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

Next Step: CT Abdomen and Pelvis with IV Contrast

For this patient with classic clinical presentation of appendicitis (12 hours of right lower abdominal pain with tenderness and rebound), the next step is CT abdomen and pelvis with intravenous contrast, not immediate appendectomy. 1

Rationale for Imaging Before Surgery

• CT imaging is the recommended diagnostic modality for adults with suspected appendicitis, achieving sensitivities of 90-100% and specificities of 94.8-100% for diagnosing appendicitis 1, 2
• Proceeding directly to appendectomy without imaging risks unnecessary surgery if appendicitis is absent (negative appendectomy carries long-term morbidity) and missing alternative diagnoses that could explain the symptoms 2
• CT with IV contrast is specifically recommended over unenhanced CT, as IV contrast increases sensitivity to 96% compared to 91% for unenhanced CT 1, 3
• Oral or rectal contrast is not necessary and may delay diagnosis—IV contrast alone provides excellent diagnostic accuracy 2

Why Not Immediate Surgery

• Both laparoscopic and open appendectomy are acceptable procedures, but operative intervention should occur after diagnostic confirmation 1
• The negative appendectomy rate based on clinical determination alone without imaging is unacceptably high at 25%, which has been reduced to 1.7-7.7% with routine CT use 1, 2
• Surgery may be deferred for a short period as appropriate according to individual institutional circumstances while obtaining imaging 1

Why Not Observation Alone

• While observation with IV fluids for 24 hours might be considered for low-risk patients, this patient has classic findings (right lower quadrant pain, tenderness, and rebound) that warrant definitive diagnostic imaging 4
• Patients with suspected appendicitis that can neither be confirmed nor excluded require careful follow-up, but those with high clinical suspicion should undergo imaging 1
• Delayed diagnosis may result in perforation, which carries significantly higher mortality (approximately 5% for perforated appendicitis versus <0.1% for non-gangrenous appendicitis) 4

Why Not Plain Abdominal X-ray

• Plain radiography of the abdomen has limited utility (rated only 4 out of 9 on appropriateness criteria) and may only be useful when there is concern for perforation and free air 1
• CT is far superior for both confirming appendicitis and identifying alternative diagnoses 1

CT Protocol Specifications

• Use helical CT of the abdomen and pelvis with intravenous contrast but not oral or rectal contrast 1
• This protocol provides optimal sensitivity (96-100%) and specificity (94.8-100%) while avoiding delays associated with oral contrast administration 1, 2
• The scan should cover the entire abdomen and pelvis, not just a focused appendiceal view, as non-focused imaging with IV contrast has higher sensitivity 1

Management After CT Results

• If CT confirms appendicitis, administer broad-spectrum antibiotics immediately (covering aerobic gram-negative organisms and anaerobes) and proceed with appendectomy as soon as reasonably feasible 1, 2
• If CT shows complicated appendicitis with large periappendiceal abscess or phlegmon, percutaneous drainage may be warranted rather than immediate appendectomy 2
• If CT is negative but clinical suspicion remains high, consider observation with 24-hour follow-up to ensure resolution of signs and symptoms due to the low but measurable risk of false-negative results 1

Common Pitfalls to Avoid

• Do not rely on clinical scoring systems alone (such as Alvarado score) to exclude appendicitis—studies show 8.4% of patients with appendicitis had low Alvarado scores, and one study found 72% of patients with very low scores (1-4) ultimately had appendicitis 2
• Do not delay imaging to administer oral contrast, as this provides no diagnostic benefit and postpones definitive diagnosis 2
• In female patients of childbearing potential, perform pregnancy testing prior to CT imaging 1