Donut Leave it to Chance: Frozen Circumferential Biopsies Reduce Rates of Transition Zone Pull-through

This study evaluates the role of intraoperative frozen-section circumferential biopsies ("donuts") in preventing transition zone (TZ) pull-through (PT) in patients with Hirschsprung disease (HSCR).

We performed a single-institution retrospective review of intraoperative and final pathology reports for all PTs between 2020-2026 in which a frozen-section donut was obtained from planned anastomotic site based on previously confirmed normal full-thickness biopsy. If the initial donut was abnormal, additional proximal donuts were obtained. Donuts were considered normal when ganglion cells were present circumferentially, and fewer than two hypertrophic submucosal nerves were observed per high-power field.

Frozen-section donuts were sent for intraoperative consultation in 134 PTs. Fourteen cases required two donuts, and two cases required three; among these 16 cases, 14 were due to abnormal pathology, and two for technical reasons. Final pathology was concordant with frozen-section findings in 130 patients (97.0%). Additional donuts prevented TZ PT in 13 patients (9.6%). Two patients (1.5%) had circumferential ganglion cells with hypertrophic nerves on final pathology despite normal frozen-section results. Non-circumferential ganglion cells were identified in two patients: one was accepted after two abnormal donuts and discussion with family; the other resulted from inaccurate donut processing.

In this series, frozen-section circumferential biopsies reduced the incidence of TZ in PT, with only 3.0% of patients demonstrating TZ on final pathology and an additional 9.6% prevented intraoperatively. Routine use of this technique, alongside ongoing improvements in pathologic processing, enhances intraoperative decision-making and may contribute to safer, more effective PT procedures for HSCR.

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