What are the possible causes and treatments for intermittent sharp left lower quadrant abdominal pain?

Intermittent Sharp Left Lower Quadrant Abdominal Pain

For intermittent sharp left lower quadrant pain, obtain CT abdomen and pelvis with IV contrast as the definitive diagnostic test, which has 98% accuracy and will guide all subsequent management decisions. 1

Immediate Triage: When to Send to Emergency Department

Evaluate for red flag symptoms that require immediate emergency evaluation:

• Fever combined with left lower quadrant pain suggests complicated diverticulitis or intra-abdominal infection 1
• Inability to pass gas or stool with abdominal distension indicates possible bowel obstruction (present in 90% of large bowel obstructions) 1
• Severe abdominal tenderness with guarding or rebound suggests peritonitis from perforation 1
• Vomiting, bloody stools, or signs of shock (tachycardia, hypotension, confusion) require emergent evaluation 1
• Progressively worsening pain over several days warrants urgent assessment 1

If any of these are present, send immediately to the emergency department for imaging and possible surgical intervention 1.

Diagnostic Approach for Stable Patients

Initial Imaging Strategy

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 test 1, 2. This modality:

• Detects diverticulitis with sensitivity and specificity approaching 100% 2
• Identifies complications including abscess, perforation, fistula, and obstruction 1
• Reduces hospital admissions by >50% through accurate risk stratification 1
• Reveals alternative diagnoses that present similarly (colitis, epiploic appendagitis, urolithiasis, malignancy) 3

Special Population Consideration

For premenopausal women, obtain pelvic/transvaginal ultrasound first if gynecologic pathology is suspected (ovarian cyst, torsion, ectopic pregnancy, pelvic inflammatory disease) 1, 2. However, if gynecologic causes are excluded clinically or sonographically, proceed directly to CT with IV contrast 2.

Alternative Imaging When CT Contraindicated

If IV contrast is contraindicated (severe renal insufficiency, contrast allergy):

• CT without IV contrast is acceptable (rated 6/9 by ACR) but less accurate for detecting abscesses 1
• Ultrasound with graded compression can be used but is operator-dependent and limited in obese patients 1

Most Common Diagnoses and Their Management

Diverticulitis (Most Common Cause)

Clinical diagnosis alone is unreliable with misdiagnosis rates of 34-68% 1. The classic triad of left lower quadrant pain, fever, and leukocytosis is present in only 25% of cases 1.

When all three criteria are present (left lower quadrant tenderness, CRP >50 mg/L, absence of vomiting), diagnostic accuracy reaches 97%, but this occurs in only 24% of patients 1.

Uncomplicated Diverticulitis (CT shows bowel wall thickening, pericolonic fat stranding, no abscess/perforation):

• Conservative treatment without antibiotics is appropriate for immunocompetent patients 4
• Antibiotic therapy for no more than 7 days only in immunocompromised or elderly patients 4
• Outpatient management is appropriate if patient can tolerate oral intake 1

Complicated Diverticulitis with Small Abscess (<3-4 cm):

• Antibiotic therapy alone for 7 days 4

Complicated Diverticulitis with Large Abscess (>3-4 cm):

• Percutaneous drainage combined with antibiotic therapy for 4 days 4
• If drainage not feasible: antibiotics alone for immunocompetent, stable patients; surgical intervention for critically ill or immunocompromised patients 4

Perforation with Peritonitis:

• Emergent surgery required 1
• Primary resection and anastomosis for stable patients without comorbidities 4
• Hartmann's procedure for critically ill patients or those with multiple comorbidities 4

Other Colonic Causes

• Colitis (infectious, ischemic, inflammatory bowel disease): CT shows bowel wall thickening, mucosal enhancement 3
• Epiploic appendagitis: Self-limited condition showing oval fat-density lesion adjacent to colon on CT 3
• Fecal impaction: Clinical diagnosis with plain radiography or CT confirmation 3

Non-Colonic Causes

• Left-sided urolithiasis: CT without contrast is diagnostic 3
• Spontaneous retroperitoneal or rectus sheath hemorrhage: CT with contrast shows hematoma 3
• Gynecologic pathology in women: ovarian cyst, torsion, ectopic pregnancy 5

Critical Pitfalls to Avoid

Malignancy Masquerading as Diverticulitis

Pericolonic lymphadenopathy >1 cm with or without pericolonic edema on CT suggests cancer rather than diverticulitis 1, 6. These patients require:

• Colonoscopy for tissue diagnosis 1
• Oncology referral if malignancy confirmed

Routine colonoscopy after CT-confirmed uncomplicated diverticulitis is NOT warranted except for age-appropriate screening, unless abscess, perforation, or fistula was present 1.

Left-Sided Appendicitis

In patients with intestinal malrotation, appendicitis can present with left lower quadrant pain 7. CT will identify the malpositioned appendix and establish the correct diagnosis 7.

Management of Recurrent Intermittent Pain

If structural pathology has been excluded by CT and colonoscopy:

• Functional bowel disorders (irritable bowel syndrome) become most likely 6
• Pain related to bowel movements or dietary triggers supports IBS diagnosis 6
• Gastroenterology referral for functional bowel disorder management 6

Red flags requiring repeat evaluation:

• Weight loss, anemia, or change in bowel habits warrant repeat colonoscopy 6
• New pericolonic lymphadenopathy >1 cm on repeat imaging suggests malignancy 6
• Cyclical pain in women requires pelvic ultrasound for gynecologic etiology 6

Antibiotic Regimens When Indicated

For immunocompromised/elderly patients with uncomplicated diverticulitis or those with complicated diverticulitis requiring antibiotics:

Standard regimen for community-acquired infection:

• Ertapenem 1 g q24h 4
• OR Eravacycline 1 mg/kg q12h 4

If septic shock present:

• Meropenem 1 g q6h by extended infusion 4
• OR Doripenem 500 mg q8h by extended infusion 4
• OR Imipenem/cilastatin 500 mg q6h by extended infusion 4

Duration: 4 days if source control adequate in immunocompetent patients; up to 7 days in immunocompromised or critically ill patients 4.