Value of Biochemical Amniotic Fluid Analysis and Fetal Magnetic Resonance Imaging in the Prenatal Diagnosis of Congenital Microgastria.

Introduction: Congenital microgastria (CM) is a rare condition due to early interruption of stomach development between the 4th and 8th week of gestation, leading to a small midline tubular stomach. Prenatal diagnosis of CM is a challenge with important implications. This study explores the value of biochemical amniotic fluid (AF) analysis and fetal magnetic resonance imaging (MRI) for the prenatal diagnosis of CM in case of nonvisible stomach on fetal ultrasound.

Case Presentation: Four cases of CM were retrospectively investigated in terms of fetal ultrasound, MRI findings, and biochemical AF analyses. The patients were referred to the Prenatal Diagnosis Unit of the Hôpital Femme Mère Enfant (Lyon, France) at a mean age of 21 weeks of gestation for absent or small fetal stomach on ultrasound with a suspected diagnosis of esophageal atresia (EA). Ultrasound examination confirmed that the stomach was absent in two of the four fetuses and small in the other two. This feature was associated with a congenital heart defect in two cases and a terminal transverse limb defect in one case. Standard genetic workup (array-CGH) results were normal. Biochemical AF analysis, including the EA index, was not suggestive of EA. Fetal MRI showed a small midline tubular stomach, associated with a dilated esophagus, highly suggestive of CM.

Conclusion: If the fetal stomach is absent on ultrasound, CM should be considered if the AF volume is normal, especially during the third trimester, and if the EA index is not suggestive of gastrointestinal obstruction. In these cases, the diagnosis can be confirmed by fetal MRI, through observation of a small midline tubular stomach associated with a dilated esophagus.