Neutropenic Enterocolitis (Typhlitis)
The most likely diagnosis is neutropenic enterocolitis (typhlitis), a life-threatening complication of chemotherapy-induced severe neutropenia that presents with the classic triad of profound neutropenia, fever, and diffuse abdominal pain localizing to the right lower quadrant with diarrhea. 1, 2
Clinical Reasoning
This patient's presentation is pathognomonic for neutropenic enterocolitis:
- Severe neutropenia (WBC 300/mm³) occurring 1-2 weeks after chemotherapy completion 2, 3
- Diffuse abdominal pain with right lower quadrant localization and mild guarding 1, 2
- Diarrhea as part of the gastrointestinal symptom complex 1, 2
- No antibiotic prophylaxis, increasing infection risk 3
The American Society of Clinical Oncology recognizes typhlitis as the most common cause of acute abdominal pain in neutropenic cancer patients, typically occurring 1-2 weeks after chemotherapy initiation 2, 3. The cecum and terminal ileum are preferentially affected due to chemotherapeutic damage to the intestinal mucosa in the context of absolute neutropenia 1, 4.
Immediate Diagnostic Workup
Obtain contrast-enhanced CT abdomen/pelvis immediately - this is the gold standard showing bowel wall thickening >4 mm (transversal) or >30 mm (longitudinal) in the cecum and terminal ileum 2. CT can also identify pneumatosis intestinalis, pericolic fluid collections, abscesses, or free air suggesting perforation 1.
Additional essential tests include:
- Blood cultures (at least two sets) before antibiotics 3
- Stool for C. difficile toxin using two-step approach to exclude concurrent infection 2, 5
- Abdominal ultrasound if CT unavailable - bowel wall thickening >5 mm is diagnostic, with mortality risk dramatically increasing when thickness exceeds 10 mm (60% vs 4.2%) 1, 2
Management Algorithm
Conservative Medical Management (First-Line)
Start immediately with broad-spectrum antibiotics with anti-pseudomonal coverage 2:
- Complete bowel rest with nasogastric suction 1, 8
- Total parenteral nutrition 1, 2, 8
- IV hydration and electrolyte correction 2, 5
- Consider G-CSF to accelerate neutrophil recovery 2, 9
Critical: Avoid laxatives or antidiarrheal agents - these can precipitate perforation 8.
Surgical Intervention Indications
Obtain early surgical consultation but reserve intervention for 2, 5:
- Bowel perforation or free air on imaging 1, 2
- Intestinal obstruction 2, 8
- Massive hemorrhage 8, 9
- Abscess formation 1, 8
- Progressive clinical deterioration despite 24-48 hours of maximal medical therapy 2, 5
Surgical approach when indicated: Right hemicolectomy with ileostomy and mucous fistula - failure to remove necrotic focus is fatal in these immunocompromised patients 8.
Prognosis and Monitoring
Mortality rates reach 29.5% in patients with positive radiologic findings, emphasizing the critical importance of early CT scanning and aggressive medical management 2, 3. Serial abdominal examinations every 4-6 hours are essential to detect clinical deterioration 5. Repeat imaging within 48 hours if no clinical improvement 5.
Common Pitfalls to Avoid
- Do not assume normal vital signs exclude serious pathology - fever and peritoneal signs may be absent or subtle in immunocompromised patients 5
- Do not delay CT imaging - this can lead to missed life-threatening complications 5
- Do not withhold antibiotics pending culture results if the patient appears systemically ill 5
- Do not use antimotility agents until infectious causes are excluded 5
The incidence of neutropenic enterocolitis is increasing, particularly with high-dose chemotherapy regimens including taxanes and cytarabine 1, 10. Gram-negative bacteria, especially Pseudomonas aeruginosa, remain the main causative pathogens with high associated mortality 3, 10.