Is manometry essential for surgery of chronic fissure-in-ano?

Although many studies reported the association between high anal sphincter pressures and anal fissures, one question is open to date: is manometry really necessary for surgical management/does manometry influence the outcome?

Between October 1, 1990 and December 31, 1991, lateral sphincterotomy was performed in 177 patients with chronic anal fissure. In all patients the operation was performed as an outpatient procedure under local anesthetic. Electromanometry of the anal canal was carried out preoperatively to demonstrate the raised resting pressure profile within the anal canal. At the same time the maximum squeezing pressure was determined by electromanometry, and electromyography was performed to detect dysfunction of the external sphincter or the levators. The control group consisted of 14 proctologically healthy patients with a resting pressure of 74.4 +/- 8.9 and a maximum squeezing pressure of 130.2 +/- 15 (cm H2O). On the basis of resting pressures determined in healthy patients, an upper limit of 90 was defined as normal, taking into account the standard deviation and standard error rate. For statistical comparison patients were divided into two groups, retrospectively. All patients in Group A had a resting pressure of < or = 90, and all patients in Group B had a resting pressure of > 90. Six weeks after operation electromanometry was again performed to determine the resting pressure profile and maximum squeezing pressure of the sphincter system, and patients were examined to determine whether the fissure had healed.

As a result of the lateral sphincterotomy, the resting pressure was lowered in all patients from 106.6 +/- 21.5 to 80.9 +/- 10.4 and maximum squeezing pressure from 149.3 +/- 27.6 to 135.3 +/- 27.2. Both results were highly significant (P < 0.001, chi-squared). Regarding either reduction in postoperative resting pressure or continence, Groups A and B did not differ statistically. In Group A soiling occurred in 3.2 percent and Grade 1 incontinence in 3.2 percent (1 patient each), and in Group B only one patient (0.7 percent) complained of soiling. Recurrences occurred in 9.7 percent of patients in Group A and in 2.1 percent of patients in Group B (3 patients in each case).

Electromanometric examinations showed that internal sphincterotomy significantly reduces pressure within the anal canal, thus permitting the anal fissure to heal. No significant continence problems were observed. Although manometric selection of patients leads to different results regarding both postoperative continence and recurrence, these differences are not statistically significant. Therefore, it follows that, in experienced hands and using a standardized technique, manometry before surgical management of anal fissure by lateral sphincterotomy is probably superfluous.