Quality Corner: Perianal and perirectal abscess; Pneumomediastinum

Authors: Cassandra Mackey, MD (EM Resident Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) and Christine Kulstad, MD (EM Attending Physician, UT Southwestern Medical Center / Parkland Memorial Hospital) // Edited by: Alex Koyfman, MD (@EMHighAK) and Brit Long, MD (@long_brit)

Welcome to Quality Corner, an emDocs series evaluating tough cases and potential areas for improvement. The cases described below are based on ED bouncebacks, with all identifying details removed, and are limited to what was documented in the medical record.

Case 1 – Perianal/Perirectal abscess

A 45-year-old male with past medical history of diabetes presented with redness, swelling, and pain around his rectum. He had no systemic symptoms such as fever, nausea, or malaise, and his vital signs were within normal limits. Physical exam was normal except for a golf ball sized abscess near his rectum. His labs were unremarkable. The general surgery service was consulted and drained the abscess at the bedside. They recommended follow-up in clinic in one week and to discharge the patient with antibiotics.

The patient returns a few days later with worsening pain and drainage from the site. He had a greater area of swelling, and the overlying skin was now doughy. Review of his first visit showed that due to miscommunication during sign out, the patient had been discharged without antibiotics. General surgery was again consulted, and the patient was taken to the OR. He has been seen again for recurrent abscesses due to the formation of a fistula.

Case Discussion

This case highlights the dangers of handoffs, with a miss for the prescription for antibiotics. But I’ll leave that extensive discussion for another time and instead focus on perianal and perirectal abscesses. Discussing the management of these makes it seem straightforward, but when you have a patient in front of you, it is less so.

Perianal abscesses begin with infection of anal crypt gland, usually polymicrobial. A perianal abscess occurs when that infection tracts down to the perianal skin, manifesting as a superficial, tender mass near the anus. When the infection tracts to any other space- intersphincteric, ischiorectal, or supralevator- a perirectal abscess results1. This is one of the few remaining situations where a digital rectal exam (DRE) is critical, as a intersphincteric or supralevator abscess may have little to no external findings but be palpable on DRE.  Isolated perianal abscess is the only type of abscess that can be adequately treated in ED2. Surgical referral is important due to frequent formation of fistulas. In fact, it is recommended to make the incision as close to the anus as possible so that if a fistula forms, it will be as short as possible3. Perirectal abscesses should be drained by surgeons in the OR.  How can you tell if one is present? Generally, those abscesses are associated with more systemic symptoms. Inter-sphincteric and supralevator are not visible externally, so imaging is critical for both diagnosis and to determine the extent of the infection.

What about antibiotics?

Antibiotics are not necessary for simple perianal abscesses in healthy patients. Packing of the abscess cavity has also not been proven to be helpful3. Antibiotics should be given to patients at high risk for complications such as elderly patients, diabetic patients, immunosuppressed patients, significant cellulitis surrounding the site, and those with systemic symptoms. In fact, some authors advocate IV antibiotics, surgical consult, and admission for this group2. Is that plausible for all patients? Imaging, typically a CT with IV contrast, should be performed in most of these patients to determine whether a perirectal abscess is present, in which case admission and drainage in the OR is indicated. A diabetic or elderly patient without systemic signs of illness and good follow-up could be discharged with oral antibiotics, such as amoxicillin-clavulanate or ciprofloxacin/metronidazole1, and clear instructions to return if worse.

Take Home Points

  • Simple perianal abscesses can be drained in ED with referral to surgery.
  • Concern for perirectal abscess warrants imaging, usually CT with IV contrast.
  • Perirectal abscesses should be drained in OR.
  • Give antibiotics for patients who are at high risk for complications.

Case 2 – Pneumomediastinum

A 50-year-old female with PMH of cancer with lung metastases presented with chest pain and dyspnea. Her heart rate was 112, but she had otherwise normal vital signs, including oxygen saturation. Physical exam was unremarkable, except for the tachycardia, which was also present on EKG as sinus tachycardia. She was taking rivaroxaban as prescribed. CMC, BMP, and troponin were unchanged from her baseline. A CXR was obtained due to chest pain and dyspnea, and the preliminary read by the radiology resident was unchanged from the previous CXR two weeks ago. She was given additional pain medications and was discharged home with a diagnosis of chest pain from metastatic lesions.

Twelve hours later the patient was called back for abnormal CXR, namely for the presence of pneumomediastinum. Her vital signs and exam were similar, with an additional history of a worsening cough obtained. Should additional testing or treatment be ordered? What should the patient’s disposition be at this time?

Case Discussion

This is another reminder to look at all your own radiographs! For those in academic centers, you may have more experience reading CXRs than the night shift resident. Pneumomediastinum can be spontaneous, or secondary to underlying lung disease (i.e. asthma, COPD), trauma, malignancy, prolonged coughing or choking, or iatrogenic injury4. Typical symptoms are chest pain and shortness of breath, as evidenced by our patient, but the condition may also present with voice changes, subcutaneous air, and the elusive Hamman’s sign – a crunching sound with the cardiac cycle. The very unfortunate patient may present similarly to tamponade, as the air can compress venous return to the heart, but most patients are hemodynamically stable4.

The final radiology read suggests CT chest if clinically indicated. Is it? For this patient with a likely cause of her pneumomediastinum – history of malignancy with frequent coughing –  further testing is unlikely to help. For a patient with a traumatic cause or not fully defined etiology, CT would help to rule out other problems requiring intervention such as esophageal injury5. If the diagnosis or cause is unclear, CT chest may be helpful6.

Treatment is conservative. Analgesics should be provided to treat pain, and cough suppression should be attempted.  Additionally, the patient should be counseled to avoid Valsalva maneuvers.  Oxygen therapy is often given to speed absorption of the mediastinal air4. There are no clear evidence-based recommendations for disposition. Patients who have traumatic injury will likely be admitted for observation. Unstable patients require a thoracic surgery consult for possible VATS, and crashing patient may even need a thoracotomy4. Spontaneous, and other non-traumatic patients, can be sent home if they are stable This is another opportunity for shared decision-making.

Take Home Points

  • Read your own radiographs.
  • Conservative treatment is recommended for hemodynamically stable patients with pneumomediastinum.
  • Consider chest CT for traumatic injury causing pneumomediastinum.


References/Further Reading:

  1. Perianal and perirectal abscess – UpToDate. Available at: https://www.uptodate.com/contents/perianal-and-perirectal-abscess?search=perianal&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1. (Accessed: 30th January 2018)
  2. Steele, S. R. et al. Practice parameters for the management of perianal abscess and fistula-in-ano. Dis. Colon Rectum 54, 1465–1474 (2011).
  3. Cydulka, R. K. et al. in Tintinalli’s Emergency Medicine Manual, Eighth Edition (McGraw-Hill Education / Medical, 2017).
  4. Kouritas, V. K. et al. Pneumomediastinum. J. Thorac. Dis. 7, S44–S49 (2015).
  5. Dissanaike, S., Shalhub, S. & Jurkovich, G. J. The evaluation of pneumomediastinum in blunt trauma patients. J. Trauma 65, 1340–1345 (2008).
  6. Gunluoglu, M. Z. et al. Diagnosis and Treatment of Spontaneous Pneumomediastinum. Thorac. Cardiovasc. Surg. 57, 229–231 (2009).

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