Malignant diseases of the vagina are either primary vaginal cancers or metastatic cancers from adjacent or distant organs. Primary vaginal cancers are defined as arising solely from the vagina, with no involvement of the external cervical os proximally or the vulva distally. The importance of this definition lies in the different clinical approaches to the treatment of upper and lower vaginal cancer.
According to the International Federation of Gynecology and Obstetrics (FIGO), a vaginal lesion involving the external os of the cervix should be considered cervical cancer and treated as such; a tumor involving both the vulva and the vagina should be considered vulvar cancer.
About 80% of vaginal cancers are metastatic, primarily from the cervix or endometrium. Metastatic cancer from the vulva, ovaries, choriocarcinoma, rectosigmoid, and bladder are less common. These cancers usually invade the vagina directly. Cancers from distant sites that metastasize to the vagina through the blood or lymphatic system also occur, including colon cancer, renal cell carcinoma, melanoma, and breast cancer.
Although primary vaginal carcinoma is a rare gynecologic malignancy, its impact on women’s health should not be underestimated, especially when considering the demographic increase in elderly women. As more women survive past age 60 years, physicians need to consider the likelihood that more women will present with vaginal cancer.
Because the 5-year survival rate of treated early-stage vaginal cancer is significantly higher than that of vaginal cancer in the advanced stages, early detection is key to improving treatment outcomes. To improve outcomes of primary vaginal carcinoma, select referral oncology centers should see additional cases per month in order to plan appropriate randomized, prospective studies. This would increase the experience of any of these centers in treating primary vaginal carcinoma.
History of pelvic exenteration
In 1946, Alexander Brunschwig published the first cases of pelvic exenteration. In his first series, 5 of 22 surgical patients died from the operation itself. The original procedure consisted of connecting the ureters to the colostomy. In 1950, Bricker modified the procedure by isolating a loop of ileum, closing one end, anastomosing the ureters to it, and bringing the patent end out as a stoma.
Since then, several other modifications have improved the outcome of this procedure. Today, with vaginal reconstruction and continent vesicostomy, the procedure is accepted as a surgical treatment in selected cases.
Occurrence of vaginal cancer
Primary vaginal carcinoma is rare, constituting only 1-2% of all malignant gynecologic tumors. It ranks fifth in frequency behind cancer of the uterus, cervix, ovary, and vulva. The age-adjusted incidence in the United States is 0.6 per 100,000 population. The strict criteria used in defining vaginal carcinoma contribute to this low incidence.
In June 2006, the Advisory Committee on Immunization Practices (ACIP) voted to recommend the first vaccine developed to prevent cervical cancer and other diseases caused by HPV type 6, 11, 16, and 18. The vaccine is almost 100% effective in preventing precancerous lesions of the cervix, vulva and vagina, and genital warts caused by the HPV 6, 11, 16, and 18. The FDA has approved Gardasil for girls and women ages 9-26. In 2014, Gardasil 9 was approved to prevent disease from HPV type 6, 11, 16, 18, 31, 33, 45, 52 and 58. The 9-valent HPV vaccine is licensed in the United States for women and men aged 9-45 years.
The vagina is located in the true pelvis, which also contains the rest of the internal genital tract, the rectosigmoid, the bladder, the proximal urethra, and the pelvic portions of the ureters. The pelvic organs are partially covered by the peritoneum. The endopelvic fascia covers these organs and forms their supporting ligaments in conjunction with the pelvic vasculature and musculature.
The pelvic cavity is divided into anterior and posterior compartments by the transversely positioned broad ligament. The uterus is centered within the broad ligament and is attached to the round ligaments, which run anterolaterally within the broad ligament from the uterus to the pelvic wall.
Anterior and posterior cul-de-sacs
The anterior cul-de-sac, also known as the vesicouterine pouch, is located between the uterus and the bladder. It has small, lateral recesses known as the paravesical fossae. This pouch ends where the cervix and the bladder connect and does not extend down to the vagina.
The posterior cul-de-sac, known as the rectouterine pouch of Douglas, is located between the uterus (posteriorly) and the rectum (anteriorly). It is continuous with the pararectal fossae and contrary to the anterior pouch. It extends about 1-2cm down to the vagina, separating the cervix from the rectum.
