What is the best course of action for a 31-year-old female with right lower quadrant (RLQ) pain, elevated white blood cell (WBC) count, and a 0.41 cm appendix on CT scan without periappendiceal fat stranding or appendicolith?

Management of 31-Year-Old Female with RLQ Pain and Equivocal CT Findings

Direct Recommendation

This patient does NOT have appendicitis based on imaging and should be managed conservatively with close clinical observation, pain control, and consideration of alternative diagnoses—immediate appendectomy is not indicated. 1, 2

Rationale for Conservative Management

CT Findings Argue Against Appendicitis

• An appendiceal diameter of 0.41 cm (4.1 mm) is well below the diagnostic threshold for appendicitis, which requires maximal outer diameter >6 mm on CT 1
• The absence of periappendiceal fat stranding is a critical negative finding, as fat stranding is one of the most reliable CT signs of appendicitis with high specificity 1
• The absence of appendicolith further reduces the likelihood of appendicitis, as appendicoliths identify patients at higher risk for complicated disease 2
• CT demonstrates 95% sensitivity and 94% specificity for appendicitis in adults, meaning this negative study is highly reliable 1

Clinical Context Interpretation

• The elevated WBC count (18,000) and WBCs in urinalysis suggest an alternative diagnosis, potentially urinary tract infection, pyelonephritis, or other infectious/inflammatory process 1, 3
• The combination of leukocytosis with negative CT findings for appendicitis should prompt investigation of non-appendiceal causes of RLQ pain [1, @27@]
• In reproductive-age women, CT identifies alternative diagnoses in 94% of non-appendiceal cases, including gynecologic pathology, right colonic diverticulitis, inflammatory bowel disease, and genitourinary conditions 1, 4

Recommended Management Algorithm

Immediate Actions

• Obtain urinalysis with culture and sensitivity to evaluate for urinary tract infection or pyelonephritis given WBCs in urinalysis 1
• Obtain urine or serum pregnancy test if not already done, as this is mandatory in all reproductive-age women with abdominal pain 4
• Review CT images for alternative diagnoses including ovarian pathology (cyst, torsion), renal/ureteral stone, colitis, or other inflammatory conditions [1, @27@]
• Provide appropriate analgesia with opioids, NSAIDs, or acetaminophen as pain control is a priority and does not delay necessary intervention 3

Clinical Observation Protocol

• Admit for 12-24 hour observation with serial abdominal examinations to monitor for evolving peritonitis or worsening symptoms 3, 5
• Repeat WBC count in 12-24 hours to assess trajectory of leukocytosis 1
• If symptoms worsen or new peritoneal signs develop, obtain surgical consultation immediately 3
• If symptoms improve with conservative management, discharge with strict return precautions for worsening pain, fever, or inability to tolerate oral intake 3

Alternative Diagnoses to Consider

• Urinary tract infection or pyelonephritis (most likely given WBCs in urinalysis and leukocytosis) 1
• Ovarian pathology including hemorrhagic cyst, ovarian torsion, or functional ovarian pain 1, 4
• Right colonic diverticulitis (seen in 8% of RLQ pain cases) 1
• Infectious enterocolitis including typhlitis or inflammatory terminal ileitis 1
• Inflammatory bowel disease (Crohn's disease affecting terminal ileum) 1

Critical Pitfalls to Avoid

• Do not proceed to appendectomy based solely on clinical findings when CT is definitively negative, as this leads to unnecessary surgery with associated morbidity 1
• Do not ignore the urinalysis findings, as pyuria with leukocytosis strongly suggests urinary tract pathology requiring antibiotic therapy 1
• Do not assume appendicitis is ruled out forever—if symptoms evolve or worsen despite initial negative imaging, repeat imaging or surgical consultation is warranted 3, 5
• Do not discharge without clear return precautions, as perforation risk increases with delayed diagnosis if appendicitis develops later 3, 6

When to Reconsider Appendicitis

• If repeat imaging shows appendiceal diameter ≥7 mm, fat stranding, or appendicolith, then appendicitis becomes the diagnosis and surgical consultation is mandatory 1, 2
• If clinical deterioration occurs with peritoneal signs (rigidity, rebound tenderness, guarding), obtain immediate surgical consultation regardless of initial imaging 3
• If symptoms persist beyond 24-48 hours without alternative explanation, consider repeat CT or MRI to reassess for evolving appendicitis 5, 7