Optimal visualization of the fetal four-chamber and outflow tract views with transabdominal ultrasound in the morbidly obese: Are we there yet?

Completion of Fetal Anatomy Evaluations in Women With Body Mass Index ≥ 50 kg/m2

OBJECTIVES

As maternal body mass index (BMI) increases, fetal anatomy ultrasound becomes more challenging, less sensitive, and less likely to be complete. We sought to report our experience of incomplete evaluation of anatomy in patients with BMI of 50 kg/m2 or greater.

METHODS

This is a retrospective cohort of singleton gestations in mothers with BMI of 50 kg/m2 or greater, undergoing anatomy evaluations between 2017 and 2021 at 9 maternal-fetal-medicine sites in Houston, TX. Patient variables and scan results were collected throughout pregnancy to provide a longitudinal assessment of the primary outcome, completion rate (percent of all scans which optimally captured 24 American Institute of Ultrasound in Medicine-recommended images). Secondary outcomes included the rate of optimal capture of each individual structure.

RESULTS

In total, 293 patients with BMI ≥50 kg/m2 were identified. Only 28% of initial scans were complete, but over the entire pregnancy, a complete anatomic evaluation was achieved in 76% of women, largely due to weekly ultrasounds done for antenatal testing later in pregnancy. Neither BMI, placental location, nor amniotic fluid volume affected completion rate. The most difficult views are the outflow tracts, 4-chamber view, and spine.

CONCLUSIONS

One quarter of women with BMI of 50 kg/m2 or greater will not have a complete fetal anatomic evaluation by the end of pregnancy, since even basic fetal anatomic views are technically challenging to complete. Solutions deserve further attention, and may include first trimester imaging, transvaginal imaging, and optimization of ultrasound machine settings.

The Extended Fetal Cardiac Examination: Is It Feasible in a High-Risk Practice?

The aims of this study were to demonstrate the feasibility of obtaining additional cardiac views as proposed on an extended fetal cardiac examination and to see if there was any variation in individual components of that examination stratified by sonographer training, patient body habitus, or equipment. We retrospectively reviewed 200 consecutive detailed second-trimester high-risk fetal obstetric sonograms that included additional extended cardiac views. We analyzed the percentage of the time individual views were obtained, with variation based on (1) a sonographer with greater than 3 years of training compared with a group with 6 to 12 months of training, (2) 2 different ultrasound units, and (3) different body mass indices. Overall, the highest rate of visualization was achieved with the 4-chamber view (98.2%), whereas the 3-vessel tracheal view had the lowest percentage of visualization (40.2%), among the less experienced sonographers. Differences in successful completion of the extended cardiac views were not statistically different between the sonographer with a level of training greater than 3 years as compared with those with 6 to 12 months' training except for the 3-vessel tracheal view (P < 0.001). There is no statistically significant difference in our ultrasound equipment, when considering only inexperienced sonographers. Increasing body mass index had an inverse relationship with obtaining the components of the detailed cardiac examination. Using state-of-the-art ultrasound equipment and with focused additional training of obstetric sonographers, the majority of extended cardiac views can be obtained. There are exceptions.

Second trimester ultrasound detection of fetal anomalies in the obese obstetrical population: a systematic review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this review is to identify, appraise and synthesize the best available evidence on the impact of maternal obesity on mid second trimester ultrasound detection of fetal anomalies in pregnancy.