Je moet 's nachts toch iets te doen hebben...Perianal abscess represents an infection of the soft tissues surrounding the anal canal, with formation of a discrete abscess cavity. The severity and depth of the abscess are quite variable, and the abscess cavity frequently is associated with formation of a fistulous tract. For that reason, both perianal abscess and perianal fistula are discussed in this article.
Problem: Anorectal abscesses originate from infection arising in the cryptoglandular epithelium lining the anal canal. The internal anal sphincter is believed to serve normally as a barrier to infection passing from the gut lumen to the deep perirectal tissues. This barrier can be breached through the crypts of Morgagni, which can penetrate through the internal sphincter into the intersphincteric space. Once
infection gains access to the intersphincteric space, it has easy access to the adjacent perirectal spaces. Extension of the infection can involve the intersphincteric space, ischiorectal space, or even the supralevator space. In some instances, the abscess remains contained within the intersphincteric space. The variety of anatomic sequelae of the primary infection is translated into variable clinical presentations.
Frequency: The peak incidence of anorectal abscesses is in the
third to fourth decades of life. Men are affected more frequently than women, with a male-to-female predominance of 2:1 to 3:1. Approximately 30% of patients with anorectal abscesses report a previous history of similar abscesses that either resolved spontaneously or required surgical intervention. A higher incidence of abscess formation appears to correspond with the spring and summer seasons. While demographics point to a clear disparity in the occurrence of anal abscesses with respect to age and sex, no obvious pattern exists among various countries or regions of the world. Although suggested, a direct relationship between bowel habits, frequent diarrhea, and poor personal hygiene and the formation of anorectal abscesses remains unproved.
The occurrence of perianal abscesses in infants also is quite common. The exact mechanism is poorly understood but does not appear to be related to constipation. Fortunately, in infants this condition is quite benign and rarely requires any operative intervention other than simple drainage.
Pathophysiology: Perirectal abscesses and fistulas represent anorectal disorders that arise predominately from the obstruction of anal crypts. Normal anatomy demonstrates anywhere from 4-10 anal glands drained by respective crypts at the level of the dentate line. Anal glands normally function to lubricate the anal canal. Obstruction of anal crypts results in stasis of glandular secretions and, when subsequently infected, suppuration and abscess formation within the anal gland results. The abscess typically forms in the intersphincteric space and can spread along various potential spaces. Common organisms implicated in abscess formation include Escherichia coli, Enterococcus species, and Bacteroides species; however, no specific bacterium has been identified as a unique cause of abscesses. Less common causes of anorectal abscess that must be considered in the differential diagnosis include tuberculosis, cancer, Crohn disease, trauma, leukemia, and lymphoma.
Clinical: The classic locations of anorectal abscesses listed in order of decreasing frequency are as follows: perianal 60%, ischiorectal 20%, intersphincteric 5%, supralevator 4%, and submucosal 1%.Clinical presentation correlates with the anatomical location of the abscess.
Patients with perianal abscesses typically complain of dull perianal discomfort and pruritus. Their perianal pain often is exacerbated by movement and increased perineal pressure from sitting or defecation. Physical examination demonstrates a small, erythematous, well-defined, fluctuant, subcutaneous mass near the anal orifice.
Patients with ischiorectal abscesses often present with systemic fevers, chills, and severe perirectal pain and fullness consistent with the more advanced nature of this process. External signs are minimal and may include erythema, induration, or fluctuance. On digital rectal examination (DRE), a fluctuant indurated mass may be encountered. Optimal physical assessment of an ischiorectal abscess may require anesthesia to alleviate patient discomfort that would otherwise limit the extent of the examination.
As a rule, the presence of an abscess is an indication for incision and drainage. Watchful waiting while administering antibiotics is inadequate.
Medical therapy: In most patients with anorectal abscess, adjuvant medical therapy with antibiotics generally is not necessary. The presence of a systemic inflammatory response, diabetes, or immunosuppression justifies concomitant use of antibiotics.
Surgical therapy: Treatment of anorectal abscesses involves early surgical drainage of the purulent collection. Primary antibiotic therapy alone is ineffective in resolving the underlying infection and simply postpones surgical intervention. Any delay in surgical drainage of anorectal abscesses prolongs infection, augments tissue damage, may impair sphincter continence function, and may promote stricture and/or fistula formation. The ability to drain an anorectal abscess depends on location, patient comfort, and accessibility of the abscess.
Drainage of perianal or superficial abscesses usually can be accomplished in the office or emergency department using local anesthetics. A small incision is made over the area of fluctuance in close proximity to the anal verge. Pus is collected and sent for culture. Hemostasis is achieved with manual pressure, and the wound is packed with iodophor gauze. The gauze is removed after 24 hours, and the patient is instructed to take sitz baths 3 times a day and after bowel movements. Postoperative analgesics and stool softeners are prescribed to relieve pain and prevent constipation. The patient typically will follow up with his/her physician in 2-3 weeks for wound evaluation and inspection for possible fistula in ano.
Approximately two thirds of patients with rectal abscesses treated by incision and drainage or by spontaneous drainage will develop a chronic anal fistula.
The recurrence rate of anorectal fistulas after fistulotomy, fistulectomy, or use of a Seton is about 1.5%.
The overall incidence of major fecal incontinence after surgical management of complex suprasphincteric fistulas is estimated at approximately 7%.
"Dear life, When I said "can my day get any worse?" it was a rhetorical question, not a challenge."