Monorchism is the medical term for having only one testicle, a condition that might be present from birth or acquired later in life. Individuals can live a normal life with monorchism. The remaining reproductive organ is typically capable of taking on the full function of two. This means that for most individuals, the condition does not impact overall health, hormone balance, or the ability to father children.
The Remaining Testicle: Functional Compensation
The single remaining testicle is biologically designed to compensate for the absence of the other. This compensation primarily involves two processes: endocrine function, which is the production of the hormone testosterone, and exocrine function, which is the production of sperm. The testicle often undergoes a mild, benign enlargement, known as compensatory hypertrophy, which increases its capacity to perform these functions.
Testosterone production is generally maintained at normal, healthy levels by the remaining testicle. The body’s endocrine system, specifically the pituitary gland, detects the overall hormone level and adjusts the output of signaling hormones like luteinizing hormone (LH) and follicle-stimulating hormone (FSH). This hormonal feedback loop stimulates the solitary testicle’s Leydig cells to produce sufficient testosterone to support male characteristics, muscle mass, and overall well-being.
Spermatogenesis, the process of sperm creation, is typically unaffected. The seminiferous tubules within the lone testicle are capable of producing enough sperm to achieve a viable sperm count for conception. Unless the loss of the first testicle was due to a condition that also affected the underlying health or function of the remaining one, fertility rates are often similar to those of the general population.
Common Reasons for Monorchism
Monorchism can be divided into congenital and acquired causes, reflecting whether the condition was present at birth or developed later. Congenital monorchism means the testicle was absent from the start, often due to a condition called Vanishing Testis Syndrome (VTS). In VTS, a testicle forms during fetal development but disappears before birth, likely due to a vascular event or torsion in the womb.
The most common reason for acquired monorchism is a necessary surgical removal, known as an orchiectomy. This procedure is performed to treat conditions like testicular cancer, which is the most common solid malignancy in men aged 15 to 34. Trauma or severe infection that damages the organ beyond repair can also necessitate removal.
Another cause is testicular torsion, an emergency condition where the spermatic cord twists, cutting off blood supply. If the twist is not corrected quickly—typically within six hours—the testicle may be irreversibly damaged and require surgical removal. This is a common cause of acquired monorchism in pre-pubertal and adolescent boys.
Long-Term Health Monitoring and Psychological Impact
Having only one testicle requires preventative health measures and long-term monitoring of the remaining organ. Individuals are typically advised to perform regular testicular self-examinations to check for any lumps, swelling, or changes in size or texture. Early detection of any issues, such as testicular cancer, is important for the best possible treatment outcomes.
Professional check-ups, including physical exams and blood tests, are routine, especially if monorchism resulted from cancer. Surveillance protocols monitor for recurrence or the development of a new cancer in the remaining testicle, which has a slightly elevated risk. For those with a history of cryptorchidism, or undescended testicle, this close monitoring is also standard practice due to associated risk factors.
The psychological and cosmetic impact can be significant for some individuals. The perception of masculinity, body image, and self-esteem can be affected by the feeling of loss or shame following an orchiectomy. This is particularly true for younger men who may experience emotional distress or anxiety related to the change in appearance.
A testicular prosthesis is available, which is a silicone implant designed to mimic the size and feel of a natural testicle. Implantation of a prosthesis is an elective procedure that can help restore a symmetrical appearance and has been shown to improve body image, self-confidence, and overall satisfaction for many patients. The decision to use a prosthesis is highly personal, but it offers a way to alleviate the non-biological effects of monorchism.