Vulvovaginal and Müllerian Anomalies

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Chapter 548 Vulvovaginal and Müllerian Anomalies

The sequence of events that occur in a developing embryo and early fetus to create a normal reproductive system includes cellular differentiation, duct elongation, fusion, resorption, canalization, and programmed cell death. Any of these processes can be interrupted during formation of the reproductive system, creating gonadal, müllerian, and/or vulvovaginal anomalies (see Table 548-1 on the Nelson Textbook of Pediatrics website at www.expertconsult.com). Genetic, epigenetic, enzymatic, and environmental factors all have some role in the process (see Table 548-2 on the Nelson Textbook of Pediatrics website at www.expertconsult.com)image. Most clinicians use the standard classification system adopted by the American Society for Reproductive Medicine (originally the American Fertility Society [AFS] classification). Others have proposed modified and more-detailed anatomic classification systems such as the modified AFS system or the VCUAM (vagina, cervix, uterus, and adnexa-associated malformation) system.

Table 548-1 COMMON MÜLLERIAN ANOMALIES

ANOMALY DESCRIPTION
Hydrocolpos Accumulation of mucus or nonsanguineous fluid in the vagina
Hemihematometra Atretic segment of vagina with menstrual fluid accumulation
Hydrosalpinx Accumulation of serous fluid in the fallopian tube, often an end result of pyosalpinx
Didelphic uterus Two cervices, each associated with one uterine horn
Bicornuate uterus One cervix associated with two uterine horns
Unicornuate uterus Result of failure of one müllerian duct to descend

Table 548-2 HERITABLE DISORDERS ASSOCIATED WITH MÜLLERIAN ANOMALIES

MODE OF INHERITANCE DISORDER ASSOCIATED MÜLLERIAN DEFECT
Autosomal dominant Camptobrachydactyly Longitudinal vaginal septa
Hand-foot-genital Incomplete müllerian fusion
Autosomal recessive Kaufan-McCusick Transverse vaginal septa
Johanson-Blizzard Longitudinal vaginal septa
Renal-genital-middle ear anomalies Vaginal atresia
Fraser syndrome Incomplete müllerian fusion
Uterine hernia syndrome Persistent müllerian duct derivatives
Polygenic/multifactorial Mayer-Rokitansky-Küster-Hauser syndrome Müllerian aplasia
X linked Uterine hernia syndrome Persistent müllerian duct derivatives

Embryology (Pathogenesis)

Phenotypic sexual differentiation, especially during formation of the vulvovaginal and müllerian systems, is determined from genetic (46,XX), gonadal, and hormonal influences (Chapter 576). The genetic sex of the embryo is determined at fertilization when the gamete pronuclei fuse. The primordial germ cells (oogonia or spermatogonia) migrate from the yolk sac to the gonadal ridges. The primitive gonads are indistinguishable until about the 7th wk of development. Gonadal development determines the progression or regression of the genital ducts and subsequent hormonal production and, thus, the external genitalia. Critical areas in the SRY region (sex-determining region on the Y chromosome) are believed to be the factors that drive the development of a testis from a primitive gonad as well as spermatogenesis. The testis begins to develop between 6 and 7 wk of gestation, first with Sertoli cells followed by Leydig cells, and testosterone production begins at about 8 wk of gestation. The genital tract begins to differentiate later than the gonads. The differentiation of the wolffian ducts begins with an increase in testosterone, and the local action of testosterone activates development of the epididymis, vas deferens, and seminal vesicle. Further male genital duct and external genital structures depend on the conversion of testosterone to dihydrotestosterone (DHT).

In a 46,XX embryo, female sexual differentiation occurs about 2 wk later than gonadal differentiation in the male. Because the ovaries develop prior to and separately from the müllerian ducts, females with müllerian ductal anomalies usually have normal ovaries and steroid hormone production. The regression of the wolffian ducts results from the lack of local gonadal testosterone production, and the persistence of the müllerian (or paramesonephric) ducts results from the absence of AMH (antimüllerian hormone or müllerian-inhibiting substance) production. The müllerian ducts continue to differentiate into the fallopian tubes, uterus, and upper vagina without interference from AMH. There are complex interactions among the mesonephric, paramesonephric, and metanephric ducts (the metanephros becomes the adult kidney) early in embryonic development, and normal development of the müllerian system depends on such interaction. If this process is interrupted, coexisting müllerian and renal anomalies are often discovered in the female patient at the time of evaluation. Differentiation along the female pathway is often referred to as the default pathway, but it is an extremely intricate process regulated by the absence, presence, or dosage compensation of numerous gene products (e.g., SRY, SF-1, WTI, SOX9, Wnt-4, GATA4, DAX-1, BMP4, HOX genes, etc.) and remains not entirely understood.

