A structured diagnostic framework helps radiologists categorize high and low obstructions using standardized imaging patterns.

A comprehensive pattern-based imaging approach to neonatal bowel obstruction provides radiologists with a practical framework for distinguishing between common causes of this surgical emergency, according to research. The method categorizes obstructions into six upper gastrointestinal (UGI) patterns and four contrast enema patterns, helping guide efficient diagnosis and clinical decision-making.

Neonatal bowel obstruction, which occurs in approximately 1 in 2,000 births, is the most common surgical emergency in neonates. The study, led by Nathan C. Hull, MD, of the Mayo Clinic’s Division of Pediatric Radiology, found that the causes of disease in neonates differ from those in older children and adults, requiring distinct imaging strategies.

Imaging Algorithm for Obstruction Localization

The diagnostic process begins with abdominal radiography to categorize obstructions as high (proximal to the ileum) or low (involving the ileum or colon). High obstructions—typically showing fewer than three or four dilated bowel loops in the upper to mid-abdomen—warrant a fluoroscopic UGI series. In contrast, low obstructions—more than four dilated loops extending into the pelvis—call for a fluoroscopic contrast enema. If imaging is equivocal, both studies may be required, starting with UGI to rule out potentially life-threatening conditions such as malrotation with midgut volvulus.

Six UGI Patterns for High Obstructions

• Pattern 1: Normal anatomy with duodenojejunal junction left of the spine, no narrowing or dilation.

• Pattern 2: Duodenal web—dilated proximal duodenum with a thin intraluminal membrane, the classic “windsock sign.”

• Pattern 3: Duodenal stenosis or annular pancreas—focal narrowing of the descending duodenum.

• Pattern 4: Malrotation—abnormal duodenojejunal junction with atypical bowel positioning.

• Pattern 5: Malrotation with midgut volvulus— “corkscrew” configuration of the bowel.

• Pattern 6: Duodenal obstruction—abrupt contrast cutoff, concerning for volvulus.

Four Enema Patterns for Low Obstructions

• Pattern 1: Classic Hirschsprung disease—abrupt caliber change at the rectosigmoid junction with a rectosigmoid ratio of less than 1.

• Pattern 2: Small left colon syndrome—narrow left colon with meconium filling defects; typically self-limited.

• Pattern 3: Diffuse microcolon—associated with conditions like ileal atresia, meconium ileus, total colonic Hirschsprung, or rare functional disorders.

• Pattern 4: Short microcolon—seen in colonic atresia, showing reduced length and caliber.

Clinical Impact and Diagnostic Accuracy

The pattern-based approach enhances radiologists’ ability to rapidly identify and triage neonatal obstructions. For example:

• Midgut volvulus, a surgical emergency, may not be visible on radiographs. UGI has a sensitivity of 54%–79% and specificity of 98%, while ultrasound achieves 83%–100% sensitivity and 91%–100% specificity.

• Hirschsprung disease diagnosis via contrast enema yields 70% sensitivity and 83% specificity. A rectal suction biopsy is recommended for definitive diagnosis if suspicion persists despite normal imaging.

The article also highlights that certain diagnoses—such as duodenal atresia, esophageal atresia, or inguinal hernia—may be suggested by radiographs alone, while others require additional fluoroscopic or ultrasound evaluation.

Pattern Recognition for Rare and Critical Conditions

The framework also includes imaging clues for rare but critical conditions. For instance, megacystis-microcolon–intestinal hypoperistalsis syndrome, a lethal motility disorder, presents with a diffuse microcolon on enema and urinary tract dilation on ultrasound.

Conclusion

This systematic, pattern-based imaging approach provides radiologists with standardized tools to facilitate accurate and timely diagnosis of neonatal bowel obstruction, thereby supporting prompt intervention and potentially improving surgical outcomes in this population.

Disclosures can be found in the published review.

Source: Radiology