Background To evaluate feasibility, safety, and outcomes of a reverse bowel cleansing colonoscopy using magnesium sulfate, sodium sulfate and potassium sulfate concentrate oral solution for patients presenting with acute lower gastrointestinal bleeding (LGIB), with suboptimal bowel preparation following emergency enemas.

Methods A prospective study was conducted between January 2023 and December 2023. Patients admitted to the intensive care unit (ICU) with a primary diagnosis of severe lower gastrointestinal bleeding were enrolled. And an immediate colonoscopy within the first 8h after saline solution enema without oral bowel preparation was performed, aided by water jet pumps and mechanical suction devices. Magnesium sulfate, sodium sulfate and potassium sulfate concentrate oral solution was added to the water jet tank. During the colonoscopy procedure, the solution was injected from left to right through the colon and ended up at the cecum. Completion of the emergency colonoscopy was typically marked by the insertion of the scope to the ileocecal junction. The completion rate, the time taken for the procedure, localization and cause of intestinal bleeding, and treatment strategies, as well as monitoring the patients for any recurrent bleeding and mortality events within 30 days post-colonoscopy were documented and analyzed.

Results In total, 18 patients presenting with hematochezia were evaluated. No mortality events occurred within 30 days post-colonoscopy. The completion rate of the emergency colonoscopy was 88.9% (16/18). However, endoscopic visualization was felt to be adequate to definitively identify the source of bleeding in all procedures, with no colonoscopy repeated due to inadequate preparation. Mean insertion and withdrawal time were 6.33±3.27min (2-13 min) and 12.50±2.88min (7-17min), respectively. Sources of LGIB were identified in 61.1% of first attempted colonoscopies, and the location of 71.4% of cases was in the right colon. Endoscopic intervention was required in 66.7% of cases and rebleeding occurred in 21.5%. Two cases need colectomy and recurrent bleeding of the colonic diverticulum after the endoscopic intervention.

Conclusions Hydroflush emergency colonoscopy with magnesium sulfate, sodium sulfate, and potassium sulfate concentrate oral solution is feasible and safe in acute LGIB, and it deserves further research.