Many events or medical conditions can cause testicular and scrotal pain in men and boys, including:  

• Trauma. The most common cause of testicular and scrotal pain is trauma. Scrotal trauma does not cause severe injury in most circumstances, although it is usually quite painful. Trauma may result in a bruise or more significant injury. Severe testicular and/or scrotal trauma can occur when a testicle is compressed against the pubic bones either by a direct blow or straddle injury. In some instances, surgery may be necessary.
  
  
• Testicular torsion. Occurs when the testicles and spermatic cord are twisted around inside the scrotum, often cutting off blood supply internally and causing severe pain and swelling. Torsion is the most serious form of testicular injury and should be considered a medical emergency. Though most common in boys aged 12 to 18, it can occur in males of any age. Pain usually appears quickly after physical activity or testicular trauma. In addition to pain in the testicles, torsion may cause nausea and vomiting. It is usually distinguished by a “bell clapper” deformity in which the testes are misaligned.

Irreversible damage to the testes can occur after 12 hours of ischemia (lack of blood flow) resulting from torsion. As a result, immediate exploratory surgery is often necessary to prevent permanent harm. Manual detorsion (untwisting) may be used in cases where surgery is not necessary or readily available. Anyone who suspects he has this condition should seek immediate medical assistance.

• Torsion of the appendix testis. The appendix testis is a piece of tissue attached to the testicle. Its function is not known. If the appendix testis becomes torsed (twisted), it can restrict blood supply and cause intense testicular pain. This injury typically affects young boys. The onset of pain tends to be gradual, with a blue dot often appearing at the site of injury. Torsion of the appendix testis is difficult to diagnose and does not usually occur in conjunction with testicular torsion. The appendix testis may be surgically removed in severe cases.
  

• Epididymitis. The epididymis is a coiled, tube-like structure located in the testicles that aids in the production of sperm. The epididymis can become infected under certain conditions, causing epididymitis. It can occur in two forms:
  
  
• Infectious epididymitis. This occurs when the epididymis becomes infected with bacteria, usually from certain sexually transmitted diseases (STDs) such as chlamydia or gonorrhea. It is more common in younger men and is usually treatable with antibiotics. Although relatively rare, serious illness can occur as a result in some instances. Infectious epididymitis is usually distinguished by severe swelling and pain in the testicles and scrotum. It can be accompanied by symptoms similar to a urinary tract infection, such as high fever or difficulty or pain during urinating (dysuria).
  
  
• Noninfectious epididymitis. Occasionally, epididymitis is caused by unintended urine reflux through the ejaculatory ducts into the epididymis, causing inflammation, swelling and blockage. Noninfectious epididymitis is more common in older men. This condition is typically not serious and is usually treated with common remedies such as anti-inflammatories, rest and scrotal support.   
  
  
• Inguinal hernia. This condition occurs when a part of the intestine bulges through a weakened segment of the groin or abdomen and may enter the scrotum. It is the most common type of hernia in men and can cause extreme testicular pain. A strangulated hernia, in which blood supply to intestinal tissue is constricted, requires immediate medical attention.
  
  
• Testicular vasocongestion. The feeling of temporary aching, heaviness or discomfort in the testicles that can result from sexual arousal without an orgasm. The condition is caused by enlarged, swollen arteries in the scrotum that take several minutes or hours to dissipate after sexual arousal.
  
  
• Post-vasectomy. A vasectomy (a procedure that permanently sterilizes a man) may cause testicular pain at the site of the internal division in some men. Sperm leakage and accumulation may occur within the epididymis, which may cause testicular or scrotal pain. In addition, those who later undergo a vasectomy reversal, which sometimes but not always allows a man to regain fertility, may find this more complicated operation to cause much more pain than their vasectomy did.
  
  
• Orchitis. Inflammation of one or both testicles. It is usually caused by a bacterial infection from STDs. Men without proper mumps vaccinations or who get frequent urinary tract infections can acquire non-sexually transmitted orchitis. Most cases require antibiotic treatment to cure the infection.
  
  
• Prostatitis. Infection and inflammation of prostate gland can cause pain and burning in the scrotal area.
  
  
• Mumps. Adult males with mumps may experience complications including swelling of the scrotum and intense testicular pain. Some men with mumps may also experience orchitis.
  
