How should I evaluate and manage a patient who has constipation accompanied by an elevated white‑blood cell count?

Evaluation and Management of Constipation with Elevated White Blood Cell Count

In a patient presenting with constipation and leukocytosis, your immediate priority is to rule out life-threatening intra-abdominal complications—specifically fecal impaction with urinary obstruction, intestinal obstruction with strangulation, perforated diverticulitis, or inflammatory bowel disease with toxic megacolon.

Initial Diagnostic Approach

Immediate Laboratory Assessment

Obtain the following tests to stratify risk and identify the underlying cause:

• Complete blood count with differential: Neutrophil predominance suggests bacterial infection, intestinal ischemia, or inflammatory bowel disease, whereas lymphocyte predominance would favor a viral process (less likely with constipation) 1, 2
• C-reactive protein (CRP): CRP >50 mg/L suggests bacterial or inflammatory etiology; CRP >170 mg/L predicts severe colonic inflammation with 87.5% sensitivity and 91.1% specificity 2
• Comprehensive metabolic panel: Assess electrolytes, renal function, and liver enzymes to detect complications of obstruction or systemic illness 1
• Serum lactate: Levels ≥2.0 mmol/L predict bowel strangulation and ischemia 3

Critical Imaging

• CT abdomen/pelvis with IV contrast is mandatory to identify fecal impaction, intestinal obstruction, diverticulitis with abscess or perforation, colonic wall thickening, free air, or signs of ischemia 1, 3
• Look specifically for dilated fecally loaded rectum and colon, which can cause obstructive uropathy 4

Physical Examination Priorities

• Digital rectal examination (DRE) is essential to diagnose distal fecal impaction and assess for rectal masses or strictures 1, 5
• Assess for peritoneal signs (guarding, rebound tenderness) that indicate perforation or ischemia 1
• Examine for abdominal distention, high-pitched bowel sounds (obstruction), or absent bowel sounds (ileus/perforation) 3

Risk Stratification Based on Clinical Presentation

High-Risk Features Requiring Urgent Intervention

If any of the following are present, the patient requires immediate surgical consultation 1:

• Peritoneal signs suggesting perforation or ischemia
• Lactate ≥2.0 mmol/L (suggests strangulation) 3
• CT evidence of free air, bowel wall pneumatosis, or portal venous gas
• Hemodynamic instability or septic shock
• Neutropenia (absolute neutrophil count <0.5 × 10⁹/L) with fever—contraindication to enemas 1

Moderate-Risk Features: Inflammatory or Infectious Etiology

Inflammatory Bowel Disease (IBD) Flare:

• Suspect IBD when CRP >20 mg/L with ESR >15 mm/hr, which confers an ~8-fold higher risk of disease relapse 2
• Obtain fecal calprotectin: values >150–250 µg/g indicate significant mucosal inflammation and warrant endoscopic evaluation 2, 5
• Rule out Clostridioides difficile infection with stool toxin assay or NAAT, especially if recent antibiotic exposure or healthcare contact 1, 2, 6
• Consider cytomegalovirus (CMV) colitis in immunosuppressed patients with IBD 1

Complicated Diverticulitis:

• Left lower quadrant pain, fever, and leukocytosis with CT showing colonic wall thickening and pericolic inflammation suggest diverticulitis 1
• Small abscesses (<3–4 cm) may be treated with antibiotics alone for 7 days; larger abscesses require percutaneous drainage plus 4 days of antibiotics 1
• If perforation or fecal peritonitis is present, surgical resection (Hartmann's procedure or primary anastomosis) is required 1

Lower-Risk Features: Simple Constipation with Reactive Leukocytosis

If imaging shows only fecal loading without obstruction, perforation, or severe inflammation:

• Fecal impaction is the likely diagnosis and can cause urinary tract obstruction, leading to hydronephrosis and secondary infection with leukocytosis 4
• Elevated WBC may be reactive to urinary tract infection or mild colonic inflammation from chronic stasis 4

Management Algorithm

Step 1: Address Life-Threatening Complications

• Surgical consultation for perforation, ischemia, or complete obstruction 1, 3
• Broad-spectrum antibiotics (e.g., piperacillin-tazobactam or a carbapenem) if septic shock or peritonitis is present 1
• Fluid resuscitation and correction of electrolyte abnormalities 1

Step 2: Treat Fecal Impaction (if confirmed by DRE or imaging)

Distal impaction:

• Digital fragmentation and extraction of stool, followed by glycerin suppository or water/oil retention enema 1, 5
• Once partially cleared, administer polyethylene glycol (PEG) orally to soften remaining stool 1, 5

Proximal impaction (sigmoid/descending colon):

• PEG lavage solution (e.g., GoLYTELY) to wash out stool, provided no complete obstruction is present 1

Contraindications to enemas 1:

• Neutropenia (WBC <0.5 × 10⁹/L)
• Thrombocytopenia
• Recent colorectal or pelvic surgery
• Suspected perforation or ischemia
• Recent pelvic radiotherapy

Step 3: Initiate Maintenance Bowel Regimen

After disimpaction, prevent recurrence with 1, 5:

• Osmotic laxatives: PEG 17 g daily (first-line) or lactulose
• Stimulant laxatives: Senna or bisacodyl (especially if opioid-induced constipation)
• Lifestyle modifications: Adequate hydration, dietary fiber (20–30 g/day), physical activity, and scheduled toileting

Avoid bulk laxatives (psyllium) in opioid-induced constipation, as they can worsen obstruction 1

Step 4: Rule Out and Treat Infectious Causes

• Stool culture for Salmonella, Shigella, Campylobacter, and enterohemorrhagic E. coli if diarrhea develops or if there is concern for infectious colitis 2
• Stool C. difficile testing (toxin or NAAT) in all patients with recent antibiotic exposure 1, 2, 6
• If C. difficile is positive, treat with oral vancomycin 125 mg four times daily or fidaxomicin 200 mg twice daily 6

Step 5: Consider Endoscopy for Persistent or Severe Cases

Indications for colonoscopy or flexible sigmoidoscopy 2, 5:

• Persistent symptoms beyond 7–13 days despite appropriate therapy
• Fecal calprotectin >150–250 µg/g
• Bloody stools or severe systemic toxicity
• Strong clinical suspicion for IBD or ischemic colitis

Obtain colonic biopsies to differentiate IBD, ischemic colitis, pseudomembranous colitis, or other non-C. difficile causes 6

Common Pitfalls and Caveats

• Do not dismiss leukocytosis as "reactive" without imaging: Elevated WBC with constipation can signal impending perforation, strangulation, or severe diverticulitis 1, 3
• Beware of obstructive uropathy: Fecal impaction can compress the bladder neck or ureters, causing hydronephrosis and secondary UTI with leukocytosis 4
• Avoid NSAIDs: They can exacerbate IBD and provoke inflammatory diarrhea if the patient has underlying colitis 2
• Neutropenic patients are at high risk: Enemas and digital disimpaction are contraindicated; consider PEG lavage only and involve oncology/infectious disease early 1
• Elderly patients are particularly vulnerable: They have higher rates of constipation, fecal impaction, and complications; ensure access to toilets, optimize toileting schedules, and individualize laxative therapy based on comorbidities 1, 5