What are the recommended steps for evaluating and treating left lower quadrant mild abdominal pain without nausea, vomiting, diarrhea, or constipation?

Evaluation and Management of Left Lower Quadrant Mild Abdominal Pain

Initial Diagnostic Approach

Order CT abdomen and pelvis with IV contrast immediately as the preferred imaging modality, which has 98% diagnostic accuracy and is rated 8/9 (usually appropriate) by the American College of Radiology. 1

Why CT with IV Contrast is Essential

• Clinical examination alone is unreliable with misdiagnosis rates of 34-68%, making imaging mandatory even for mild presentations 1
• CT with IV contrast detects complications (abscess, perforation, fistula), identifies alternative diagnoses, and reduces hospital admissions by >50% 1
• The imaging provides comprehensive evaluation of all abdominal organs in a single examination and guides appropriate treatment planning 1

Key Clinical Assessment Points

Before ordering imaging, evaluate for these specific features:

• Fever and leukocytosis: The classic triad of left lower quadrant pain, fever, and leukocytosis suggests diverticulitis, though present in only 25% of cases 1
• CRP >50 mg/L with absence of vomiting: When combined with left lower quadrant tenderness, this triad has 97% accuracy for diverticulitis, but occurs in only 24% of patients 1
• Obtain complete blood count with differential and C-reactive protein levels 2

Special Population Considerations

For premenopausal women, order pelvic/transvaginal ultrasound as initial imaging if gynecologic pathology is suspected, rather than CT. 1

• Consider pregnancy testing before CT in women of reproductive age 1
• Gynecologic causes must be clinically or sonographically excluded before proceeding to CT in female patients of childbearing age 1

Differential Diagnosis to Consider

The most common causes of left lower quadrant pain include:

• Acute diverticulitis of sigmoid or descending colon (most common in adults) 1
• Colitis and inflammatory bowel disease 1
• Epiploic appendagitis 1, 3
• Bowel obstruction 1
• Urolithiasis or pyelonephritis 1, 3
• Ovarian and fallopian tube pathology in women 1
• Perforated carcinoma 3

Management Based on CT Findings

If Uncomplicated Diverticulitis is Diagnosed

For immunocompetent patients with uncomplicated diverticulitis, conservative management WITHOUT antibiotics is recommended. 1

• Clear liquid diet advancement with oral analgesics for pain control 1
• Antibiotics should ONLY be used in immunocompromised or elderly patients, limited to maximum 7 days 1
• If antibiotics are needed, use Ertapenem 1 g q24h or Eravacycline 1 mg/kg q12h 1

If Complicated Diverticulitis is Found

• Small abscess (<3-4 cm): Antibiotic therapy alone for 7 days without drainage 1
• Large abscess (≥3-4 cm): Percutaneous drainage PLUS antibiotics for 4 days 1
• Stop antibiotics at 4 days in immunocompetent, non-critically ill patients if source control is adequate 1

Critical CT Findings Requiring Different Management

Look for these specific findings that suggest cancer rather than diverticulitis:

• Pericolonic lymphadenopathy >1 cm with or without pericolonic edema 1
• Luminal colon mass 1

These findings require colonoscopy after acute episode resolves, whereas routine colonoscopy after uncomplicated diverticulitis is NOT warranted except for age-appropriate screening. 1

When to Escalate Care

Despite mild presentation, immediate emergency evaluation is needed if any of these develop:

• Fever with inability to pass gas or stool 1
• Severe abdominal tenderness with guarding or rebound 1
• Vomiting or bloody stools 1
• Signs of shock or progressively worsening pain 1
• Toxic appearance (rapid breathing, rapid heartbeat, confusion) 1

Alternative Imaging if CT Contraindicated

• CT without IV contrast is acceptable when IV contrast is contraindicated, though less accurate for detecting abscesses (rated 6/9) 1
• Ultrasound with graded compression can reduce unnecessary CT examinations but is operator-dependent and limited in obese patients 1, 3

Critical Pitfalls to Avoid

• Do not rely on clinical triad alone—it is present in only 25% of diverticulitis cases 1
• Do not order plain radiography—it has very limited diagnostic value 4
• Do not perform routine colonoscopy after CT-confirmed uncomplicated diverticulitis unless abscess, perforation, fistula is present, or age-appropriate screening is due 1
• Do not continue antibiotics beyond 7 days in uncomplicated cases, as this increases resistance without improving outcomes 1