By 10 wk of gestation, the caudal portions of the müllerian ducts fuse together in the midline to form the uterus, cervix, and upper vagina, in a Y-shaped structure, with the open upper arms of the Y forming the primordial fallopian tubes. Initially the müllerian ducts are solid cords that gradually canalize as they grow along and cross the mesonephric ducts ventrally and fuse in the midline. The mesonephric ducts caudally open into the urogenital sinus, and the müllerian ducts contact the dorsal wall of the urogenital sinus, where proliferation of the cells at the point of contact form the müllerian tubercle. Cells between the müllerian tubercle and the urogenital sinus continue to proliferate, forming the vaginal plate. At the same time of the midline fusion of the müllerian ducts, the medial walls begin to degenerate and resorption occurs to form the central cavity of the uterovaginal canal. Uterine septal resorption is thought to occur in a caudal to cephalad direction and to be complete at approximately 20 wk of gestation. This theory has been scrutinized because some anomalies do not fit the standard classification system. It is possible that septal resorption starts at some point in the middle and proceeds in both directions. At about 16 wk of gestation the central cells of the vaginal plate desquamate and resorption occurs, forming the vaginal lumen. The lumen of the vagina is initially separated from the urogenital sinus by a thin hymenal membrane. The hymenal membrane undergoes central resorption and perforates before birth. The sequential steps in this intricate process could be interrupted at countless points along the pathway of differentiation.

Clinical Manifestations

Vulvovaginal and müllerian anomalies can manifest at a variety of chronological time points during a female’s life: from infancy, through childhood and adolescence, and adulthood (see Table 548-1). The majority of external genitalia malformations manifest at birth, and often even subtle deviations from normal in either a male or female newborn warrant evaluation. Structural reproductive tract abnormalities can be seen at birth or can cluster at menarche or any time during a woman’s reproductive life. Some müllerian anomalies are asymptomatic, whereas others can cause gynecologic, obstetric, or infertility issues.

Clinical manifestations and treatments depend on the specific type of müllerian anomaly and are varied. There may be a pelvic mass, which may or may not be associated with symptoms. A mass bulging at the introitus or within the vagina indicates complete or partial outflow tract obstruction. An adolescent can present with pelvic pain either in association with primary amenorrhea or several months after the onset of menarche. Patients also may be asymptomatic until they present with miscarriage, pregnancy loss, or preterm delivery. When presentation is acutely symptomatic, emergency management may be required. Obstruction can result from a number of distinct anomalies including an imperforate hymen, transverse vaginal septum, and noncommunicating rudimentary horn. As menstrual fluid accumulates proximal to the obstruction, the resulting hematocolpos and hematometra cause cyclic pain or a pelvic mass.

Laboratory Findings

Several radiographic studies have been used, often in combination, to aid in diagnosis including ultrasound, hysterosalpingogram (HSG), sonohysterography (saline-infusion sonography), and MRI. Laparoscopy and hysteroscopy was the gold standard for evaluation of müllerian anomalies, but the new standard may be MRI due to its noninvasive, high-quality capabilities. MRI is the most sensitive and specific imaging technique used for evaluating müllerian anomalies because it can image nearly all reproductive structures, blood flow, external contours, junctional zone resolution on T2 weighted images, and associated renal and other associated anomalies. MRI also has a high correlation with surgical findings because of its multiplanar capabilities and high spatial resolution. Three-dimensional ultrasound (3D US) is another useful diagnostic tool and may be superior to traditional pelvic ultrasound and HSG. Evaluation of the external contour of the uterus is important for differentiating types of uterine anomalies. This often requires a combination of radiologic modalities for uterine cavity, external contour, and possible tubal patency. Diagnostic laparoscopy or hysteroscopy may be necessary depending on the presentation, but it is used less with the advancement of MRI and other imaging.

