Classification, diagnosis, and clinical prevention and treatment of testicular torsion and hydrocele.

The testicles are protected by the scrotum and have a high degree of mobility, making them susceptible to injury. Common causes of injury are direct violence. Compression of the testicle between the pubic bone and thigh is often related to sports activities, such as ball injuries or kicks; serious car accidents, fights, straddling, or accidental ligation of spermatic cord vessels during other surgical procedures can all cause testicular injury and lead to atrophy. Injuries can be classified according to severity as testicular contusion, laceration (rupture of the tunica albuginea), dislocation, or torsion. The testicle can also dislocate to the groin, perineum, and thigh. Clinically, testicular contusions typically involve only minor bleeding and mild edema, which gradually resolves. More extensive lacerations can lead to complete testicular rupture, often resulting in secondary infection and eventually atrophy. If the testicle is not ruptured, bleeding is limited to the tunica albuginea, but may be accompanied by scrotal hematoma or hydrocele. After injury, edema occurs both inside and outside the testicle, and epididymitis and acute hydrocele may develop. In cases of severe contusion, the spermatogenic parenchyma may partially or completely lose its motility. Testicular injury causes severe local pain that can radiate to the lower abdomen, lumbar region, or upper abdomen, and may lead to painful shock. However, sometimes the pain is not severe, and the main symptoms are local swelling or scrotal hematoma, which may be accompanied by nausea or severe vomiting.

Diagnosis of testicular injury relies primarily on a clear history of trauma, local tenderness, and scrotal hematoma formation. The scrotal skin is bruised and purplish, the testis is enlarged and hard, and extremely tender. The final diagnosis of testicular rupture mainly depends on surgical exploration. Depending on the injury, it is also important to consider any accompanying injuries, especially urethral injury, pelvic fracture, or internal organ damage. The treatment principles for testicular injury are analgesia, correction of painful shock, reduction of testicular tension, and control of bleeding. Resection is only considered when the spermatic artery is ruptured or the testicular rupture is severe and deemed unsustainable. Simultaneously, every effort should be made to preserve the damaged testicular tissue; even the remaining tunica albuginea can retain endocrine function. When testicular blood supply is lost and resection is necessary, a testicular flap can be transplanted into the rectus abdominis muscle, which often has clinical significance.

Testicular torsion was previously considered a rare condition, but with advancements in diagnostic techniques in recent years, our understanding of it has deepened. This disease can occur in people ranging from newborns to those over 70 years old, but it most commonly affects adolescents. Statistics show that its incidence rate is as high as 1.5%–1.8% in males aged 12–19, and 0.5% in those aged 25, making it relatively common. The onset is often without obvious cause; the testicle can torsion spontaneously. 40% of cases occur during sleep or immediately upon waking, while others occur after strenuous exercise, sexual activity, or trauma. Testicular torsion is more frequent in the colder months of December and January, accounting for 24% of all cases annually.

Why does testicular torsion occur? In a normal male scrotum, there is an oval-shaped testis on each side, suspended by the spermatic cord and fixed to the bottom of the scrotum by the testicular ligament. They are completely surrounded by the visceral layer of the tunica vaginalis and have a certain degree of mobility. Torsion is generally uncommon. The testis is supplied with blood by three arteries from the abdominal cavity through the spermatic cord to the scrotum. Testicular torsion is mainly caused by anatomical abnormalities, such as variations in the tunica vaginalis or abnormal testicular suspension, and is often bilateral. Exercise and trauma can stimulate the cremaster muscle, increasing its contractility; vagal nerve excitation during sleep can also increase the contractility of the cremaster muscle with penile erection, both of which can cause the cremaster muscle fibers to twist, leading to testicular torsion. During puberty, abnormal testicular suspension, coupled with the increased weight of the testis, makes testicular torsion more likely. Typical symptoms of testicular torsion include sudden swelling and tenderness of one side of the scrotum, with pain radiating to the lower abdomen, groin, or thigh. Some individuals may also experience nausea, vomiting, fever, and difficulty walking. Clinically, testicular torsion is easily confused with orchitis, epididymitis, hernia, hydrocele, and acute scrotal trauma, and careful differentiation is necessary. Sometimes, testicular torsion is difficult to diagnose based solely on symptoms and signs, requiring color Doppler ultrasound or isotope scanning. When testicular torsion occurs, venous return in the testis is obstructed, leading to edema, hemorrhage, and arterial occlusion, ultimately causing testicular necrosis due to tissue ischemia. If the patient does not seek medical attention promptly, or if an inexperienced doctor mistakenly identifies it as orchitis or epididymitis and treats it as a general inflammation, delaying surgical intervention, it often results in serious consequences. The prognosis of testicular torsion generally depends on the time from onset to treatment. If the torsion occurs within 5 hours, 80% of cases can preserve testicular function; if it occurs after 10 hours, only 20% retain function; and if testicular ischemia lasts more than 24 hours, the spermatogenic and endocrine functions of the testis will be irreversibly damaged, making future fertility impossible.

