The impact of maternal obesity on satisfactory detailed anatomic ultrasound image acquisition

To assess the impact of maternal body mass index (BMI) on ultrasound visualisation of fetal morphology.

Singleton pregnancies undergoing targeted ultrasound fetal anatomic evaluation at 18- to 25-weeks gestation from 1/05 to 12/05 were included. Ultrasound reports and maternal medical records were reviewed for maternal characteristics and documentation of adequatecy of ultrasound visualisation for each organ system was obtained by individual chart review. BMI was divided into normal (18.5-24.9 kg/m2) and obese (>30 kg/m2) groups. Overweight women (BMI 25-29.9 kg/m2) were excluded. Suboptimal visualisation for each organ system was compared between BMI groups. Multivariable analysis controlled for sonographer, physician, US equipment, race, parity, fetal lie, weight and gestational age.

Eight hundred fourteen patients were included (Normal = 148, Obese = 666). The frequency of suboptimal visualisation was significantly increased in the obese group for the cardiovascular system SV (50.9% vs. 26.9%, p < 0.0001), facial soft tissue SV (39.1% vs. 19.3%p < 0.0001) and abdominal wall SV (2.7% vs. 0%, p < 0.0001). Suboptimal visualisation declined with advancing gestational age.

Suboptimal fetal anatomic visualisation is increased with maternal obesity, but declines with advancing gestational age in both normal weight and obese populations.