What is the appropriate management for a patient with a 2-week history of lower abdominal pain?

Management of 2-Week History of Lower Abdominal Pain

CT abdomen and pelvis with IV contrast is the imaging modality of choice for evaluating lower abdominal pain of unclear etiology, as it provides comprehensive assessment of the most likely diagnoses including diverticulitis, appendicitis, inflammatory bowel disease, and other intra-abdominal pathology. 1

Initial Clinical Assessment

Key Historical and Physical Examination Features to Elicit

• Pain location and character: Left lower quadrant pain suggests diverticulitis; right lower quadrant suggests appendicitis; diffuse pain broadens the differential 1, 2
• Associated symptoms: Fever and leukocytosis indicate inflammatory or infectious processes requiring urgent evaluation 1
• Gastrointestinal symptoms: Constipation with distension suggests bowel obstruction; diarrhea may indicate inflammatory bowel disease or colitis 1, 2
• Constitutional symptoms: Weight loss, sitophobia (food fear), and postprandial pain raise concern for chronic mesenteric ischemia or malignancy 1, 3
• Gynecologic considerations: In patients with female reproductive organs, consider ectopic pregnancy, pelvic inflammatory disease, and adnexal torsion 4

Laboratory Evaluation

• Complete blood count with differential (elevated WBC and left shift suggest infection) 1, 4
• C-reactive protein and procalcitonin (markers of inflammation) 1, 4
• Hepatobiliary markers, electrolytes, creatinine, glucose 4
• Urinalysis (to exclude urinary tract infection or urolithiasis) 5, 4
• Lipase if upper abdominal component present 4
• Pregnancy test in all patients with reproductive potential 4

Imaging Strategy

Primary Imaging Recommendation

CT abdomen and pelvis with IV contrast is usually appropriate (rating 8-9/9) for nonlocalized or lower abdominal pain. 1 This modality:

• Changes diagnosis in 49-54% of patients with abdominal pain 1
• Has 95% sensitivity and 94% specificity for appendicitis 1
• Provides comprehensive evaluation of diverticulitis, inflammatory bowel disease, abscess, perforation, and malignancy 1
• Detects alternative diagnoses in 94.3% of cases when appendicitis is excluded 1

Alternative Imaging Considerations

• Ultrasound: May be appropriate as initial study in younger patients or when radiation exposure is a concern, though has limited sensitivity (87.1%) compared to CT 1, 5
• MRI without and with IV contrast: Appropriate alternative when IV contrast is contraindicated or in pregnant patients, with diagnostic accuracy approaching 99% in some studies 1
• Plain radiography: Not recommended as it has very limited diagnostic value except when perforation or obstruction is clinically obvious 1, 3

Specific Diagnostic Considerations for 2-Week Duration

Left Lower Quadrant Pain: Diverticulitis

For patients with left lower quadrant pain, fever, and tenderness, diverticulitis is the primary consideration. 1

• Uncomplicated diverticulitis: Conservative management without antibiotics is appropriate in immunocompetent patients with CT-confirmed uncomplicated disease 1
• Complicated diverticulitis with abscess: Small abscesses (<3-4 cm) may be treated with antibiotics alone for 7 days; larger abscesses require percutaneous drainage plus antibiotics for 4 days 1
• Antibiotic duration: 4 days in immunocompetent patients with adequate source control; up to 7 days in immunocompromised or critically ill patients 1

Right Lower Quadrant Pain: Appendicitis

While less common with 2-week duration, subacute appendicitis with abscess formation should be considered. 1, 6

• CT has 95% sensitivity and 94% specificity for appendicitis 1
• Patients with confirmed appendicitis require hospital admission and surgical consultation 6

Inflammatory Bowel Disease

Two-week duration raises suspicion for inflammatory bowel disease (IBD), particularly if associated with diarrhea, weight loss, or recurrent symptoms. 1, 6

• CT can identify bowel wall thickening, inflammation, and complications 1
• Ultrasound may assess disease activity in known Crohn disease 1
• Outpatient management is frequently possible, but admission may be required for severe disease 6

Management Algorithm

Immediate Actions

1. Ensure hemodynamic stability: Initiate IV fluid resuscitation if volume depleted 1
2. Obtain laboratory studies: CBC, CRP, metabolic panel, urinalysis, pregnancy test 4
3. Order CT abdomen and pelvis with IV contrast unless contraindicated 1

Based on CT Findings

Diverticulitis without abscess:

• Immunocompetent: Conservative management without antibiotics 1
• Immunocompromised/elderly: Antibiotics for up to 7 days 1

Diverticulitis with small abscess (<3-4 cm):

• Antibiotics alone for 7 days 1

Diverticulitis with large abscess:

• Percutaneous drainage plus antibiotics for 4 days 1
• If drainage not feasible: antibiotics alone in stable patients; surgical intervention in critically ill 1

Appendicitis:

• Hospital admission and surgical consultation 6

Inflammatory bowel disease:

• Consider outpatient management with gastroenterology referral 6
• Admission if severe disease, obstruction, or perforation 6

No definitive diagnosis on CT:

• Consider alternative diagnoses including gynecologic pathology, urolithiasis, or functional disorders 1, 4
• Serial examination and close follow-up 6

Critical Pitfalls to Avoid

• Do not dismiss persistent pain without imaging: CT alters diagnosis in nearly half of cases, and serious pathology may present with atypical features 1
• Do not assume benign etiology based on 2-week duration: Subacute presentations of appendicitis, diverticulitis, and IBD are common 6
• Do not overlook gynecologic causes: Always consider ectopic pregnancy, pelvic inflammatory disease, and adnexal torsion in patients with reproductive organs 4
• Do not use plain radiography as primary imaging: It has very limited diagnostic value except for obvious perforation or obstruction 1, 3
• Do not delay antibiotics if sepsis suspected: Start broad-spectrum antibiotics immediately after blood cultures in septic patients 1

Special Considerations

Pregnant patients: Use ultrasound first; if nondiagnostic, proceed to MRI rather than CT when available 1, 4

Patients with contrast allergy or renal insufficiency: CT without IV contrast is appropriate, though diagnostic accuracy is reduced 1

Recurrent symptoms after negative initial CT: Repeat CT has low diagnostic yield (5.9% on fourth CT or greater); consider alternative diagnoses or functional disorders 1