Cystic fibrosis causes the buildup of thick, sticky mucus within vital organ systems in the human body. One of these systems affects the reproduction system in males with cystic fibrosis. Approximately 98% of CF men are infertile due to the inability of the vas deferens to properly function. The vas deferens is the tube which carries sperm from the testis to the penis. The epididymis sits on top of the testis like a cap. Normally, the vas deferens carries the newly made sperm to the back of the prostate gland where it joins the outlets of the seminal vesicles. The sperm can then be released into the semen during intercourse. In CF the vas deferens almost always fails to develop properly.
Thanks to reproductive technologies, sperm can be extracted from the epididymis (fine tubules behind the testis) by procedures such as microepididymal sperm aspiration (MESA), or testicular sperm extraction (TESE), or percutaneous epididymal sperm aspiration (PESA).
Sperm are collected during an operation, generally done under local anesthesia. Once collected; a single sperm is injected directly into the egg through intracytoplasmic sperm injection (ICSI). This procedure is done in combination with in vitro fertilization.
According to the Mayo Clinic though, almost all men with cystic fibrosis are infertile because the tube that connects the testes and prostate gland (vas deferens) is either blocked with mucus or missing entirely. Certain fertility treatments and surgical procedures sometimes make it possible for men with cystic fibrosis to become fathers.