Male reproductive tube blockage leads to lower live births

This study examined whether blockage of tubes that transport sperm in men affects live birth rate. 

Infertility, or the inability to conceive, affects 5-15% of couples worldwide. Conception requires the production of functional sperm and seminal fluid (fluid that holds sperm cells), transport of the semen through intact sperm ducts, and a normal ejaculation mechanism.

Male infertility may occur for a number of reasons, including problems with sperm delivery. Certain genetic diseases, such as cystic fibrosis, can cause blockage of the vas deferens (the duct through which sperm travels from the testis towards the prostate gland). In the case of blockage, intracytoplasmic sperm injection (ICSI) may be used to inject sperm (from the male partner) directly into the egg (from the female partner).

This study examined 945 men with low sperm counts due to blockage of the reproductive tract. The authors were particularly interested in a specific form of blockage caused by the complete absence of the main tubes that transport sperm (the vas deferens). All men underwent ICSI treatment.

The rates of fertilization and clinical pregnancy after ICSI were similar in men who had normal working tubes compared to those that did not. However, the rate of miscarriage/stillbirth was higher in men lacking the tubes (24%) compared to those with normal tubes (13%). The rate of live births was lower in men lacking the tubes (71%) , compared to those with normal tubes (85%). Absence of the vas deferens tubes was linked to a faulty gene in these men, called CFTR. Severe mutations in this gene can cause cystic fibrosis, however, these men had a particular mutation that did not cause cystic fibrosis, and instead it prevented the normal formation of the vas deferens tubes. 

The authors conclude that sperm from men lacking vas deferens tubes may be of lower quality. This is possibly due to a faulty CFTR gene. 

The female partner was not assessed for CFTR gene mutations, it’s possible that lower live births could be linked to female problems also. 

If you are concerned about any of the issues in this article, please discuss them with your doctor.