Imperforate hymen is a disorder of the female genital tract in which the hymen does not open during embryonic period and causes vaginal outflow obstruction of secretions and blood. It is either diagnosed in newborns and infants, or in teenage girls that present with abdominal pain, a pelvic mass, and amenorrhea. The diagnosis can be made during a physical examination, whereas surgical therapy successfully alleviates all symptoms.
If the diagnosis is not made early on, the imperforate hymen is usually asymptomatic until menstruation cycles start, but due to complete obstruction of the vaginal orifice, the secretions produced under stimulation of estrogen from the mother during pregnancy can lead to mechanical obstruction of the urethra and bladder . As a result, hydroureteronephrosis may ensue and a pelvic mass, most commonly found at the introitus , is often seen in neonates and infants . In adolescent girls, symptoms most frequently appear around 12 and 13 years , and an expanding abdominal mass accompanied by cyclic lower abdominal pain is characteristic for this condition , whereas dysuria and urinary hesitancy are reported when the urinary system is affected . Failure of blood passage results in amenorrhea , which may not be detected early on. Rare cases have described recurrent urinary tract infections (UTIs) and pelvic abscesses and sciatica as presenting symptoms .
The diagnosis of the imperforate hymen can be made during the physical examination of the external genitalia when a bluish bulging hymen is observed beneath the labia during inspection . A distended vagina can also be detected during a rectal examination when a pelvic mass is felt . Ultrasonography may reveal findings such as distension of the uterus (hydrometra), vagina distended with fluid or blood (hydrocolpos and hematocolpos, respectively) and a cystic retropubic mass  .
Depending on the presence of symptoms or complications, surgical approaches include complete hymenectomy or hymenotomy, with a goal of re-establishing vaginal outflow   . Various incisions, including T-shaped, cruciform, cyclical and X-shaped may be used . If the diagnosis is made during neonatal period or infancy and if there are no signs of obstruction of the urinary system, a planned hymenotomy after the onset of puberty and before menarche is the recommended strategy . Preservation of hymenal tissue may be possible through alternative surgical methods and it is not uncommon of patients families to consider this procedure due to cultural and religious reasons . Surgery will allow passage of blood and secretions through the vaginal orifice and no further measures are necessary . In rare cases, amenorrhea and reduced menstrual flow may recur due to the failure of hymenotomy .
If the condition is recognized early, the prognosis is very good with appropriate surgical therapy. But the diagnosis is often missed , and if not recognized for a significant amount of time, complications such as infections, hydronephrosis, endometriosis and even infertility may develop . Moreover, case reports have shown that a turbo ovarian abscess and sepsis may develop, further emphasizing the need for an early diagnosis .
The reason why this condition appears remains unknown. In virtually all cases, imperforate hymen develops sporadically, but reports of familial cases have been described, suggesting a possible genetic component in the pathogenesis . Unlike other congenital vaginal anomalies (such as vaginal atresia), the imperforate hymen is rarely associated with other malformations .
Imperforate hymen is considered to be a rare entity, with incidence rates ranging between 0.014%-0.1% (between 1 in 1,000-200,000 newborn females)   , but it is termed as the most common obstructive congenital anomaly of the female genital tract  . So far, risk factors for this condition have not been identified. The diagnosis is made in two age groups - in infants and toddler girls less than 4 years of age and in prepubertal and pubertal teenage girls older than 10 years, when almost 100% of cases are symptomatic .
The hymen is an embryological remnant of mesodermal tissue and is formed from the caudal end of the paramesonephric ducts and urogenital sinus in the proximity of the Müller's duct   . Perforation of this anatomical structure is expected to occur during the eighth week of gestation when a fold of mucous membrane remains around the vaginal entrance  . For still unknown reasons, this layer of epithelialized connective tissue persists and forms a transverse septum, obstructing the vaginal opening at the level of introitus  . Vaginal secretions produced under maternal estrogen stimulation accumulate in newborn babies and cause mechanical obstruction, while a similar mechanism explains why signs and symptoms of this condition appear following menarche . Namely, blood products are unable to pass through the vaginal orifice and begin to compress adjacent organs - the bladder, bowel or pelvic veins . In cases that are left undiagnosed for a prolonged period of time, mechanical compression may lead to severe obstruction of the urinary tract and retrograde blood flow into the endometrial and tubal systems .
