Is it normal for one of a man’s testicles to be larger than the other?

It is usually a normal physiological phenomenon for a man to have one testicle larger than the other. Under normal circumstances, there may be slight differences between the two testes, primarily due to variations in the distribution of blood vessels within the scrotum, differences in their anatomical positions, or habitual lifestyle factors.

Most differences in testicle size are considered normal physiological variations. The two testes are usually not exactly symmetrical, and a difference in diameter of 10% to 15% is considered normal. Different degrees of contraction in the muscles of the scrotal wall can lead to visual differences, and uneven blood distribution after prolonged sitting or exercise can also temporarily affect the appearance. Non-pathological factors such as varicocele and hydrocele can also cause mild asymmetry, and these conditions usually do not come accompanied by pain or functional impairment.

In a few cases, pathological changes should be watched out for. Acute orchitis can cause significant unilateral swelling accompanied by severe pain, while tuberculous infection of the epididymis may lead to hardening and atrophy of one testicle. Testicular tumors may initially present as painless swelling, and untreated cryptorchidism can affect development. After a trauma, a hematoma or torsion can cause sudden asymmetry, accompanied by skin bruising.

It is recommended to regularly monitor changes in the testicles by self-examination on an annual basis. Gently roll them between your thumb and index finger to check their texture and shape. Avoid wearing tight underwear to reduce local pressure, and take care to dissipate heat from the scrotum when working in hot environments. If you notice a significant increase in size in a short period of time, the presence of an abnormal lump, or a sensation of heaviness, you should seek medical attention from a urologist promptly. Maintaining moderate exercise regularly to promote blood circulation in the pelvis, and following a balanced diet, can help preserve the health of the reproductive system.