CT Abdomen and Pelvis with IV Contrast
For a 45-year-old male with right lower quadrant pain, decreased appetite, and RLQ tenderness concerning for appendicitis, obtain CT abdomen and pelvis with IV contrast as the next step in management. 1, 2
Rationale for CT as First-Line Imaging
CT abdomen and pelvis with IV contrast is rated 8/9 on the ACR Appropriateness Criteria for suspected appendicitis in adults, providing sensitivity of 85.7-100% and specificity of 94.8-100%. 1, 2
The American College of Radiology designates CT with IV contrast as "usually appropriate" for adults presenting with classic clinical features of appendicitis (RLQ pain, anorexia, tenderness), which this patient demonstrates. 1
CT has reduced negative appendectomy rates from historical 14.7% to 1.7-7.7%, directly improving patient outcomes by preventing unnecessary surgery while identifying those requiring urgent intervention. 2
Beyond appendicitis, CT identifies alternative diagnoses in 94.3% of cases when appendicitis is not present, including colitis, inflammatory bowel disease, diverticulitis, and other conditions requiring hospitalization or invasive treatment. 1
Why Not Ultrasound First?
While ultrasound is rated 6/9 and can be used as initial screening followed by CT if inconclusive, this stepwise approach is primarily recommended for radiation reduction in younger patients or when clinical suspicion is lower. 1, 2
In a 45-year-old male with classic appendicitis presentation, the high pre-test probability justifies proceeding directly to the most accurate test rather than risking diagnostic delay with a potentially inconclusive ultrasound. 1, 2
The WSES guidelines emphasize that early clinical evaluation should optimize diagnostic testing to enable earlier implementation of proper management—delaying definitive imaging risks appendiceal perforation. 1
Technical Considerations
Oral or rectal contrast is not necessary and may be omitted based on institutional preference, avoiding delays that could increase perforation risk. 1
IV contrast is essential for optimal visualization of vascular structures, solid organs, and inflammatory changes. 1
If low-dose CT protocols are available, they reduce radiation exposure to approximately 22% of standard-dose without compromising diagnostic accuracy. 1
Clinical Context and Pitfalls
The patient's presentation—periumbilical pain migrating to RLQ with anorexia and localized tenderness—represents classic appendicitis symptoms that warrant urgent imaging rather than observation. 1
Common pitfall: The patient is described as "afebrile" with "stable vitals," but fever and leukocytosis are present in only 50% of appendicitis cases and their absence does not exclude the diagnosis. 3
Physical examination alone has notoriously poor diagnostic accuracy for appendicitis, with negative appendectomy rates as high as 25% when relying on clinical assessment alone. 3
Migratory pain from periumbilical to RLQ increases the likelihood of appendicitis and should prompt definitive imaging. 1
Alternative Diagnoses to Consider
CT will also evaluate for non-appendiceal causes of RLQ pain including: cecal diverticulitis, Crohn's disease, infectious colitis, mesenteric adenitis, epiploic appendagitis, and in males, testicular torsion with referred pain. 1
If gynecologic pathology becomes a concern during evaluation, pelvic ultrasound may be added, but this is less likely in a male patient. 1
Management After Imaging
If CT confirms appendicitis, proceed to surgical consultation for appendectomy (laparoscopic preferred). 1
If CT shows periappendiceal abscess, management may include percutaneous drainage with interval appendectomy versus immediate surgery depending on abscess size and clinical status. 1
Empiric antibiotics covering anaerobic bacteria (metronidazole) and gram-negative organisms (fluoroquinolone or cephalosporin) should be initiated if appendicitis is confirmed, as intra-abdominal infections require antimicrobial therapy in conjunction with surgical intervention. 1, 4