Why do men only have one testicle?

Men with only one testicle may be caused by congenital cryptorchidism, testicular atrophy after torsion, trauma or surgical removal, etc. It usually manifests as unilateral emptiness or asymmetric volume of the scrotum. The diagnosis can be confirmed through ultrasound examination, hormone level testing, etc. If necessary, surgical correction or hormone replacement therapy is required.

1. Congenital cryptorchidism

Incomplete descent of the testicles into the scrotum during embryonic stages may lead to unilateral cryptorchidism, which may be related to maternal hormonal abnormalities or genetic factors. The patient had a palpable mass in the groin area, accompanied by scrotal hypoplasia on the affected side. After diagnosis, orchiopexy can be performed before the age of 2 years. If diagnosed in adulthood, the risk of testicular malignancy needs to be assessed. Commonly used examinations include ultrasound and magnetic resonance imaging.

2. Testicular atrophy after torsion

Testicular torsion that is not reset within 6 hours will lead to ischemic necrosis and eventually atrophic changes. The typical manifestation is sudden severe pain that then resolves spontaneously but the testicular volume decreases. Emergency surgical reduction and fixation are required in the acute stage. If there are no complications after atrophy, the patient can be observed and followed up, and residual tissue can be removed if necessary.

3. Traumatic loss

Severe impact or penetrating trauma to the perineum may cause testicular rupture, requiring surgical removal of the damaged testicle. It is often accompanied by a history of scrotal hematoma and severe pain. Post-traumatic ultrasound is required to evaluate contralateral testicular function. Adolescent patients may consider implanting a prosthesis later.

4. Tumor resection

Testicular malignant tumors such as seminoma require radical orchiectomy, which may be related to a history of cryptorchidism or family inheritance. Postoperative radiotherapy or chemotherapy should be selected according to the pathological type, and tumor markers and chest CT should be monitored regularly. The five-year survival rate is closely related to early diagnosis.

5. Congenital monorchidism

Very few abnormalities of embryonic development can lead to complete absence of testicles, often accompanied by ipsilateral nephroureter malformation. Hermaphroditism needs to be ruled out through chromosomal examination, androgen levels need to be evaluated after puberty, and testosterone undecanoate capsules need to be supplemented if necessary to maintain secondary sex characteristics.

People with unilateral testicular absence should avoid strenuous confrontational exercise to protect the remaining testicle, and have annual ultrasound and hormone level monitoring. Maintaining a balanced diet helps endocrine balance, and supplementing zinc and vitamin D appropriately. If you find abnormal enlargement of the scrotum, a feeling of bloating, or fertility problems, you need to go to a urology department for evaluation in a timely manner. After surgery, patients need to follow the doctor's advice for regular check-ups and avoid using drugs that affect testicular function such as steroid preparations.