Colposuspension is a surgical procedure for treatment of canine urinary incontinence.
Surgical treatment of USMI is typically reserved for patients in which appropriate medical management has failed, that have adverse reactions to recommended medications, or that have medical conditions precluding the use of medical therapies. The goal of surgical treatment of USMI is to increase urethral resistance to the outflow of urine. To accomplish this, surgical procedures focus on correcting caudal displacement of the bladder neck to (1) increase intraabdominal forces and provide improved MUCP within the urethra (colposuspension, urethropexy, and urethral lengthening), (2) increase urethral resistance by reducing the diameter of the urethral lumen (urethropexy and submucosal collagen implants), and (3) improve functional urethral length (colposuspension, urethral lengthening). The surgical procedures reported in the veterinary literature to improve USMI in small animal patients have all been adapted and modified from procedures performed on women with diagnosed stress incontinence.
Colposuspension uses the placement of sutures between the vagina and the prepubic tendon to create urethral resistance to urine outflow. This procedure results in cranial advancement and repositioning of the bladder neck and proximal urethra, exposing these structures to intraabdominal pressure. In addition, the urethra, cradled by the vagina, is positioned over the edge of the pelvic brim, which applies additional external compression. Colposuspension is the surgical procedure most commonly performed to treat spayed dogs with USMI. Colposuspension alone was reported to be curative in approximately 50% of patients; in approximately 40% of the remaining patients, continence was improved.
A recent study evaluated the immediate urodynamic response to colposuspension in normal beagles. Leak point pressures were significantly increased, while MUCPs were decreased. Urethral length was assessed using measurements from vaginourethrograms and urethral pressure profiles and was determined to be slightly increased based on evaluation of lateral radiographs. Urodynamic studies indicated that the total profile length and the functional profile length were significantly increased. The long-term effects of colposuspension also have been examined in female dogs with USMI. Two months after colposuspension, 12 of 22 female dogs achieved complete continence. However, only three dogs remained completely continent 12 months after surgery. When medical therapy was instituted after surgery, an additional eight dogs regained complete urinary continence and nine were improved.
With the patient in dorsal recumbency, clip and aseptically prepare the ventral abdomen from the xyphoid over the pubis, including the perivulvar region. Aseptically pass an appropriate-size balloon-tip urethral catheter transurethrally into the bladder. Perform a caudal midline celiotomy from the umbilicus, extending over the cranial aspect of the pubis, and identify and isolate the insertion of the rectus abdominis muscles and prepubic tendon. Expose the bladder, proximal urethra, and uterus or uterine body remnant. If the patient is intact, OVH is performed at this point.
Place a stay suture through the apex of the bladder for traction and manipulation and an Allis tissue forceps on the uterine body remnant for cranial traction. A peritoneal reflection forming the vesicogenital pouch exists between the dorsal aspect of the pelvic urethra and the ventral aspect of the vagina, tethering these structures together. This intimate anatomic association allows cranial traction of the uterine body remnant and vagina to result in cranial movement of the bladder neck and urethra.
With cranial traction applied to the bladder and uterine body remnant, use a curved mosquito hemostat or right-angled forceps to bluntly dissect a small window through the periurethral fascia along each side of the urethra immediately cranial to the pubic brim, exposing the vagina dorsal to the urethra. Take care to avoid excessive dissection and disruption of the neurovascular supply to the vagina and urethra, positioned dorsolaterally within the pelvic canal. Identify the lateral wall of the vagina and grasp it with atraumatic forceps positioned on each side of the urethra. Based on the size of the patient, pre-place one or two 2-0 nonabsorbable monofilament sutures through the seromuscular layer of the vaginal wall on each side of the urethra and through the prepubic tendon, entering and exiting lateral to the insertion of the rectus abdominis muscle. Firm cranial traction on both the bladder and uterine remnant is needed to achieve cranial positioning while these sutures are tied on either side of the urethra. Insert a mosquito hemostat between the ventral aspect of the urethra and the pelvic brim to ensure that the urethra is not completely obstructed. Close the abdomen in a routine manner.
A urethral catheter with a closed urinary collection system should be maintained for 24 hours after surgery. Transient dysuria and stranguria due to urethral inflammation and partial urethral obstruction can occur after catheter removal. Complete urethral obstruction after colposuspension is rare. If complete urethral obstruction occurs, replacement of the urethral catheter for an additional 24 to 36 hours and administration of an NSAID are indicated. Attempts to manually express the bladder to void its contents may cause patient discomfort. Persistent complete urethral obstruction that does not respond to appropriate conservative treatment over a period of 3 to 5 days after surgery may require removal of the colposuspension sutures between the vaginal wall and prepubic tendon.