In a 21-year-old female presenting to the emergency department with 12 hours of right lower quadrant pain, tenderness and rebound, what is the next appropriate step in management?

CT Abdomen and Pelvis with IV Contrast is the Next Step

In a 21-year-old female with 12 hours of right lower quadrant pain, tenderness, and rebound, you should obtain a CT abdomen and pelvis with IV contrast immediately before proceeding to surgery. 1, 2

Why Imaging Before Surgery is Critical

Even with classic clinical findings of appendicitis, imaging is essential because:

• Clinical assessment alone misdiagnoses appendicitis in 34-68% of cases, leading to negative appendectomy rates as high as 25% when surgery is performed without imaging 1, 2
• Preoperative CT reduces the negative appendectomy rate to 1.7-7.7%, dramatically improving patient outcomes 2
• CT identifies alternative diagnoses in 23-45% of patients presenting with right lower quadrant pain and classic symptoms, fundamentally changing management 1, 2

Diagnostic Performance of CT

CT abdomen and pelvis with IV contrast demonstrates:

• Sensitivity of 85.7-100% for detecting acute appendicitis 1, 2, 3
• Specificity of 94.8-100% for ruling out appendicitis 1, 2, 3
• Ability to detect perforation, abscess formation, and periappendiceal inflammation with high reliability 2

Common Alternative Diagnoses Detected by CT

In young women with right lower quadrant pain, CT frequently identifies:

• Gynecologic pathology in approximately 21.6% of alternative diagnoses, including ovarian torsion, ruptured ovarian cyst, ectopic pregnancy, and pelvic inflammatory disease 2
• Gastrointestinal conditions in 46% of alternative diagnoses, including right-sided colonic diverticulitis (8% of cases), Crohn's disease, and intestinal obstruction 2
• Genitourinary pathology such as ureteral stones and pyelonephritis 2

Optimal CT Protocol

Order CT abdomen and pelvis with IV contrast only (no oral contrast) because:

• This protocol achieves 90-100% sensitivity and 94.8-100% specificity 2, 3
• Avoiding oral contrast eliminates delays associated with contrast administration without compromising diagnostic accuracy 2, 4
• Rapid acquisition allows for timely surgical consultation when appendicitis is confirmed 2

Critical Pitfalls to Avoid

• Do not rely on absence of fever to exclude appendicitis—fever is absent in approximately 50% of appendicitis cases 2, 3
• Do not proceed directly to appendectomy without imaging, as this exposes the patient to unnecessary surgery in up to 25% of cases 1, 2
• Do not order plain abdominal X-rays, as they provide very limited sensitivity for detecting appendicitis 2
• Do not delay imaging if symptoms persist or worsen during any observation period 2

Management After CT

• If appendicitis is confirmed: Proceed immediately to surgical consultation for appendectomy 2, 3
• If perforated appendicitis with abscess: Consider percutaneous drainage followed by interval appendectomy 2, 3
• If CT is negative but clinical suspicion remains high: Diagnostic laparoscopy provides both diagnostic and therapeutic value 2, 3
• If alternative diagnosis identified: Triage to appropriate specialty management 2

Why Not the Other Options?

• Option A (Open appendectomy): Proceeding directly to surgery without imaging risks a 14.7-25% negative appendectomy rate and misses alternative diagnoses in nearly half of cases 2
• Option C (Abdominal X-ray): Plain radiography has very limited sensitivity for appendicitis and does not adequately evaluate alternative diagnoses 2
• Option D (IV fluids and 24-hour observation): While supportive care is appropriate, delaying definitive imaging increases the risk of perforation and associated morbidity, and observation alone does not provide a diagnosis 2