Therefore, sudden swelling and pain in the scrotum, especially in adolescents, should raise suspicion. A simple way to initially differentiate between orchitis, epididymitis, or testicular torsion is to gently elevate the scrotum. If the pain does not lessen but worsens, testicular torsion should be considered, and a medical examination should be sought immediately. Once testicular torsion is diagnosed, the most effective treatment is surgical reduction. After reduction, the testicle must be properly immobilized to prevent recurrence.

The testis and epididymis are covered by a tunica vaginalis, and the space between the testis and the tunica vaginalis is called the tunica vaginalis sac. Normally, the sac contains a small amount of fluid, and the exudation and absorption of this fluid are in balance. When fluid exudation increases or absorption decreases, the amount of fluid in the sac exceeds the normal level, which is called "hydrocele." Hydrocele can occur at any age. It is more common in southern regions with a higher incidence of parasitic diseases. The incidence rate in infants is 1.75%. There are many causes of hydrocele, which can be broadly classified into communicating and non-communicating types. Communicating hydrocele formation is similar to that of a hernia. After the peritoneum descends with the testis into the scrotum and forms the tunica vaginalis, the small tubules connecting to the abdominal cavity (i.e., the processus vaginalis is not closed) have small openings, preventing viscera from entering the tunica vaginalis, but allowing peritoneal fluid to enter, thus forming a hydrocele. When lying flat, the fluid can flow back into the abdominal cavity through these tubules, hence the name communicating hydrocele. If the fluid cannot flow back into the abdominal cavity when lying flat, it indicates that the superior tubules are closed, which is called non-communicating hydrocele. Inflammation, trauma, or poor absorption of local exudate in the epididymis can also lead to non-communicating hydrocele. Clinically, an oval or pear-shaped cystic mass can be seen in the scrotum, accompanied by a feeling of heaviness. The mass shrinks or remains unchanged when lying down, so it needs to be differentiated from hernia and testicular tumor. The simplest method is the transillumination test. The doctor shines a flashlight from behind the mass and observes it from the front with an opaque cardboard tube. If light can pass through the mass, it is a hydrocele; otherwise, it may be a hernia, hematocele, pyometra, or testicular tumor. Hydrocele in children under 2 years old usually resolves spontaneously. If the fluid does not resolve and is excessive, it can compress the testis and affect testicular development. Surgical treatment is generally recommended. For communicating hydrocele, an incision should be made in the lower abdomen, and a small tube communicating with the tunica vaginalis should be ligated high near the peritoneum to prevent recurrence. Local aspiration or injection of medication is ineffective and can complicate future surgeries.

