O2180: Prenatal Sonographic Measurement of Intra-Abdominal Bowel Dilation Predicts Complex Gastroschisis

Background: Simple gastroschisis is typically associated with favorable outcomes. In contrast, complex gastroschisis, defined as gastroschisis with associated intestinal stenosis, atresia, necrosis, perforation, or volvulus, is linked to prolonged hospital stays, long-term complications, and increased mortality. Unlike many other prenatal diagnoses, there is currently no widely accepted method for stratifying patients into simple or complex gastroschisis subtypes. Prior meta-analyses have suggested that intra-abdominal bowel dilation (IABD), measured prenatally, may serve as a marker for complex gastroschisis; however, the optimal IABD cutoff values for predicting complexity have not been clearly defined. This study aimed to identify the IABD measurement at 20–25 weeks’ gestation (the typical window when gastroschisis is seen at fetal centers) that predicts complex gastroschisis.

Methods: A retrospective review was conducted of patients with gastroschisis who received prenatal care and delivered at a tertiary children’s hospital between January 1, 2012, and December 31, 2024. Prenatal ultrasounds performed between 20 and 25 weeks of gestation were reviewed, and the largest intra-abdominal bowel diameter, measured from inner wall to inner wall, was recorded. Postnatally, patients were classified as having either simple or complex gastroschisis based on the presence of intestinal stenosis, atresia, necrosis, perforation, volvulus, or prolonged hospitalization. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of IABD cutoffs ≥6, 7, 8, 9, and 10 mm were analyzed.

Results: Seventy-five patients with gastroschisis and prenatal ultrasounds between 20–25 weeks’ gestation were analyzed. At an IABD cutoff of ≥10 mm, sensitivity was 0.10, specificity was 1.0, PPV was 1.0, and NPV was 0.625. Identical values were observed for IABD cutoffs of ≥9 mm and ≥8 mm. At a threshold of ≥7 mm, sensitivity was 0.13, specificity remained 1.0, PPV was 1.0, and NPV was 0.63. At a threshold of ≥6 mm, sensitivity increased to 0.27, specificity decreased to 0.96, PPV was 0.80, and NPV was 0.66. The percentage of complex gastroschisis patients with IABD ≥6 mm was 26.7%, compared to 13.3% at ≥7 mm and 10.0% at thresholds ≥8 mm, ≥9 mm, and ≥10 mm (Table). No patients with simple gastroschisis had an IABD ≥7 mm.

Conclusion: An IABD cutoff of ≥7 mm at 20–25 weeks’ gestation is highly specific for identifying fetuses with complex gastroschisis and can also effectively exclude those with simple gastroschisis. This threshold may be a valuable tool for prenatal counseling, allowing clinicians to identify patients at risk for greater morbidity who may benefit from delivery at centers with pediatric surgical expertise and closer monitoring. This cutoff may also help select candidates for potential fetal intervention while sparing those unlikely to benefit. Incorporating IABD into prenatal risk stratification could enhance counseling, optimize delivery planning, and potentially improve outcomes for infants with gastroschisis.