  
• Swelling. Some men develop pain from testicle or scrotal swelling. This may occur for a number or reasons (e.g., injury, sexually transmitted disease), or the cause may be unknown.
  
  
• Interstitial cystitis (IC). This chronic inflammation of the bladder is far more common in women but also afflicts many men. It can affect the urethra and prostate. Symptoms may include testicular pain, scrotal pain or sexual pain during ejaculation.  
  
  
• Henoch-Schonlein purpura. This disease causes purple skin spots, joint pain and occasional scrotal pain.
  
  
• Fournier’s gangrene. A rare bacterial infection of the skin surrounding the genitals, Fournier’s gangrene occurs when a cut or abrasion becomes infected. It can destroy the surrounding skin, tissue and muscle or even be fatal if it enters the bloodstream..

Referred pain from a condition or injury in a different part of the body can also cause testicular or scrotal pain. For example, passage of a kidney stone down through the urinary system typically causes intense abdominal pain or pelvic pain but can also be experienced as testicular pain. Blood in the urine (hematuria) can also suggest a kidney stone. A urinary tract infection can also cause referred pain in the scrotal area. Tumors or other problems in the spine may also be experienced as referred pain in the testicular area.  

Other types of referred pain that can cause testicular or scrotal pain include:

• Abdominal inflammations. Conditions such as appendicitis, pancreatitis (inflammation of the pancreas), diverticulitis (inflammation of abnormal sacs in the colon) and peritonitis (inflammation of the abdominal membrane) sometimes cause testicular pain in addition abdominal or pelvic pain.
  
  
• Aortic aneurysm. This is a bulging of part of the wall of the aorta, the large artery that directs blood from the heart to the rest of the body. Thoracic (upper back) and abdominal aneurysms seldom produce symptoms but in some cases can cause back pain, abdominal pain or testicular pain. A ruptured aneurysm, an often-fatal medical emergency, is often marked by sudden and severe abdominal or back pain and can also cause severe testicular or scrotal pain.
  
  
• Lymphocytic choriomeningitis. This rodent-borne viral infectious disease presents as meningitis or encephalitis. Symptoms can include fever, malaise, loss of appetite, muscle pain, headache, nausea, vomiting, cough, sore throat, joint pain, chest pain and testicular pain.
  
  
• Familial Mediterranean fever (FMF). This inherited disorder is marked by fever, peritonitis and sometimes scrotal pain that may be severe.

Certain conditions and diseases of the testicles and/or scrotum may indirectly cause testicular and scrotal pain, including:

• Testicular cancer. Although relatively rare, it is the most common form of cancer in men ages 18 to 40. Tumors on the scrotum are usually painless masses often discovered during routine physical examinations. Pain is usually a late symptom of the testicular cancer. However, a rapidly growing tumor can also cause scrotal pain in some cases.
  
  
• Cryptorchidism. This occurs when the testes do not properly descend into the scrotum during fetal development, usually in premature males. It may result in the testes being improperly located in the abdomen or elsewhere, causing discomfort and increasing the risk of testicular cancer. Surgery may be necessary in some cases because cryptorchid testes cannot be put into the scrotum manually. However, the problem often corrects itself by age 1.
  
  
• Varicocele. This term refers to varicose (dilated or swollen) veins in the testicles, and occurs in about 20 percent of post-pubertal males. Varicocele may cause aching scrotal pain while standing or other symptoms (e.g., testicular atrophy, low fertility) and is treated surgically in men hoping to remain fertile. In older men who have finished reproducing and have only minor pain, treatment with anti-inflammatory drugs and scrotal support may be sufficient.
  
  
• Epididymal cysts. An epididymal cyst is a harmless swelling arising from the epididymis (a coiled, tube-like structure aiding in sperm production). Occasionally, these might cause discomfort in the testicular/scrotal area. They can be removed surgically if necessary, although they usually do not require further treatment.
  
  
• Spermatoceles. Cyst-like collections of sperm, usually found in the head of the epididymis. Rarely, they can cause painful symptoms in men. In these instances, surgical removal may be required.
  
  
• Hydroceles. These occur when fluid surrounds a testicle, and are usually painless. In rare instances where pain occurs, surgical removal of the inflamed tissue may be necessary.