What are the potential causes and management options for left lower quadrant pain in a male patient?

Left Lower Quadrant Pain in Males: Diagnostic and Management Approach

Immediate Diagnostic Strategy

Order CT abdomen and pelvis with IV contrast immediately for any male patient presenting with left lower quadrant pain—this is the gold standard imaging modality with 98% diagnostic accuracy and should be your default approach. 1

The American College of Radiology rates CT with IV contrast as 8/9 (usually appropriate) and emphasizes that clinical diagnosis alone is unreliable, with misdiagnosis rates between 34-68%. 1 This imaging modality not only confirms diverticulitis but also identifies alternative diagnoses in nearly half of cases, fundamentally altering management. 1, 2

Differential Diagnosis Framework

Most Common Causes in Adult Males:

• Sigmoid diverticulitis - the predominant cause in adults 1
• Colitis and inflammatory bowel disease 1
• Renal colic or pyelonephritis 1, 3
• Bowel obstruction 1
• Incarcerated hernia 4
• Epiploic appendagitis 1, 3

Rare but Critical Diagnoses:

• Left-sided appendicitis (in patients with situs inversus or intestinal malrotation) - this is an easily missed diagnosis that requires high clinical suspicion 4, 5, 6, 7
• Leaking abdominal aortic aneurysm 4
• Psoas abscess 4
• Perforated colon cancer 3

Red Flag Assessment: When to Send to Emergency Department

Immediate Emergency Evaluation Required for:

• Fever combined with left lower quadrant pain (suggests complicated diverticulitis, though classic triad present in only 25% of cases) 1
• Inability to pass gas or stool with abdominal distension (present in 90% of large bowel obstructions) 1
• Signs of peritonitis: diffuse tenderness, guarding, rebound tenderness, or absent bowel sounds 1
• Toxic appearance: fever, rapid breathing, tachycardia, confusion, or septic shock 1
• Bloody stools 1
• Progressively worsening pain over several days 1

These symptoms matter because perforation can lead to fecal peritonitis and septic shock, abscess formation requires drainage or surgery, and complete obstruction can cause bowel necrosis. 1

CT Interpretation and Treatment Algorithm

For Uncomplicated Diverticulitis (no abscess, perforation, or fistula):

• Immunocompetent patients: Conservative management WITHOUT antibiotics - clear liquid diet advancement and oral analgesics 1
• Immunocompromised or elderly patients: Antibiotics for maximum 7 days (Ertapenem 1g q24h or Eravacycline 1mg/kg q12h) 1

For Complicated Diverticulitis:

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 if source control is adequate in immunocompetent, non-critically ill patients 1

Perforation with diffuse peritonitis:

• Emergency surgical consultation for primary resection and anastomosis (stable patients) or Hartmann's procedure (critically ill patients) 1

Septic shock:

• Escalate immediately to Meropenem 1g q6h by extended infusion, Doripenem 500mg q8h by extended infusion, or Imipenem/cilastatin 500mg q6h by extended infusion 1

Clinical Diagnostic Criteria (When CT May Not Be Immediately Available)

When all three criteria are present, diverticulitis diagnosis has 97% accuracy (though this occurs in only 24% of patients): 1

• Left lower quadrant tenderness
• CRP >50 mg/L
• Absence of vomiting

However, do not rely on clinical examination alone to make definitive treatment decisions. 1

Special Considerations and Pitfalls

Critical Pitfall - Left-Sided Appendicitis:

In patients with atypical presentation or those not responding to standard diverticulitis treatment, consider situs inversus or intestinal malrotation with left-sided appendicitis. 4, 5, 6, 7 CT scan is essential for establishing this diagnosis, as clinical signs and symptoms lack uniformity. 6

CT Findings Suggesting Cancer Rather Than Diverticulitis:

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

Colonoscopy Timing:

Routine colonoscopy after CT-confirmed uncomplicated diverticulitis is NOT warranted except for: 1

• Age-appropriate colon cancer screening not yet performed
• Abnormal pericolic lymph nodes on CT
• Luminal colon mass on CT
• Presence of abscess, perforation, or fistula

Outpatient Management for Mild Cases

For patients with known diverticulosis presenting with mild, intermittent left lower quadrant pain without fever or peritonitis signs, imaging may not be necessary and conservative outpatient management without antibiotics is appropriate. 1

However, order CT immediately if any of the following develop: 1

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

Laboratory Markers to Guide Severity Assessment

• CRP >170 mg/L: Predicts severe diverticulitis with 87.5% sensitivity and 91.1% specificity 1
• White blood cell count with left shift >75%: Suggests bacterial infection 1
• Elevated lactate: Signifies systemic infection and sepsis 1

If signs of infection persist beyond 7 days, obtain repeat imaging to assess for inadequate source control. 1 Do not continue antibiotics beyond 7 days in uncomplicated cases, as this increases resistance without improving outcomes. 1