Pediatric Imperforate Hymen 

Imperforate hymen is the most common and most distal form of vaginal outflow obstruction.^[1] As a consequence of normal development, the central portion of the hymenal membrane is usually absent. This absence creates the typical configuration of a ringlike structure at the level of the vaginal vestibule. Persistence of the intact hymenal membrane results in the condition of imperforate hymen. Diagnosis and management of imperforate hymen are straightforward, but an understanding of the differential diagnosis of vaginal outflow obstruction is imperative.

For excellent patient education resources, visit eMedicine's Women's Health Center. Also, see eMedicine's patient education articles Amenorrhea and Female Sexual Problems.

The imperforate hymen is a solid membrane interposed between the proximal uterovaginal tract and the introitus. Ambroise Pare first described this condition in 1633.^[2] It is classified as a vertical fusion defect. However, it differs from other vertical fusion defects in that it is not derived from the müllerian system. The configuration and normal size of the hymenal orifice in prepubertal girls has received attention in the context of evaluating potential child abuse.^[3]

Anatomic variations of the patent hymen exist, with the most common being an annular or circumferential hymen in which the hymen completely surrounds the vaginal orifice and has a central opening. Other appearances of the hymen include crescentic, fimbriated, septate, cribriform, and microperforate forms. In some patients, perforations do not become confluent, and a cribriform pattern with multiple small perforations may be observed.^[4]

Vaginal abnormalities in the premenarchal patient include hymenal and vaginal cysts, urethral prolapse, labial agglutination, vaginitis, foreign bodies, and lichen sclerosis.

Frequency

Imperforate hymen is the most frequent cause of vaginal outflow obstruction, occurring in 0.1% of infant girls.

The hymen originates from the embryonic vagina buds from the urogenital sinus. As a consequence, the hymen is a composite of vaginal epithelium and epithelium of the urogenital sinus interposed by mesoderm. Once the hymen becomes perforated or forms a central canal, it establishes a communication between the upper vaginal tract and the vestibule of the vagina (see the image below).^[5]

Specific etiologies for the failure to establish patency are not evident. The cause may be related to failure of apoptosis due to a genetically transmitted signal, or it may be related to an inappropriate hormonal milieu. Familial inheritance in successive generations has been described.^[6]

Any obstruction of the vaginal tract during the prenatal, perinatal, or adolescent period results in the entrapment of vaginal and uterine secretions. In patients with imperforate hymen, this obstruction is at the level of the introitus and becomes evident when the distensible membrane bulges between the labia. Various terms, such as mucocolpos, hematocolpos, and pyocolpos, are used to describe this condition depending on the nature of the retained contents.

In fetal development and in the immediate perinatal period, mucoid secretions from the uterovaginal tract result in mucocolpos under the influence of maternal estrogens. When the diagnosis is made in adolescence, the retained secretions consist of menstrual products, and the resulting mass effect in the vagina and uterus are referred to as hematocolpos and hematometrocolpos, respectively. Reflux of the endometrial tissue through the fallopian tubes (ie, hematosalpinx) may result in secondary endometriosis.

An accumulation of infected material within the vaginal cavity (ie, pyocolpos) may result from an infection that is ascending through microperforations in the membrane.

Clinical presentations of imperforate hymen range from an incidental finding on physical examination of an asymptomatic patient to findings discovered on an evaluation for primary amenorrhea or abdominal or back pain.

The neonate with imperforate hymen typically presents with a bulging membrane between the labia (see the image below). The membrane may be white because it is distended from trapped mucoid material secreted as a result of stimulation by maternal estrogen. In severe cases, the distention is in the distal vaginal tract and extends proximally into the uterus. A lower abdominal midline mass may be evident on physical examination because the shallow pelvis of a neonate allows the uterus to be palpated above the pubis symphysis. This mucocolpos can lead to urinary tract infections or bladder obstruction. The fact that most patients with imperforate hymen present during early adolescence suggests that the diagnosis is often overlooked during neonatal examination.

In the prepubertal child, an imperforate hymen can be mistakenly diagnosed as labial agglutination or a congenitally absent vagina. The differentiation on gross physical examination is often difficult because of the lack of estrogenization of the perineum. Placing the patient in the knee-chest position aids physical examination in this age group. Have the patient kneel on the examination table with her elbows on the table and her face resting in her hands. Gently spread the buttocks and labia and have the patient exhale or blow.^[7] If the examination is still difficult, sedation or anesthesia may be necessary. If an abnormality is suspected, rectal examination or ultrasonography may help in making the proper diagnosis.