The main causes of testicular congestion and swelling are as follows: (1) Bacterial infection: mostly descending infection from the prostate. Long-term catheterization, urethroscopy, or the spread of epididymitis can all lead to testicular congestion. Infection can also occur primary in the testis. The most common pathogens are Escherichia coli, Enterococcus faecalis, Staphylococcus, Streptococcus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and other intestinal bacteria. In addition to appropriate antibiotic treatment, antipyretics, scrotal embrittlement to relieve pain and protect the testis, oral analgesics, local physiotherapy, and other treatment measures can also be used. This type of infection can lead to infertility, abscess formation (fluctuation upon palpation), and acute hydrocele. If the testicular abscess ruptures, pyosalpinx can also form. Therefore, early identification and treatment are necessary, and attention should be paid to bed rest and active follow-up. Testicular congestion in children should be distinguished from spermatic cord (testicular) torsion and incarcerated hernia. Orchitis has a slow onset, while testicular torsion progresses rapidly and is extremely painful. (2) Viral infection: Mumps-related testicular congestion accounts for about 20% of viral orchitis. It usually occurs on the seventh day after the onset of mumps, and occasionally simple testicular congestion without mumps symptoms can be seen. The testes of half of the patients will atrophy, but since testicular congestion usually occurs on one side, the chance of infertility is not high. Other viruses that may cause testicular congestion include Coxsackievirus and EB virus, which may also be accompanied by mononucleosis. (3) Parasitic infection: The most common parasitic infection that causes testicular swelling is filariasis. It mainly causes lymphatic obstruction, but it is sometimes difficult to distinguish from vascular obstruction. Filariasis-related orchitis is mostly unilateral, sometimes accompanied by hydrocele and thickening of the tunica vaginalis. The hydrocele may be chylous. (4) Testicular torsion: It can occur in any age group, but is more common in young people and children. When an excessively long mesentery torsos due to excessive activity, the obstruction of blood supply will first affect venous return. As arterial blood continues to flow in, the low-pressure veins continue to dilate, eventually achieving a balance in the arteriovenous system, resulting in testicular swelling. Due to the obstruction of blood circulation, young men or boys will experience acute testicular pain, clinically manifested as testicular swelling and significant tenderness. Unless treated promptly, mild cases may lead to testicular atrophy, while severe cases may result in hemorrhagic necrosis of the testis and epididymis. Therefore, scrotal exploration should be performed as early as possible to reposition the torsioned spermatic cord and fix the testis to the scrotal wall. Bilateral testicular fixation is recommended; otherwise, testicular torsion may easily recur in the contralateral testis. If the testis has already necrotized, orchiectomy is necessary. (5) Varicocele: Due to insufficiency of the valves in the spermatic veins, vascular dilation occurs, and the lesion is more common on the left side. Sometimes it may be accompanied by male infertility. High ligation of the veins can improve semen quality in 70% of patients. Right-sided varicocele may sometimes be accompanied by retroperitoneal diseases, such as tumors. Therefore, special attention should be paid to newly occurring right-sided varicocele, and further detailed examination is necessary. (6) Trauma: Various traumas to the perineum can affect the testis. Blunt trauma causes testicular swelling and tenderness, with symptoms similar to orchitis. A thorough medical history is key to accurate diagnosis. Treatment should vary depending on the individual and symptoms, and sometimes surgical exploration is required. The goal is to preserve testicular function as much as possible. Penetrating or open wounds are less common, but they are clearly visible during physical examination and are not difficult to diagnose. For these types of wounds, debridement is required to remove necrotic tissue and preserve as much intact tissue as possible. Animal bites are also seen in rural areas. (7) Tumors: Testicular tumors are the most common tumors of the scrotum, with an incidence of about one in 100,000, and almost all of them are malignant. Clinical symptoms are often not obvious, and a few may have pain; the testis is enlarged but still retains its original shape, with a smooth surface, hard and heavy texture, and its volume often exceeds the size of a testicular volume measuring instrument. However, it needs to be differentiated from hydrocele, testicular hematoma and inflammation after injury, and it is not advisable to blindly perform experimental puncture or biopsy. (8) Sexual response: In addition to the testicular congestion and swelling during normal sexual arousal, if the sexual activity lasts too long and is repeatedly stimulated, dull pain in the testicle may occur. It is especially common in young people who have been caressing for a long time during their courtship but have not progressed to the stage of orgasm; adults who intentionally control themselves from ejaculating during sexual activity in order to achieve the so-called "replenishing the brain with essence" in the bedroom; and those who are separated from their spouses and are frequently sexually stimulated but have not been able to ejaculate. All of these symptoms can be quickly relieved by ejaculating through masturbation or intercourse.

In summary, testicular congestion can be a normal reaction, such as that seen during sexual activity, or it can be pathological, such as that caused by a retroperitoneal tumor. A comprehensive and thorough physical examination will help determine the cause. If the initial examination leaves the diagnosis unclear or difficult to treat, referral to a higher-level or specialized hospital is recommended. Patients should not take this lightly; seeking active and timely treatment is essential.