Can We Rely on Frozen Sections of a Rectal Biopsy for One-stage Trans-anal Pull-through Operation in Hirschsprung's Disease?

OBJECTIVE Successful results after one-stage trans-anal pull-through (OSTAPT) operation for Hirschsprung's disease (HD) depend on accurate identification of the aganglionic segment in intra-operative frozen section (FS). Misinterpretation of the findings of the rectal biopsy is an anxiety-evoking pitfall for the surgeon. This study aims to describe our experiences in comparing results of FS and permanent Section (PS) rectal biopsies in children with HD who were candidates for OSTAPT in a single-step operation. METHODS Subjects under the age of 14 years, admitted from March 2000 to July 2008 in a university-affiliated children's hospital for open rectal biopsy to diagnose HD were included in the study. All biopsies were taken 2-3 cm above the dentate line. 210 specimens of full-thickness rectal biopsy were obtained for both frozen section and permanent biopsy from all patients, examined by two well experienced pediatric pathologists for ascertaining the presence of ganglion cells, and the results were compared. Analysis was performed by SPSS Software version 11.5. FINDINGS Two-hundred one infants and children underwent FS rectal biopsy to exclude HD. Positive results were seen in 63.8% of the specimens examined as PS and in 58.3% of FS samples. 93.9% of positive results in FS studies were confirmed by PS studies. 6.1% of FS reports were false positive and 21.7% were false negative (P<0.001). The sensitivity of FS was 85.8% and specificity 90.2%. Positive predictive value (PPV) was 93.9% and negative predictive value (NPV) was 78.3% in FS studies (P<0.001). The accuracy of FS was 80.4%. CONCLUSION Although FS of the rectal biopsy is useful in defining the aganglionic segment during operation, according to this study, it cannot be used as the sole base for performing primary pull-through operation before the results of the permanent section are on hand.