CT Fistulography or CT Abdomen/Pelvis with IV Contrast
For a patient with suspected enterocutaneous fistula and recurrent omphalitis, the next best investigation is CT fistulography or contrast-enhanced CT of the abdomen and pelvis, as this combination will both confirm the fistula tract and identify the underlying congenital anomaly (persistent omphalomesenteric duct or urachal remnant) that is causing the recurrent umbilical infections.
Clinical Reasoning
The history of recurrent omphalitis in an adult is a critical clue that points toward an underlying anatomical abnormality rather than simple infection. Recurrent omphalitis in adults typically indicates infected remnants of either the omphalomesenteric (vitelline) duct or the allantois (urachal remnant) 1. When combined with a suspected enterocutaneous fistula, this strongly suggests a persistent omphalomesenteric duct connecting the umbilicus to the bowel.
Why CT Fistulography is Optimal
CT fistulography involves injecting contrast directly into the cutaneous opening during CT scanning, which provides superior anatomic detail of the fistula tract compared to standard imaging 2. This technique:
- Delineates the exact fistula tract from skin through subcutaneous tissues, muscles, and peritoneum to the bowel
- Identifies the specific bowel segment involved (typically ileum with omphalomesenteric duct remnants)
- Detects associated abscesses or fluid collections along the tract
- Prevents misdiagnosis as simple cellulitis when gastrointestinal symptoms are absent 2, 3
Alternative: Standard Contrast-Enhanced CT
If CT fistulography is not immediately available or the cutaneous opening is not accessible, contrast-enhanced CT of the abdomen and pelvis with IV contrast is the next best option 4, 5. The ACR Appropriateness Criteria consistently rate this as the primary imaging modality for enterocutaneous fistulas, with sensitivity of 70-76.5% for fistula detection 6, 7.
For this specific scenario, adding oral contrast may help distinguish the fistula tract from adjacent bowel loops 4. However, IV contrast alone is often sufficient to identify enhancing fistulous tracts 5.
What to Look For on Imaging
The CT should demonstrate:
- Bowel in close contact with the umbilical region 2
- Enhancing tract extending from bowel to skin 5
- Gas or fluid within the tract
- Associated abscess formation (common with infected remnants)
- The specific bowel segment involved (typically distal ileum for omphalomesenteric duct)
Why Not Other Modalities?
Ultrasound: While useful for initial screening and mentioned in the literature for identifying umbilical remnants 1, 8, it has limited ability to fully characterize complex fistula tracts and misses up to 79% of complicated enterocutaneous fistulas 9, 6
Fluoroscopic contrast enema or fistulography: Has very low sensitivity (7.7-34%) for enterocutaneous fistulas 6 and has been largely replaced by CT
MRI: Excellent soft tissue resolution but less sensitive for extraluminal gas, more time-consuming, and less available in acute settings 5. Reserve for surgical planning if needed
Management Implications
Once the diagnosis is confirmed, this patient will require:
- Surgical resection of the involved bowel segment and the entire fistula tract including the omphalomesenteric duct remnant 3, 10
- Restoration of intestinal continuity (typically side-to-side anastomosis) 3
- Complete excision of the umbilical remnant to prevent recurrence 1
The combination of enterocutaneous fistula with recurrent omphalitis has a high mortality risk if not promptly diagnosed and treated surgically 3, 10, making accurate anatomic imaging essential for surgical planning.
Common Pitfall to Avoid
Do not mistake this presentation for simple cellulitis or superficial umbilical infection, especially when gastrointestinal symptoms are absent 2. The recurrent nature of the omphalitis is the key clinical feature that should trigger investigation for an underlying anatomical communication with the bowel 1.