Paediatrics: Disorders of sex development

Disorders of sex development

Terminology

·  Sexual determination refers to the process that occurs from the time of conception until the foetal bipotential gonad has been fully determined as either an ovary or testis.

·  Sexual differentiation refers to the process that occurs from the time gonadal sex is determined until s sexual characteristics are fully expressed and fertility achieved.

Disorders of sexual development

The complex process of sexual determination and differentiation may be interrupted. Numerous disorders that can result in genital ambiguity and uncertainty about an infant’s sex are recognized. Disorders of sexual dif-ferentiation may be classified as genetic defects of gonadal determination or defects in androgen biosynthesis, metabolism, and action (excess or deficiency).

Assessment

History

A detailed history should be obtained and should include:

·Family history: ambiguous genitalia; disorders/problems of puberty; inguinal hernia.

·Prenatal history: maternal health; drugs taken during pregnancy; maternal virilization during pregnancy.

·History of previous stillbirths or neonatal death?

Examination

·General examination: dysmorphic features or midline defects; state of hydration; BP.

·Are the gonads palpable? If ‘yes’ they are likely to be testes or ovotestes.

·Assess the degree of virilization:

·  Prader stage (Fig 13.2).

·  External masculinization score.

·Measure the length of the phallus:

·  Normal term penis is about 3cm (stretched length from pubic tubercle to tip of penis).

·  Micropenis is a length <2.0–2.5cm.

·Penis: presence of chordee.

·Vagina: locate opening?

·Appearance of labioscrotal folds.

·Position of urethral opening.

·Skin—pigmentation of genital skin: hyperpigmentation with excessive adrenocorticotrophin (ACTH) and opiomelanocortin in CAH.

In preterm girls clitoris and labia minora are relatively prominent. In pre-term boys, testes remain undescended until 34wks gestation.