Anal abscess

Note: This article is meant to generally encompass the conditions generally known variously as "anal abscess", "rectal abscess", "peri-rectal abscess" and "peri-anal abscess."

An anal abscess is an abscess (a large pocket of infection) adjacent to the anus. The condition invariably becomes extremely painful, and usually worsens over the course of just a few days. The pain may be limited and sporadic at first, but invariably worsens to a constant pain which can become very severe when body position is changed (e.g., when standing up, rolling over, and so forth). Depending upon the exact location of the abscess, there can also be excruciating pain during bowel movements, though this is not always the case. This condition may occur in isolation, but is frequently indicative of another underlying disorder, such as Crohn's disease.

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Differential Diagnosis

This condition is often mis-diagnosed initially by the patient as a bad case of hemorrhoids, since this is almost always the cause of any sudden anal discomfort. The presence of the abscess, however, is to be suspected when the pain quickly worsens over one or two days and the usual hemorrhoid treatments are ineffective in bringing relief. Furthermore, any serious abscess will eventually begin to cause signs and symptoms of general infection, including fever and nighttime chills.

A physician can rule out a hemorrhoid with a simple visual inspection, and usually appreciate an abscess by touch.

Cause

Abscesses are caused by a high density infection of (usually) common bacteria which collect in one place or another for any variety of reasons. Anal abscesses, without treatment, are likely to spread and affect other parts of the body, particularly the groin and rectal lumen. All abscesses can progress to serious generalized infections requiring lengthy hospitalizations if not treated.

Historically, many rectal abscesses are caused by bacteria common in the digestive system, such as E. coli. While this still continues often to be the case, there has recently been an uptick in the causative organism being staphylococcus, as well as the difficult to treat community-acquired methicillin-resistant S. aureus. Because of the increasing appearance of more exotic bacteria in anal abscesses, microbiological examination will always performed on the surgical exudate to determine the proper course of any antibiotic treatment.

Treatment

Anal abscesses, unfortunately, cannot be treated by a simple course of antibiotics or other medications. Even small abscesses will need the attention of a surgeon immediately. Treatment is possible in an emergency room under local anesthesia, but it is highly preferred to be formally admitted to a hospital and to have the surgery performed in an operating room under general anesthesia.

Generally speaking, a fairly small but deep incision is performed close to the root of the abscess. The surgeon will allow the abscess to drain its exudate and attempt to discover any other related lesions in the area. This is one of the most basic types of surgery, and is usually performed in less than thirty minutes by the surgical team. Generally, a portion of the exudate is sent for microbiological analysis to determine the type of infecting bacteria. The incision is not closed (stitched), as the damaged tissues must heal from the inside toward the skin over a period of time.

The patient is often sent home within twenty-four hours of the surgery, and is instructed to perform several 'sitz baths' per day, whereby a small basin (which usually fits over a toilet) is filled with warm water (and possibly, salts) and the affected area is soaked for a period of time. During the week following the surgery, many patients will have some form of antibiotic therapy, along with some form of pain management therapy, consistent with the nature of the abscess.

The patient usually experiences an almost complete relief of the severe pain associated to his/her abscess upon waking from anethesia; the pain associated with the opening and draining incision during the post-operative period is often mild in comparison. In many cases, the patient is completely healed with no discomfort whatsoever within just one or two weeks of the surgery.

Complications

In severe or recurrent abscesses, a fistula may develop, connecting the rectum to the skin. This requires more intensive surgery. Furthermore, any untreated abscess may (and most likely will) continue to expand, eventually becoming a serious systemic infection.