Appendiceal Endometriosis: Is Diagnosis Dependent on Pathology Evaluation? A Prospective Cohort Study

STUDY OBJECTIVE: To evaluate the diagnosis of appendiceal endometriosis (AppE) in coincidental appendectomy specimens using standard versus modified histopathologic analysis. DESIGN: Prospective analysis of 300 consecutive patients undergoing coincidental appendectomy at the time of a primary gynecologic procedure. SETTING: Academic tertiary referral hospital in the northeastern United States. PATIENTS: Women aged 22 to 52 years undergoing gynecologic surgery for the management of endometriosis or chronic pelvic pain between 2013 and 2015. INTERVENTIONS: Each appendix specimen underwent standard pathologic analysis with 4 sections performed. Modified pathologic analysis, consisting of standard analysis plus serial sectioning and complete evaluation of the appendix and mesoappendix, was then performed. The first pathologist reviewed all the slides to render a diagnosis. The slides of the subjects with abnormal pathology were rereviewed. On rereview, the diagnosis was confirmed, and the data on which protocol, standard or modified, achieved the diagnosis was rendered. The pathologist performing the second review was blinded to whether the slides from the standard or modified histopathology protocol achieved the original diagnosis. This allowed each specimen to serve as its own control. MEASUREMENTS AND MAIN RESULTS: The primary outcome is the detection of AppE. The standard analysis identified endometriosis in 7.7% (n=23) of appendiceal specimens, whereas the modified analysis identified endometriosis in 10.0% (n=30; odds ratio 1.3; confidence interval, 1.1-1.7; p=.01). When all pathology findings were combined, the standard analysis identified abnormal pathology in 9.3% (n=28) of the specimens, whereas the modified analysis identified abnormal pathology in 12.3% (n=37; odds ratio 1.4; confidence interval, 1.1-1.7; p <.01). Other abnormal appendiceal pathology identified in this study included polyps, neuroendocrine tumors, and acute appendicitis. The average number of slides required for the standard analysis was 1.4 compared with 4.9 slides for the modified analysis. At this institution, the average increase in the cost of slide production for the modified protocol was $12.07. CONCLUSION: Modified pathologic analysis resulted in a significantly higher rate of diagnosis of endometriosis and abnormal pathology in coincidental appendectomy performed during a primary gynecologic procedure for endometriosis and/or chronic pelvic pain. The use of a standard pathologic protocol likely contributes to underdiagnosis of AppE. The implementation of a modified histopathologic protocol should be considered for improving diagnosis rates of appendiceal pathology in coincidental appendectomy specimens.