Flow-chart of the technical biopsing aspects assessed in the present study. Bioelectrical measurements were performed for rectal biopsies (n = 580) from all the individuals enrolled in the study (n = 132) to assess tissue viability . Bowel preparation included enemas of either NaCl 0.9%, glycerol 12% (v/v) or oral mannitol 20% (w/v) solutions. Two different biopsy forceps were tested, namely jumbo (3.4 mm Ø) and standard (2.5 mm Ø), independently of bowel preparation. Macroscopic and histologic evaluation of rectal biopsies was achieved for 107 and 78 individuals, respectively. Patient assessment surveys were carried out for 75 individuals undergoing sigmoidoscopy with rectal biopsy collection by biopsy forceps, divided into 4 age groups, namely (yrs): 0–9; 10–9; 20–29; ≥30.