The treatment of chronic fissure in ano with nitrate ointment

A chronic anal fissure may be regarded as an ischaemic ulcer. Until recently, its treatment necessitated surgical intervention to lower the tension of the internal sphincter (lateral internal sphincterotomy), or manual dilatation of the anus. A disadvantage of both methods is the risk of permanent sphincter injury resulting in reduced continence. Local application of ointment containing nitroglycerin (glyceryltrinitrate) or isosorbide dinitrate reduces the pressure at rest in the anal canal and increases the anodermal blood circulation. Both ointments in most patients lead to healing of the chronic anal fissure. Nitroglycerin ointment in a prospective, randomized trial brought about better healing than placebo treatment. The advantage of the ointment treatment, the needlessness of sphincterotomy, is particularly important in cases of existing sphincter abnormalities. It has the disadvantage that it takes longer for the fissure pain to abate. The principal side effect is headache. In over 50% of the patients the treatment has to be continued for longer than 6 weeks. Little is known as yet about the risk of recurrence. Before surgical interventions as the treatment of first choice can be definitely replaced by treatment with nitrate ointment the good results of the ointment treatment have to be confirmed. Also, more has to be found out about the risk of recurrence, the optimal duration of the treatment and the choice of the type of nitrate ointment.