What is the best course of action for a patient with a 2-day history of left lower quadrant (LLQ) pain that started in the hip, and also has a glioblastoma multiforme (GBM) with recent seizures?

Immediate CT Imaging with IV Contrast is Essential

For a patient with GBM and recent seizures presenting with 2-day history of LLQ pain that started in the hip, obtain CT abdomen/pelvis with IV contrast immediately to rule out life-threatening complications and guide management. 1, 2

Critical Initial Assessment

This clinical scenario requires urgent evaluation because:

• Clinical diagnosis alone is unreliable with misdiagnosis rates of 34-68% without imaging 1, 2
• GBM patients have unique vulnerabilities including immunosuppression from tumor effects, potential steroid use, and seizure-related complications 1
• The pain migration pattern (hip to LLQ) suggests evolving pathology requiring definitive imaging 1

Imaging Strategy

CT abdomen/pelvis with IV contrast is rated 8/9 (usually appropriate) by the American College of Radiology and provides:

• 98% diagnostic accuracy for acute abdominal pathology 1, 2
• Detection of complications (abscess, perforation, fistula) 1, 2
• Identification of alternative diagnoses (bowel obstruction, hernia, urolithiasis) 1, 3
• Risk stratification that reduces unnecessary hospital admissions by >50% 2

Why IV Contrast Matters

IV contrast improves characterization of bowel wall pathology, pericolic abnormalities, vascular pathology, and fluid collections with sensitivity/specificity approaching 100% for diverticulitis 2. If IV contrast is contraindicated, CT without contrast is acceptable (rated 6/9) but less accurate for detecting abscesses 1, 2.

Differential Diagnosis Priority

Most likely: Acute diverticulitis (most common cause of LLQ pain in adults, affecting 10% at age 40, increasing to 70% in elderly) 1, 3

Critical alternatives to exclude:

• Bowel obstruction (90% have inability to pass gas/stool) 2
• Perforation with peritonitis (requires emergent surgery) 2, 4
• Urolithiasis or pyelonephritis 1, 3
• Epiploic appendagitis 1, 3

Red Flags Requiring Emergency Surgery

Immediately assess for:

• Signs of peritonitis (diffuse tenderness, guarding, rebound, absent bowel sounds) indicating perforation 2, 4
• Hemodynamic instability (hypotension, tachycardia, altered mental status) 4
• Complete bowel obstruction (inability to pass gas/stool with distension) 2
• Toxic appearance (fever, rapid breathing, confusion, septic shock) 2

GBM-Specific Considerations

Seizure Management Context

Continue current antiepileptic therapy but avoid enzyme-inducing agents (phenytoin, carbamazepine, phenobarbital) that interfere with chemotherapy 1. Preferred agents include levetiracetam, lamotrigine, pregabalin, or valproic acid 1.

Levetiracetam specifically may prolong survival in GBM patients with methylated MGMT promoters undergoing temozolomide chemotherapy 5.

Steroid Status Assessment

Determine current dexamethasone dose as this affects infection risk and diagnostic interpretation:

• Steroids are indicated only for symptomatic cerebral edema (typically 8-16 mg/day dexamethasone) 1
• Rapid tapering is recommended to avoid myopathy, lymphopenia, infection risk, and osteoporosis 1
• Prolonged steroid use increases infection susceptibility, making complicated diverticulitis more likely 1

Immunosuppression Impact

GBM patients are functionally immunocompromised due to:

• Tumor-induced immune dysfunction 1
• Potential steroid therapy 1
• Recent chemotherapy effects 1

This mandates more aggressive antibiotic therapy if diverticulitis is confirmed 2, 4.

Management Algorithm Based on CT Findings

If Uncomplicated Diverticulitis (bowel wall thickening, pericolonic fat stranding, no abscess/perforation)

For immunocompetent patients: Conservative management without antibiotics is appropriate 2, 4

For this GBM patient (immunocompromised):

• Antibiotic therapy for 7 days maximum 2, 4
• Ertapenem 1g q24h OR Eravacycline 1mg/kg q12h 2
• Outpatient management if tolerating oral intake 2, 4
• Clear liquid diet advancement 4

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

• Antibiotic therapy alone for 7 days 2, 4
• Hospital admission for IV antibiotics given immunocompromised status 2, 4
• Same antibiotic regimens as above 2

If Complicated Diverticulitis with Large Abscess (≥4 cm)

• Percutaneous drainage PLUS antibiotics for 4 days 2, 4
• Interventional radiology consultation for CT-guided drainage 4
• Stop antibiotics at 4 days if adequate source control 4
• Continue up to 7 days only if immunocompromised or critically ill 4

If Perforation, Free Air, or Peritonitis

Emergent surgical consultation required 2, 4

Critical Pitfalls to Avoid

Do not delay imaging for clinical observation - the 2-day symptom duration with pain migration warrants immediate CT evaluation 1, 2

Do not assume diverticulitis without imaging - CT findings suggesting cancer include pericolonic lymphadenopathy >1 cm, which requires colonoscopy 1, 2

Do not continue antibiotics beyond 7 days in uncomplicated cases as this increases resistance without improving outcomes 4

Do not order routine colonoscopy after CT-confirmed uncomplicated diverticulitis unless: age-appropriate screening not done, abnormal pericolonic lymph nodes, luminal mass visualized, or uncertain diagnosis 1, 2

Monitoring Parameters

• Repeat imaging if symptoms persist beyond 7 days to assess for inadequate source control 4
• Monitor for concurrent autonomic dysfunction given seizure history 1
• Frequent neurological checks to ensure seizure control maintained 1
• Inflammatory markers (CRP, WBC) to guide antibiotic duration 4