DIAGNOSIS.—The manifestations of this disease are so characteristic of the lesion that it seems almost impossible for an error to be made in its diagnosis. The peculiar nature of the pain, the time of its occurrence (either during or some time after an evacuation of the bowels), its continued increase until it becomes almost unbearable, and its gradual decline and entire subsidence until the next evacuation, are symptoms clearly pointing to fissure, and in most instances should be sufficient evidence to establish a diagnosis; yet in a number of well-authenticated cases mistakes have been made, and patients suffering from this disease have been treated for neuralgia, uterine or vesical trouble, stricture, and even hemorrhoids. Anal fissure is very readily distinguished from neuralgia by the absence in the latter of any breach of surface or of any other disease of the mucous membrane of the rectum; by the entire want of connection between the pain and the alvine evacuations; and by the constant suffering. In neuralgia the pain caused by pressure with the finger in the anus is not confined to one spot, as it is in fissure, but all portions of the bowel are alike tender. It is true that the morbid sensibility of the rectum and anus caused by a fissure and that caused by neuralgia are often so intimately blended that it is sometimes no easy matter to distinguish between them; nothing but the detection itself, in some cases, of the fissure, which can always be discovered by a thorough examination, will clear up the diagnosis.[24] The symptoms of anal fissure often simulate so closely those of uterine disease and bladder affections that the surgeon is led astray and overlooks the real seat and true nature of the malady. Occasionally the spasmodic condition of the sphincter in these cases simulates the symptoms of stricture; but a thorough examination will dispel all uncertainty by revealing the presence of the ulcer. Frequently uterine trouble or hemorrhoids are found associated with the fissure, and in this event the case is treated for either one or the other of the first two complaints, the presence of the other lesion being unsuspected and consequently neglected. In all such instances a careful inspection of all the parts concerned will at once remove all errors in diagnosis and dispel all doubts. In children, the fact must always be borne in mind that fissures and other erosions about the anal orifice may be due to the scratching induced by the irritation of pin-worms.