Enough is enough: how many rectal suction biopsies do you need to diagnose Hirschsprung's disease?

Rectal suction biopsy (RSB) is the gold standard for diagnosing Hirschsprung's disease (HD) in infants. Despite being a common procedure, no standard exists on the number of biopsy specimens and their respective level within the rectum.

We conducted a retrospective review of epidemiological and pathological data of patients who underwent RSB at our institution between January 2011 and May 2022. During RSB we obtain 4 specimens: at 1 cm, 3 cm and 5 cm above the dentate line, besides one specimen at the dentate line. We used a logistic regression model for statistical analysis and included control variables (e.g. underlying disease, weight at first biopsy, gestational age).

A total of 92 patients underwent 115 biopsies, with an average of 3.77 specimens per session. Of the specimens taken at 1 cm above the dentate line 73.9% were conclusive, at 3 cm 75.9% and at 5 cm 79.2%. Specimens taken at the dentate line were squamous or transitional epithelia in 31.5% and therefore of no use for HD diagnostics. The specimen at 3 cm shows the highest discriminative power whether the biopsy session was diagnostic (p-value < 1%).

We propose that a total of three specimens, namely one at 1 cm, one at 3 cm and one at 5 cm above the dentate line, is enough to diagnose or exclude HD.