Various studies concluded that examination of external genitalia in newborns may identify a range of congenital anomalies, including imperforate hymen, which can help in making the diagnosis as early as possible  . Other authors suggest evaluation of all female relatives of the affected patients, as familial cases have been described in the literature .
Imperforate hymen is the most common congenital condition of the female genital tract, seen in approximately 0.014%-0.1% of all newborn females . This layer of epithelialized connective tissue should normally rupture during the third month of gestation, but for reasons yet to be discovered, failure of this process occurs, leading to complete closure of the vaginal opening at the level of introitus  . As a result, vaginal secretions or blood during menstrual cycles are not able to pass, eventually leading to symptoms by mechanically compressing the adjacent organs and structures, including the bladder and the ureters, the bowel or pelvic veins . Symptoms may appear early on in the first few years of life, or from the onset of menarche, which is much more common . Cyclic abdominal pain and the presence of a pelvic mass is most frequently reported, while urinary retention may cause dysuria and hesitancy . In rare cases, the severe obstruction may lead to hydronephrosis, endometriosis, and even sterility, but blood accumulation can also predispose patients to an infection that may be life-threatening . For this reason, an early diagnosis is vital in reducing the risk of complications  . A simple examination of the external genitalia is sufficient, as the bulging bluish hymen can be seen during inspection without any doubt, whereas ultrasonography can be useful for assessing the severity of organ compression  . Surgical treatment (either hymenectomy or hymenotomy) effectively enables passage of contents through the vaginal orifice and a very low rate of recurrence is observed . Because the condition is easy to diagnose, but also because the diagnosis is often missed, unfortunately , many studies suggest the mandatory examination of the external genitalia in newborn babies , so that early recognition may prevent the onset of potentially life-threatening complications such as hydronephrosis and sepsis .
Imperforate hymen is a congenital condition of the female genitalia. The hymen is a layer of connective tissue that covers the external opening of the vagina and around the eighth week of fetal development, it is supposed to rupture and allow passage of vaginal secretions in newborns and blood products when the menstrual cycle is initiated in pubertal girls. For some reason, however, the hymen does not rupture, causing complete closure of the vaginal opening, which leads to accumulation of fluid in the urogenital tract. The condition is rare, appearing in 0.014%-0.1% of all female newborn babies and symptoms appear as a result of mechanical compression of adjacent organs by the accumulated fluid (vaginal secretions in infants and blood products in pubertal girls), most notably the kidneys and the bowel. Most common symptoms are abdominal pain that may be cyclic in nature (following menstruation cycles), the presence of a pelvic mass and urinary complaints in the form of painful urination and hesitancy. In rare cases, teenage girls may notice that their first menstruation cycle is late, but the complete closure of the vaginal opening masks its true onset. The diagnosis is very easy to make since the bulging hymen may be readily seen during simple inspection of external genitalia. Unfortunately, the diagnosis is still often missed and for this reason, many authors suggest that this type of exam should be performed in all female newborn babies on a regular basis. Ultrasonography may be useful for assessment of the kidneys and the bladder. The goal of treatment is to allow passage of fluid and blood products through the vagina and two surgical modalities are used in the setting of the imperforate hymen. Either complete removal of the hymen (hymenectomy) or by making an incision through this membrane (hymenotomy) can be performed. Urinary flow obstruction, endometriosis, the infection that may even lead to sepsis, but also infertility, are some of the complications that have been documented in these patients, which is why an early diagnosis is vital.