Acute non-traumatic abdominal pain by quadrant: relative yield of CT and clinical evaluation for diagnosis in 1000 patients

Objective To determine the relative diagnostic yield of contrast-enhanced CT in adults presenting with symptoms referable to a specific abdominal quadrant. Methods Electronic health records review systematically identified patients meeting the following inclusion criteria: adults (>= 18 years) undergoing IV contrast-enhanced abdominopelvic CT for acute non-traumatic symptoms referable to a specific abdominal quadrant (RLQ/LLQ/LUQ/RUQ). The CT-based diagnosis and any clinical diagnosis in the absence of CT diagnosis were recorded. The final cohort of 1000 subjects (mean age, 48.1 years; 647F/353M) consisted of consecutive sub-cohorts of 250 patients for each abdominal quadrant. Positive oral contrast was utilized in 91.6% (916/1000) of cases. Results A positive CT diagnosis was provided in 47.3% (473/1000) of all patients, and was highest for LLQ (58.8%) and RLQ (58.0%) symptoms, including diverticulitis and appendicitis in 23.6% and 24.8% cases, respectively. CT positivity was lower for the LUQ (34.4%) and RUQ (38.0%) (p < 0.0001), with no single diagnosis representing > 5% of cases. However, all quadrants provided valuable triage of 218 hospital admissions (21.8%), 83.0% were CT positive, whereas 62.7% of 782 discharged patients were CT negative. Only 7.0% of CT-negative patients were admitted. A clinical-only diagnosis was provided in 9.3% of the total cohort (93/1000), representing 17.6% of the CT-negative cohort (93/527). Conclusion The rate of positive CT diagnosis is considerably higher for the lower abdominal quadrants, predominately due to appendicitis and diverticulitis. However, CT results (positive vs. negative) for all four quadrants strongly correlated with hospital admission versus discharge. Clinical-only diagnosis represented < 10% of all cases.