When an adolescent presents with primary amenorrhea, careful physical examination is essential. The presence or absence of secondary sexual characteristics should be noted. The most common clinical presentation includes primary amenorrhea. The adolescent with imperforate hymen typically presents with symptoms of lower abdominal or pelvic pain that may initially be cyclical. A thorough history should be obtained, and the patient and family should be questioned about the patient's abdominal or pelvic pain. They should be asked about cyclical pain, a history of vaginal bleeding (which suggests secondary amenorrhea), a family history of genitourinary abnormalities including imperforate hymen, and other factors to determine if any underlying endocrinologic problem is present. During questioning, the patient and family usually recognize a cyclic pattern to the patient's abdominal symptoms.

Additional presenting symptoms of imperforate hymen include back pain, urinary retention (37%-60% of patients), and constipation.^[8] Although cyclic lower abdominal pain is most frequently reported as the presenting symptom in young women, back pain and urinary retention have also prompted evaluation and resolved after hymenotomy.

In patients with a history of amenorrhea, abdominopelvic pain, and secondary sexual characteristics, the most likely diagnosis is obstruction of the uterovaginal tract with consequent hydrometrocolpos (see the image below). However, the etiology may be the consequence of various developmental anomalies. A lower abdominal mass may be palpated on physical examination, or a pelvic mass may be found on bimanual rectal examination. The diagnosis of imperforate hymen is often established during examination when a distended bluish membrane is observed at the introitus. In the absence of this finding, only imaging findings can establish the level of obstruction.

The differential diagnoses of uterovaginal obstruction include disorders of vaginal development, such as a transverse vaginal septum or complete vaginal agenesis, which may be associated with other developmental anomalies (eg, Rokitansky-Küster-Maier-Hauser syndrome). Duplication anomalies of the uterovaginal tract often involve one tract that is decompressed and one that is obstructed. In these patients, abdominal and back pain occurs despite their having a cyclic menstrual period. One must always consider other noncongenital conditions, such as malignancies of the upper or lower genital tract, in the differential diagnoses.

Several reports describe the prenatal diagnosis of imperforate hymen. Fetal diagnosis has occurred as early as 25 weeks' gestation. A thin bulging membrane separating the labia in association with a distended vagina is apparent on ultrasonography.^[9] These findings are usually noted during an evaluation for fetal ascites and are thought to result from distal urinary tract obstruction. However, they can also be related to reflux of uterine contents through the fallopian tubes. Ascites and bladder outlet obstruction are the most common associated findings in the fetal period.^[10] Intestinal, cardiac, and anorectal defects have not been reported in conjunction with imperforate hymen.

Surgical intervention is most often required in the adolescent who presents with symptomatic vaginal outflow obstruction. Establishing a patent hymen is necessary to eliminate pain and discomfort and to establish a functional genital tract. Avoidance of persistent obstruction preserves the patient's fertility by reducing the risk of secondary endometriosis.

In the infant with a bulging hymenal membrane due to the effects of maternal estrogen, the diagnosis is evident, and surgical therapy can be undertaken promptly.

On occasion, the diagnosis is made serendipitously in asymptomatic premenarchal girls. Intervention can justifiably be delayed until they approach menarche. This delay ensures that a previously nonvisualized orifice, such as an anterior crescentic opening, is absent. The presence of such an opening may obviate surgical intervention.

Careful evaluation of the perineum of the newborn is essential. Under the influence of maternal estrogens, the female neonate typically has full labia majora. Inspection of the introitus reveals that the hymenal membrane is pink and slightly edematous. The edges of the hymenal membrane may even appear fimbriated. In the newborn with an imperforate hymen, the membrane is often bulging because of retained mucoid secretions. One must distinguish imperforate hymen from a vaginal cyst, which fills the introitus but is attached to only one vaginal aspect.

In the symptomatic female adolescent, genital examination typically reveals a bulging bluish membrane across the vaginal vestibule, which represents the hematocolpos (ie, menstrual products retained in the vagina). If bulging is not noted in the resting state, it may be elicited by having the patient perform a Valsalva maneuver.

The diagnosis should not be confirmed by aspirating secretions beyond the obstruction because this procedure may result in iatrogenic pyocolpos. Instead, the diagnosis should be confirmed by performing noninvasive imaging studies (eg, ultrasonography, MRI) to determine the extent of the vaginal outflow obstruction and to diagnose other associated anomalies. Although rare, combined anomalies (ie, imperforate hymen and a transverse vaginal septum) can occur.^[11]

Surgical intervention is contraindicated only when the evaluating physician is unfamiliar with the condition and the differential diagnoses and when imaging modalities that help in excluding complicated anomalies of vaginal development are unavailable. Because evacuation of hematocolpos rarely requires emergency intervention, referral to a tertiary care center should be considered.