Fetal anatomic evaluation in the overweight and obese gravida

OBJECTIVES: To evaluate the rate of completion of anatomic surveys of fetuses in overweight and obese gravid patients as compared with normal controls. METHODS: This was a retrospective review of anatomic ultrasound scans performed between 2004 and 2007. Women were stratified by prepregnancy body mass index (BMI) into normal weight (BMI, 18.5-24.9 kg/m(2)), overweight (BMI, 25.0-29.9 kg/m(2)) and obese Class I (BMI, 30.0-34.9 kg/m(2)), Class II (BMI, 35.0-39.9 kg/m(2)) and Class III (BMI >or= 40.0 kg/m(2)) groups. Rates of completion of basic and comprehensive scans, gestational age at completion and number of scans required were compared. RESULTS: For the 7140 patients included, completion rates for both the basic (normal weight, n = 2253 (79%); overweight, n = 1771 (76%); obese Class I, n = 767 (72%), Class II, n = 323 (61%) and Class III, n = 171 (49%)) and comprehensive (normal weight, n = 1234 (43%); overweight, n = 930 (40%); obese Class I, n = 404 (38%), Class II, n = 215 (41%) and Class III, n = 108 (31%)) surveys decreased significantly with increasing BMI (P < 0.00001). For surveys completed, the mean number of scans required was significantly higher for obese patients (basic: normal weight 1.3 vs. obese Class III 1.9; comprehensive: normal weight 1.7 vs. obese Class III, 2.2)(P < 0.00001). The overall completion rate improved at each gestational week, but was best between 20 and 23 weeks for obese patients. CONCLUSIONS: As maternal BMI increases, the rate of completion of anatomic surveys decreases and the number of scans required increases. Delaying the initial survey until 20 weeks' gestation may improve the capacity to complete the examination in a single visit. It should be noted that these results represent completion rates at a tertiary referral center, and therefore may not reflect community experience.