Hypoplastic uterus also called uterine hypoplasia, small uterus or underdeveloped uterus, is when a girl is born with a uterus (womb) that is abnormally small. Hypoplastic uterus is a congenital disorder, meaning it is present at birth.
Hypoplastic uterus can characterized by 1):
- Simple uterine hypoplasia: form of the uterus is normal, but is small in size
- Elongated uterine hypoplasia: an elongated uterus with normal fundus
- Malformative uterine hypoplasia: an abnormally shaped uterus (uterus is arcuate or T- or Y-shaped).
Hypoplastic uterus causes
Hypoplastic uterus occurs when the uterus fails to fully develop in the fetus. The cause of this abnormal fetal development is not yet known.
Hypoplastic uterus may be one symptom of a broader condition known as Mayer-Rokitansky-Küster-Hauser syndrome, a disorder in which the girl’s uterus and vagina are absent or underdeveloped due to an early arrest in development of mullerian ducts, in addition to other abnormalities 2). Women with Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome are characterized by the presence of 46 XX karyotype, normal female secondary sex characters, normal ovarian functions, and underdeveloped vagina. The incidence is 1 per 4000-10,000 female births 3). MRKH syndrome is a class 1 mullerian duct anomaly 4) and it has been subdivided into typical or type A and atypical or type B 5). Patients with type A syndrome have symmetric muscular buds, normal fallopian tubes. Patients with type B have asymmetric muscular buds, abnormal fallopian tubes, and may be associated with other congenital anomalies such as renal, skeletal, hearing, cardiac, and ocular anomalies. Familial distribution of these cases suggests the potential for a genetic link. Out of few genes which are identified in causation, one candidate is a mutation of the WNT4 gene, a developmental gene which regulates growth and differentiation during embryogenesis 6). Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome is the second most common cause of failure to start having periods at puberty (primary amenorrhea) after gonadal dysgenesis.
Hypoplastic uterus may also be associated with Perrault syndrome 7) and Swyer syndrome 8).
Swyer syndrome is also called pure 46XY gonadal dysgenesis, is a condition that affects sexual development. Sexual development is usually determined by an individual’s chromosomes; however, in Swyer syndrome, sexual development does not match the affected individual’s chromosomal makeup.
People usually have 46 chromosomes in each cell. Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics. Girls and women typically have two X chromosomes (46,XX karyotype), while boys and men usually have one X chromosome and one Y chromosome (46,XY karyotype). In Swyer syndrome (46XY gonadal dysgenesis), individuals with one X chromosome and one Y chromosome in each cell, the pattern typically found in boys and men, have female reproductive structures.
People with Swyer syndrome have typical female external genitalia. The uterus and fallopian tubes are normally-formed, but the gonads (ovaries or testes) are not functional; affected individuals have undeveloped clumps of tissue called streak gonads. Because of the lack of development of the gonads, The residual gonadal tissue often becomes cancerous, so it is usually removed surgically early in life.
People with Swyer syndrome are typically raised as girls and have a female gender identity. Because they do not have functional ovaries, affected individuals usually begin hormone replacement therapy during adolescence to induce menstruation and development of female secondary sex characteristics such as breast enlargement and uterine growth. Hormone replacement therapy also helps reduce the risk of reduced bone density (osteopenia and osteoporosis). Women with this disorder do not produce eggs (ova), but they may be able to become pregnant with a donated egg or embryo.
Swyer syndrome usually affects only sexual development; such cases are called isolated Swyer syndrome. However, depending on the genetic cause, Swyer syndrome may also occur along with health conditions such as nerve problems (neuropathy) or as part of a syndrome such as campomelic dysplasia, which causes severe skeletal abnormalities.
Perrault syndrome is a rare genetic condition that causes different patterns of signs and symptoms in affected males and females. A key feature of Perrault syndrome is hearing loss, sensorineural hearing loss in females and deafness alone in affected males 9). Affected females also have abnormalities of the ovaries. Neurological problems occur in some affected males and females.
In Perrault syndrome, the problems with hearing are caused by changes in the inner ear, which is known as sensorineural hearing loss. The impairment usually affects both ears and can be present at birth or begin in early childhood. Unless hearing is completely impaired at birth, the hearing problems worsen over time.
Females with Perrault syndrome have abnormal or missing ovaries (ovarian dysgenesis), although their external genitalia are normal. Severely affected girls do not begin menstruation by age 16 (primary amenorrhea), and most never have a menstrual period. Less severely affected women have an early loss of ovarian function (primary ovarian insufficiency); their menstrual periods begin in adolescence, but they become less frequent and eventually stop before age 40. Women with Perrault syndrome may have difficulty conceiving or be unable to have biological children (infertile).
Neurological problems in individuals with Perrault syndrome can include intellectual disability, difficulty with balance and coordinating movements (ataxia), and loss of sensation and weakness in the limbs (peripheral neuropathy). However, not everyone with this condition has neurological problems.
