Anal manometry improves the outcome of surgery for fistula-in-ano

The aim of this prospective study is to investigate whether anal manometry is useful in orienting the surgical policy and improving the clinical and functional results following surgery for fistula-in-ano. Anal manometry was performed preoperatively and postoperatively in 96 patients. The results of surgery, in terms of both fecal soiling and recurrence rate, were analyzed and compared with those of another group of 36 subjects. Some operative maneuvers, such as internal sphincterotomy, laying open of the fistula with division of striated muscle, or use of a seton, were carried out according to the preoperative sphincter pattern as shown by anal manometry in the first group. A standard procedure was followed in the control group. The recurrence rate was 3 percent in the anal manometry group and 13 percent in the control group (P less than 0.01); postoperative soiling occurred in 14 percent of patients in the anal manometry group compared with 31 percent of patients in the control group (P less than 0.001). The functional results in transsphincteric and suprasphincteric fistulas, which are usually considered at higher risk for postoperative incontinence, were better in the anal manometry group, due to greater use of the seton. No increase in recurrence rate was observed in these complex fistulas after anal manometry. Internal sphincterotomy led to a disordered continence, mainly when associated with division of striated muscle; a significant decrease in resting tone from 56 +/- 22 to 47 +/- 50 and voluntary contraction from 114 +/- 30 to 85 +/- 28 mm Hg (mean +/- S) was found after surgery in patients with soiling. In conclusion, the routine use of anal manometry may be recommended in the management of patients with fistula-in-ano as it improves the clinical and functional outcome of surgery.