الفهرس 
Embryological and Anatomical Considerations of Genital System?Only 14 pages are availabe for public view
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Abstract
Human sex development is a highly complex process under the control of multiple genes and hormones. Both male and female sexual differentiation follows a timetable of events with predictable development of the gonads, internal genital ducts, and the external genitalia. Completion of sexual maturation occurs during the pubertal years. Abnormalities of sexual differentiation may occur at any step along this way.
Individuals with a congenital discrepancy between external genitalia and gonadal or chromosomal sex are classified as having disorders of sex development (DSD). Many of these individuals present as newborns with an atypical genital appearance often termed ambiguous genitalia. Yet, not all DSDs result in ambiguous external genitalia; some disorders can have normal external genitalia namely Turner syndrome (45,XO) with female phenotype and Klinefelter’s syndrome (47,XXY) with male phenotype.
DSD can be classified on a pathophysiologic basis as disorders of chromosomal, gonadal, or phenotypic sex origin. On the basis of gonadal histologic features, these disorders were originally classified into four broad groups: female pseudohermaphroditism, male pseudohermaphroditism, true
hermaphroditism, and gonadal dysgenesis (either mixed or pure).
The birth of a child with ambiguous genitalia is a matter of a medical and social emergency to decide the appropriate sex rearing and eventually to prevent the associated metabolic disorders in some types of DSD (e.g. type II CAH, which is associated by salt wasting and electrolytes disturbance).
Evaluation of patients with ambiguous genitalia and overall DSD is a challenging problem, so a multidisciplinary team including, but not limited to, an experienced endocrinologist, geneticist and radiologist, using a coordinated approach so that timely and proper gender assignment can be reached early in life.
Physical examination, biochemical and chromosomal (Karyotyping) assays are essential in the clinical evaluation of patients with DSD. Anatomical display of the internal genitalia is important not only in gender assignment, but also in planning of surgical corrective procedures which lessens the psychological disorders. Therefore radiological imaging is indicated in depicting urogenital anatomy in patients with ambiguous genitalia.
US should be considered the primary imaging modality and the screening tool in the assessment of DSD. The higher
accuracy of US can be gained by using multi-approach US rather than the routine use of pelvic or inguinal scanning. It’s valuable for identification of internal genital structures especially uterus and testes. It is not invasive, cost effective and easily available. Yet it has limitations such as poor demonstration of complex anomalies and being operator dependent.
Genitography is essential for evaluation of ductal anatomy in DSD because most of the patients have urogenital sinus malformation. Genitography is used to assess the urethra, vagina, any fistulous connections, and complex tracts since it has the ability to show the anatomy of the lower genitourinary tract in detail for mapping surgical strategy; however it’s invasive and cannot show all of the genital organs.
MRI with its multi-planner capability, its superior tissue characterization and excellent spatial resolution could be reserved when US fails to identify the gonads. It is useful in morphologic evaluation of Müllerian duct structures, the gonads even if ectopic.
MRI can also be shown to be useful in differentiation between the penis and clitoral hypertrophy as supporting structures of the penis such as the bulbospongiosus muscle and the transverse perineal muscle can be identified.
MRI is useful in studying gonadal neoplasms that develop in dysgenetic gonads, gonads of ovotesticular DSD, and undescended testicles. DWMRI raises the diagnostic accuracy of the conventional MRI in identification and locating the undescended testis, besides its role in catch up the malignancy and differentiating between benign and malignant lesion.
Furthermore, MRI does not involve radiation exposure and most of MRI examinations for assessment of DSDs are done without the need of contrast injection except if there is suspicion of gonadal malignancy or other associated pathologies.