In order to examine a patient with supposed fistula, he should be placed in a recumbent position on a table or an examining-chair, preferably on the side on which the external opening is situated, with the legs well drawn up toward the abdomen, and the buttocks brought to the edge of the couch.
Fig. 21—Silver Probe attached to handle.
The anus and the surrounding parts should be carefully examined to detect any apparent lesion. If the external orifice of the sinus is prominent, or if there is a sentinel granulation present, the outlet of the fistula will be obvious; but when it is small and located between folds of the skin, its situation may be demonstrated by making pressure with the top of the finger in the suspected locality, which will usually cause a little drop of matter to exude. The site of a fistula may often be detected by feeling gently all around the anus with the forefinger and finding an induration which feels like a pipe-stem beneath the skin. A flexible silver probe (Fig. 21) should now be passed along the fistulous track. In doing this, considerable care is requisite, and the utmost gentleness should be observed, bearing in mind that the probe is to be directed by its own weight through the sinus, and not by force applied by the hand of the surgeon. If it does not pass easily, bend it and see if it cannot be coaxed along the channel. In many cases it will pass directly into the bowel. When the probe has been passed as far as it will go without the use of any force, introduce the finger gently into the rectum. This should be subsequent to the passage of the probe, as otherwise the introduction of the finger into the bowel will set up a spasm of the sphincter muscles, which will greatly interfere with the passage of the probe. When the finger is in the bowel it will frequently come in contact with the probe, which fact demonstrates the presence of a complete fistulous track; in other cases the mucous membrane is felt to intervene between the digit and the probe. In such cases the internal opening generally exists, but is difficult to discover,—sometimes because the examiner searches for it too high in the bowel. Palpation with the sensitive tip of the finger will often render the presence of the inner orifice obvious, by coming in contact with an indurated mass of tissue. If such a spot be felt, the finger should be placed upon it and the probe passed toward the finger. Make sure that the fistula is a complete one, by feeling the probe touch the finger. There may not be an internal opening; if not, see how near the probe comes to the surface of the bowel.
Fig. 22—Pratt's Speculum.
If a doubt still exists as to the completeness of the track, one of a variety of specula (Figs. 22, 23, 24) may be introduced into the rectum, and the outer orifice of the sinus injected with either milk or a solution of iodine, when if there be an internal opening the appearance of the colored fluid within the bowel will set the question at rest.
If the inner opening be not discovered by these methods, the case must be looked upon as one of external rectal fistula.
Fig. 23—O'Neil's Speculum.