AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Perirectal and perianal abscesses are commonly encountered ED problems. Timely and appropriate treatment is needed to prevent serious morbidity and mortality.

This article focuses on perirectal abscess and provides some discussion of perianal abscess. These entities are distinct, with potentially different ED evaluation and different treatment and disposition. Differentiation of the more complex perirectal abscess from the simple perianal abscess is crucial.

Pathophysiology

Perirectal abscess arises from infection of the mucus-secreting anal glands, which drain into the anal crypts. Blockage of the duct is believed to be the initiating cause of infection. The abscess can then progress to involve the potential spaces filled with fatty areolar tissue, which have little resistance to infection. These spaces include the perianal, intersphincteric, ischiorectal, deep postanal space (connecting the ischiorectal space on each side posteriorly), and supralevator spaces. These spaces may become infected alone or in combination with one another.

Perirectal abscess is usually an aerobic and anaerobic polymicrobial infection. Bacteroides fragilis is the predominant anaerobe. Other common bacteria include Escherichia coli and those of the genera Proteus, Bacteroides, and Streptococcus. Sources of bacteria are skin, bowel, and, rarely, the vagina.¹

A variety of disease states is associated with the development of an abscess; these include Crohn disease, carcinoma, radiation fibrosis, trauma, Hodgkin disease, and immunocompromised states. Associated infectious causes include Chlamydia, Actinomyces, Gonococcus, Streptococcus, Bacteroides, and Proteus species; Staphylococcus aureus and Escherichia coli; and herpes, tuberculosis, and lymphogranuloma venereum.

In contradistinction to perirectal abscess, perianal abscess is easily palpable and is not accompanied by fever, leukocytosis, and sepsis in the immunocompetent patient.

Mortality/Morbidity

In rare instances, inappropriately treated perirectal abscess may result in death.

• Perirectal abscess results in fistula formation in 25-50% of cases.
• Bacteremia and sepsis may result, especially in immunocompromised patients.
• In infants, fistula formation ensues after drainage of an abscess in 35% of cases.
• Urinary retention (often resulting in lengthened hospitalization) occurs in 5% of cases.
• Fournier gangrene has occasionally been reported.

Race

No racial predilection has been found.

Sex

Men are affected more frequently than women, with a male-to-female predominance of 2:1 to 3:1.

Age

Perirectal abscess occurs in all age groups, from infants to elderly persons. The peak incidence is in the third and fourth decades of life.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

The history is critical in leading the physician to consider the diagnosis.

• Dull, aching, or throbbing pain in the perirectal or perianal area is present in 99% of patients. The pain worsens when sitting and immediately before defecation, when the rectum is full; the pain decreases after defecation but persists between bowel movements. Perianal abscess presents with more localized pain.
• • The pain often worsens as the abscess increases in size.
  • Coughing and sneezing, straining, or any Valsalva maneuver aggravates the pain.
• Rectal or perirectal drainage (27%)
• Fever and/or chills (23%)
• Constipation (13%)
• Anorexia (12%)

Physical

The physical examination findings may be normal, but a history that raises suspicion of a perirectal abscess should lead the physician to continue to pursue the diagnosis.

• A tender fluctuant mass may be palpated at the anal verge (perianal abscess) or on rectal examination (perirectal abscess). Perirectal abscess can be extensive and can spread to an area distant from the anal verge, yet only a diffuse, tender mass may be palpable through either the rectal wall or the overlying skin.
• Fever
• Localized erythema
• Purulent drainage
• Signs of sepsis may be seen in cases of perirectal abscess in which the infection has become systemic.

Causes

The cause of perirectal abscess is believed to be blockage of the perianal gland duct with resultant infection, rupture, and abscess formation. Risk factors are as follows:

• Immunosuppression
• Diabetes
• Crohn disease
• Ulcerative colitis
• Pregnancy

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Perianal abscess

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Traditional laboratory studies cannot be used to exclude the diagnosis of perirectal abscess. A high index of suspicion must be maintained, and reliance on historical and physical findings is imperative. The following laboratory studies may represent adjuncts to clinical findings.
• • Complete blood counts may show leukocytosis. However, this study may produce normal findings, and leukocytosis is not diagnostic.
  • Blood cultures may be indicated but only in immunocompromised patients and in those who appear to be septic. In one study, blood cultures were performed on 14 patients with perirectal abscesses. None of the blood cultures showed growth.

