Utility of saline infusion test in anal incontinence

Abstract

Objectives:Our aim was to evaluate the utility of the saline infusion test into the rectum in patients with anal incontinence and to dilucidate which factors could be related to the results of this test. Methods:The study has been performed in 22 healthy volunteers (l2F,IOM; age 46:':7 ys) and in 291 patients with anal incontinence (237F,54M; age 55:': 15 ). 84 patients related incontinence of liquids only and the other 207 incontinence of liquids and solids. Incontinence was always assessed according to the Miller's severity score, the presence of soiling, the need to wear a pad and the use of astringents. All subjects underwent a standard anorectal manometry rectal sensation. Saline infusion was performed introducing into the rectum a volume of 1500 mL at a constant rate of 60 mUmin by a pump. Volume of the first leak and total retained volume, so as the threshold of rectal sensation during the infusion was evaluated in all cases. Results: Saline leakage during the test was detected in 2 healthy volunteers (10%) and in 244 patients (84%). Mean percentage retention of the infused volume was 99:':2% in healthy people and 46:':36% in the incontinence group (p<O.OOI). Mean tolerated volume before leakage was 1458:':135 ml in healthy volunteers and 496:':511ml in patients (p<O.OOI).Taking the mean 2SD for controls as the cutoff, sensitivity. and specificity of the saline perfusion test were 81% and 95 % for retention percentage and 84% and 91% for first leakage. No statistical differences in sensitivity and specificity were found in patients with incontinence for liquids compared to patients with incontinence for liquids and solids. A significant correlation was observed when analyzing retention percentage versus the onset of leakage.Miller's scores, maximum resting pressure and squeeze anal pressure. Phatological saline infusion test was significantly associated to high Miller's severity scores, use of pad, presence of soiling, female gender and absence of rectal sensation during the performance test. Conclusions: Saline infusion test is adequate to discriminate anal incontinent patients from healthy continent volunteers. It may be helpful in the evaluation of patients with anal incontinence. The percentage of retention and the presence of abnormal leakage is associated to the severity of the incontinence, the female gender and the absence of rectal sensation during the test.