Recommended Diagnostic and Management Approach
CT abdomen and pelvis with IV contrast is the most appropriate initial imaging study for this patient with RLQ pain, given the need to evaluate for appendicitis, right colonic diverticulitis, and complications related to her known mesenteric panniculitis and history of colonic polyps. 1
Rationale for CT as First-Line Imaging
CT abdomen and pelvis with IV contrast is rated "usually appropriate" by the American College of Radiology for RLQ pain evaluation, achieving 95% sensitivity and 94% specificity for appendicitis while simultaneously identifying alternative diagnoses in 94.3% of cases. 1
The patient's presentation—constant throbbing RLQ pain lasting several days with chronic constipation—requires imaging that can evaluate multiple potential etiologies beyond appendicitis, including complications of her known mesenteric panniculitis, colonic pathology (given her high-risk polyp history), and right-sided diverticulitis. 1, 2
CT without enteral contrast is preferred to avoid delays in diagnosis and treatment, with sensitivities ranging from 90-100% and specificities from 94.8-100% for appendicitis. 1
Key Differential Diagnoses to Consider
The imaging must evaluate for:
Appendicitis: Although she lacks fever, nausea, or vomiting (the "classic triad" is present in only 50% of cases), appendicitis remains the most common surgical cause of RLQ pain and must be excluded. 1
Right colonic diverticulitis: A common cause of RLQ pain that CT readily identifies. 1, 3
Mesenteric panniculitis complications: While typically asymptomatic (found incidentally in 0.6-2.4% of CT scans), MP can rarely cause abdominal pain and may be associated with mass effect or bowel complications. 4, 5
Colonic pathology: Given her high-risk polyp history, malignancy or inflammatory bowel disease must be considered. 1, 2
Constipation-related pain: Her chronic constipation may be contributing, though this is a diagnosis of exclusion after CT excludes surgical emergencies. 6
Management Based on CT Results
If CT Shows Acute Surgical Pathology (Appendicitis, Diverticulitis, Obstruction)
- Immediate surgical consultation is warranted. 1
- Among patients with CT-identified pathology, 41% require hospitalization and 22% need surgical or image-guided intervention. 6
If CT Shows Only Constipation or No Acute Findings
- Initiate bowel regimen with stool softeners and/or osmotic laxatives. 6
- Provide symptomatic pain relief with appropriate analgesics. 6
- Reassess within 24-48 hours to ensure symptom improvement. 6
- Among patients with negative CT findings, only 14% require hospitalization and 4% need intervention. 6
If CT Shows Stable Mesenteric Panniculitis
- No specific treatment is required if asymptomatic or minimally symptomatic, as MP is typically a benign age-related finding. 4, 5
- Consider glucocorticoids or tamoxifen only if MP is causing significant symptoms. 4
Critical Red Flags Requiring Reimaging
Watch for clinical deterioration including:
- Fever development. 6
- Persistent vomiting. 6
- Worsening or peritoneal pain. 6
- Inability to tolerate oral intake. 6
Avoid unnecessary repeat imaging if symptoms are stable or improving, as this increases radiation exposure without changing management. 6
Important Clinical Pitfalls
Do not dismiss persistent pain that fails to improve with conservative management after 24-48 hours—consider alternative diagnoses or delayed presentation of appendicitis. 6
The absence of fever and leukocytosis does not exclude appendicitis, particularly in atypical presentations or early disease. 1
Mesenteric panniculitis can mimic malignancy (particularly lymphoma) on imaging, so correlation with clinical context and her cancer history is essential. 4
Her history of breast cancer warrants consideration of metastatic disease or treatment-related complications, though these are less likely causes of acute RLQ pain. 2