Imaging Studies

• Plain radiographs are rarely helpful and should not be obtained, barring exploration for some complication of the abscess or to search for another cause of pain or fever when the diagnosis is in doubt. In such a case, a chest radiograph yields the most benefit, especially if free air is seen under the diaphragm, or if chest pathology mimicking abdominal pathology is found.
• CT (with intravenous and possibly oral contrast) may be used to determine the existence and anatomy of a perirectal abscess and should be used liberally. Whereas ultrasonography may be useful in the diagnosis of submucosal and intersphincteric abscesses, CT can detect a deeper abscess and is therefore more useful.
• Endoanorectal, transperineal, and transvaginal ultrasonography may be used to determine the existence, extent, and location of an abscess. Ultrasonography is an accurate, painless, and cost-effective method for documenting perirectal and perianal fluid collections, fistulas, or sinus tracts, and it can be performed at the bedside.
• MRI is useful in identifying deep abscesses and is also useful in detecting granulation tissue, which may be useful in detecting fistulae.

Procedures

• If the diagnosis of perianal or perirectal abscess is in doubt, aspiration with an 18-gauge needle may be performed. Aspiration of pus confirms the diagnosis. However, ultrasonography, CT, and MRI are more comfortable methods of confirming or excluding the diagnosis and should be used if available.
• Adequate analgesia before aspiration is mandatory.
• • Lidocaine (1%) subcutaneously over and around the periphery of the abscess, intramuscular or intravenous narcotics, and/or nitrous oxide are recommended.
  • Ethylene chloride spray applied to the suspected area immediately before aspiration may also be helpful in decreasing the discomfort of aspiration. Ethylene chloride's cooling effect renders pain receptors temporarily unable to transmit pain signals to the cerebral cortex.
  • Conscious sedation may also be used if the physician is trained and prepared to manage the airway. If this route is taken, cardiac monitoring, pulse oximetry, and airway management equipment must be available, including suctioning devices, bag-valve-mask, and endotracheal intubation equipment. This technique should only be used by physicians highly skilled in cardiac and airway management.
  • Conscious sedation may be used for aspiration to confirm the existence of an abscess or to initiate abscess drainage with the knowledge that such a procedure is a temporizing measure until the patient can have an appropriate definitive surgical procedure in the operating suite.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Emergency Department Care

Recognition of a perirectal abscess is the primary ED goal. Determination of the exact anatomic space or spaces involved is best left to the surgical consultant.

The isolated perianal abscess that is not associated with deeper, perirectal abscesses is the only type of anorectal abscess that can be adequately treated in an ED setting and is very rare.

Perirectal abscess must be treated in the operating suite, where optimal anesthesia can be achieved and the abscess and any fistula or other complication may be treated definitively. The "point" of a deep abscess must not be mistaken for a superficial perianal abscess. Inadequate ED debridement of a perirectal abscess may result in increased morbidity and even mortality. ED debridement of perirectal abscesses should not be performed. Because the ED lacks adequate anesthesia, ED treatment of perirectal abscesses is inhumane.

A simple (and, by definition, superficial) perianal abscess may be incised and drained in the ED. Adequate analgesia should be obtained by using the steps discussed in Procedures. Conscious sedation may be considered for pain control and to make the procedure as humane as possible. The patient may be discharged home after appropriate wound care with instructions for Sitz baths and routine follow-up care.

Superficial perianal abscesses are uncommon; thus, the provider should err on the side of assuming a deeper process exists if the diagnosis is in doubt.

• As an example, optimal treatment of ischiorectal abscesses is incision and drainage often followed by fistulotomy under general anesthesia in the operating suite.  
• • The performance of an extensive and complete surgical procedure by a consultant with accurate anatomical knowledge of the region is imperative to avoid serious complications. Such treatment results in a lower recurrence rate.
  • The need for the routine use of antibiotics has not been established. Intravenous antibiotics may be used as preventive or therapeutic measures in patients who are immunocompromised, in those who appear septic, or in those who have heart valve abnormalities or prostheses.
  • Ascertain tetanus immunity. When acceptable immunity cannot be established, follow the currently recommended guidelines for high-risk wounds.
• The goal in treating any abscess is to make an incision to surgically release pus and to remove any dead tissue, and then to keep the surgical incision open by the use of a drain, either (1) a Penrose drain, which may be sutured to the incisional margin and later removed, or (2) iodoform gauze stripping. In the case of perianal abscess, the procedure involves sterile preparation, adequate analgesia, incision and drainage often facilitated by irrigation of the abscess cavity, blunt disruption of any loculations (a gloved fingertip is ideal for this), debridement of any accessible necrotic tissue, and placement of a drain.
• • Do not pack the abscess full of iodoform gauze. The intent is to keep the surgical incision open so that pus and other material can drain. If iodoform gauze stripping is used, using a limited amount of gauze is important, that is, just enough to keep the wound open. Packing the wound full of iodoform gauze does not improve the outcome, and, in fact, it may worsen the prognosis by creating a large foreign body that may become a nidus of infection. This nidus could perpetuate the infection and cause the abscess to enlarge, spread to other areas, erode into vessels or into the peritoneal cavity, and, occasionally, it could cause sepsis and death.
  • In one pediatric case, an incision and drainage (I&D) and packing was performed on a large perirectal abscess in the ED. This packing was left in the wound for days. Shortly thereafter, sepsis and seeding of the myocardium developed with a resultant myocardial abscess. This myocardial abscess eventually ruptured into the pericardial sac, causing tamponade and sudden death.

