Factors that influence the decision to perform a karyotype in suspected disorders of sex development: lessons from the Scottish genital anomaly network register.

Background: Although a karyotype represents the first objective evidence of investigating a case of suspected disorder of sex development (DSD), the factors that influence the clinician's decision to initiate investigations are unclear.

Methods: Cases of suspected DSD in Scotland were identified through the Scottish Genital Anomaly Network (SGAN) Register. The timing as well as other factors that influence the decision to perform a karyotype were subsequently studied.

Results: Out of the 572 cases on the register, 383 (67%) were classified as having a non-specific disorder of under-masculinisation. In 463 (81%) cases, the sex of rearing was male, in 71 (12%) female, and in 38 (7%) cases data regarding sex of rearing were unavailable. A karyotype was reported to have been performed in 153/572 (27%) cases. Infants in Scotland with suspected DSD are more likely to have a karyotype performed in the presence of a low external masculinisation score, bilateral impalpable testes, proximal hypospadias, or associated malformations.

Discussion: These data represent the first attempt at benchmarking the decision to check a karyotype and investigate infants with suspected DSD. Whilst this decision may be related to the complexity of the genital anomaly, there are other factors that may influence this decision, and these require further exploration through more rigorous systems for data collection.