Even though there are numerous causes for<unk> , all of the known contributing factors can be placed into 2 major distinct categories: Dysfunction of ejaculatory reflex * Ejaculatory dysfunction is when a male is unable to ejaculate properly at the time of sexual climax. Ejaculatory reflex dysfunction is one of the leading causes in male infertility. * Some conditions in which ejaculatory reflex dysfunction is observed is multiple sclerosis, diabetic neuropathy, spinal cord injuries, or side effects of certain medications. Examples of dysfunction of ejaculatory reflex include: Retrograde ejaculation *This means that the sperm is produced in the testes but on its way out, it gets misdirected into the bladder rather than coming out through the urethra. This can lead to a low volume of semen<unk>  or no semen production (Aspermia). Structural or functional damage to the bladder neck muscle causes the backflow of semen during the ejaculation. Nerve damage caused by medical conditions such as diabetes or multiple sclerosis can affect the function of bladder neck muscle. Also, surgery or trauma along with the medications used for hypertension and benign prostatic hyperplasia can contribute to bladder neck problems. Retrograde ejaculation can be diagnosed by the presence of sperm in the urine. Anatomical defects * Anatomical or functional defects of the seminal tract may cause flow obstruction of seminal pathways. This can be observed in people with genetic mutations (specifically the CFTR gene) or ejaculatory duct obstruction(s) such as prostate or seminal vesicle cysts. *Mutations of the CFTR gene on chromosome 7 can cause an overproduction of thick, sticky mucus in organs with mucus glands, contribute to infertility through clogging the spermatic duct with mucus, and cause congenital bilateral absence of the vas deferens. Examples of anatomical defects include: Congenital absence of vas deferens and seminal vesicle *In the male reproductive system, we have structures such as vas deferens and seminal vesicles which play an important role in transportation and production of semen or ejaculate. Abnormalities or absence of these structures can lead to low volume of semen and infertility in males. This condition can also be caused by the mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene which encodes for chloride channel protein. Blockage of the ejaculatory duct *This is a condition that is caused by obstruction of either one or both ejaculatory ducts leading to<unk> . The etiology of ejaculatory duct obstruction can be congenital or acquired. The presence of a prostatic cysts, ejaculatory duct stones, or post surgical inflammation of the duct can block the normal flow of semen through the reproductive tract. Hypogonadism *Insufficient or low levels of testosterone in the body can affect the proper functioning of the male reproductive structures and thus lead to decreased secretions or<unk> . Long-term exposure to drugs with anti-androgen properties (e.g. spironolactone) can also lead to infertility or low volume of semen. Testosterone is produced by the testes and can be used to diagnose hypogonadism. Drugs Drugs can have various types of impact on the male body, side effects of medications may affect male fertility, spermatogenesis, and even sexual function. Drugs can affect sperm parameters by inhibiting normal exocrine functions of the testes which can lead to a decrease in production of sperm, or by creating hormone imbalances. For an example, anti-androgenic drugs like spironolactone, cimetidine, and ketoconazole can disrupt androgens in the glands and seminal tract to cause a decrease in production of semen volume. Furthermore, common drugs used to treat hypertension and benign prostatic hyperplasia (increased size of prostate) like tamsulosin are attracted to dopamine and serotonin receptors in the brain to cause a decrease in sperm volume through a mechanism that remains unknown. Certain medications in the following classes of drugs may affect spermatogenesis or sperm parameters*: * Immunosuppressants * Non-steroidal anti-inflammatory drugs (NSAIDs) and salicylates * Inhibitors of thyrosine kinases * Opiates * Treatment for benign prostatic hyperplasia * Hormonal treatments and antiadrenergic drugs * Antibiotics, antifungals, antiparasites, antivirals, and antimalarials * Antidepressants * Anti-gastroesophageal reflux drugs * Anti-epileptic drugs * Antihypertensive drugs Certain medications in the following classes of drugs may affect male sexual libido or sexual function**: * Immunomodulators * Inhibitors of protein kinases * Opioids * Analgesics * Treatment of benign prostatic hyperplasia * Antiadrenergic drugs * Hormonal treatments * Diuretics * Antiretroviral therapy * Antihistamines * Antidepressants "For most of the drugs that are likely to affect spermatogenesis and/or sperm parameters, the levels of scientific evidence are still insufficient (with the exception of Sirolimus, Sulfasalazine, exogenous testosterone, Finasteride and Cyproterone acetate, for which the levels of evidence are higher). In some cases, data in men do not even exist, and the toxicity of a drug for the male reproductive organs is determined solely on the basis of animal models." "For a certain number of pharmaceutical molecules that are likely to affect the sexual function of men being treated, the actual imputability of the drug is often difficult to pinpoint owing to the effect of the illness itself on sexuality (cardiovascular disease and erectile dysfunction; depressive illness and loss of desire, etc.)" Furthermore, hyperthyroidism, an excess of thyroid hormones, has been associated with reduced semen volume, reduced sperm density, motility, and morphology. Studies in humans show that an excess of circulating thyroid hormones during thyrotoxicosis results in asthenozoospermia, oligozoospermia, and teratozoospermia. These abnormalities frequently associate with semen alterations like reduced semen volume.
Hypospermia
Oligospermia
Azoospermia
Hematospermia
Teratospermia
Globozoospermia
Asthenozoospermia
Spermatorrhea