A female patient presents with fever, generalized myalgia, and abdominal pain. What is the appropriate diagnostic and treatment approach?

Diagnostic and Treatment Approach for Fever, Myalgia, and Abdominal Pain in a Female Patient

Obtain CT abdomen and pelvis with IV contrast immediately as the gold standard imaging study, as this changes the leading diagnosis in 49% of cases and is specifically recommended for nonlocalized abdominal pain with fever. 1

Initial Diagnostic Workup

Mandatory Laboratory Tests

• Obtain urine or serum β-hCG pregnancy test immediately before any imaging in all women of reproductive age, regardless of reported sexual history or contraceptive use 2
• Order complete blood count (CBC) to assess for leukocytosis suggesting infection or inflammation 3, 2
• Measure C-reactive protein (CRP), which has superior sensitivity and specificity compared to white blood cell count for identifying surgical disease and is a significant predictor of hospital admission (OR = 6.24) 3, 4
• Perform urinalysis to evaluate for urinary tract infection or pyelonephritis 2
• Consider nucleic acid amplification tests (NAATs) for Chlamydia trachomatis and Neisseria gonorrhoeae if sexually active, as pelvic inflammatory disease detection increases by 280% with CT imaging 1, 2

Imaging Strategy

CT abdomen and pelvis with IV contrast is the single most appropriate initial imaging study for this presentation 1, 3. This modality:

• Changes admission status in 24% and alters surgical plans in 25% of patients with nontraumatic abdominal complaints 1
• Increases detection of cholecystitis/cholangitis by 100% and pelvic inflammatory disease by 280% compared to clinical assessment alone 1
• Reveals the source of sepsis in patients with fever of unknown origin 1
• Detects pseudomembranous (C. difficile) colitis in 88% of cases 1

Abnormal imaging findings are the strongest predictor of hospital admission (OR = 6.47) 4

Critical Differential Diagnoses to Rule Out

Life-Threatening Conditions Requiring Immediate Intervention

• Intra-abdominal abscess: presents with fever, diffuse or localized abdominal pain; CT detects abscesses and guides percutaneous drainage 1, 3
• Appendicitis with perforation: most common surgical emergency; atypical presentations possible with fever and generalized pain 3
• Hollow organ perforation: presents with acute abdominal pain, fever, tachycardia, and peritonitis requiring immediate surgical evaluation 5
• Pelvic inflammatory disease: especially in sexually active women; detection dramatically improved with CT imaging 1, 2
• Cholecystitis/cholangitis: detection increases 100% with CT compared to clinical assessment 1

Important Non-Surgical Considerations

• Familial Mediterranean Fever (FMF) with protracted febrile myalgia syndrome (PFMS): consider in patients with recurrent episodes of fever, myalgia, and abdominal pain lasting weeks; more than half present with PFMS as first manifestation of FMF 6, 7, 8
• Inflammatory bowel disease complications: Crohn's disease or ulcerative colitis with abscess or phlegmon formation presents with fever and abdominal pain 1, 5

Management Algorithm

If CT Shows Surgical Pathology

• Uncomplicated appendicitis: proceed to appendectomy as standard of care 3
• Perforated appendicitis with small abscess (<3-4 cm): treat with antibiotic therapy alone for 7 days 3
• Large abscess: perform percutaneous drainage combined with antibiotic therapy 1, 3
• Initiate broad-spectrum antibiotics immediately for complicated intra-abdominal infection 3

If CT is Negative or Shows Non-Surgical Pathology

• Consider FMF if patient has recurrent episodes, ethnic background (Mediterranean, Middle Eastern, Turkish), or family history; genetic testing for MEFV gene mutations confirms diagnosis 9, 6, 8
• PFMS responds rapidly to corticosteroids in 77% of cases; anakinra is effective in all corticosteroid-refractory cases 8
• Start colchicine for confirmed FMF to prevent attacks and avoid amyloid nephropathy as the most dangerous complication 9, 7

Pain Management

• Provide immediate pain relief without withholding medication while awaiting diagnosis, as pain control facilitates better physical examination without affecting diagnostic accuracy 3
• Use oral NSAIDs (ibuprofen) for mild-to-moderate pain if no contraindications exist 3
• Administer intravenous opioid analgesics titrated to effect for severe pain 3

Critical Clinical Pearls and Pitfalls

Common Pitfalls to Avoid

• Never assume a patient is not pregnant based on history alone—always obtain objective β-hCG testing, as this fundamentally changes the diagnostic approach and imaging safety 2
• Laboratory values may be normal despite serious infection, especially in elderly patients 5
• Do not delay CT imaging for oral contrast administration, as this delays diagnosis without clear diagnostic advantage 1
• The long duration of PFMS (weeks) may be misleading if it occurs at FMF manifestation; ask specifically about family history and ethnic background 8

Red Flags Requiring Immediate Intervention

• Hypotension, respiratory distress with tachypnea, decreased urine output, or abdominal rigidity indicate sepsis or peritonitis requiring immediate resuscitation and source control 5
• Persistent fever beyond 48-72 hours of treatment or failure of symptoms to improve indicate high risk of ongoing intra-abdominal infection requiring additional intervention 3