What is the next step in management for a patient presenting to the Emergency Room (ER) with 12 hours of right lower abdominal pain, tenderness, and rebound tenderness, suggestive of acute appendicitis?

CT Abdomen and Pelvis with IV Contrast is the Next Step

For a patient presenting with 12 hours of right lower quadrant pain, tenderness, and rebound tenderness suggestive of acute appendicitis, CT abdomen and pelvis with IV contrast should be performed immediately rather than proceeding directly to appendectomy or observation. 1

Rationale for Imaging Before Surgery

The negative appendectomy rate based on clinical determination alone is unacceptably high at 14.7-25%, even with classic presentation. 1 Preoperative CT imaging reduces this rate dramatically to 1.7-7.7%, significantly improving patient outcomes and avoiding unnecessary surgical complications. 1

CT abdomen and pelvis with IV contrast demonstrates exceptional diagnostic accuracy with sensitivity of 90-100% and specificity of 94.8-100% for acute appendicitis. 1 This allows for:

• Confident early diagnosis in positive cases, reducing delays and perforation risk with attendant morbidity and mortality 1
• Confident exclusion of diagnosis in negative cases, decreasing unnecessary surgeries 1
• Identification of alternative diagnoses in 23-45% of patients with right lower quadrant pain, fundamentally changing management 1

Why Not Proceed Directly to Appendectomy

Even with classic clinical presentation (right lower quadrant pain, tenderness, rebound), imaging remains essential because:

• Classic presentation occurs in only approximately 50% of appendicitis cases 1
• Physical examination alone has poor diagnostic accuracy, particularly in certain populations 1
• Alternative surgical and non-surgical conditions frequently mimic appendicitis, including right colonic diverticulitis (8%), ureteral stones, intestinal obstruction (3%), gynecologic pathology (21.6%), and other gastrointestinal conditions (46%) 1

Proceeding directly to open appendectomy without imaging risks unnecessary surgery if appendicitis is absent and missing alternative diagnoses that explain the symptoms. 2

Why Not Observation for 24 Hours

A step-up diagnostic approach should be used, beginning with clinical and laboratory examination and progressing to imaging, but not delaying definitive diagnosis with prolonged observation. 1

The presence of rebound tenderness indicates peritoneal irritation and warrants immediate diagnostic imaging rather than watchful waiting. 1, 2 Delays in diagnosis can lead to:

• Increased perforation rates with attendant morbidity and mortality 1
• Progression from uncomplicated to complicated appendicitis 1, 3
• Missed alternative diagnoses requiring urgent intervention 1

Optimal CT Protocol

Order CT abdomen and pelvis with IV contrast WITHOUT oral contrast for optimal results. 1, 2

Key advantages of this protocol:

• IV contrast increases sensitivity to 96% compared to unenhanced CT 2, 4
• Oral contrast is not necessary and may delay diagnosis 2
• Rapid acquisition allows for timely surgical planning 1
• Excellent assessment for perforation, abscess formation, and alternative diagnoses 1, 2

Management After CT Results

If CT confirms appendicitis: Proceed with immediate surgical consultation and broad-spectrum antibiotics covering aerobic gram-negative organisms and anaerobes. 1, 2, 3 Both laparoscopic and open appendectomy are acceptable, with surgery performed as soon as reasonably feasible. 2, 3

If CT shows complicated appendicitis with large periappendiceal abscess or phlegmon: Consider percutaneous drainage rather than immediate appendectomy. 2, 3

If CT is negative: Consider alternative diagnoses and appropriate management based on imaging findings. 1

Common Pitfalls to Avoid

• Do not rely on absence of fever to exclude appendicitis—fever is absent in approximately 50% of cases. 1, 5
• Do not use clinical scoring systems (Alvarado score) alone—these have not improved diagnostic accuracy sufficiently to replace imaging. 1
• Do not delay imaging for oral contrast administration—IV contrast alone provides excellent diagnostic accuracy. 2
• Do not assume classic presentation guarantees appendicitis—alternative diagnoses are common even with typical symptoms. 1