Routine use of circumferential 'Doughnut' biopsy in pull through surgery for hirschsprung's disease: Advantages and limitations

Aims: The aim of this study was to review the use of the on-table "doughnut" biopsy for frozen section assessment of bowel in the operative management of Hirschsprung's disease (HD). Methods: This was a single-center retrospective review of doughnut histopathology reports, operation notes, and slides from 2010 to 2017. Data were assessed for the presence of transition zone (TZ) features and the subsequent decision as to the level of pull-through. Results: Fifty-five patients had a doughnut biopsy taken as part of their intraoperative frozen section histopathology for pull-through for HD during the study period. Forty-eight required a single doughnut, six required a second more proximal doughnut, and one required a third doughnut. Of the 55 first doughnuts, 37 were identified as normal bowel, 17 were TZ, and not defined in the report in one case. Of the 17 TZ doughnuts, 8 were accepted for pull-through and 7 underwent second doughnuts (normal = 4 and TZ = 3). The third doughnut (one case) was normal. TZ was accepted for pull-through in 10/54 (18.5%) patients despite the use of a doughnut. However, TZ was avoided in six (11.1%), where the single-point biopsy was "normal." Conclusions: The doughnut allows the entire circumference of pull-through level to be assessed, enabling TZ identification that can be missed by single seromuscular biopsies. This allows identification and avoidance of TZ pull-through, although sometimes, it is accepted for other reasons.