Consultations

• When the diagnosis of perirectal abscess is made or is being entertained, expeditious consultation with a surgeon is mandatory.
• • Timely and appropriate operative treatment prevents more serious complications such as extension of the abscess or serious systemic infection.
  • The appropriate surgical treatment of perirectal abscess is complex and painful and therefore should not be undertaken in the ED. General or spinal anesthesia is necessary to obtain the appropriate anesthetic result.
  • A newer technique includes endoscopic ultrasonographic-guided drainage of deep pelvic abscesses with stent placement for drainage of pus. In one study, this technique successfully treated most patients who underwent this treatment, requiring no further intervention. 

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Antibiotics are unnecessary in otherwise healthy individuals. The practitioner should provide appropriate empiric intravenous antibiotic coverage for patients who are elderly or immunosuppressed, patients who have comorbidities, patients with a heart valve abnormality or prosthetic valve likely to benefit from antibiotic prophylaxis, or those in whom infection has become systemic. Predisposing or comorbid factors may guide empiric antibiotic selection.

Analgesia is necessary for pain control and may be given orally or via an intravenous route, in conjunction with anesthetics if needle aspiration or I&D of an abscess is performed.

Anxiolytics may help certain patients who are apprehensive about needle aspiration, I&D, imaging studies, or surgery.

Drug Category: Antibiotics

Appropriate antibiotic coverage should be given intravenously preoperatively and postoperatively, either based on Gram stain or an empiric basis, as a preventive measure, for elderly patients, patients with immunosuppression, patients with heart valve abnormality or prosthesis, and those with comorbid states.

Drug Category: Anesthetics

These agents may help to blunt the pain of a diagnostic needle aspiration but is only partially effective.

Drug Category: Pain medication

Pain control is essential to quality patient care. Analgesics ensure patient comfort, promote pulmonary toilet, and have sedating properties, which are beneficial for patients who experience pain. These agents are used for comfort and sedation and to blunt discomfort of diagnostic needle aspiration.

Drug Category: Antiemetics

These agents are used to treat emesis.

Drug Category: Benzodiazepines

By binding to specific receptor sites these agents appear to potentiate the effects of γ-aminobutyric acid (GABA) and to facilitate inhibitory GABA neurotransmission and other inhibitory transmitters. Benzodiazepines are anxiolytics that may help patients apprehensive about needle aspiration, imaging studies, or surgery. Conscious sedatives may be considered by the emergency physician with equipment and experience necessary to manage the patient's airway if spontaneous ventilation become compromised.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• The patient with perirectal abscess should be admitted to the surgical service unless other medical conditions or complications from the abscess necessitate a primary medical admission, with the surgeon acting as a consultant. Consider admitting a patient with a perirectal abscess to a medical service with the surgeon as a consultant if the patient is elderly, febrile, hypotensive, or immune compromised or has significant comorbidities.
• Generally, the treatment of a perirectal abscess is incision and debridement in an operating suite performed by an experienced surgeon.

Further Outpatient Care

• Advise patients to return immediately to the ED or to another provider for any unusual symptoms, including persistent pain or fever.
• After inpatient surgical treatment, a surgeon should closely monitor patients because of the frequent occurrence of fistula or recurrence of the abscess.
• An otherwise healthy patient with a simple isolated perianal abscess may be treated in the ED with incision and drainage and released with timely follow-up care. Keep in mind that a simple perianal abscess is very, very rare. The overwhelming likelihood, when one considers the diagnosis of perianal abscess, is that the provider is only observing the point of a perirectal abscess.

In/Out Patient Meds

• Provide adequate outpatient analgesia such as codeine with acetaminophen or an oxycodone-containing compound.
• Outpatient antibiotics may be indicated and are best chosen according to the culture and sensitivity of pathogens derived from the abscess.

