Fetal stomach bubble visibility at 15 weeks
A contracted or small fetal stomach bubble can be a normal transient finding on mid-trimester ultrasound. Intermittent nonvisualization or a very small stomach on a given scan after 14 weeks has been documented, with many pregnancies having normal outcomes. [1]
Interpretation of a “contracted” fetal stomach bubble
Sonographic assessment of the fetal stomach can be limited by brief physiologic variability. In a prospective study of pregnancies in which a normal fluid-filled fetal stomach could not be seen after 14 weeks, the abnormal feature sometimes resolved on subsequent examination. [1]
Prognostic significance of nonvisualization or persistent small stomach
Persistent absence or consistently very small stomach visualization is more concerning than a transient finding. In the same prospective cohort, pregnancy outcomes varied widely, and transient nonvisualization was not synonymous with abnormal outcome. [1]
Practical next steps on ultrasound
Repeat evaluation at the same visit or at a follow-up scan is a common approach when stomach visualization is limited. A normal fluid-filled stomach was seen on the next sonogram in many cases in the prospective cohort. [1]
Indications for closer evaluation
Further assessment is generally warranted when stomach visualization remains abnormal on repeat imaging or when additional findings are present. In the cohort, abnormal outcome rates increased when other sonographic abnormalities were observed and also when amniotic fluid abnormalities were present. [1]
What to communicate to the clinician
The ultrasound report details that most influence management are the gestational age, whether the stomach appears intermittently versus persistently abnormal, and whether additional fetal or fluid findings are present. These variables were associated with outcome in the prospective study. [1]
Evidence summary
In a prospective cohort of 31 pregnancies with inability to visualize a normal fluid-filled fetal stomach after 14 weeks, overall abnormal outcomes occurred in 48%, while normal outcomes occurred in 16 cases. Outcomes were more favorable when the finding was transient and less favorable when other abnormalities were present. [1]