A doppler ultrasound scan of the scrotum is nearly 90% accurate in diagnosis identifying the absence of blood flow in the twisted testicle, which distinguishes torsion from epididymitis.

Radionuclide scanning of the scrotum is the most accurate, imaging technique, but it is not routinely available, particularly with the urgency that might be required. The agent of choice for this purpose is technetium-99m pertechnetate. Initially it provides a radionuclide angiogram, followed by a static image after the radionuclide has perfused the tissue. In the healthy patient, initial images show symmetric flow to the testes, and delayed images show uniformly symmetric activity.

The diagnosis should be made on the history and presenting signs and symptoms. With a convincing history and physical exam immediate surgery is recommended and doppler ultrasound should only be obtained in low suspicion cases to rule out torsion.

Because polyorchidism is very uncommon, there is no standard treatment for the condition. Prior to advances in ultrasound technology, it was common practice to remove the supernumerary testicle. Several cases have been described where routine follow-up examinations conducted over a period of years showed that the supernumerary testicle was stable.

A meta-analysis in 2009 suggested removing non-scrotal supernumerary testicles because of the increased risk of cancer, and regular follow-up in the remaining cases to ensure that the supernumerary testicle remains stable.

The most common diagnostic dilemma in otherwise normal boys is distinguishing a retractile testis from a testis that will not descend spontaneously into the scrotum. Retractile testes are more common than truly undescended testes and do not need to be operated on. In normal males, as the cremaster muscle relaxes or contracts, the testis moves lower or higher ("retracts") in the scrotum. This cremasteric reflex is much more active in infant boys than older men. A retractile testis high in the scrotum can be difficult to distinguish from a position in the lower inguinal canal. Though there are various maneuvers used to do so, such as using a cross-legged position, soaping the examiner's fingers, or examining in a warm bath, the benefit of surgery in these cases can be a matter of clinical judgment.

In the minority of cases with bilaterally non-palpable testes, further testing to locate the testes, assess their function, and exclude additional problems is often useful. Pelvic ultrasound or magnetic resonance imaging performed and interpreted by a radiologist can often, but not invariably, locate the testes while confirming absence of a uterus. A karyotype can confirm or exclude forms of dysgenetic primary hypogonadism, such as Klinefelter syndrome or mixed gonadal dysgenesis.

Hormone levels (especially gonadotropins and AMH) can help confirm that there are hormonally functional testes worth attempting to rescue, as can stimulation with a few injections of human chorionic gonadotropin to elicit a rise of the testosterone level. Occasionally these tests reveal an unsuspected and more complicated intersex condition.

In the even smaller minority of cryptorchid infants who have other obvious birth defects of the genitalia, further testing is crucial and has a high likelihood of detecting an intersex condition or other anatomic anomalies. Ambiguity can indicate either impaired androgen synthesis or reduced sensitivity. The presence of a uterus by pelvic ultrasound suggests either persistent Müllerian duct syndrome (AMH deficiency or insensitivity) or a severely virilized genetic female with congenital adrenal hyperplasia. An unambiguous micropenis, especially accompanied by hypoglycemia or jaundice, suggests congenital hypopituitarism.

Through diagnostic ultrasound the accumulation of fluids can be diagnosed correctly.

Most cases of polyorchidism are asymptomatic, and are discovered incidentally, in the course of treating another condition. In the majority of cases, the supernumerary testicle is found in the scrotum.

However, polyorchidism can occur in conjunction with cryptorchidism, where the supernumerary testicle is undescended or found elsewhere in the body. These cases are associated with a significant increase in the incidence of testicular cancer: 0.004% for the general population vs 5.7% for a supernumerary testicle not found in the scrotum.

Polyorchidism can also occur in conjunction with infertility, inguinal hernia, testicular torsion, epididymitis, hydrocele testis and varicocele. However, it is not clear whether polyorchidism causes or aggravates these conditions, or whether the existence of these conditions leads sufferers to seek medical attention and thus become diagnosed with a previously undetected supernumerary testicle.

Individuals with CAVD can reproduce with the assistance of modern technology with a combination of testicular sperm extraction and intracytoplasmic sperm injection (ICSI). However, as the risk of either cystic fibrosis or renal agenesis is likely to be higher in the children, genetic counseling is generally recommended.

Spermatoceles can be discovered as incidental scrotal masses found on physical examination by a physician. They may also be discovered by self-inspection of the scrotum and testicles.

Finding a painless, cystic mass at the head of the epididymis, that transilluminates and can be clearly differentiated from the testicle, is generally sufficient. If uncertainty exists, ultrasonography of the scrotum can confirm if it is spermatocele.

If an individual finds what he suspects to be a spermatocele, he is advised to consult a urologist.

