Urinary Bladder Eversion and Prolapse
Stacey R. Byers
Definition and Etiology
Urinary bladder eversion and prolapse are uncommon events that occur during or shortly after parturition.1 With eversion, forceful straining moves the bladder fundus caudally, eventually turning the bladder inside out.
The bladder is then forced out of the urethral orifice. Prolapse of the bladder is more frequently associated with dystocia. In this condition a full-thickness tear of the vaginal wall occurs during delivery, allowing the bladder (and possibly other viscera) to be displaced from the abdominal cavity into the vagina.Clinical Signs and Differential Diagnosis
Females with either eversion or prolapse of the bladder have a smooth, spherical mass within the vagina, usually protruding from the vulva. The female may be alert and ambulatory, but if concurrent hypocalcemia, exhaustion, or peritonitis exists, the animal may be recumbent and depressed. Careful vaginal examination is required to differentiate these two conditions from each other and from vaginal prolapse, vaginal polyps, fat protrusion from a vaginal tear, vaginal neoplasia, fetal membranes, and uterine prolapse.1 Epidural anesthesia is necessary to prevent straining to reduce fecal contamination while cleaning the perineum and vestibule and to reduce the risk of viscera herniation through the urethra (bladder eversion) or through the vaginal tear (bladder prolapse).
With urinary bladder eversion, the mucosal surface of the bladder is exposed. The ureteral openings may be visible on its dorsal aspect, although these may be occluded and difficult to see if the wall of the bladder is edematous. Vaginal palpation reveals that the protruding tissue originates from the urethral orifice. With time, constriction of the everted bladder by the narrow urethra may cause venous congestion, edema, thrombosis, and eventual necrosis.
Palpation and ultrasonographic examination are required for detection of herniation of other viscera through the urethral orifice and into the interior of the everted bladder. Careful fine-needle aspiration of the interior of the eversion has been used to differentiate eversion from prolapse of the bladder. With bladder eversion, aspiration may yield peritoneal fluid, but laceration of herniated bowel is a concern.In contrast, the serosal surface of the bladder is exposed with urinary bladder prolapse. Careful palpation of the vagina reveals that the bladder protrudes from a full-thickness tear in the floor or lateral wall of the vagina. Other viscera may be present in the vagina, as well. Fine-needle aspiration yields urine from the bladder lumen.
Treatment and Prognosis
Manual reduction of an everted bladder may not be possible if it is edematous or if other viscera have herniated into its interior. The dorsal aspect of the urethra may be incised to widen the route through which the bladder is to be replaced.1 Viability of the involved structures is of primary concern for prognosis, and laparotomy is required for assessment of the viability of herniated bowel. Bladder paralysis and rupture are potential sequelae to ischemic damage that develops during eversion. Cystitis and pyelonephritis may develop, and antibiotic therapy is warranted if repair is attempted. Animals with chronic conditions may develop hydroureter, hydronephrosis, and renal failure.2
A bladder prolapse can be resolved by first passing a flexible catheter into the urethra to remove urine from the bladder. This also confirms the diagnosis and facilitates bladder replacement. After catheterization and removal of urine, the bladder can be replaced into the abdominal cavity, and the vaginal tear can be sutured. Severe contamination of the peritoneal cavity may render attempts at treatment unjustified. Antibiotic therapy is indicated for surgical candidates.