CT Abdomen and Pelvis with IV Contrast is the Next Step
In a 21-year-old female presenting with 12 hours of right lower quadrant pain and rebound tenderness, obtain CT abdomen and pelvis with IV contrast immediately—do not proceed directly to appendectomy without preoperative imaging. 1, 2
Why Imaging Before Surgery is Essential
Even with classic clinical findings of appendicitis (RLQ pain, rebound tenderness), preoperative CT is mandatory because:
- Clinical assessment alone misdiagnoses appendicitis in 34-68% of cases, leading to negative appendectomy rates of 14.7-25% when imaging is omitted 3, 4
- Preoperative CT reduces negative appendectomy rates to 1.7-7.7%, dramatically improving diagnostic accuracy 3
- In reproductive-age women specifically, CT reduces negative appendectomy rates from 42% to 17% (p < 0.038), while saving an average of $1,412 per patient 4
Diagnostic Performance of CT
CT abdomen and pelvis with IV contrast demonstrates:
- Sensitivity of 85.7-100% and specificity of 94.8-100% for acute appendicitis 1, 3
- Identifies alternative diagnoses in 23-45% of patients presenting with RLQ pain and classic symptoms, fundamentally changing management 1, 3
- Detects gynecologic pathology in 21.6% of alternative diagnoses—particularly important in a 21-year-old female 3
Critical Alternative Diagnoses CT Will Detect
In young women with RLQ pain and peritoneal signs, CT frequently identifies:
- Gynecologic emergencies: ovarian torsion, ruptured ovarian cyst, ectopic pregnancy, pelvic inflammatory disease 3
- Right colonic diverticulitis (8% of RLQ pain cases) 1
- Bowel obstruction (3% of cases) 1
- Ureteral stones 1
- Inflammatory bowel disease (terminal ileitis) 3
Why Not Proceed Directly to Surgery
- The "classic" presentation occurs in only ~50% of appendicitis cases—fever is absent in 50% of patients, making clinical diagnosis unreliable 3, 5
- Immediate appendectomy without imaging carries a 25% negative appendectomy rate in reproductive-age women 3, 4
- CT changes management in 43% of patients initially suspected to have appendicitis clinically 5
Optimal CT Protocol
Order CT abdomen and pelvis with IV contrast only (no oral contrast needed):
- IV contrast alone provides rapid acquisition without delays from oral contrast administration 3
- Maintains 90-100% sensitivity and 94.8-100% specificity 1, 6
- Allows assessment for perforation, abscess formation, and periappendiceal inflammation 3
Management After CT
If CT confirms appendicitis: Proceed to immediate surgical consultation for appendectomy 3
If CT shows perforated appendicitis with abscess: Consider percutaneous drainage followed by interval appendectomy 3
If CT is negative but shows alternative diagnosis: Manage accordingly (gynecologic consultation, medical management, etc.) 1, 3
If CT is completely negative: The patient can often be discharged with close follow-up, as CT correctly excludes surgical pathology in 96.8% of cases 7
Common Pitfalls to Avoid
- Do not assume rebound tenderness equals appendicitis—peritoneal signs occur with multiple gynecologic and GI conditions in young women 3
- Do not skip imaging in reproductive-age women—this population has the highest rate of alternative diagnoses requiring different management 4
- Do not order ultrasound first in this scenario—with clear peritoneal signs and 12 hours of symptoms, CT provides definitive diagnosis without the 20-81% non-visualization rate of ultrasound 2
- Do not order abdominal X-ray—it provides very limited sensitivity for appendicitis and other acute abdominal pathology 3