Diagnosis of müllerian anomalies should include a physical exam, pelvic ultrasound, possibly MRI, and renal and skeletal inspections for associated anomalies. Renal anomalies are noted in 30-40% and skeletal anomalies are associated in 10-15% of patients with müllerian anomalies. Unilateral renal agenesis occurs in 15% of patients. The most common skeletal anomalies are vertebral. Patients usually have a normal female karyotype (46,XX), but several familial segregations and gene mutations and/or abnormal karyotypes have been reported (see Table 548-2). About 5-8% of patients with congenital müllerian anomalies have abnormal karyotypes. Most malformations are sporadic, with a polygenic mechanism and multifactorial etiology.

Adolescent patients can present with acute obstruction of the outflow tract due to a müllerian anomaly, which requires emergency evaluation and surgical treatment. A small percentage of girls present with concomitant urinary retention due to an altered urethral angle or pressure on the sacral plexus. Urinary hesitancy and incomplete emptying symptoms may be present before abdominopelvic pain from the obstruction in a patient of any age.

Uterine Anomalies

Anomalous development of the uterus may be symmetric or asymmetric and/or obstructed or nonobstructed. Patients can present with primary amenorrhea or have either irregular or regular menstrual cycles. There may be an asymptomatic pelvic mass or dysmenorrhea. In adolescents and adults, pregnancy loss can cause the first suspicion of a uterine anomaly. Treatment is highly specific to the specific anomaly.

Uterine Didelphys

A uterine didelphys is the result a complete failure of fusion and represents 5% of müllerian anomalies. There are 2 fallopian tubes, 2 completely separate uterine cavities, 2 cervices, and often 2 vaginal canals or 2 partial canals because of an associated longitudinal vaginal septum (75% of the time). Evaluation for renal anomalies should be pursued because they are common as well. At times, the longitudinal septum attaches to 1 sidewall and obstructs 1 side of the vagina (or hemivagina). The combination of uterine didelphys, obstructed hemivagina, and ipsilateral renal agenesis is a variant of the broad spectrum of müllerian anomalies that is referred to as the Heryln-Werner-Wunderlich syndrome (HWWS) or obstructed hemivagina and ipsilateral renal anomaly (OHVIRA) syndrome in the literature (Fig. 548-1). Adolescents with this disorder usually present with abdominal pain shortly after menarche. Although there still may be a risk of adverse pregnancy outcomes with a uterine didelphys (preterm labor, malpresentation), overall pregnancy outcomes are generally good and are associated with less risk than in other uterine anomalies.

Vaginal Anomalies

Congenital Absence of the Vagina and Mayer-Rokitansky-Küster-Hauser Syndrome

Vaginal agenesis or atresia results when the vaginal plate fails to canalize. On physical exam it appears as an extremely foreshortened vagina, sometimes referred to as a vaginal dimple. Isolated (partial) vaginal agenesis involves an area of aplasia between the distal vaginal portion and a normal upper vagina, cervix, and uterus. On initial presentation it may be confused with a low transverse septum or imperforate hymen, and therefore clear delineation of the anomaly is critical before attempting surgical repair. It can also manifest with cyclic pain and a bulging mass just after menarche. Surgical repair and reconstruction are complicated and individualized and best performed with consultation of specialists.

Uterine and vaginal agenesis often occur together because of their close association during development, when müllerian ductal development fails early in the process. The most common cause of vaginal agenesis is Mayer-Rokitansky-Kuster-Hauser syndrome (MRKH), with an incidence reported at 1:4,000-10,000 female births. The cause is unknown and likely has a multigenetic and multifactorial etiology. MRKH is characterized by primary amenorrhea, normal vulva, anomalies of the uterus (usually aplasia or agenesis), attenuated fallopian tubes, normal ovaries, normal female karyotype and phenotype, and associated anomalies (most commonly renal and skeletal). The vagina either is completely absent or only has a small dimpled opening. MRI imaging is often necessary to determine if any small uterine remnant is present (often located on the pelvic sidewall or near the ovaries and only a small fibromuscular remnant) and to clearly delineate the anomaly. Absence of the vagina and uterus has significant anatomic, physiologic, and psychologic implications for the patient and family. Any diagnosis of müllerian agenesis must be differentiated from androgen insensitivity (testicular feminization) as well; karyotype, serum testosterone levels, and pubic hair distribution usually help distinguish the two.

Lesions involving other organ systems occur in association with the Mayer-Rokitansky-Küster-Hauser syndrome. The most common are urinary tract anomalies (15-40%) primarily involving unilateral absence of a kidney, a horseshoe or pelvic kidney, and skeletal anomalies (5-10%), which primarily involve vertebral development.

