eMedicine Specialties > Emergency Medicine > Gastrointestinal
Perirectal Abscess: Differential Diagnoses & Workup
Updated: Aug 15, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Differential Diagnoses
| Abdominal Pain in Elderly Persons | Proctitis |
| Anal Fistulas and Fissures | Rectal Prolapse |
| Hemorrhoids | |
| Inflammatory Bowel Disease | |
| Necrotizing Fasciitis |
Other Problems to Be Considered
Perianal abscess
Workup
Laboratory 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.
More on Perirectal Abscess |
| Overview: Perirectal Abscess |
 Differential Diagnoses & Workup: Perirectal Abscess |
| Treatment & Medication: Perirectal Abscess |
| Follow-up: Perirectal Abscess |
| References |
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References
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Further Reading
Keywords
perirectal abscess, perianal abscess, infection of the mucus-secreting anal glands, anorectal abscess
