Potential renal transplant candidates with end-stage renal disease (PtESRD) often experience inadequate bowel preparation due to restrictions on bowel cleansing agents, limited fluid intake, comorbidities, and the pharmacologic effects of their medications.

We aimed to evaluate the safety and effectiveness of a revised, personalized bowel preparation protocol in improving colonoscopy outcomes among PtESRD patients undergoing pre-transplant evaluation.

All patients referred for screening/surveillance colonoscopy by the nephrologist were included unless canceled for non-preparation-related medical reasons. A personalized preparation protocol was implemented between 06/2024-02/2025, including a 5-days low-fiber diet, daily bisacodyl, tailored fluid intake, and reduced-volume PEG 3350 with ascorbic acid (PtESRD group). The control group (historical cohort, 01/2022–05/2024) received standard preparation: 2-days low-fiber followed by clear liquid diet and 3 liter PEG 3350 solution. The groups were compared by clinical and demographic characteristics. The primary outcome was inadequate bowel preparation, defined as a Boston Bowel Preparation Scale (BBPS) score<6. Risk factors were evaluated using logistic regression analysis.

A total of 156 inpatients were included (mean age 65.2 ± 0.7 years, range 39.1–84.5 years; 116 [74.4%] male). Of these, 62 patients (39.7%) received bowel preparation with the modified PtESRD protocol, while 94 patients (60.3%) followed the standard protocol. Clinical and demographic characteristics, including age, sex, BMI, diabetes mellitus, and use of motility-affecting medications or disorders, were similar between the groups (p=NS for all). Active smoking was more prevalent in the control group (23.4% vs. PtESRD 8.1%, p=0.017). The proportion of patients with a BBPS<6 was significantly lower in the PtESRD group compared to control (40.3% vs. 66%; P=0.002). This effect was consistent across all three colonic segments: right (33.9% vs. 62.8%, p<0.001), transverse (25.8% vs. 45.7%, p=0.012) and left (23.0% vs. 53.8%, p<0.001). The proportion of complete preparation failures (BBPS=0) was significantly lower among ptESRD (3.2%) compared to 27.7% among controls (p<0.001). Complete colonoscopy, defined as cecal or ileal intubation, was achieved in 98.4% of PtESRD patients compared to 81.9% of controls (p < 0.001). In multivariate regression analysis, the PtESRD protocol was an independent protective factor, reducing the rate of inadequate bowel preparation by 65% (OR 0.365, 95% CI 0.180–0.741, p = 0.005), adjusted for sex, age, BMI, active smoking, and diabetes mellitus. 

This proof-of-concept study shows that the PtESRD protocol improves bowel preparation and colonoscopy completion rates in hospitalized ESRD transplant candidates. Its independent predictive value supports its use and highlights the potential of tailored protocols in high-risk patients. Further prospective studies are needed to confirm these findings and guide broader implementation.