Immobile or dead spermatozoa in semen

Necrospermia is defined as the percentage of dead sperm in a semen analysis sample >42%, and is usually measured by assessing the membrane integrity of the cells, as determined by a dye exclusion assay. In spite of its relatively straightforward definition, the causes and impact of necrospermia on male fertility are still relatively poorly understood.

Necrospermia is commonly seen in men with spinal cord injuries, infections, chronic medical conditions, and after exposure to toxic substances. 

Undescended testes

Cryptorchidism, also called undescended testes, is the absence of one or both testes from the scrotum. Testes are exposed to higher temperature and this harms the viability of sperm.

Klinefelter syndrome

Klinefelter syndrome also known as 47,XXY or XXY, is the set of symptoms that result from two or more X chromosomes in males. The abnormal chromosomes cause abnormal development of testes, resulting in low sperm production and low viability. 

Kallmann syndrome

Kallmann syndrome is a rare genetic condition that is characterised by a failure to start or a failure to complete puberty. It is also accompanied by a lack of sense of smell (anosmia) or a highly reduced sense of smell (hyposmia). Decreased function of the sex hormone-producing glands is caused by a deficiency of both testes from the scrotum. 

Varicocele

A varicocele is an abnormally dilated venous network that drains blood from the testicles. The condition leads to rise in temperature of testis and raise testicular temperature, resulting in less sperm production and death of whatever sperms are produced.

Anorexia Nervosa

Anorexia nervosa is an eating disorder characterized by a low weight, fear of gaining weight, a strong desire to be thin, and food restriction. Many people with anorexia see themselves as overweight even though they are in fact underweight. Food restriction and underweight (anorexia nervosa), obesity, smoking, and alcohol all have negative effects on the gonadotropin-releasing hormone (GnRH) pulse generator and gonadal function. Age and diet are important determinants of fertility in both men and women. Men with eating disorder have less ability to produce low count of sperm and necrospermia.

Thyroid disorder

A thyroid disease is a medical condition impairing the function of the thyroid. Sperm development requires normal level of thyroid hormone. Low thyroid hormone causes low decreased levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and thus presence of immobile or dead sperm.

With necrospermia, fertilization rates are lower but in vitro fertilization (IVF) with Intracytoplasmic sperm injection (ICSI) improves the chances of conception.