Males with cystic fibrosis may be azoospermic due to congenital bilateral absence of the vasa deferentia (CBAVD). This may be diagnosed based on clinical and laboratory findings.
Clinical findings:
(1) vasa deferentia absent or thin fibrous cords on palpation
(2) rectal ultrasound shows abnormalities in the vasa deferentia and seminal vesicles
Semen analysis:
(1) azoospermia
(2) low volume of ejaculate (< 2 mL)
(3) acidic pH (pH < 7)
(4) failure to coagulate
(5) low fructose concentration
(6) elevated citric acid concentration
(7) elevated acid phosphatase
Other laboratory findings:
(1) mutation in one or both CFTR genes
where:
• Routine genetic screening tests detect most but not all mutations (about 80%), so a negative genetic test does not exclude the diagnosis.
• The 5T allele is common in males with CBAVD.
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