A rectovestibular fistula, also referred to simply as a vestibular fistula, is an anorectal congenital disorder where an abnormal connection (fistula) exists between the rectum and the vulval vestibule of the female genitalia.
If the fistula occurs within the hymen, it is known as a rectovaginal fistula, a much rarer condition. [Source: Wikipedia 
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