We wanted to determine the usefulness of the computed tomography (CT) findings for making the diagnosis between periappendiceal inflammation (PAI) with appendicitis and pelvic inflammatory disease (PID) for the women presenting with right lower quadrant pain.

We retrospectively analyzed the CT findings of 83 women with right lower quadrant pain: PAI in 36 and PID in 47 patients. We reviewed the CT images, including the appendiceal diameter and the enhancing wall thickening, the cecal thickening, the location of the appendix, thickening of the right anterior renal fascia, abscess, mesenteric fatty infiltration, ascites, heterogeneous uterine enhancement and paralytic ileus. Statistical analysis was performed by using the t-test for the diameter of appendix, and the x2 test or Fisher's exact test for the CT findings.

The mean diameter of the appendix was 11.0±3.4 mm for the PAI subjects and it was 6.7±2.0 mm for the PID subjects (p<0.0001). Wall thickening of the appendix was more commonly detected in PAI (25 subjects, 69%) than in PID (15 subjects, 32%) (p=0.0007). Thickening of the right anterior renal fascia was more commonly detected in PAI (18 subjects, 50%) than in PID (7 subjects, 15%). Cecal thickening, ascitis, heterogeneous uterine enhancement and paralytic ileus were not significantly different between PAI and PID. Abscess and mesenteric fatty infiltration were more frequently detected in the RLQ, and in the abdomen or pelvic cavity in PAI and PID, respectively (p<0.05). There was no significant difference in the distribution of ascites between the diseases.

The CT findings of the appendiceal diameter, enhancing wall thickening and thickening of the right anterior renal fascia are useful for making the diagnosis of PAI. The abdominal and pelvic distributions of abscess and mesenteric fatty infiltration are highly suggestive findings of PID.