Perianal abscess is a simple type of anorectal abscess characterized by collection of purulent material on the skin surface surrounding the anus. It arises from the cryptoglandular epithelium of the anal canal.
The most common manifestations of abscesses are pain and swelling in the perianal region. Occasionally discharge of pus can be noted from the abscess. Infection is characterized by fever, redness, swelling, and pain. Patients often complain of perianal discomfort and pruritus. When the abscess open link spreads to perianal space, induration, erythema, or fluctuance may occur. But the symptoms may not be prominent as the region has abundant subcutaneous tissue. Movement or pressure at the perianal region, as in sitting or defecation, may aggravate pain. When the abscess spreads to ischiorectal region, fever, chill and severe perirectal pain may develop as symptoms. Pain at defecation may result in constipation.
Physical examination along with clinical history of the patient help in the diagnosis of perianal abscesses. Anorectal observation is often performed in the office or emergency department. Physical examination may reveal indurated area adjacent to anus. Anesthesia is required only in case of intersphincteric and supralevator abscesses. Presence of other anorectal abscesses may be confirmed with the help of laboratory tests. Specific laboratory tests are not indicated otherwise in case of perianal abscesses. WBC count may be elevated. Imaging techniques are generally not used unless the abscesses are complicated. Anal ultrasonography is occasionally used to diagnose anorectal abscesses. As it causes considerable discomfort, it is not used in case of intersphincteric and supralevator abscesses. Culture of the content from the abscess is sometimes recommended in case of recurrent anorectal abscess. Infection-causing pathogen can be identified using microbiological culture methods. The contents are stained to check for acid-fast bacilli. Microscopic examination of the content would help to rule out tuberculosis. Differential diagnosis include anal fissure, thrombosed hemorrhoid, pilonidal abscess, infected epidermoid inclusion cyst, perianal hidradenitis suppurativa, and sexually transmitted diseases. Radiological studies are not helpful in the diagnosis of this condition.
Risk factors like history of Crohn’s disease should be considered. Perianal pain usually begins one to two days before the presentation and it may gradually become more severe . They may complain of swelling and warmth of the tissues surrounding anus. Coughing, sneezing and bowel movements often increase the pain. Rectal bleeding may not be reported unless there is spontaneous drainage.
Draining the abscess without delay helps to prevent it from spreading into a necrotizing, soft-tissue infection . This may further lead to life-threatening sepsis. Perianal abscesses can be drained externally using local anesthesia. If the abscesses develop into intersphincteric or supralevator abscesses, general anesthesia may be needed for anal examination and drainage. It is usually drained into the anal canal and rectum . The wound should be cleaned thoroughly with warm water, 2 to 3 times daily after drainage. Warm water bath is recommended for cleansing after bowel movements. If there is drainage, absorbent dressings are used to prevent staining. More fiber should be included in the diet to prevent the formation of hard stools.
There is no standard antibiotic regime for the control of abscesses. Broad-spectrum antibiotics are often given preoperatively and discontinued one day after surgery. Generally, penicillin or cephalosporin is given in combination with clindamycin, ciprofloxacin, or metromidazole. If necrotizing soft tissue infection is present, more aggressive surgical intervention is recommended.
In most of the cases, the symptoms show considerable improvement if abscess is adequately drained. If the abscess is not completely drained, re-examination is suggested to ensure that the abscess is fully drained. For those who have recurrent abscesses, examination by general surgeon would help to rule out the possibility of fistula as the underlying cause. Other risk factors like HIV, immunosuppression, and TB also should be excluded.
Mortality due to anorectal abscesses in general, and perianal abscesses in specific, is very low . About 50% of the patients develop fistulas . Recurrence is reported in 10% of the patients with perianal abscesses. One of the studies showed that 37% of the patients with abscesses develop recurrent sepsis . About two thirds of the patients who have spontaneous drainage or are treated by incision, develop chronic fistula, and about 43% of the patients develop fecal incontinence after surgical intervention for treating fistula. Post-operative urinary retention and post-ejaculation urethral irritation are also reported as complications.
Anal abscesses are caused by infection or obstruction of the anal cryptal glands . Abscesses may be formed by aerobic or anaerobic bacteria, including Bacteroides fragilis, Peptostreptococcus, Fusobacterium, and Clostridium. Aerobic forms like Staphylococcus aureus, Streptococcus and Escherichia coli also are known to infect anal glands . The cryptal glands may become obstructed by the accumulation of debris, allowing the growth of bacteria.
