What is the appropriate evaluation and management for a patient presenting with sharp lower left quadrant pain?

Sharp Lower Left Quadrant Pain: Evaluation and Management

Immediate Imaging Strategy

Order CT abdomen and pelvis with IV contrast immediately for most patients presenting with sharp left lower quadrant pain—this is the gold standard with 98% diagnostic accuracy and should be your default imaging choice. 1, 2

The American College of Radiology rates CT with IV contrast as 8/9 (usually appropriate) because it simultaneously identifies life-threatening complications, guides treatment decisions, detects alternative diagnoses, and reduces unnecessary hospital admissions by over 50%. 2

Key Exception for Premenopausal Women

• If gynecologic pathology is suspected clinically, start with pelvic/transvaginal ultrasound before proceeding to CT. 1, 2
• Always obtain pregnancy testing before ordering CT in women of reproductive age. 2

Critical Red Flags Requiring Emergency Evaluation

Immediately escalate care if any of the following are present:

• Fever with left lower quadrant pain (suggests complicated diverticulitis or perforation) 2
• Inability to pass gas or stool (present in 90% of large bowel obstructions) 2
• Peritoneal signs: guarding, rebound tenderness, or absent bowel sounds (indicates possible perforation) 2
• Hemodynamic instability: tachycardia, hypotension, confusion, or signs of septic shock 2
• Bloody stools or progressively worsening pain over several days 2

These findings mandate immediate surgical consultation, as perforation with peritonitis requires emergent surgery. 2

Laboratory Workup

Order the following to risk-stratify:

• CRP >170 mg/L predicts severe diverticulitis with 87.5% sensitivity and 91.1% specificity 2
• White blood cell count with differential (left shift >75% suggests bacterial infection) 2
• When all three criteria are present (left lower quadrant tenderness, CRP >50 mg/L, absence of vomiting), diagnostic accuracy reaches 97%, though this occurs in only 24% of patients 2

Common Pitfall

Clinical diagnosis alone is unreliable with misdiagnosis rates of 34-68%—never rely on physical examination alone to make treatment decisions. 2

CT Interpretation and Treatment Algorithm

Uncomplicated Diverticulitis (bowel wall thickening with pericolonic fat stranding, no abscess/perforation)

For immunocompetent patients: Conservative management WITHOUT antibiotics is recommended. 2

• Clear liquid diet with gradual advancement 2
• Oral analgesics for pain control 2
• Outpatient management is appropriate if patient can tolerate oral intake 2

For immunocompromised or elderly patients only: Antibiotics for maximum 7 days 2

• Ertapenem 1 g q24h OR Eravacycline 1 mg/kg q12h 2

Complicated Diverticulitis with Small Abscess (<4 cm)

• Antibiotics alone for 7 days without drainage 2
• Same antibiotic regimens as above 2

Complicated Diverticulitis with Large Abscess (≥4 cm)

Percutaneous drainage PLUS antibiotics for 4 days (not 7 days—stop at 4 days if source control is adequate in immunocompetent, non-critically ill patients). 2

Perforation with Free Air or Diffuse Peritonitis

Emergency surgical consultation required: 2

• Clinically stable patients without major comorbidities: Primary resection and anastomosis with or without diverting stoma 2
• Critically ill or multiple comorbidities: Hartmann's procedure 2

Septic Shock

Escalate immediately to broad-spectrum carbapenem therapy: 2

• Meropenem 1 g q6h by extended infusion, OR 2
• Doripenem 500 mg q8h by extended infusion, OR 2
• Imipenem/cilastatin 500 mg q6h by extended infusion 2

Alternative Diagnoses to Consider

The differential for left lower quadrant pain is broad: 2, 3

• Epiploic appendagitis: Self-limited condition showing oval fat-density lesion with surrounding inflammation on CT—requires no treatment, resolves in 1 week 4
• Colitis (infectious, ischemic, or inflammatory bowel disease) 2
• Left-sided urolithiasis or pyelonephritis 3
• Bowel obstruction or hernia 2
• Atypical appendicitis: Rare but important—long appendix projecting into left lower quadrant or situs inversus can present with left-sided pain 5, 6

Colonoscopy Timing: Critical Pitfall

Routine colonoscopy after CT-confirmed uncomplicated diverticulitis is NOT warranted. 1, 2

Only perform colonoscopy if:

• Age-appropriate colon cancer screening not yet performed 1, 2
• Pericolonic lymph nodes >1 cm on CT (suggests malignancy rather than diverticulitis) 1, 2
• Luminal colon mass visualized on CT 1, 2
• Uncertain diagnosis (inflammatory bowel disease vs. ischemic colitis) 1
• Presence of abscess, perforation, or fistula 2

Mild Intermittent Pain in Known Diverticulosis

Imaging may not be necessary in patients with known diverticulosis presenting with mild, intermittent left lower quadrant pain without fever or peritoneal signs. 2

Conservative outpatient management without antibiotics is appropriate, but order CT immediately if any of the following develop: 2

• Fever
• Severe or progressively worsening pain
• Inability to tolerate oral intake
• Signs of peritonitis
• Persistent symptoms beyond 2-3 days despite conservative management