A 25-year-old Caucasian man is undergoing evaluation for azoospermia. The patient has been monogamous with his long-term girlfriend and does not use contraception during sexual intercourse. They have been trying to conceive for the past year with no success. The patient has a past medical history of recurrent pneumonia with frequent hospitalizations for antibiotic treatment. He takes no medications and does not use tobacco, alcohol, or illicit drugs. The patient has no allergies and his immunizations are up-to-date. His family history is unknown as he was adopted as an infant. Physical examination shows digital clubbing. A transrectal ultrasound shows bilateral absence of the vas deferens. Which of the following tests would most likely confirm the underlying diagnosis of this patient's condition?

Question

A 25-year-old Caucasian man is undergoing evaluation for azoospermia.  The patient has been monogamous with his long-term girlfriend and does not use contraception during sexual intercourse.  They have been trying to conceive for the past year with no success.  The patient has a past medical history of recurrent pneumonia with frequent hospitalizations for antibiotic treatment.  He takes no medications and does not use tobacco, alcohol, or illicit drugs.  The patient has no allergies and his immunizations are up-to-date.  His family history is unknown as he was adopted as an infant.  Physical examination shows digital clubbing.  A transrectal ultrasound shows bilateral absence of the vas deferens.  Which of the following tests would most likely confirm the underlying diagnosis of this patient's condition?

Quizplus · Accepted Answer

Eductional Objective: CFTR gene mutations are the most common cause of congenital bilateral absence of the vas deferens (CBAVD).  Patients with CBAVD have azoospermia and infertility but normal levels of FSH, LH, and testosterone.  Elevated sweat chloride levels are diagnostic of cystic fibrosis.

A 25-Year-Old Caucasian Man Is Undergoing Evaluation for Azoospermia