There are several reasons why rectal abscesses so frequently degenerate into fistula?. One is that, owing to an inter nal opening communicating with the bowel, small particles of focal matter find their way into the sinus, and, acting as foreign bodies, prevent the healing; another, that, owing to the frequent movement of the parts by the sphincter muscles, sufficient rest is not obtained for the completion of the reparative process; and, finally, the vessels near the rectum, not being well supported and the veins having no valves, there is a decided tend ency to stasis, which is unfavorable to granulation.
According to Harrison Cripps, the sur face of the fistulous track is lined with a smooth, gelatinous membrane, which, when examined under the microscope, is found to consist of granulation-tissue exactly analogous to that which lines the interior of a chronic abscess. The leu cocytes constituting the outer wall of this membrane are but loosely adherent, and, constantly becoming free, they form the chief part of the pus which drains from the fistula.
This disease is commonly met with during middle life, but it is by no means restricted to this period. The Allinghams state that they have operated upon an infant in arms and upon persons over eighty years old.
Course and Prognosis.—This disease, untreated, has a tendency to progress. The longer its duration, the more tort uous and complicated does a fistula be come. Hence the earlier the patient sub mits to treatment, the more favorable will be the prognosis. Again, the time and extent of the treatment necessary to effect a permanent cure will be corre spondingly diminished.
Treatment.—PREVENTIVE.—When a patient presents the symptoms of a threatened abscess in the vicinity of the rectum, he should be directed to go to bed, or at least to avoid all undue ex ercise; the bowels should be thoroughly evacuated, preferably by the use of a saline; the diet should be nutritious; and, if the case be seen early, hot fo mentations and poultices may be applied to the parts. The early adoption of these measures may abort the threatened abscess, but very little encouragement can be given the patient.
If there be reason to suspect that pus has formed or is forming, it will be de sirable to make a free incision into the centre of the affected site with a sharp, curved bistoury, if the trouble is super ficial, or, if it is deep, with a narrow straight knife. When pus is present and is deeply situated, the evacuation of the abscess will be aided by the introduction of the forefinger into the bowel; the swelling may thus be pushed forward, rendered tense, and made more apparent.
In opening these abscesses, if possible, ether or nitrous-oxide gas should be given. The patient should lie on the side upon which the threatened abscess is situated; the upper leg should be bent forward upon the abdomen. When pus is present, the operator should stand out of the line of its exit, for when the cavity is opened the pus often squirts out a con siderable distance. After the matter has been discharged, the forefinger should be introduced into the abscess-cavity for the purpose of breaking down any secondary cavities or loculi that may exist. When this has been accomplished the abscess should be washed with biehloride-of-mer miry solution, 1 to 4000, after which a rubber drainage-tube should be inserted; or a piece of iodoform gauze should be lightly placed between the lips of the in cision, to prevent its closing too rapidly and also to allow free drainage. Careful daily attention should be paid to the wound while the cavity of the abscess is contracting, as it is important to main tain a free and dependent outlet for the discharge that may continue to be se creted, but stuffing and distension of the cavity should be avoided. If a drainage-tube be used, it should be shortened from day to day as the wall of the abscess contracts.
After an operation for rectal abscess the patient should be kept quiet for sev eral days, and if great care be taken, both with the subsequent drainage and in keeping the orifice open, the parts may heal without the formation of a fistula.