Interinstitutional comparison of frozen section consultation in small hospitals: a College of American Pathologists Q-Probes study of 18,532 frozen section consultation diagnoses in 233 small hospitals

Abstract

Objective: To study pathology intraoperative consultation practices and the accuracy of diagnoses made by frozen section.

Design: In 1994, participants in the College of American Pathologists Q-Probes laboratory quality improvement program each completed questionnaires and prospectively collected data on up to 20 frozen section procedures performed over a 5-month period.

Setting: Surgical pathology laboratories serving private and public hospitals with 300 or fewer occupied beds.

Participants: Two hundred thirty-two North American institutions and one New Zealand institution.

Main outcome measures: The discordance and deferral rates of frozen section diagnoses and the reasons for frozen section discordance relative to corresponding diagnoses made on permanent (paraffin) sections. Calculation of frozen section discordance rates excluded diagnoses of subtypes or grade of malignancy, biopsies on specimens in which there was no gross lesion (eg, mammographic specimens), thyroid follicular lesions, tissue taken only to determine adequacy for other studies (eg, 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 cases, 859 (4.6%) diagnoses were deferred until permanent sections were available for review; 17,357 (98.2%) nondeferred diagnoses agreed with, and 316 (1.8%) disagreed with, those diagnoses rendered on permanent sections. The most common cause of discordance was underdiagnosis of neoplasia, usually due to block- or tissue-sampling errors.

Conclusions: We recommend that laboratories routinely monitor frozen section discordance, 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 diagnoses in the final report, and periodically assess the value of performing frozen section examinations.