Surgical Disease of the Vulva and Vagina

Anatomy

The vulva is the external portion of the reproductive tract. The vertical opening of the vulva is formed by the labia or lips, which meet at the dorsal and ventral commissures. The clitoris, a homolog of the male penis, lies within the clitoral fossa just inside the ventral commissure of the vulva.

The vestibule lies dorsal and cranial to the clitoral fossa, and opens to the exterior at the vulva. The vestibule is oriented dorsally and turns 90° to horizontal as it clears the ischial arch. The urethral tubercle containing the external urethral orifice lies on the ventral floor of the vestibule, near the vaginovestibular junction. The portion of the tubular tract caudal to this point is shared by the reproductive and urinary systems. Lymph nodules are present in the subepithelial tissue of the vestibule, particularly in the area opposite the urethral tubercle.

The vagina extends from the vestibule to the external cervical os. It is highly distensible except for the portion immediately surrounding the cervix. There is extensive longitudinal folding of the vaginal mucosa. A dorsal longitudinal fold is present leading toward the cervix. The external cervical os projects ventrally into the vaginal lumen and is undercut by a ventral fornix.

Vaginal Examination

Inspection of the vaginal tract is made through the vulva. It should begin with visual inspection of vulvar conformation, perivulvar skin, and labia. The size and turgidity of the vulva should be related to the stage of estrous cycle. The presence and character of any discharge should be noted. The clitoris and vaginal mucosa are examined by parting the labia. The normal clitoris is relatively small and has a mucosal surface. The mucosa should appear smooth and pink along the entire length of the tract.

The cranial vestibule and caudal vagina can be examined visually and digitally. Visual inspection is aided by use of an otoscope or vaginal speculum. Digital examination with a lubricated, gloved finger is necessary to evaluate the texture of the mucosa and identify physical abnormalities such as vaginal bands or strictures. Irritation of the vestibular mucosa leads to hyperplasia of the subepithelial lymph nodules, which is identified as a "sandpaper" texture to the mucosa.

Vaginoscopy is necessary for visual evaluation of the cranial vagina. The vaginal mucosa is edematous during proestrus. Edema decreases and the folds become angulated as estrogen levels fall and progesterone levels increase during estrus. Mucosal pallor increases during estrus. The cervix protrudes into the vagina and is directed ventrally. It is differentiated from the surrounding vaginal folds by its characteristic cobblestone appearance. The external os is located in the midst of the cobblestones. If vaginoscopy is performed during estrus, serosanguinous discharge can be seen discharging from the external os. At the onset of diestrus and throughout diestrus and anestrus, the vaginal folds are flattened. A longitudinal striped appearance is apparent in early diestrus.

Exfoliative vaginal cytology is a useful technique to examine the vagina and determine the nature of vaginal conditions and discharges. Vaginal cytology can determine the presence or absence of estrogen influence and inflammation. Estrogen influence is evidenced by a large percentage of cornified squamous epithelial cells, usually more than 50%. Inflammation is indicated by the presence of large numbers of degenerate and nondegenerate neutrophils. The only exception to this is early diestrus when large numbers of non degenerate neutrophils are considered normal. This technique is useful in identifying the stage of the estrous cycle and as a diagnostic tool for vaginal discharges.

Episiotomy

Episiotomy is indicated to provide better exposure of the vestibule and distal vagina in conjunction with other surgical procedures. A vertical incision is made from the dorsal commissure directly on the midline to extend the vulvar opening and provide increased exposure to pelvic tissues that are not accessible via laparotomy.

Episioplasty

Episioplasty is a reconstructive procedure that is indicated when the vulva is concealed by redundant perivulvar skin [1-3]. Turbulent urine flow and moisture retention lead to recurrent perivulvar pyoderma, vaginitis, vestibulitis, and urinary tract infections. The condition is commonly seen in bitches spayed prepubertally that have a juvenile vulva that is recessed within skin folds. In episioplasty, excess skin is removed dorsally and laterally to expose the vulva (Fig. 77-1). If vaginal discharge is present and not completely resolved by surgery, estrogen therapy may be considered. Treatment with estrogen thickens the vaginal epithelium, thus helping to resolve the chronic inflammation. Fatal bone marrow suppression is a risk of chronic estrogen use; therefore, low-dose therapy is used and tapered off over time, thus identifying the lowest effective dose. Weight loss is recommended prior to surgery in obese patients. Weight gain following surgery may cause the redundant skin fold to recur.

Figure 77-1. Postsurgical appearance of the vulva after episioplasty as treatment for chronic urinary tract infections and perivulvar inflammation. (From Textbook of Veterinary Internal Medicine, 6th ed. Ettinger SJ, Feldman EC (eds). Philadelphia: Elsevier, 2005, p.1689, with permission from the publisher).

Vaginal Fold Prolapse

(Vaginal Hyperplasia)