Transverse Vaginal Septa (Vertical Fusion Defects)

Vertical fusion defects can result in a transverse septum, which may be imperforate and associated with hematocolpos or hematometra in adolescents or with mucocolpos in infants. These are much less common anomalies, reportedly found in 1:80,000 females. Most patients present with amenorrhea and cyclical pain around the time of menarche. Patients who have a small opening in the transverse septa might present with prolonged vaginal drainage and discharge. Transverse vaginal septa vary in location in the vagina (15-20% in the lower third, but most in the middle or upper third of the vagina) and thickness, but are generally ≤1 cm thick. High locations, thick septa, and narrow vaginal orifices present challenging surgical cases.

Transverse vaginal septa may be associated with other congenital anomalies, although this occurs less often than with müllerian agenesis. These patients have a functional normal uterus, unlike women with MRKH. There is also an increased incidence of endometriosis secondary to retrograde menstruation.

Evaluation of transverse vaginal septa includes careful pelvic examination and often pelvic imaging, usually with MRI and ultrasound, to delineate the anatomic abnormalities. MRI is especially helpful to determine the thickness of the septum and presence of a cervix and for surgical planning. Diagnosis and treatment plans should be made as soon as possible after menarche, because significant accumulation of hematometria and/or hematosalpinx could affect future reproductive success by negatively affecting uterine and/or tubal function.

Treatment

An imperforate hymen requires resection to prevent or relieve the outflow tract obstruction. Many approach it with a horizontal or cruciate incision, excision of excess tissue, and reanastomosis of the mucosal edges. Repair should be done at time of diagnosis, if the patient is symptomatic. Although the lesion may be repaired any time during infancy, childhood, or adolescence, surgery is facilitated by estrogen stimulation and thus is ideally performed in adolescence, either after puberty or menarche.

Treatment of congenital absence of the vagina is usually delayed until the patient is ready to be sexually active. The nonsurgical approach is the most common first-line therapy due to the high success rate and extremely low morbidity. It requires dedicated use of dilators to create a functional vagina. The series of dilators come in progressively increasing sizes and require a commitment and maturity on the part of the patient to comply with daily use (20-30 min daily). If done correctly it is possible to achieve a functional vaginal length (6-8 cm), width, and physiologic angle for intercourse in about 6-8 wk of therapy. When the ultimate size that accommodates coitus is reached, then the patient must use the dilator or have coitus with a frequency that maintains adequate length.

Surgical approaches require more expertise and often some postoperative vaginal dilation to ensure a functional result. Controversy exists among surgical subspecialties, because pediatric surgeons and pediatric urologists often recommend creating the neovagina in infancy. Pediatric gynecologists and reproductive endocrinologists believe better outcomes result from creating the neovagina when the young woman is interested in sexual activity and can participate in the decision to have surgery and in her own postoperative recovery. There is no consensus as to the best surgical option; the most-used procedures include 2 surgical approaches followed by dilators or an approach using a loop of bowel out of which to construct a vagina. Patients need to be counseled about the ability to use their own oocytes and a gestational carrier through IVF to achieve pregnancy. These therapies can be quite complicated physically and emotionally. They are best approached in a multidisciplinary fashion, often with the assistance of psychologic counseling and surgeons with specialized training.

For transverse vaginal septa, treatment is surgical resection of the obstruction through a vaginal approach. Some surgeons advocate waiting ≥1 menstrual cycles or using preoperative dilators from below to increase the depth and circumference of the distal vagina and to allow menstrual blood to accumulate and dilate the upper portion of the vagina. Complete resection of the septum, with primary anastomosis of the upper and lower mucosal segments, should be attempted. A vaginal stent is sometimes placed postoperatively in the vagina to maintain patency and allow squamous epithelization of the upper vagina and cervix. Follow-up dilation may be necessary after the stent is removed. Careful preoperative assessment is important because surgeons who begin a case believing they are operating on an imperforate hymen can find themselves in entirely different and more complex surgical planes. Regardless of the approach, vaginoplasty is often best deferred until the patient is mature and physically and psychologically prepared to participate in the healing process and postoperative dilator treatments.

Longitudinal vaginal septa themselves do not lead to adverse reproductive outcomes but may be symptomatic in a patient, causing dyspareunia, difficulties with tampon insertion, or impedance during vaginal birth. Such complaints can warrant a resection of the vaginal septa. In a small number of patients there may be unilateral obstruction of a hemivagina, which would require incision and resection.

Vulvar and Other Anomalies

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