This is an opening between the urethra and vagina and is usually due to obstetric injury. 

Symptomatology depends upon location. Fistulae in the urethra close to the bladder neck are often associated with incontinence. Inspection will usually identify a large fistula, whereas urethroscopy, cystoscopy and vaginoscopy may be needed to detect a smaller one. It is important to rule out an associated vesicovaginal fistula. 

TREATMENT 

Most are repaired after some 12 weeks to allow the original inflammation of the injury to settle. Symptomatic fistulae are best repaired by careful excision and layered closure. The use of a labial fat pad (Martius flap) or gracilis muscle flap may be useful. A Foley catheter is left for about 14 days. Complications include incontinence, recurrent fistula formation and urethral stricture.