What are the management steps for left lower quadrant abdominal pain?

Management of Left Lower Quadrant Abdominal Pain

Begin with immediate CT abdomen and pelvis with IV contrast in all patients with left lower quadrant pain presenting to the emergency setting, as this has 98% diagnostic accuracy and will guide all subsequent management decisions. 1

Initial Risk Stratification

Before imaging, rapidly assess for red flag symptoms requiring immediate surgical consultation:

• Fever with inability to pass gas or stool 1
• Severe abdominal tenderness with guarding or rebound 1
• Signs of shock (hypotension, tachycardia, altered mental status) 1
• Bloody stools combined with hemodynamic instability 1

If any of these are present, obtain emergent surgical consultation while simultaneously ordering CT imaging. 1

Diagnostic Imaging Protocol

CT abdomen and pelvis with IV contrast is rated 8/9 (usually appropriate) by the American College of Radiology and should be the first-line imaging study. 1 This single test provides:

• Detection of diverticulitis with 98-100% sensitivity 1
• Identification of complications (abscess, perforation, fistula) 2
• Recognition of alternative diagnoses 1
• Guidance for treatment decisions that reduce hospital admissions by >50% 1

Special population exception: In premenopausal women, obtain pelvic/transvaginal ultrasound first if gynecologic pathology is suspected clinically. 1

CT Interpretation: Critical Findings

Look specifically for these features on CT:

• Pericolonic lymphadenopathy >1 cm - This strongly suggests perforated colon cancer rather than diverticulitis and mandates colonoscopy 1, 3
• Intestinal wall thickening with pericolonic fat stranding 2
• Extraluminal gas or intra-abdominal fluid indicating perforation 2
• Abscess size - measure carefully as this determines drainage strategy 2

Management Algorithm Based on CT Findings

Uncomplicated Diverticulitis (no abscess, no perforation)

Conservative management WITHOUT antibiotics is appropriate for immunocompetent patients. 2, 1

• Outpatient management with clear liquid diet advancement 1
• Pain control with oral analgesics 1
• Close follow-up within 48-72 hours 1

Use antibiotics ONLY in immunocompromised or elderly patients, limited to 7 days maximum: 2, 1

• Ertapenem 1 g IV/IM every 24 hours 2, 1
• OR Eravacycline 1 mg/kg IV every 12 hours 2, 1

Complicated Diverticulitis with Small Abscess (<4 cm)

Antibiotic therapy alone for 7 days without drainage: 2, 1

• Same antibiotic regimens as above 2
• Hospital admission for initial 24-48 hours 2
• NPO initially, advance diet as tolerated 2

Complicated Diverticulitis with Large Abscess (≥4 cm)

Percutaneous drainage combined with antibiotics for 4 days in immunocompetent, non-critically ill patients: 2, 1

• Coordinate with interventional radiology for CT-guided drainage 2
• Same antibiotic regimens as uncomplicated disease 2
• If drainage not feasible in stable immunocompetent patients, antibiotics alone may be attempted 2
• If drainage not feasible in critically ill or immunocompromised patients, proceed directly to surgery 2

Septic Shock (any stage of diverticulitis)

Escalate to broad-spectrum carbapenem therapy with extended infusions: 2, 1

• Meropenem 1 g IV every 6 hours by extended infusion or continuous infusion 2
• OR Doripenem 500 mg IV every 8 hours by extended infusion 2
• OR Imipenem/cilastatin 500 mg IV every 6 hours by extended infusion 2
• OR Eravacycline 1 mg/kg IV every 12 hours 2

Generalized Peritonitis or Free Perforation

Emergent surgical intervention is mandatory: 2, 1

• Primary resection and anastomosis with or without diverting stoma in clinically stable patients without major comorbidities 2
• Hartmann's procedure in critically ill patients or those with multiple major comorbidities 2
• Laparoscopic peritoneal lavage is controversial and only for purulent (not fecal) peritonitis 2

Duration of Antibiotic Therapy

Stop antibiotics at 4 days in immunocompetent, non-critically ill patients if source control is adequate. 2

Continue up to 7 days in immunocompromised or critically ill patients, guided by clinical response and inflammatory markers. 2

If signs of infection persist beyond 7 days, obtain repeat imaging to assess for inadequate source control. 2

Critical Pitfalls to Avoid

Do not rely on clinical diagnosis alone - misdiagnosis rates are 34-68% without imaging. 1 The classic triad of left lower quadrant pain, fever, and leukocytosis is present in only 25% of diverticulitis cases. 1

Do not miss colon cancer - pericolonic lymphadenopathy >1 cm is the key distinguishing feature between perforated cancer and diverticulitis. 1, 3 If present, colonoscopy is mandatory after acute inflammation resolves. 1

Do not order routine colonoscopy after uncomplicated diverticulitis - this is only indicated for age-appropriate screening or if abscess, perforation, or fistula was present. 1

Do not continue antibiotics beyond 7 days in uncomplicated cases - this increases resistance without improving outcomes. 2

Alternative Diagnoses to Consider

While diverticulitis is the most common cause (affecting 5-25% of patients with diverticulosis), CT will identify: 1

• Colitis (infectious, ischemic, inflammatory bowel disease) 4
• Urolithiasis 4
• Epiploic appendagitis 4, 5
• Gynecologic pathology in women 1, 6
• Perforated colon cancer 1, 3
• Fecal impaction 4