Abnormal fetal gastrointestinal system morphology Gastric pseudomass 2022-04-10T18:56:11Z The origin of echogenic masses within the gastric lumen is incompletely understood. As they are seen in multiple planes, technical issues are unlikely. They may be due to swallowed cells that aggregate because of the relatively poor peristaltic activity in the stomach early in the second trimester. When intraamniotic bleeding has occurred, these pseudomasses are commonly visualized. They inevitably disappear during follow-up examinations and are not associated with an adverse neonatal outcome. At US examination from the second trimester onward, the fetal stomach appears as a uniformly anechoic, sharply circumscribed round structure in the left upper quadrant. However, debris is commonly visualized in the stomach, forming a pseudomass.