Although I have been managing anal fistulas for many years, I have not, similar to other surgeons, found a universal “golden method” for curing every patient. Branched fistulas, in particular, require thorough preoperative diagnostics and careful surgical planning, which in most cases involves a staged approach. Among such fistulas are anal fistulas with scrotal extension.

By definition, a fistula with scrotal extension is a fistula whose external opening is located on the scrotal skin or just beneath the scrotum on the perineal skin. Fistulas with scrotal extension are classified as complex fistulas. Complex fistulas are potentially associated with a higher risk of recurrence or deterioration of continence after surgery. This group includes transsphincteric fistulas involving more than 30% of the sphincter mass, suprasphincteric, extrasphincteric, horseshoe, anterior fistulas in women, fistulas associated with inflammatory bowel disease, recurrent fistulas, and branched fistulas.

Regardless of the amount of sphincter muscle mass involved (low vs. high fistula), a fistula with scrotal extension is a branched fistula and thus falls within the category of complex fistulas. In contrast, simple fistulas include intersphincteric fistulas and low transsphincteric fistulas involving less than 30% of the sphincter mass (1). According to Goodsall’s rule, a fistula tract typically extends from the external opening toward the nearest crypt (anterior or posterior). However, in the case of fistulas with scrotal extension, this rule often does not apply. In some patients, the internal opening is located in the posterior crypt, making the fistula tract indirect, coursing through the ischiorectal fossa and subsequently through the perineal tissues into the scrotum.

Although anal fistulas with scrotal extension are relatively rare (2), infection within the scrotal tissues can be particularly dangerous. If surgical treatment is not initiated early, it may lead to fulminant perineal necrotizing fasciitis – Fournier’s gangrene. Apart from cryptoglandular infection, the causes of fistulas with scrotal extension may include sexually transmitted diseases (e.g., gonorrhea), perianal Crohn’s disease, and, less commonly, ulcerative colitis. In my clinical practice, I have also encountered a case where a fistula with scrotal extension complicated by perineal phlegmon was the first manifestation of HIV infection. Some authors suggest that scrotal involvement without concomitant inflammatory bowel disease is rare (3). My own practical observations do not confirm this. I have operated on many patients with such fistulas who did not suffer from inflammatory bowel disease. The literature indicates that most of these fistulas are low. This was confirmed by Araki et al. (4), who analyzed 56 patients with anal fistulas extending to the scrotum. The majority were low transsphincteric or intersphincteric fistulas with internal openings located in the anterior crypt – in these cases, the course was consistent with Goodsall’s rule. Surgical treatment in this group was associated with few complications, low recurrence rates, and a low incidence of incontinence. In contrast, high transsphincteric or suprasphincteric fistulas with posterior internal openings did not follow Goodsall’s rule and were associated with higher recurrence rates after surgery (4).

The fistula tract to the scrotum most commonly runs within the superficial layers of the perineal fascia, composed of loose connective tissue. A low transsphincteric fistula with an anterior internal opening penetrates the superficial portion of the external anal sphincter and then enters the perineal tissues. It may course at varying depths and eventually open onto the scrotal skin. Because the scrotal skin is thick, the fistula may sometimes branch before reaching the surface, creating multiple external openings.