Ambiguous Genitalia in the Newborn

Ambiguous genitalia in a newborn are the clinical sign of atypical sexual development of the external genitalia . This condition is rare and can result from various underlying factors, including certain disorders with potentially severe consequences, such as cortisol deficiency due to congenital adrenal hyperplasia. Therefore, it is crucial to promptly determine etiology when ambiguity is observed. The formation of typical male or female external genitalia is a complex process involving a cascade of genetic and physiological events that begin with sex determination and progress through the differentiation of internal and external reproductive structures. When this process is disrupted and does not occur in the typical manner, it is referred to as a difference or disorder of sex development (DSD). Not all DSD cases present with ambiguous genitalia at birth; for example, complete androgen insensitivity syndrome does not, but all cases of ambiguous genitalia are the result of a DSD. This chapter focuses on genital ambiguity associated with DSD in newborns who have either a 46,XY or 46,XX chromosomal sex. However, DSD with genital ambiguity may also be observed in newborns with other combinations of sex chromosomes, such as 45,X/46,XY. The chapter offers a comprehensive overview of the evaluation and management of newborns with ambiguous genitalia. It emphasizes the importance of a structured medical assessment of the external genitalia to diagnose and determine the underlying cause of genital ambiguity. It includes tables for differential diagnosis and step-by-step workup algorithms to guide medical professionals in their evaluation. It also includes additional information on structured physical assessments of external genitalia and tables with normative values for hormonal measurements, which are recommended in the diagnostic process. As the etiology of genital ambiguity in newborns is diverse and can have significant implications for management, the authors stress that obtaining an accurate diagnosis through a professional medical workup is crucial. The chapter highlights the recommendation for newborns with ambiguous genitalia (DSD) to be cared for by highly specialized, interdisciplinary DSD teams. These teams are equipped with medical and psychosocial expertise, and specialized psychologists are available to support parents and caregivers. The chapter recognizes that having a child with ambiguous genitalia can be very stressful for parents. It underscores the importance of early education, access to expert care through DSD network teams, psychological support, shared decision-making, and promoting acceptance and inclusivity. By providing comprehensive support and guidance, families can better navigate the challenges and uncertainties they may encounter when caring for a newborn with ambiguous genitalia. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG.