Case Study: Extrasphincteric Sinus Tract in a Patient with Recurrent Perianal Abscesses

Case at a Glance

A woman in her 30s with a multi-year history of recurrent perianal abscesses, previously managed with antibiotics, underwent a pelvic MRI that revealed an extrasphincteric sinus tract. This case highlights the diagnostic journey and the patient's concerns regarding treatment options and potential impact on continence.

Patient's Story

The patient is a healthy woman in her 30s with a BMI of 22, who is a non-smoker and does not consume alcohol. For several years, she has experienced recurrent perianal abscesses, which have significantly impacted her quality of life. These episodes were managed conservatively with courses of antibiotics. An initial pelvic MRI performed three years ago did not reveal any underlying tract. Due to the persistence of her symptoms, a repeat MRI was ordered. The patient expressed considerable anxiety about the diagnosis, fearing a complex condition that would preclude a simple surgical cure and potentially risk her continence.

Initial Assessment

The working diagnosis prior to the latest imaging was a recurrent perianal fistula. Based on this suspected diagnosis, surgical options, including the potential placement of a seton drain, had been discussed with the patient as a possible management strategy. The patient's history was negative for inflammatory bowel disease or other significant comorbidities.

The Diagnostic Journey

To better characterize the recurring perianal sepsis, a pelvic MRI was performed. The goal was to identify and map any potential fistulous tract and its relationship to the anal sphincter complex to guide definitive treatment. Unlike her scan three years prior, this MRI successfully visualized the underlying pathology.

Final Diagnosis

The official MRI report described a sinus tract, distinct from a classic fistula-in-ano. The findings were reported as: "There is a sinus tract with external opening at the left intergluteal cleft. The sinus extends cranially over approximately 4 cm and terminates in the extra sphincteric soft tissue at the 1 o'clock position of the lower anal canal. Low signal suggestive of some fibrosis is noted. No undrained sepsis evident." The key finding is that the tract terminates in the soft tissue outside the sphincter complex without a clear internal opening into the anal canal, classifying it as an extrasphincteric sinus tract.

Treatment Plan

The patient is currently awaiting a follow-up consultation with her colorectal surgeon to discuss the findings and formulate a treatment plan. The MRI results suggest that a simple fistulotomy, which involves cutting through the sphincter muscle, may not be the appropriate or necessary procedure. Given the extrasphincteric location of the tract's termination and the presence of fibrosis without active infection, surgical options may include:

1. Examination Under Anesthesia (EUA) to confirm the tract's anatomy and probe for any subtle internal opening.
2. Sinusectomy: Excision of the entire sinus tract.
3. A sphincter-sparing procedure if the tract is found to be more complex than imaging suggests.

Outcome and Follow-up

The immediate outcome is a definitive diagnosis that helps guide surgical planning. The patient's primary concern remains the preservation of fecal continence. The long-term plan will be established following her surgical consultation. Follow-up will be critical to ensure complete resolution of the tract and to monitor for any recurrence or functional complications post-operatively.