Vaginal fold prolapse results from an individual’s exaggerated response to estrogen stimulation during estrus [2,4,5,6]. Historically, this condition has been referred to as vaginal hyperplasia, which is a misnomer. Occurring only during proestrus and estrus, the vaginal epithelium thickens normally owing to the effect of estrogen, a protective mechanism for the vagina during copulation. In cases of vaginal fold prolapse, the protruding mass has pronounced edema in the underlying tissues overlaid by multiple layers of cornified squamous epithelial mucosa, thus leading to the description of hyperplasia. With vaginal fold prolapse, a mass can be observed when the vulvar lips are parted or it can be seen protruding from the lips of the vulva. The tissue involved usually originates from the vaginal floor cranial to the urethral papilla. The vaginal lumen is dorsal to the mass, which differentiates vaginal fold prolapse from vaginal prolapse, which usually presents as a circular doughnut-shaped mass. Biopsy shows hyperplastic, cornified epithelium characteristic of estrus. The mass usually regresses spontaneously following estrus but recurrence rates during subsequent estrous cycles is high. In some cases the mass is present throughout diestrus or pregnancy. Permanent resolution is achieved by ovariohysterectomy. Surgical removal of the protruding mass is indicated if it is large or if extensive mucosal damage is present [4,6]. The external urethral orifice should be identified on the ventral aspect of the mass and catheterized to prevent damage during surgery. Approximately 25% of surgical cases recur in animals that have not had ovariohysterectomy. Potential complications include dysuria if the weight of the mass impinges on the urethra or if urethral damage occurs during surgery. Vaginal fold prolapse is most commonly seen in young, brachycephalic, and large breed dogs. Breeding of affected dogs is not recommended as the condition may be hereditary.

Vaginal Prolapse

Vaginal prolapse is less common than vaginal fold prolapse. It is identified as a doughnut-shaped eversion of the entire vaginal circumference, with the vaginal lumen in the center. Prolapse typically occurs during estrus or parturition, when excessive straining occurs in the presence of relaxed perivulvar tissue. It may occur as a result of forced separation of a copulatory tie, protracted labor, or constipation. It is heritable and is most common in brachycephalic breeds. Surgical correction consists of reducing the prolapse. Resection may be necessary if significant tissue damage is present. Episiotomy, manual compression to reduce edema, and traction on the uterus through a ventral midline incision may aid reduction. Reduction is maintained in the immediate postoperative period by placing nonabsorbable sutures across the labia. Cervipexy may decrease the incidence of recurrence. This is accomplished by tacking the cervix to the prepubic tendon. Care must be taken not to involve the urethra.

Vaginal Tumors

Vaginal tumors in the bitch are typically benign [7]. The common signalment is an older, intact female with a history of straining to urinate and defecate, vulvar discharge, or a mass protruding from the vulva. The most common tumor types are leiomyomas, fibromas, lipomas, and transmissible venereal tumors (TVT). TVT can metastasize via lymphatics or be spread to the mouth by licking. Malignant leiomyosarcomas are seen rarely. Intraluminal tumors are usually pedunculated and may protrude from the vulva. These can typically be excised. Extraluminal tumors may cause bulging of the perineum. Extensive dissection may be required to remove extraluminal masses. TVT is most common in free-roaming dogs. Some TVTs can regress spontaneously after several months. Multiple masses are common and complete excision is difficult. Recurrence is common unless the tumors are also treated with radiation and chemotherapy. Chemotherapy with vincristine (0.025 mg/kg, IV, weekly, for 2-8 treatments) is considered the treatment of choice. Debulking of the tumor(s) may assist in therapy.

Clitoral Enlargement

Clitoral enlargement occurs owing to abnormalities of sexual differentiation (male pseudohermaphroditism), exposure to exogenous androgens, or excess sex hormone production secondary to hyperadrenocorticism (Fig. 77-2). The bitch may present for excessive licking of the vulvar area, reluctance to sit, vulvar discharge, or appearance of a mass protruding from the vulva. An os clitoris may be present in cases of abnormal sexual differentiation. Friction between the enlarged clitoris and vulva may cause inflammation and vaginitis. The tissue may also be traumatized from exposure if it protrudes from the vulva. Surgery is indicated if the enlarged clitoris is causing clinical signs or if an os clitoris is present. The clitoris will not regress with removal of androgen influence if an os clitoris is present. Accurate location of the urethra is critical prior to surgery.

Figure 77-2. Clitoris of a male pseudohermaphrodite, showing penis-like anatomy. (From Textbook of Veterinary Internal Medicine, 6th ed. Ettinger SJ, Feldman EC (eds). Philadelphia: Elsevier, 2005, p.1689, with permission from the publisher).

Trauma

Trauma to the vulva and vagina may occur as a result of dogfights, breeding injuries, attempts to disrupt a coital tie, dystocia, malicious acts, or be iatrogenic. Lacerations are usually longitudinal. Contusions or puncture wounds may also occur. Treatment is usually not necessary for minor injuries. Surgical correction is indicated for large lacerations or puncture wounds. Estrual bitches should be confined to prevent mating and reinjury.

Developmental Abnormalities

A variety of congenital developmental abnormalities may occur that partially obstruct the vagina or vestibule and require surgical correction, especially in breeding animals. The paired Müllerian (paramesonephric) ducts fuse embryologically to form the tubular reproductive tract in the female. The urogenital sinus fuses with the ducts and develops into the vestibule. The hymen forms at the vaginovestibular junction. Congenital abnormalities arise from incomplete fusion of these embryologic structures or from incomplete perforation of the hymen. Abnormalities manifest as vertical bands or circumferential strictures and most commonly occur in the area of the vaginovestibular junction. The true incidence of congenital vaginal abnormalities is unknown because many cases are asymptomatic until breeding is attempted. Vaginal bands and strictures cause partial obstructions that can prevent natural mating and/or whelping. Other possible signs include chronic vaginitis and vulvar discharge. Digital examination, vaginoscopy, and contrast vaginography are useful diagnostic tools. Vertical bands can be small enough to break down digitally or may be thicker and require surgical resection (Fig. 77-3). Strictures can be dilated or surgically resected but scarring and recurrence are common. Partial vaginectomy has been reported as the most successful procedure for resolving clinical signs.

Figure 77-3. An instrument is used to demonstrate a large dorsoventral vaginal septum. The urethra is catheterized and an episiotomy increases surgical exposure.