# Tolerability and impact on postoperative morbidity of preoperative bowel preparation in Crohn’s disease patients: results of prospective observational study

## TL;DR

This study examines whether preoperative bowel prep causes issues in Crohn’s patients and finds it is generally safe.

## Contribution

The study provides new evidence that incomplete bowel preparation does not increase postoperative complications in Crohn’s disease patients.

## Key findings

- 29% of patients experienced nausea, vomiting, or abdominal pain during bowel prep.
- Incomplete bowel prep was not linked to higher anastomotic complication rates.
- Small bowel dilatation was observed in 32% of patients but did not significantly increase surgical conversion rates.

## Abstract

Preoperative mechanical bowel preparation (MBP) and oral antibiotics (OA) are widely used to decrease the risk of postoperative septic complications after colorectal resections. Unfortunately, it is not clear whether bowel preparation can lead to symptoms of small bowel obstruction, which might even increase the risk of postoperative morbidity.

Consecutive Crohn’s disease patients undergoing bowel resections with formation of ileocolic or colocolic anastomosis were included in the present prospective observational study. Urgent surgery, surgery without preoperative MBP, colorectal cancer, and fecal diversion were exclusion criteria. A polyethylene glycol solution (2 L) was used for MBP. OA consisted of paramomycin and metronidazole taken at 7 p.m. and 11 p.m. at the evening before surgery. Occurrence of complications at the anastomotic site (leakage, peritonitis, abscess, or fistula in direct proximity to the anastomosis) was a primary outcome measure. Complications of MBP were recorded. Mechanical bowel preparation was defined as “incomplete” when patients took a lesser amount of MBP solution than scheduled.

Between 2016 and 2024, ileocolic or colorectal resections with formation of an anastomosis were performed in 284 patients with Crohn’s disease. Nausea, vomiting, or abdominal pain occurred during the MBP in 29% of patients (n = 78), leading to termination of intake in 53 patients (19%). Women (p < 0.001), patients hospitalized urgently because of acute abdominal pain (p = 0.008), patients presenting with severe anemia before surgery (p = 0.007), and patients scheduled for resections completed by ileocolic anastomosis as opposed to colocolic or colorectal anastomosis (p = 0.01) demonstrated a significantly increased risk of incomplete MBP. Thirty-two percent of patients demonstrated apparent dilatation of small bowel at the time of surgery. The incidence of anastomotic complications was 4% in patients who were able to complete MBP and 7.5% after an incomplete MBP (p = 0.27). There were no deaths. The conversion rate from laparoscopy to open surgery was increased in patients with small bowel dilatation (17% vs. 6%); however, the difference was not statistically significant (p = 0.13).

There is a considerable incidence of obstructive symptoms after preoperative mechanical bowel preparation in Crohn’s disease patients. Nevertheless, an incomplete MBP is not associated with increased risk of intra- or postoperative complications and can be used safely in that particular population.

The online version contains supplementary material available at 10.1007/s00384-026-05084-z.