A woman may complain to her provider that her vaginal opening feels or appears enlarged. This can be the result of pelvic organ prolapse or a damaged perineal body. This problem is not life-threatening, but a woman may complain of a bulge coming out her vagina, sexual dysfunction, or defecatory dysfunction. The urogynecologic term for this is an enlarged “genital hiatus”, although other providers may use the terms “relaxed vaginal outlet” or “enlarged vaginal introitus.” None of these terms are an actual diagnosis, but rather a physical exam finding of which a patient may or may not be symptomatic.
There is no formal diagnosis for an enlarged vaginal introitus, as patients usually present with a specific complaint that is resultant from her pelvic organ support defects. An enlarged vaginal introitus can be related to stretching of the introitus from prolapse of the vagina (cystocele or rectocele), from weakening of the distal rectovaginal septum, or from disruption of the perineal body (example: perineal lacerations at vaginal delivery).
Gynecologists can determine from a pelvic exam which of these anatomic areas are disrupted. The Pelvic Organ Prolapse Quantification (POP-Q) system, a standardized method with nine values, describes site-specific prolapse. One of these values, the “genital hiatus,” measures from the mid-urethra to the posterior midline hymen.  There is no absolute “normal” for the length of a patient’s vaginal introitus, but 2 to 6cm is most commonly observed in asymptomatic patients in the author’s experience. Patients with an enlarged vaginal introitus are not always symptomatic.
In the United States, the exact incidence of enlarged vaginal introitus is unknown because not all patients are symptomatic and this finding alone is not a medical diagnosis. Prevalence of pelvic organ prolapse, however, has been studied and an enlarged vaginal introitus may be seen in these women. In patients age 40 and older, the rate of symptomatic pelvic organ prolapse is estimated to be 3.8%.  The lifetime risk of needing a surgery for pelvic organ prolapse has been reported as 12.6%.  For more information about diagnosis and treatment, see the Medscape article: Pelvic Organ Prolapse
The main support for the pelvic organs is provided by a group of muscles collectively called the levator ani. An intact pelvic floor allows the pelvic and abdominal viscera to "rest" on the levator ani, significantly reducing the tension on the supporting fascia and ligaments. Externally, the perineal body is the conversion of the bulbocavernosus, transverse perineal, and external anal sphincter muscles.
With stretching of the muscles and endopelvic fascia (example: pregnancy, years of straining, advancing age) or with trauma to the tissues with a perineal laceration at time of childbirth, neuromuscular changes occur that result in the pelvic organs no longer having the same support to remain suspended in the pelvis. Disruption of the perineal body may allow for descent of the posterior vaginal wall through the introitus. Clinical measurements of the vaginal introitus correlate with severity of pelvic organ prolapse. [4, 5]
Pelvic floor disorders are rarely caused by a single event. Delancey describes a conceptual model, the Lifespan Model, which suggests that these disorders are the result of different combinations of biologic and lifestyle factors.  The first phase consists of “predisposing factors”, such as genetics, nutrition, and toilet training. Although a specific genetic predisposition has not been identified, collagen type 3 alpha 1 has been found to be associated with pelvic organ prolapse.  The second phase includes “inciting factors”, such as childbirth and obstetric interventions at time of delivery. The third and final phase of the model consists of “intervening factors” which include obesity, age, high impact aerobics, heavy lifting or straining, among other repetitive traumas caused to the pelvic floor. Collectively over a lifetime, the pelvic floor experiences dysfunction that may lead to symptomatic pelvic floor disorders. 
Symptoms of patients with an enlarged vaginal introitus may vary from completely asymptomatic to bothersome daily complaints. History taking and a careful pelvic exam are essential for proper management of these patients.
Those with an enlarged vaginal introitus who also have a rectocele may complain of a bulge coming from her vagina or defecatory dysfunction, including constipation or even the need to splint a finger on the perineum or in the vagina to evacuate the rectum.
Some women complain of sexual dysfunction. A patient may state she no longer feels the same amount of sexual pleasure, attributing this to her “relaxed” vaginal opening. This complaint alone is an uncommon reason to perform a revision perineorrhaphy, which would reapproximate the perineal body.
The surgical procedure to repair an enlarged vaginal introitus is called a perineorrhaphy. However, surgical repair is not necessary unless the patient has bothersome symptoms and has failed conservative therapy. The potential for postoperative dyspareunia is rarely justified to repair an asymptomatic rectocele, perineocele or defective perineal body support.
A survey of almost 200 gynecologists indicated that the decision to perform a perineorrhaphy, which reapproximates the perineal body and thus decreases the size of the vaginal introitus, is made with the patient in the office in about 65% of cases; other times it is made in the operating room either after an exam under anesthesia or after a concomitant pelvic organ prolapse repair. Size of the vaginal introitus and concomitant prolapse repairs are the most common reason to perform the procedure. Dyspareunia, sexual dysfunction, and cosmesis are less important to surgeons when making the decision of whether or not to perform a perineorrhaphy. 
The vagina can be anatomically divided into the proximal, middle, and distal regions. The proximal segment, or the apex, is stabilized by the cardinal and uterosacral ligaments. Uterine and vault prolapse are both associated with damage to these supportive structures
The mid portion of the vagina is attached laterally to the pelvic sidewalls by the lower portion of the paracolpium to the arcus tendineus fascia pelvis (ATFP), which creates the superior lateral vaginal sulcus observed during a physical examination. The pubocervical fascia stretches between the ATFP to support the anterior vaginal wall and bladder. A cystocele can occur when damage the pubocervical fascia in the central or lateral areas are weakened. In a similar fashion, the posterior vaginal wall in the mid vagina is supported centrally and laterally by the rectovaginal fascia, which is attached to the fascia of the levator ani musculature. Defects in this support can lead to a rectocele.
The distal vagina is firmly attached to the surrounding structures, including the urethra and symphysis pubis anteriorly, levator ani laterally, and perineal body musculature posteriorly. 
Although no absolute contraindications exist to performing a procedure to decrease the size of the vaginal introitus, such a surgery is not performed unless the patient is symptomatic. In many cases, these procedures are performed in conjunction with other pelvic prolapse repairs.