normal, 29% overweight, 27% obese. Completion rates differed significantly between groups (64% normal, 64% overweight, 61% class I, 55% class II, 47% class III, p < 0.001). The screen positive rates (>or=1 marker) differed significantly overall (16% normal, 13% overweight, 15% class I, 12% class II, 10% class III, p < 0.02), but not for complete examinations (p = 0.42).

Since completion rates for ultrasound aneuploidy screening are inversely related to maternal obesity, obese women are underscreened.