ANATOMY: Fig. 1 Fig. 2 Fig. 3 Fig. 4
It is attached at its upper end to the uterus,
just above the cervix.
The spaces between the cervix and the vagina are known as the anterior,
posterior,
and lateral vaginal sacs.
Because the vagina is attached to the uterus at a point higher in the back than in the front,
the posterior vaginal wall measures about 3 cm more than the anterior wall.
The vagina is attached to the lateral pelvic wall by endopelvic aponeurotic connections to the tendinous arch,
which extends from the pubic bone to the sciatic spine.
This connection converts the vaginal lumen into a transverse cleft with the anterior and posterior walls in contact.
The vagina is in intimate contact with the anterior part of the urethra,
the neck of the bladder and the trigonal region,
and with the posterior part of the bladder; behind,
it is related to the perineal body,
the anal canal,
the lower part of the rectum and the posterior cul-de-sac (or Douglas).
It is separated from the lower part of the urinary tract and the digestive tract by its layers of endopelvic aponeurosis lining.
EMBRIOLOGY: Fig. 5
Until the sixth week of intrauterine life the embryos do not have differences,
presenting both paramesonephric ducts (Müller's ducts) and mesonephric ducts (Wolff's ducts).
The first,
will give rise to the formation of the Fallopian tubes and the uterine duct that later will originate the uterus and the upper third of the vagina.
Shortly after the end of the paramesonephric ducts reach the urogenital sinus,
two massive evaginations are generated from the pelvic part of the sinus,
called sinovaginal bulbs,
which proliferate and form the vaginal plaque,
which will increase the distance between the uterus and the urogenital sinus,
giving rise to the lower two thirds of the vagina,
remaining separated from the outermost portion of the urogenital sinus by the hymen,
which during perinatal life will form a small hole.
The definitive channeling from the vagina to the uterus is produced by vacuolation of the caudal paramesonephric tissues and the sinovaginal bulbs.
HISTOLOGY:
The vaginal wall is constituted by three layers: the mucosa,
the muscular and the adventitia.
The mucosa is roughened and forms small folds.
This mucosa is lined by a stratified squamous epithelium that is generally non-keratinized and contains glycogen.
This stratified epithelium is divided into several layers: basal (one row of cells),
parabasal (two to five rows of cells),
intermediate and superficial (both with variable thickness).
Below the epithelium is the lamina propria which consists of a connective tissue,
with abundant elastic fibers and nerves and few blood vessels are observed.
The muscular layer is constituted by smooth muscular fibers that are arranged in a circular manner near the mucosa and longitudinally in the external part.
These two layers are not well defined and some of these longitudinal fibers pass to form the cardinal ligaments.
The adventitia is formed by a loose vascular connective tissue with abundant nerves,
venous and lymphatic plexuses.
VAGINAL TUMORS:
Primary vaginal cancer accounts for about 3% of all malignancies of the female genital tract.
The estimated incidence of invasive vaginal cancer is 0.42 per 100,000 women,
the majority are squamous cell carcinomas.
Although primary vaginal cancer is uncommon,
metastases in the vagina are not.
According to the International Federation of Gynecology and Obstetrics (FIGO),
cancer cases should be classified as vaginal carcinomas only after the physician has ruled out another origin.
Diagnosis:
Initially it is clinical by visualization of a lesion that requires biopsy,
it must be accompanied by cystoscopy and proctoscopy for staging,
as well as an MRI of the pelvis to obtain an image of the vaginal tumors and to evaluate if there is presence of pelvic or inguinal adenopathies.
Tumor types:
- Primary vaginal tumors are a heterogeneous group of neoplasms that tend to be multicentric.
Squamous cell carcinoma accounts for about 85% of vaginal carcinomas.
It is related to a high-risk persistent infection of the human papillomavirus.
Verrucous carcinoma is an infrequent variant of squamous cell carcinoma of the vagina.
It is well differentiated and has low malignant potential.
Adenocarcinomas represent almost all primary vaginal cancers in women under 20 years of age (related to exposure to diethylstilbestrol).
Approximately 70% of these patients are stage I at the time of diagnosis.
Most have a positive prognosis after adequate treatment.
On the other hand,
adenocarcinomas that affect women who have not been exposed to diethylstilbestrol tend to have a much worse prognosis (endometrioid,
mucinous,
mesonephric,
cystic adenoid and adenosquamous type cancer).
Sarcomas are infrequent diseases and represent <2% of all malignant vaginal neoplasms.
Leiomyosarcomas,
endometrial stromal sarcomas,
malignant mixed mullerian tumors,
undifferentiated sarcomas,
and rhabdomyosarcomas are the main types of primary vaginal sarcomas.
The most common of these is embryonal rhabdomyosarcoma (botryoid sarcoma) and affects almost exclusively girls under 5 years of age.
Malignant melanoma is an uncommon but very aggressive tumor of the vagina.
These neoplasms affect women at an average age of 60 years.
The neoplasms appear as blue-black or brown-black masses,
as plaques or as ulcerations and sometimes they are not pigmented.
The primary malignant melanomas of the urogenital mucous membranes have an aggressive behaviour and present a high rate of local failure and metastasis.
- Vaginal metastases are more frequent than primary tumors and mostly occur due to a local spread of tumors of the female urogenital tract,
and in some rare cases,
due to distant metastases of extragenital cancers (kidney,
lung,
breast).
Therefore,
a primary vaginal tumor will be diagnosed after ruling out another gynecological origin.