A patient with right lower abdominal pain, tenderness, and rebound tenderness presents to the Emergency Room (ER), what is the next step in management?

Management of Right Lower Abdominal Pain with Tenderness and Rebound

Order CT abdomen and pelvis with IV contrast immediately – this is the definitive next step for a patient presenting with right lower quadrant pain, tenderness, and rebound tenderness, as clinical examination alone has an unacceptably high negative appendectomy rate of up to 25%, and CT provides 95% sensitivity and 94% specificity for appendicitis while simultaneously identifying alternative diagnoses in 23-45% of cases 1.

Why Imaging is Essential Before Surgery

Even with classic peritoneal signs (rebound tenderness), preoperative imaging is mandatory because:

• Rebound tenderness indicates peritoneal irritation but does not confirm appendicitis as the cause 2
• CT reduces negative appendectomy rates from 14.7-25% (clinical diagnosis alone) to 1.7-7.7% (with preoperative imaging) 2
• The "classic presentation" of appendicitis is only present in approximately 50% of actual appendicitis cases 2
• CT identifies critical alternative diagnoses requiring different management, including right colonic diverticulitis (8%), ureteral stones, intestinal obstruction (3%), and gynecologic pathology (21.6% of alternative diagnoses) 1, 2

Optimal CT Protocol

Order CT abdomen and pelvis with IV contrast WITHOUT oral contrast for:

• Rapid acquisition without delays from oral contrast administration 2
• Excellent sensitivity (85.7-100%) and specificity (94.8-100%) 1, 2
• Detection of perforation, abscess formation, and periappendiceal inflammation 2
• Identification of appendiceal diameter >8.2 mm (highly specific for appendicitis) 2

Critical Pitfalls to Avoid

Do not proceed directly to surgery without imaging, even with convincing clinical findings:

• Clinical determination of appendicitis is notoriously unreliable, with negative appendectomy rates as high as 25% without imaging 1, 2
• Absence of fever does NOT exclude appendicitis – fever is absent in approximately 50% of appendicitis cases 2, 3
• Normal white blood cell count significantly reduces probability but does not exclude appendicitis 2

Do not delay imaging for oral contrast administration – IV contrast alone provides excellent diagnostic accuracy and avoids treatment delays 2

Do not rely on ultrasound as first-line imaging in adults – ultrasound has 20-81% non-visualization rates and requires CT for equivocal results anyway, causing diagnostic delays 3

Simultaneous Management While Awaiting Imaging

While the patient is being prepared for CT:

• Initiate NPO status 3
• Start IV fluid resuscitation with crystalloids 3
• Hold antibiotics until imaging confirms diagnosis (unless patient is septic) 3
• Obtain surgical consultation to expedite definitive management once diagnosis is confirmed 2

Alternative Diagnoses CT Will Identify

CT will definitively diagnose or exclude:

• Gastrointestinal causes (46% of alternative diagnoses): Right colonic diverticulitis, inflammatory bowel disease, colitis, gastroenteritis, bowel obstruction, mesenteric ischemia 1, 2, 3
• Gynecologic causes (21.6% of alternative diagnoses): Ovarian torsion, ruptured ovarian cyst, pelvic inflammatory disease, ectopic pregnancy 1, 2
• Urologic causes: Ureteral stones, pyelonephritis 1, 2
• Other surgical emergencies: Perforated viscus, abscess formation, malignancy 1, 3

Post-Imaging Management Algorithm

If CT confirms appendicitis (appendix >8.2 mm with periappendiceal inflammation):

• Immediate surgical consultation for appendectomy 2
• Initiate broad-spectrum IV antibiotics covering gram-negative and anaerobic organisms 3
• Assess for perforation or abscess requiring modified surgical approach 2

If CT shows alternative diagnosis:

• Manage according to specific pathology identified (41% of patients with non-appendiceal CT diagnosis require hospitalization, 22% require surgical or image-guided intervention) 1

If CT is negative:

• Consider discharge with strict return precautions if patient is clinically stable, able to tolerate oral intake, and has reliable follow-up access 2
• Mandatory 24-hour follow-up due to measurable false-negative rates 2
• Return immediately for worsening pain, fever, vomiting, or inability to tolerate oral intake 2