6 anatomical reasons for male infertility

Infertility statistics

In a previous article we discussed the anatomical causes of female infertility, the mechanisms behind them, and treatment options. Here we turn to the male side. In developed countries, an estimated 37% of couples’ infertility is attributed to the female only — but 8% is attributed to the male only, and 35% to both partners.¹ When looking at causes of infertility, it’s essential to evaluate the male too.

Signs of male infertility

Often there are no major signs beyond an inability to conceive. When signs do appear,² they may include:

• Sexual dysfunction — low libido, erectile dysfunction, or problems with ejaculation
• A lump, pain, or swelling in the testicular area
• Frequent respiratory infections
• Breast growth (gynecomastia)
• An inability to smell
• Decreased facial or body hair

1. Varicoceles

Varicoceles — sometimes called scrotal varicose veins — are an enlargement of the veins in the scrotum that drain the testicle. This leads to poorly functioning valves, increased testicular temperature, and problems with sperm and testosterone synthesis, reducing sperm count and quality.³ Often there are no symptoms, though some cause pain, testicular atrophy, or infertility.

2. Retrograde ejaculation

When semen enters the bladder during orgasm instead of leaving the penis, it’s called retrograde ejaculation, and little or no semen is released. Causes can include bladder, prostate, or urethral surgery; spinal injuries; diabetes; nerve damage from illness (such as uncontrolled diabetes or multiple sclerosis); and certain medications for enlarged prostate, depression, or psychosis.⁵

It’s diagnosed by testing urine after ejaculation. Apart from infertility, it doesn’t cause major harm — but when fertility is the goal, treatment may help: switching a causative medication; a drug that improves bladder-neck muscle tone (e.g., pseudoephedrine, imipramine) for mild nerve/muscle issues; or, for severe nerve or muscle damage, a fertility specialist may recommend intrauterine insemination, IVF, or intracytoplasmic sperm injection.⁵

3. Erectile dysfunction

Erectile dysfunction (ED) is the inability to attain or keep an erection long enough for intercourse — sometimes periodic, sometimes chronic. Contributors include high blood pressure, type 2 diabetes, poor vascular health, kidney disease, cancer treatments, antidepressants, anxiety/depression/stress, smoking, drug use, obesity, excess alcohol, and low testosterone.

Addressing lifestyle factors — diet, exercise, and stress — is central to treating ED. Medications exist, but dosage, side effects, and effectiveness vary, and it’s always worth asking why a pathway isn’t working. In men with ED from low testosterone, medications that encourage the body’s own testosterone production (such as clomiphene citrate, which can raise testosterone while lowering estrogen) may help once foundational causes are addressed.⁸ Note: testosterone replacement acts as a male contraceptive and should never be used by men trying to conceive.⁹

4. Ejaculatory duct blockage

A rare obstruction of one or both ejaculatory ducts is found in 1–5% of men struggling with infertility,¹⁰ preventing the release of semen and sometimes causing pelvic pain. It can be congenital or acquired — from a Mullerian duct cyst,¹¹ from epididymitis (swelling/irritation of the epididymis, often from chlamydia, gonorrhea, or a UTI),¹² or from surgery such as a vasectomy. Encouragingly, it’s often treated effectively with transurethral resection of the ejaculatory duct, performed endoscopically.

5. Hypospadias

Hypospadias is a birth defect in which the urethral opening is on the underside of the penis rather than at the tip — anywhere from just below the tip to the base.¹³ As the penis develops in utero, hormones drive urethral and foreskin development; when those hormones malfunction, the opening ends up misplaced. It can be genetic, though environment is also thought to play a role. Risk factors may include family history, maternal age over 35, genetic variations, or certain chemical exposures in pregnancy. Minor cases may need no surgery; more significant ones may need surgery to relocate the opening and sometimes straighten the shaft, often done between 6 and 12 months of age.

6. Undescended testicles

During fetal development, one or both testicles may fail to descend from the abdomen into the scrotum, making decreased fertility more likely and increasing the risk of testicular cancer.² The exact causes are unknown, but a combination of maternal health, genetics, and environmental exposures is suspected. It’s treated surgically (laparoscopic or open) — ideally before one year of age, and generally before 18 months, to reduce the risk of infertility and testicular cancer.