Some other common causes of anorectal abscesses include
Although occurrence of anal abscesses is very common, and majority of the patients with perianal abscesses may not report or seek medical help for treatment. Prevalence of perianal abscesses may thus be more common than clinical reports. Further, any anorectal discomfort or condition is often attributed to hemorrhoids. This makes prevalence estimation of specific anorectal abscesses difficult. In United States about 100,000 new cases of anorectal abscesses are reported every year . About 30% of the patients have a history of abscesses. Many of them resolve without any specific treatment or surgical intervention. Incidence of anorectal abscesses is more in the age group of 30-40 years . Abscesses are reported from children also, but is mostly mild and may not require any form of surgical intervention . Anorectal abscesses like perianal abscesses are more common in men when compared to women . No significant differences are noted in the occurrence of abscesses in different parts of the world. Some theories suggest a direct relation between development of anorectal abscesses and bowel habits. It is presumed that diarrhea and poor personal hygiene increase the chances of developing abscesses. The incidence of abscesses was found to be higher in spring and summer.
About 90% of the anorectal abscesses arise from obstruction of cryptal glands in anus . Glandular secretions accumulate allowing infection that leads to suppuration and formation of abscesses. Abscess formation usually starts in the intersphincteric space and then gradually spreads to the neighboring tissues. Infected fluid usually collects at the terminal region of the gland. Abscess increases in size and follow the path of least resistance, spreading to the surface. This results in perianal abscess. In some cases it may spread to ishiorectal fossa or to the region above levator muscles, forming ischiorectal abscess and supralevator abscesses, respectively. In about 37% of the patients, perianal abscesses are associated with anal fistulas. If not drained, perianal abscess may recur.
There is no standard method or guideline to prevent perianal abscesses. Protection from sexually transmitted diseases is key in preventing the development of abscesses. Good personal hygiene is equally important for adults and children to protect from perianal abscesses. Having more fiber in the food helps to prevent the formation of hard stools, one of the important risk factor in the development of anal abscesses.
Perianal abscess is a simple type of anorectal abscess characterized by collection of purulent material on the skin surface surrounding the anus. It arises from the cryptoglandular epithelium of the anal canal. It may extend from the intersphincteric groove to the perianal skin. Perianal abscess occurs in the form of a tender mass on the surface of the skin and represents a more chronic form of suppuration when compared to other forms of anorectal abscesses . Draining the abscess prevents it from spreading to the nearby tissues like ischiorectal space or supralevator space. This will also help to prevent it from developing into a systemic infection. Perianal and ischiorectal abscesses are the common forms of anal abscesses found among the general population. Surgical incision and drainage are the most common treatment recommended.
Perianal abscess is a collection of pus outside the anus. It can cause pain, and in addition, fatigue and fever. In some cases the abscess may break open or fail to heal, resulting in the formation of fistula. Perianal abscesses require immediate medical attention to prevent it from developing into more complicated, and life-threatening situations. Perianal abscesses often develop from an obstruction or infection of the glands in the anus. As the glands plug up with debris, secretions accumulate in the gland allowing bacterial infection. These may burst releasing the contents causing abscesses in the space surrounding rectum or anus. Occasionally abscess may enlarge leading to fever, and causing difficulty in bowel movements. Certain factors increase the risk of developing perianal abscesses. This includes diabetes, HIV, Crohn’s disease, low immunity, pregnancy, presence of foreign bodies in the anus, sexually transmitted disease, and anal fissures.
Many people with anal abscesses do not seek medical attention for treatment. Prevalence of different types of anal abscesses are not known because of this reason. It is most commonly seen in men in the age group of 30-40 years. In infants, abscesses are generally mild and may not need drainage or any other surgical intervention. Incidence of abscesses are more common in spring and summer. Some of the most common symptoms of perianal abscess include pain in the perianal area, pus collection near the anus, fever, pain during bowel movements, and fatigue. Pain during bowel movements may lead to constipation. Abscesses that are deeper lead to fever and chills. A physical examination of the rectal region is sufficient to diagnose abscesses in the anal region. For deeper abscesses, other tests and imaging techniques may be recommended.
If left untreated, anal abscesses may develop into painful anal fistulas. Draining the pus from the infected area is the most common treatment method. Drainage is usually done in the clinic or emergency room under local anesthesia. Surgery is suggested for large abscesses. The abscesses after drainage is left open for healing. Warm baths, 2 to 3 times a day, is recommended after drainage. Sitting in warm water for some time helps to reduce swelling and also in additional drainage, if needed. Antibiotics may be recommended before the surgery and continued for one day after drainage. Food rich in fiber is very important to prevent formation of hard stool. Diabetic patients may have to stay back in the hospital for monitoring infections. Good hygiene, cleanliness and protection from sexually transmitted diseases are very important in preventing anal abscesses. Occasionally abscesses may recur and some patients. In general, outcome is very good after drainage.