In a 29-year-old renal transplant patient presenting with periumbilical pain and diarrhea, and an abdominal X‑ray showing centrally located dilated jejunal loops, what is the most likely diagnosis and recommended management?

Most Likely Diagnosis: Small Bowel Obstruction

In a 29-year-old renal transplant patient with periumbilical pain, diarrhea, and centrally located dilated jejunal loops on X-ray, the most likely diagnosis is mechanical small bowel obstruction, and you should proceed urgently to CT abdomen and pelvis with IV contrast to identify the specific etiology and guide management.

Diagnostic Approach

The combination of periumbilical pain and centrally dilated jejunal loops on plain radiography in a transplant recipient demands immediate cross-sectional imaging. CT abdomen and pelvis with IV contrast is the appropriate next step 1. The ACR Appropriateness Criteria (2025) specifically note that the abdominal component of CT imaging in renal transplant patients is beneficial to evaluate for postoperative complications such as small bowel obstruction 1.

Key Differential Diagnoses to Consider:

1. Post-transplant Lymphoproliferative Disorder (PTLD)

• PTLD can present as an obstructing jejunal mass in transplant recipients 2
• Typically occurs months to years post-transplant in immunosuppressed patients
• CT will show focal mass lesion with proximal bowel dilatation
• Requires tissue diagnosis via surgical exploration

2. Adhesional Small Bowel Obstruction

• Common after any abdominal surgery including transplantation 3
• May respond to conservative management initially
• CT distinguishes simple from complicated obstruction

3. Bezoar Formation

• Increasingly recognized in transplant recipients, particularly at anastomotic sites 3
• Often requires surgical extraction when causing complete obstruction
• Dietary history is crucial

4. Jejunal Diverticulitis (Less Likely)

• Rare but can present with dilated jejunal loops and periumbilical pain 4, 5
• More common in elderly patients (typically >60 years)
• CT shows diverticula with surrounding inflammation or free air if perforated

5. Infectious Enteritis with Ileus

• Immunosuppressed patients are susceptible to atypical pathogens 6
• However, true mechanical obstruction pattern on X-ray makes this less likely
• Consider if CT shows only functional obstruction

Critical Management Algorithm

Immediate Steps:

1. NPO status, IV fluid resuscitation, nasogastric decompression
2. Obtain CT abdomen and pelvis with IV contrast urgently 1
3. Surgical consultation - do not delay if peritoneal signs present

Based on CT Findings:

If focal mass/lesion identified:

• Proceed to exploratory laparotomy
• High suspicion for PTLD given immunosuppression 2
• Intraoperative assessment with possible resection and frozen section

If adhesional obstruction without ischemia:

• Trial of conservative management (24-48 hours maximum)
• Serial abdominal exams every 4-6 hours
• Repeat imaging if no improvement or clinical deterioration
• Low threshold for surgical exploration in immunosuppressed patients

If bowel ischemia suspected:

• Emergency laparotomy
• Consider intraoperative ICG fluorescence to assess bowel viability 3
• This can prevent unnecessary resection in equivocal cases

Critical Pitfalls to Avoid

1. Delayed Imaging: Plain radiography alone is insufficient in transplant recipients. The ACR guidelines emphasize that abdominal X-rays are not beneficial for comprehensive evaluation in this population 7.

2. Prolonged Conservative Management: Immunosuppressed patients have blunted inflammatory responses and may not manifest typical peritoneal signs despite serious pathology 8. The threshold for surgical exploration should be lower than in immunocompetent patients.

3. Missing PTLD: This is a life-threatening complication unique to transplant recipients that requires tissue diagnosis 2. Any focal mass causing obstruction warrants surgical exploration.

4. Underestimating Infection Risk: While mechanical obstruction is most likely given the imaging, immunosuppressed patients can develop severe enteritis from organisms like Yersinia that require specialized culture media 6. If CT shows inflammatory changes without mechanical obstruction, pursue infectious workup aggressively.

5. Inadequate Bowel Viability Assessment: If surgery is performed and viability is questionable, use ICG fluorescence angiography rather than relying solely on conventional criteria (color, peristalsis, pulsation) 3. This technology can prevent unnecessary bowel resection.

Prognosis Considerations

Transplant patients undergoing emergency abdominal surgery have significantly higher morbidity (up to 51%) and mortality (up to 23%) compared to the general population 8. Early diagnosis and intervention before perforation or ischemia develops is critical to improving outcomes. The immunosuppressed state delays healing and increases infectious complications, making timely surgical decision-making paramount for preserving both graft function and patient survival.