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PTH-232 Retention of the ileocolic sphincter in a modified brooke ileostomy decreases the loss of key electrolytes in ileostomy fluid of patients who have undergone colectomy for ulcerative colitis

Introduction Previous published work has shown that modifying the traditional Brooke ileostomy (MBI) by retaining the ileocolic sphincter (ICS) preserves a functional high pressure zone which may improve the clinical function of the stoma. The effect of this modification (MBI) on ileal fluid biochemistry has not been reported previously by this group. This study reports the results of this modification on the electrolyte concentration in ileal fluid and also its influence on the reabsorption of urinary electrolytes by way of renal compensation. Method Ileostomy fluid specimens were collected from stoma bags in two groups of patients. Group 1 – ileocolic sphincter retained (MBI); controls – patients undergoing formation of a loop ileostomy (10 cm from the ileocolic junction) as part of an operation for rectal cancer. These samples were collected from patients and controls from stoma bags after an overnight fast. Additionally, 24hr urine collections were made from MBI patients and controls to measure the concentration of routine urinary electrolyes and, in addition, urinary magnesium and calcium. In order to compensate for the changes in urinary volume, which can be accounted for by varied water intake and different kidney efficiency, the urine results for each analyte measured were adjusted against the change in creatinine using a standard formula: adjusted concentration = mmol of analyte/mmol of urinary creatinine. Contemporaneously, routine serum electolytes were collected from patients and controls. This study was approved by the regional ethics committee and statistical analysis was performed using the Wilcoxon paired test where appropriate with p < 0.05 considered significant. Results 13 MBI patients (mean (SD) age - 52.5(17.8)yrs) were compared with 11 controls age −58.4 (10.9) yrs). Routine serum and urinary biochemistry (except sodium) in both groups was the same. Urinary sodium, calcium and magnesium were raised in patients with a modified Brooke Ileostomy (MBI), when compared to controls: urinary sodium, 8.2 ± 4.5 vs. 4.43 ± 2.19 mmols/mmol creatinine, p < 0.05, urinary calcium, 0.28 ± 0.15 vs. 0.15 ± 0.13 mmols/mmol creatinine, p < 0.03 and urinary magnesium, 0.21 ± 0.09 vs. 0.08 ± 0.04 mmols/mmol creatinine, p < 0.01. Electrolyte concentrations in ileal fluid in both patients (MBI and controls) was the same. Conclusion These results suggest that retention of the ICS in an ileostomy (MBI) has beneficial effects on the retention of ileal sodium, calcium and magnesium by virtue of the reduced reabsorption of these electrolytes from the MBI patients’ urine. Further work is required to confirm this initial finding. Disclosure of interest None Declared.