Types of Anorectal Defects in Females
Colorectal Center specialists at Cincinnati Children's Hospital Medical Center provide information about anorectal defects and treatments for females for health professionals.
* Primary approach without a colostomy in healthy full-term newborns, provided the surgeon has experience with such approach. Statistics are based on the experience of the Colorectal Center team.
Spectrum of Female Defects
At the simplest end of the spectrum of defects in the female is the perineal / cutaneous fistula. This defect is very similar to the one shown in males.
It is important to notice that in this specific defect, there is a very obvious good plane of separation between the rectum and the vagina.
The rectum passes through most of the muscle mechanism and is only deviated anteriorly in its most distal part. The fistula opens in the middle of the perineal body and, therefore, is called perineal or cutaneous.
Next in complexity is the vestibular fistula, which in terms of quality of muscles and quality of sacrum, could be compared to the rectourethral bulbar fistula in males this is by far the most common defect seen in females.
The most conspicuous and important characteristic of this defect is the fact that the anterior rectal wall and posterior vaginal wall fuse together into a single common wall without a distinctive plane of separation.
The fistula opens in an area lined by mucosa located immediately outside the hymen which is called the vestibule.
Because these patients usually have a good sacrum, the prognosis is good. For some unknown reason, however, they, suffer the highest incidence of postoperative constipation.
Occasionally, there are patients with a type of defect that could be considered intermediate, that is, between the cutaneous fistula already described and the vestibular fistula.
This defect used to be called "fourchette" fistula; the intestinal opening is located between the mucosa of the vestibule and the perineal skin.
Although we are dealing with a spectrum of defects and our classifications are arbitrary, most cases will fall into one of these categories.
The cutaneous fistula does not require a colostomy prior to its repair simply because the dissection of the rectum is much easier since it is not attached to the vagina, the amount of dissection is minimal, and the chances of complication are much less.
On the other hand, in the author's opinion, patients with vestibular fistula require a protective colostomy prior to the main repair.
As time goes by, the pediatric surgical community is gaining more experience in the management of these defects and consequently a tendency is noticed to operate on more newborns primarily, without a protective colostomy.
This tendency is to be commended since it represents an effort to decrease the number of operations and therefore the surgical trauma. However, this trend must be followed cautiously, keeping in mind that the priority must always be the benefit of the patient.
Unfortunately many babies operated on this way have suffered from post-operative infection and dehiscence, which frequently resulted in a worsening of the functional prognosis.
Primary operations without a protective colostomy can be done, in otherwise healthy babies, without severe associated defects, by surgeons with a great deal of experience, the bowel must be meticulously cleaned pre-operatively, and the patient must remain fasting several days, receiving parenteral nutrition.
Next in complexity is the vaginal fistula, an extremely unusual defect. The clue for the diagnosis is the fact that the surgeon cannot see the fistula site even by separating the labia in baby girls; the meconium seems to be coming from deep inside the vagina.
In a normal individual, the entire edge of the hymen can be seen. If a patient does not have a visible posterior rim of the hymen, she most likely has a low vaginal fistula.
These patients also have a common wall immediately above the fistula between the vaginal and rectal wall. The dissection in this area must be a meticulous one.
This defect has been largely over-diagnosed. Doctors frequently use the term "vaginal fistula" rather loosely to designate vestibular fistulae and cloacas.
For more information or to request an appointment, please contact the Colorectal Center at Cincinnati Children's.
