may be hereditary and which may cause habitual abortion and congenital malformations in the offspring. In cases of azoospermia or severe OAT, deletions in the azoospermic factor (AZF) region of the Y chromosome can occur and test- ing is advised. The prevalence of Y deletions is considerable (around 5%) in this group of patients. The presence of a Y deletion means that the defect will be passed on to sons who will then also be infertile.
When performing ICSI with surgically-retrieved sperm, based on a diagnosis of congenital bilateral absence of the vas deferens (CBAVD), both the male and the female partner should be tested for mutations in the cystic fibrosis trans- membrane regulator (CFTR) gene. Apart from causing cystic fibrosis (CF), this gene is also associated with CBAVD; 85% of all males diagnosed with CBAVD also test positive for one or two CFTR-gene mutations. In cases where the partner is a carrier of a CFTR-mutation, depending on the muta- tion involved, there is a 25% chance of a child with CF or CBAVD. Genetic counselling is mandatory in these cases.
Ultrasonography Ultrasonography is a useful tool for locating intrascrotal defects. Colour Doppler ultrasound of the scrotum can detect a varicocele in around 30% of infertile males. Testicular tumours can be found in 0.5% of infertile men, and testicular microcalcifications (a potentially premalignant condition) are detected in around 2-5% of infertile males, especially patients diagnosed with a history of cryptorchism. Transrectal ultra- sonography (TRUS) is indicated in men with a low volume of ejaculate (< 1.5 mL) to exclude obstruction of the ejaculatory
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