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Emergency Radiology

, Volume 22, Issue 3, pp 329–335 | Cite as

CT of acute perianal abscesses and infected fistulae: a pictorial essay

  • Nadia J. Khati
  • Nicole Sondel Lewis
  • Aletta Ann Frazier
  • Vincent Obias
  • Robert K. Zeman
  • Michael C. Hill
Pictorial Essay

Abstract

Computed tomography (CT) is an effective, readily available diagnostic imaging tool for evaluation of the emergency room (ER) patients with the clinical suspicion of perianal abscess and/or infected fistulous tract (anorectal sepsis). These patients usually present with perineal pain, fever, and leukocytosis. The diagnosis can be easy if the fistulous tract or abscess is visible on inspection of the perianal skin. If the tract or abscess is deep, then the clinical diagnosis can be difficult. Also, the presence of complex tracts or supralevator extension of the infection cannot be judged by external examination alone. Magnetic resonance imaging (MRI) is the best imaging test to accurately detect fistulous tracts, especially when they are complex (Omally et al. in AJR 199:W43–W53, 2012). However, in the acute setting in the ER, this imaging modality is not always immediately available. Endorectal ultrasound has also been used to identify perianal abscesses, but this modality requires hands-on expertise and can have difficulty localizing the offending fistulous tract. It may also require the use of a rectal probe, which the patient may not be able to tolerate. Contrast-enhanced CT is a very useful tool to diagnose anorectal sepsis; however, this has not received much attention in the recent literature (Yousem et al. in Radiology 167(2):331–334, 1988) aside from a paper describing CT imaging following fistulography (Liang et al. in Clin Imaging 37(6):1069–1076, 2013). An infected fistula is indicated by a fluid-/air-filled soft tissue tract surrounded by inflammation. A well-defined round to oval-shaped fluid/air collection is indicative of an abscess. The purpose of this article is to demonstrate the usefulness of contrast-enhanced CT in the diagnosis of acute anorectal sepsis in the ER setting. We will discuss the CT appearance of infected fistulous tracts and abscesses and how CT imaging can guide the ER physician in the clinical management of these patients.

Keywords

Anorectal Sepsis CT imaging Fistula Abscess 

Notes

Conflict of interest

The authors declare that they have no conflict of interest.

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Copyright information

© American Society of Emergency Radiology 2014

Authors and Affiliations

  • Nadia J. Khati
    • 1
  • Nicole Sondel Lewis
    • 2
  • Aletta Ann Frazier
    • 3
    • 4
  • Vincent Obias
    • 5
  • Robert K. Zeman
    • 6
  • Michael C. Hill
    • 1
  1. 1.Department of Radiology, Body Imaging SectionThe George Washington University HospitalWashingtonUSA
  2. 2.Department of RadiologyMedstar Georgetown University HospitalWashingtonUSA
  3. 3.Department of Diagnostic Radiology and Nuclear MedicineUniversity of Maryland Medical CenterBaltimoreUSA
  4. 4.American Institute for Radiologic PathologySilver SpringUSA
  5. 5.Division of Colon and Rectal Surgery, Department of Colon and Rectal SurgeryThe George Washington University HospitalWashingtonUSA
  6. 6.Department of Radiology and Radiation Oncology Department of RadiologyThe George Washington University HospitalWashingtonUSA

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