INTERINSTITUTIONAL COMPARISON OF FROZEN-SECTION CONSULTATION IN SMALLHOSPITALS - A COLLEGE-OF-AMERICAN-PATHOLOGISTS Q-PROBES STUDY OF 18532 FROZEN-SECTION CONSULTATION DIAGNOSES IN 233 SMALL HOSPITALS

Objective.-To study pathology intraoperative consultation practices an d the accuracy of diagnoses made by frozen section. Design.-In 1994, p articipants in the College of American Pathologists Q-Probes laborator y quality improvement program each completed questionnaires and prospe ctively collected data on up to 20 frozen section procedures performed over a 5-month period. Setting.-Surgical pathology laboratories servi ng private and public hospitals with 300 or fewer occupied beds. Parti cipants.-Two hundred thirty-two North American institutions and one Ne w Zealand institution. Main Outcome Measures.-The discordance and defe rral rates of frozen section diagnoses and the reasons for frozen sect ion discordance relative to corresponding diagnoses made on permanent (paraffin) sections. Calculation of frozen section discordance rates e xcluded diagnoses of subtypes or grade of malignancy, biopsies on spec imens in which there was no gross lesion leg, mammographic specimens), thyroid follicular lesions, tissue taken only to determine adequacy f or other studies leg, estrogen-binding proteins), and frozen sections performed to evaluate margins of specimens oriented en face. Results.- Out of 18 532 frozen section diagnoses performed on 327 884 surgical c ases, 859 (4.6%) diagnoses were deferred until permanent sections were available for review; 17 357 (98.2%) nondeferred diagnoses agreed wit h, and 316 (1.8%) disagreed with, those diagnoses rendered on permanen t sections. The most common cause of discordance was underdiagnosis of neoplasia, usually due to block- or tissue-sampling errors. Conclusio ns.-We recommend that laboratories routinely monitor frozen section di scordance, cut additional sections deeper into the frozen block and/or sample additional tissue when the initial frozen section diagnosis is negative or nonproductive, reconcile all discordant frozen section di agnoses in the final report, and periodically assess the value of perf orming frozen section examinations.