Transfer

• Hemodynamically stable patients may be transferred safely.
• Instability from a concurrent condition or sepsis makes transfer to another institution inappropriate (and possibly illegal under the Emergency Medical Treatment and Active Labor Act [EMTALA]) unless a higher level of care transfer is in the patient's best interest.

Complications

• Fistula formation
• Bacteremia and sepsis, including seeding of the infection to other areas by hematogenous spread (See Emergency Department Care.)
• Fournier gangrene
• Epidural abscess (a rare complication of fistulizing Crohn disease)
• Death

Prognosis

• With adequate treatment, the prognosis is generally excellent.

Patient Education

• For excellent patient education resources, visit eMedicine's Esophagus, Stomach, and Intestine Center. Also, see eMedicine's patient education articles Anal Abscess, Rectal Pain, and Rectal Bleeding.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Delayed diagnosis, misdiagnosis, or failure to diagnose, resulting in a complication or death
• Inadequate treatment or failure to refer for adequate surgical debridement, resulting in a complication or death
• Aspiration, hypoxic injury, or death as a result of inadequate airway management with the use of conscious sedation
• Overzealous packing of a perirectal abscess cavity (See Emergency Department Care.)

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

1. Brook I, Frazier EH. The aerobic and anaerobic bacteriology of perirectal abscesses. J Clin Microbiol. Nov 1997;35(11):2974-6. [Medline].
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3. Cataldo PA, Senagore A, Luchtefeld MA. Intrarectal ultrasound in the evaluation of perirectal abscesses. Dis Colon Rectum. Jun 1993;36(6):554-8. [Medline].
4. Chandwani D, Shih R, Cochrane D. Bedside emergency ultrasonography in the evaluation of a perirectal abscess. Am J Emerg Med. Jul 2004;22(4):315. [Medline].
5. Cuenod CA, de Parades V, Siauve N, Marteau P, Grataloup C, Hernigou A, et al. [MR imaging of ano-perineal suppurations]. J Radiol. Apr 2003;84(4 Pt 2):516-28. [Medline].
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7. Giovannini M, Bories E, Moutardier V, Pesenti C, Guillemin A, Lelong B, et al. Drainage of deep pelvic abscesses using therapeutic echo endoscopy. Endoscopy. Jun 2003;35(6):511-4. [Medline].
8. Heidemann J, Spinelli KS, Otterson MF, Binion DG. Case report: magnetic resonance imaging in the diagnosis of epidural abscess complicating perirectal fistulizing Crohn's disease. Inflamm Bowel Dis. Mar 2003;9(2):122-4. [Medline].
9. Kattan S, Youssef A. Fournier's gangrene of the scrotum following anorectal disorders. Int Urol Nephrol. 1994;26(2):215-22. [Medline].
10. Laniado M, Makowiec F, Dammann F, Jehle EC, Claussen CD, Starlinger M. Perianal complications of Crohn disease: MR imaging findings. Eur Radiol. 1997;7(7):1035-42. [Medline].
11. Lobo Martínez E, Torres Aleman A, Galindo Alvarez J, Martinez Molina E. Endoanal ultrasound in perirectal abscesses. Rev Esp Enferm Dig. Dec 1997;89(12):897-902. [Medline].
12. Marcus RH, Stine RJ, Cohen MA. Perirectal abscess. Ann Emerg Med. May 1995;25(5):597-603. [Medline].
13. Nomikos IN. Anorectal abscesses: need for accurate anatomical localization of the disease. Clin Anat. 1997;10(4):239-44. [Medline].
14. Rubens DJ, Strang JG, Bogineni-Misra S, Wexler IE. Transperineal sonography of the rectum: anatomy and pathology revealed by sonography compared with CT and MR imaging. AJR Am J Roentgenol. Mar 1998;170(3):637-42. [Medline].
15. Stewart LK, McGee J, Wilson SR. Transperineal and transvaginal sonography of perianal inflammatory disease. AJR Am J Roentgenol. Sep 2001;177(3):627-32. [Medline].
16. Stoker J, Rociu E, Wiersma TG, Lameris JS. Imaging of anorectal disease. Br J Surg. Jan 2000;87(1):10-27. [Medline].
17. Zaheer S, Reilly WT, Pemberton JH, Ilstrup D. Urinary retention after operations for benign anorectal diseases. Dis Colon Rectum. Jun 1998;41(6):696-704. [Medline].

Article Last Updated: Aug 15, 2008