The vagina itself is a muscular tube that extends from the cervix to the hymenal ring, penetrating the levator ani and the urogenital diaphragm. These latter structures provide vaginal support inferiorly. From the outermost to the innermost layers, the vagina is composed of an endopelvic fascia—which contains an abundant plexus of vessels, lymphatics, and nerves—as well as outer longitudinal and inner circular smooth muscle layers, submucosa, and mucosa.
Rectal and bladder pillars
The vagina is attached to the rectum posteriorly by the rectal pillars, while the bladder pillars provide anterior vaginal attachment to the bladder. During vaginal inspection with a speculum, the anterior and posterior sulci provide the anatomic landmark of the site of attachment of these pillars. These are most easily observed in nulliparous women.
The rectal and bladder pillars are paired, parallel, longitudinal, fibrovascular bundles containing extensive vascular and lymphatic networks between the vagina and the rectum and bladder, respectively. They both run the entire length of the vagina. The bladder pillars also contain the paravaginal tissues (paracolpium).
As it joins the lower end of the cervix, the upper end of the bladder pillar forms the vesicouterine ligament. This ligament forms a tunnel through which the ureters run inferomedially to reach the inferolateral portion of the bladder. The tunnel divides the vesicouterine ligament into anterior and posterior leaves. This anatomic structure is important during radical hysterectomy when careful dissection of the ligament is needed to mobilize the ureters. The rectal pillars receive the middle rectal arteries from the cardinal ligament.
The cardinal ligaments are wedge-shaped fibrovascular bundles containing the uterine, vaginal, inferior vesical, and middle rectal arteries and veins, as well as the lymphatic system. On each side, they run from the lateral aspect of the cervix to the lateral pelvic sidewall, traversing the pelvic plane at a 30° angle from the transverse pelvic diameter and dividing the paravesical and paravaginal spaces from the pararectal spaces.
On the pelvic wall, they insert on the endopelvic fascia and the hypogastric vasculature. The anterior part of the cardinal ligament is more vascular, while the posterior part is more fibrous and contains the autonomic system of the bladder and rectum.
An important landmark is the uterine artery that crosses the anterior-most portion of the cardinal ligament. The ureter enters the upper portion of the ligament beneath this artery (water under the bridge) and 1-2cm lateral to the isthmus of the uterus. The uterine veins cross below the ureters.
The uterosacral ligaments run from the posterolateral aspect of the cervix to the anterolateral part of the rectum. They are in close contact to the rectal pillars and straddle the posterior cul-de-sac.
Paravesical, pararectal, rectovaginal, and vesicovaginal spaces
Several avascular tissue planes are developed during pelvic surgery. The paravesical space is bordered by the symphysis pubis anteriorly, the cardinal ligaments posteriorly, the obliterated umbilical artery along the bladder medially, and the obturator internus laterally.
The pararectal space is bordered by the cardinal ligament anteriorly, the sacrum posteriorly, the rectum medially, and the hypogastric artery laterally. The rectovaginal space is bounded by the vagina anteriorly and the rectum posteriorly, while the rectal pillars form its lateral walls.
The vesicovaginal space is limited laterally by the bladder pillars, anteriorly by the bladder, and posteriorly by the vagina. To develop this space, the peritoneal reflection of the anterior cul-de-sac is entered.
The levator ani forms the major support of the pelvic structures and is the major component of the pelvic diaphragm. It is penetrated anteriorly by the rectum, vagina, and urethra. It forms the floor of all the planes discussed above.
Vaginal blood supply
The upper part of the vagina receives its blood supply from the uterine and the internal pudendal arteries, from which the vaginal artery arises. The inferior rectal artery and other branches arising from the internal pudendal artery supply the lower vagina. The vaginal venous plexus mainly drains into the pelvic wall through the parametrial veins, and to a lesser degree to the vesical and rectal plexuses.
Vaginal lymphatic system
Crossover of the vaginal lymphatic system is extensive. The middle to upper vagina communicates superiorly with the cervical lymphatics and drains into the pelvic obturator node, the internal and external iliac chains, and then the para-aortic nodes. The distal third of the vagina drains to the inguinal and then the pelvic nodes. The posterior wall lymphatics communicate with the rectal lymphatics and drain to the inferior gluteal, sacral, and rectal nodes.
The vagina stays in close proximity to the bladder and urethra anteriorly, which increases the risk of accidental injury to these structures during surgery. The sigmoid, on the other hand, reflects away from the posterior vaginal wall at its midpoint, facilitating an approach to the vagina posteriorly through the posterior cul-de-sac and a developed rectovaginal plane.