The testicles are rarely perfectly symmetrical; one often hangs lower and may appear slightly larger than the other. This asymmetry is a normal and expected feature of human anatomy, reflecting natural variations in the body’s structure. Recognizing this baseline difference is important, as it helps distinguish between a typical physiological state and a change that may require medical attention. This slight difference in size and height is generally not a cause for concern.
Explaining the Height Difference
The primary reason one testicle, most often the left, hangs lower than the other relates to the varying lengths of the internal support structures. Each testicle is suspended within the scrotum by a spermatic cord, a structure containing blood vessels, nerves, and the vas deferens, which transports sperm. The length of the left spermatic cord is frequently slightly longer than the right, resulting in the left testicle naturally descending to a lower position.
This anatomical arrangement provides a functional advantage related to temperature regulation and physical mechanics. The lower positioning helps prevent the two testicles from pressing against each other or colliding during movement, reducing potential trauma. The separation also aids in maintaining the slightly cooler temperature necessary for optimal sperm production. Scrotal muscles adjust the distance of the testicles from the body in response to temperature.
Explaining the Size Variation
A mild difference in size between the two testicles is considered standard and benign. It is common for one testicle to be up to 15% to 20% larger than the other, often existing without an underlying medical cause. This slight difference can result from minor variations in vascular structures or how each testicle developed during fetal growth.
The right testicle is sometimes slightly larger than the left, though either can be the dominant size. Paired organs throughout the body, such as the breasts or kidneys, rarely achieve perfect symmetry. As long as the change is not sudden, painful, or associated with a new lump, this minor size variation is part of the body’s normal architecture.
Key Warning Signs and Conditions
While minor asymmetry is normal, a sudden or significant change in size, shape, or the onset of pain can indicate a medical condition. Testicular Torsion occurs when the spermatic cord twists, cutting off the blood supply to the testicle. This condition causes the sudden onset of severe, intense pain, often accompanied by scrotal swelling and sometimes nausea and vomiting. Torsion requires immediate surgical attention, typically within a few hours, to save the testicle.
Epididymitis and Orchitis are inflammations, often caused by infection, that can lead to notable swelling and pain. Epididymitis affects the coiled tube at the back of the testicle where sperm mature, while orchitis is inflammation of the testicle itself. The pain is typically less sudden than torsion and is often relieved by elevating the scrotum. The condition is frequently treated with antibiotics if bacterial in origin.
Another common cause of size change is a Varicocele, which is an enlargement of the veins inside the scrotum, much like varicose veins in the legs. This condition usually affects the left side and may feel like a “bag of worms” above the testicle, often becoming more noticeable when standing. Varicoceles can sometimes cause a dull ache and, in some cases, may affect fertility. A Hydrocele is a separate condition involving a painless buildup of fluid around the testicle that causes generalized scrotal swelling.
The most serious condition that affects size and shape is Testicular Cancer, which typically presents as a painless lump or swelling, or a change in the firmness of the testicle. Unlike infections or torsion, the onset is usually more gradual, and the testicle may feel heavy. Early detection is crucial for a successful outcome, which is why self-examination is highly recommended.
When to Seek Professional Advice
Knowing the difference between normal asymmetry and an abnormal change is paramount for maintaining testicular health. Regular self-examination is an important practice, ideally performed monthly after a warm shower when the scrotal skin is relaxed. This allows a person to establish their own baseline size and feel, making new lumps or changes easier to detect.
An immediate emergency consultation is necessary if you experience sudden, severe pain, acute swelling, or are unable to relieve pain after an hour. These symptoms may indicate a time-sensitive issue requiring prompt diagnosis and treatment.
You should schedule a routine consultation with a healthcare provider for any gradual change, the discovery of a new lump or hardening, persistent discomfort, or any unexplained change in size or shape. A medical evaluation will typically include a physical exam, which may be followed by an ultrasound with color Doppler imaging. This imaging test can visualize internal structures and assess blood flow, helping to accurately distinguish between a benign mass, an infection, or a serious condition.