One bite or two? A prospective trial comparing colonoscopy biopsy technique in patients with chronic ulcerative...

Surveillance for mucosal dysplasia in patients with chronic ulcerative colitis requires numerous biopsies (often over 40). The aim of the present study was to determine if two biopsies could be obtained with jumbo forceps before removing them from the instrument (double biopsy technique), as opposed to one biopsy per pass, without sacrificing the histological quality of the biopsy material.

Twelve patients with chronic ulcerative colitis underwent colonoscopy, and four-quadrant biopsies were obtained at 10 cm intervals. For biopsies at each interval, two quadrants were obtained using the double biopsy technique and the other two quadrants were obtained individually. Two pathologists blinded to the biopsy technique examined each biopsy for technical and diagnostic qualities. The primary outcome was the histological adequacy in the evaluation of dysplasia.

A total of 468 biopsies were obtained. A higher proportion of double-biopsy specimens were inadequate for dysplasia assessment compared with single-biopsy specimens (OR=2.78, 95% CI 1.37 to 5.59; P=0.005). In the double biopsy technique group, 14 samples were deemed inadequate due to actual tissue specimen loss, compared with eight samples in the single biopsy technique. However, when analysis was repeated using only the retrieved specimens, the double biopsy technique continued to be at higher risk of obtaining inadequate specimens (OR=14.5, 95% CI 2.1 to 98.7; P=0.006).

The results of the present study suggest that the double biopsy technique is vulnerable to specimen loss and reduced histological quality, and the adoption of this technique as an equivalent method for tissue sampling may be premature.