Hypoplastic uterus symptoms
Hypoplastic uterus symptoms may include:
- Failure to start having periods at puberty (primary amenorrhea)
- Abdominal pain
- A small or no vaginal opening
Secondary sexual characteristics are usually present, suggesting that normal ovarian activity may also be present.
Hypoplastic uterus diagnosis
Because the outward genitals appear normal, hypoplastic uterus is often not diagnosed until puberty, when a girl fails to start having periods and visits her doctor.
Hypoplastic uterus diagnosis starts with a thorough medical history and physical exam, including a pelvic exam.
Additional testing may include:
- Blood tests – to test for Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome, a disorder in which the uterus and vagina are absent or underdeveloped, in addition to other abnormalities
- Ultrasound – to obtain images of the reproductive organs
- Magnetic resonance imaging (MRI) – for more detailed images of the reproductive tract
Ultrasound and MRI are best imaging tools for the diagnosis of hypoplasia of the uterus.
Hypoplastic uterus ultrasound
In an ultrasound, hypoplasia of the uterus is usually indicated if the distance between the cornu or intercrual is less than 2 cm or if the distance from the internal os to the fundus is less than 3 to 5 cm 10).
Sonographic imaging features of hypoplastic uterus:
- Vaginal stenosis or aplasia (vagina may be small or absent)
- Cervical stenosis (small, narrow cervix)
- Small uterus with poorly developed fallopian tubes
- (Sometimes a definitive diagnosis may not be possible on ultrasound imaging)
- Small uterus with no normal zonal anatomy
- In extreme cases, absence of the uterus (aplasia of the uterus)
- Constriction bands (focal thickenings of the junctional zone) may be present in the uterus (better seen on MRI)
- T-shaped configuration may be seen at times (better seen on MRI)
- Endometrial thickness, endometrial cavity area, and endometrial cavity length may be markedly reduced.
- Markedly reduced cervical length may be noted
- Reduced uterine perfusion may be seen on color Doppler imaging of the uterus.
- Mayer Rokitansky Kuster-Hauser syndrome (vaginal agenesis with partial or complete absence of the uterus) is the most common manifestation of uterine hypoplasia/ aplasia
- Others have absent vagina with a small rudimentary uterus caused by the failure of the sinovaginal bulb to develop during the embryonic stage.
- Small or reduced myometrial volume
Figure 1. Hypoplastic uterus ultrasound
Footnote: The uterus is small, measuring just 3.8 x 1.2 cm
Hypoplastic uterus treatment
Treatment depends on the underlying cause of the individual’s hypoplastic uterus and her symptoms.
The treatment of Mayer Rokitansky Kuster-Hauser syndrome syndrome is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Depending upon the affected individual’s age at diagnosis, pediatricians or internists, gynecologists, kidney specialists (nephrologists), endocrinologist, orthopedic surgeons, plastic surgeons, physical therapists, psychiatrists and other health care professionals may need to work together to ensure a comprehensive approach to treatment.
Women with Mayer Rokitansky Kuster-Hauser syndrome syndrome are encouraged to seek counseling after a diagnosis and before treatment because the diagnosis can cause anxiety and extreme psychological distress. Psychological support and counseling both professionally and through support groups is recommended for affected females and their families.
Treatment will usually include appropriate management of the physical findings associated with Mayer Rokitansky Kuster-Hauser syndrome syndrome and psychological support for the emotional issues that often accompany the diagnosis.
The treatment of vaginal aplasia consists of creating a neovagina for sexual intercourse. This should be proposed to the women when they are emotionally mature and ready to start sexual activity. Treatment may be either nonsurgical or surgical. Nonsurgical techniques are considered the first-line approach. Vaginal dilators are specially designed plastic tubes that are used to help enlarge or create a vagina. The most common method is known as Franck’s dilator method. With this method, a physician (and then woman herself) applies a vaginal dilator, which progressively stretches and widens the vagina. This daily procedure may be continued for up to six weeks to several months.
Plastic surgery may be necessary to create an artificial vagina (vaginoplasty). There are a variety of different surgical techniques that may be used and there is no consensus as to which technique is best. Females who undergo surgery to create an artificial vagina will most likely need to use vaginal dilators after the surgery to enhance the chance of success.
Because females with Mayer Rokitansky Kuster-Hauser syndrome syndrome do not have a functional uterus, they cannot bear children (infertile). However, some affected women have been able to have a child by using in vitro fertilization of their own eggs and surrogate pregnancy. However, because Mayer Rokitansky Kuster-Hauser syndrome syndrome appears to be of genetic origin, the risk of passing on the disease to children exists and any decision to conceive should therefore be undertaken after careful consultation with their physicians and appropriate medical personnel.
Females with Mayer Rokitansky Kuster-Hauser syndrome syndrome who exhibit absence of one kidney (unilateral renal agenesis) may have an increased susceptibility to urinary tract infections and/or kidney stones (renal calculi). Physicians should carefully monitor affected females for infection and prescribe antibiotics as necessary. Skeletal abnormalities may also require reconstructive surgery, physical therapy, and/or other medical management depending upon the specifics and severity of the bone deformities.
References [ + ]
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