Assessment of Anatomy
Examination and assessment by a paediatric surgeon with experience of DSD are critically important in the affected newborn. Combining expert physical examination with radiological assessment and endoscopic visualization, when necessary, can provide information on the location and state of the gonads, the urogenital sinus and Müllerian structures. During this initial assessment, the anatomy and drainage of the renal tract should also be assessed.
Ultrasonography is the first-line imaging modality and should include the adrenals, kidneys, pelvis, inguinal regions and labioscrotal folds where appropriate. In the neonate, the uterus, ovaries and adrenals should be identifiable, but the likelihood of success is dependent on the state of the child and the expertise of the operator. It should also be borne in mind that the presence of a uterine structure does not guarantee later function and intra-abdominal testes and streak gonads are difficult to identify ultrasonography. In the prepubertal adolescent, it may be difficult to confirm the presence of a uterus by ultrasonography and repeat imaging after a 6-month course of oestrogen may be required. Although MRI seems to be used more often these days, in children, its use should be considered ancillary to ultrasound and it should be reserved for cases where ultrasonography has failed to delineate the relationship of the Müllerian structures and where there are abnormalities of the urinary tract. High-resolution MRI should include the pelvis and perineum with and without fat saturation and T1 in three planes where possible. MRI can identify extra-abdominal ectopic testes and the presence of the spermatic cords, but may not be superior to ultrasound examination for identifying the presence and character of intra-abdominal testes or streak gonads. In adolescents, MRI can delineate structural anomalies such as haematocolpos or hydronephrosis, identify secretory tumours and identify the location of the intra-abdominal gonads. However, the value of this modality, as well as that of ultrasound scanning in identifying early neoplasia in retained testes remains questionable.[60,61] Apart from the above, MRI imaging of the upper abdomen in adolescents is not required unless there is an adrenal mass in which case contrast enhancement shall also be required.
Nowadays, the 'genitogram' is not routinely performed for diagnostic purposes. It has been superseded by endoscopic examination of the genital tract (genitoscopy), which provides a more detailed and thorough assessment. However, a genitogram, performed in preparation for surgery allows the placing of stents in various internal structures to allow a more focused radiological examination. These investigations should provide information on the length of the urogenital sinus, the associated Müllerian structures and the relationship of the urethra and its sphincter. In 46, XX DSD, genitoscopy can assess drainage of both the bladder and Müllerian structures and provide a detailed assessment of the urogenital anatomy. In 46, XY DSD, endoscopic examination can be used to identify any Müllerian remnants that arise from the posterior urethra.
Genitoscopy can be combined with laparoscopy, but this is not necessary in all cases of DSD. Laparoscopy is a very effective method of inspecting the internal sex organs and facilitates manipulation or biopsy of intra-abdominal gonads.[62,63] However, as laparoscopy can only visualize intraperitoneal structures, Müllerian remnants deep within the pelvis or closely attached to the bladder may not be seen. In 46, XY DSD, laparoscopy is clearly indicated in all infants with impalpable testes where the gonads need to be identified and brought down to the scrotum if possible. Laparoscopy can also be used in adolescents who present with a DSD. However, MRI may be a more suitable first-line investigation for defining the anatomy.
Clin Endocrinol. 2021;95(6):818-840. © 2021 Blackwell Publishing