Polyorchidism is an extremely rare anatomical variation defined by having more than two testicles; the presence of three (triorchidism) is the most common presentation. This congenital condition involves the development of one or more supernumerary gonads, with fewer than 250 cases documented globally. For individuals with polyorchidism, the main concerns involve reproductive capacity and potential health risks. An extra gonad does not automatically prevent a person from having children, but it requires unique considerations for monitoring and care.
Understanding Polyorchidism
Polyorchidism originates early in fetal development from an unusual division of the genital ridge, the embryonic tissue that forms reproductive organs. This division typically occurs before the eighth week of gestation, resulting in an extra testicle. The supernumerary testicle is most often found on the left side of the scrotum, but it can also be located in the inguinal canal or, less commonly, the abdominal cavity.
The classification of polyorchidism depends on the extra testicle’s anatomical connection to the reproductive tract, which dictates its functional potential. In Type A polyorchidism, the supernumerary gonad is connected to the vas deferens, the tube that transports sperm, giving it potential reproductive function. Type B polyorchidism involves an extra testicle not connected to the vas deferens, rendering it incapable of contributing to ejaculation. Most reported cases are Type A, particularly Type A3, where the extra testicle shares the epididymis and vas deferens of an adjacent testicle.
Fertility and Sperm Production
The presence of a third testicle generally does not prevent a man from having children, as fertility is often maintained. The two normally positioned testicles typically produce sufficient sperm and hormones to ensure reproductive capability. The reproductive activity of the supernumerary testicle is variable, though histological studies show that spermatogenesis (sperm creation) is normal in approximately 50% of supernumerary testicles.
Hormone levels, particularly testosterone, are usually regulated effectively by the body, even with an additional gonad. The endocrine system adjusts to maintain a normal hormonal balance, which is necessary for libido and secondary sex characteristics. This stability in hormone production is a major factor in why many men with polyorchidism experience no reproductive impairment.
If fertility challenges arise, they are usually linked to co-occurring conditions rather than the extra testicle itself. Polyorchidism is sometimes associated with anomalies like cryptorchidism (undescended testicle), a known cause of impaired spermatogenesis. Even with normal hormone levels, altered or absent spermatogenesis has been found in 11% to 26% of polyorchidism cases. Reproductive function hinges on the health and anatomical connection of all gonads, and the Type A or Type B classification determines the extra testicle’s contribution to the overall sperm count.
Associated Health Considerations
While fertility is often unaffected, polyorchidism carries specific health risks requiring careful management. The two most concerning complications are testicular malignancy (cancer) and testicular torsion. The risk of developing cancer in a supernumerary testicle is estimated to be between 4% and 7%, which is elevated compared to the general population.
The risk of cancer is significantly higher when the supernumerary testicle is undescended (cryptorchid), located outside the scrotum in the inguinal canal or abdomen. The abnormal temperature and environment in these extra-scrotal locations are the most important risk factor for malignancy. Therefore, the location of the extra testicle is a primary concern for medical surveillance.
Testicular torsion, a painful condition where the spermatic cord twists and cuts off blood supply, is another serious risk, reported in about 7% to 15% of cases. The extra mobility and anatomical variations created by the supernumerary testicle can predispose it or the adjacent testicle to twisting. Other associated anomalies frequently seen include inguinal hernia (15% to 30% of cases) and hydrocele (a fluid collection found in about 9% of patients).
Diagnosis and Ongoing Management
Polyorchidism is frequently discovered incidentally during a physical examination for an unrelated issue, such as a scrotal mass or pain. Diagnosis is typically confirmed through specialized imaging techniques. High-resolution Doppler ultrasonography is the preferred method, visualizing the presence, size, and blood flow of the supernumerary testicle, and distinguishing it from other masses.
If ultrasound findings are inconclusive, magnetic resonance imaging (MRI) may be used to characterize the tissue, as the supernumerary testicle shows the same signal intensity as the two normal gonads. Management strategies vary, with a trend toward conservative observation for many cases. If the extra testicle is located within the scrotum and shows no suspicious signs of malignancy, watchful waiting is often recommended.
This conservative approach involves regular self-examinations and professional follow-ups, including an annual ultrasound to monitor the gonad’s size and characteristics. Surgical removal (orchiectomy) is generally reserved for supernumerary testicles that are located outside the scrotum, show signs of malignancy, or are Type B and non-functional in young patients. The decision to intervene surgically balances the risk of cancer and torsion against the desire to preserve potentially functional testicular tissue.