Gastroenterology · Colonic Disorders
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The classic clinical presentation of acute diverticulitis is left lower quadrant (LLQ) pain, fever, and leukocytosis.
CT scan of the abdomen and pelvis with IV contrast is the gold standard diagnostic modality for confirming diverticulitis.
Colonoscopy is strictly contraindicated in the acute setting due to the high risk of colonic perforation.
Uncomplicated diverticulitis is managed with bowel rest and oral antibiotics covering gram-negative rods and anaerobes, such as ciprofloxacin plus metronidazole; current AGA guidance supports selective rather than routine antibiotics in mild, immunocompetent uncomplicated cases.
Hinchey classification is used to stage the severity of diverticulitis, ranging from localized pericolic abscess to fecal peritonitis.
Patients with perforated diverticulitis presenting with diffuse peritonitis or hemodynamic instability require emergent surgical intervention.
Follow-up colonoscopy is recommended 6–8 weeks after recovery from complicated diverticulitis, and is suggested (not mandatory) for uncomplicated diverticulitis only in patients with alarm symptoms or those overdue for colorectal cancer screening, to rule out colorectal malignancy.
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A 62-year-old male presents to the emergency department with a 2-day history of steady left lower quadrant abdominal pain, fever of 101.4°F, and nausea. Physical examination reveals tenderness to palpation in the LLQ with voluntary guarding but no rebound tenderness. Laboratory studies demonstrate a leukocytosis with a left shift. The patient has no history of similar symptoms and has not had a colonoscopy in over 10 years.
What is the most appropriate next step in the management of this patient?
CT scan of the abdomen and pelvis with IV contrast
The patient presents with classic signs of acute diverticulitis; a CT scan is the diagnostic test of choice to confirm the diagnosis and assess for complications like abscess or perforation.
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Etiology / Epidemiology
Common in low-fiber, high-fat diets and elderly patients. Occurs due to fecalith obstruction of diverticula.
Clinical Manifestations
LLQ pain is classic; left-sided appendicitis. Fever and leukocytosis are hallmark signs.
Diagnosis
CT abdomen/pelvis with IV contrast is the gold standard. Look for fat stranding and diverticula.
Treatment
Uncomplicated, low-risk: bowel rest; routine antibiotics are not recommended and should be reserved for high-risk, immunocompromised, or frail patients (e.g., Ciprofloxacin + Metronidazole). Avoid colonoscopy during acute phase.
Prognosis
Most resolve with conservative management (antibiotics reserved for high-risk cases). 15-25% risk of recurrence; abscess is a major complication.
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Epidemiology & Etiology
Prevalence increases significantly with age, affecting nearly 50% of individuals by age 80. Primary risk factors include low-fiber intake, obesity, and sedentary lifestyle. Chronic constipation leads to increased intraluminal pressure, promoting mucosal herniation.
Pertinent Anatomy
The sigmoid colon is the most common site due to highest intraluminal pressure. Diverticula are pseudodiverticula, involving only mucosa and submucosa herniating through the muscularis propria.
Pathophysiology
Obstruction of the diverticular neck by a fecalith leads to stasis and bacterial overgrowth. This triggers local inflammation, micro-perforation, and potential abscess formation. If the process remains contained, it is uncomplicated; if it spreads, it leads to peritonitis or fistula.
Clinical Manifestations
Patients present with steady LLQ abdominal pain, fever, and altered bowel habits. Physical exam reveals localized tenderness and guarding. Peritoneal signs (rebound, rigidity) suggest perforation. Left-sided appendicitis is the classic board descriptor.
Diagnosis
CT abdomen/pelvis with IV contrast is the diagnostic test of choice. Findings include diverticula, fat stranding, and bowel wall thickening >3mm. Colonoscopy is strictly contraindicated during the acute phase due to high risk of perforation.
Treatment
Low-risk uncomplicated cases are managed with bowel rest; the 2026 ACG guideline suggests against routine antibiotics in this group, reserving agents such as Ciprofloxacin + Metronidazole for patients with high-risk features, immunocompromise, frailty, or inability to ensure safe outpatient management. Avoid opioids if possible due to constipation. If the patient is toxic or fails outpatient therapy, admit for IV antibiotics. Surgical intervention is reserved for perforation, obstruction, or fistula.
Prognosis
Most patients improve clinically within 48-72 hours of starting treatment. Abscess formation requires drainage if >3cm. Follow-up colonoscopy is recommended 6-8 weeks after recovery from complicated diverticulitis; for uncomplicated diverticulitis, colonoscopy is suggested only in patients with alarm symptoms or those not up to date with colorectal cancer screening.
Differential Diagnosis
Colorectal cancer: weight loss and change in caliber of stool
IBD: bloody diarrhea and younger age of onset
Ischemic colitis: hematochezia and history of vascular disease
Nephrolithiasis: hematuria and colicky flank pain
Ovarian torsion: sudden onset, unilateral adnexal mass