Azoospermia is usually detected in the course of an infertility investigation. It is established on the basis of two semen analysis evaluations done at separate occasions (when the seminal specimen after centrifugation shows no sperm under the microscope) and requires a further work-up.

The investigation includes a history, a physical examination including a thorough evaluation of the scrotum and testes, laboratory tests, and possibly imaging. History includes the general health, sexual health, past fertility, libido, and sexual activity. Past exposure to a number of agents needs to be queried including medical agents like hormone/steroid therapy, antibiotics, 5-ASA inhibitors (sulfasalazine), alpha-blockers, 5 alpha-reductase inhibitors, chemotherapeutic agents, pesticides, recreational drugs (marijuana, excessive alcohol), and heat exposure of the testes. A history of surgical procedures of the genital system needs to be elicited. The family history needs to be assessed to look for genetic abnormalities.

Congenital absence of the vas deferens may be detectable on physical examination and can be confirmed by a transrectal ultrasound (TRUS). If confirmed genetic testing for cystic fibrosis is in order. Transrectal ultrasound can also assess azoospermia caused by obstruction, or anomalies related to obstruction of the ejaculatory duct, such as abnormalities within the duct itself, a median cyst of the prostate (indicating a need for cyst aspiration), or an impairment of the seminal vesicles to become enlarged or emptied.

Retrograde ejaculation is diagnosed by examining a postejaculatory urine for presence of sperm after making it alkaline and centifuging it.

Low levels of LH and FSH with low or normal testosterone levels are indicative of pretesticular problems, while high levels of gonadotropins indicate testicular problems. However, often this distinction is not clear and the differentiation between obstructive versus non-obstructive azoospermia may require a testicular biopsy. On the other hand, "In azoospermic men with a normal ejaculate volume, FSH serum level greater than two times the upper limit of the normal range is reliably diagnostic of dysfunctional spermatogenesis and, when found, a diagnostic testicular biopsy is usually unnecessary, although no consensus exists in this matter." But also, extremely high levels of FSH (>45 ID/mL) have been correlated with successful microdissection testicular sperm extraction.

Serum inhibin-B weakly indicates presence of sperm cells in the testes, raising chances for successfully achieving pregnancy through testicular sperm extraction (TESE), although the association is not very substantial, having a sensitivity of 0.65 (95% confidence interval [CI]: 0.56–0.74) and a specificity of 0.83 (CI: 0.64–0.93) for prediction the presence of sperm in the testes in non-obstructive azoospermia.

Seminal plasma proteins TEX101 and ECM1 were recently proposed for the differential diagnosis of azoospermia forms and subtypes, and for prediction of TESE outcome. Mount Sinai Hospital, Canada started clinical trial to test this hypothesis in 2016.

It is recommended that men primary hypopituitarism may be linked to a genetic cause, a genetic evaluation is indicated in men with azoospermia due to primary hypopituitarism. Azoospermic men with testicular failure are advised to undergo karyotype and Y-micro-deletion testing.

The primary management of cryptorchidism is watchful waiting, due to the high likelihood of self-resolution. Where this fails, a surgery, called orchiopexy, is effective if inguinal testes have not descended after 4–6 months. Surgery is often performed by a pediatric urologist or pediatric surgeon, but in many communities still by a general urologist or surgeon.

When the undescended testis is in the inguinal canal, hormonal therapy is sometimes attempted and very occasionally successful. The most commonly used hormone therapy is human chorionic gonadotropin (HCG). A series of hCG injections (10 injections over 5 weeks is common) is given and the status of the testis/testes is reassessed at the end. Although many trials have been published, the reported success rates range widely, from roughly 5 to 50%, probably reflecting the varying criteria for distinguishing retractile testes from low inguinal testes. Hormone treatment does have the occasional incidental benefits of allowing confirmation of Leydig cell responsiveness (proven by a rise of the testosterone by the end of the injections) or inducing additional growth of a small penis (via the testosterone rise). Some surgeons have reported facilitation of surgery, perhaps by enhancing the size, vascularity, or healing of the tissue. A newer hormonal intervention used in Europe is the use of GnRH analogs such as nafarelin or buserelin; the success rates and putative mechanism of action are similar to hCG, but some surgeons have combined the two treatments and reported higher descent rates. Limited evidence suggests that germ cell count is slightly better after hormone treatment; whether this translates into better sperm counts and fertility rates at maturity has not been established. The cost of either type of hormone treatment is less than that of surgery and the chance of complications at appropriate doses is minimal. Nevertheless, despite the potential advantages of a trial of hormonal therapy, many surgeons do not consider the success rates high enough to be worth the trouble since the surgery itself is usually simple and uncomplicated.

In cases where the testes are identified preoperatively in the inguinal canal, orchiopexy is often performed as an outpatient and has a very low complication rate. An incision is made over the inguinal canal. The testis with accompanying cord structure and blood supply is exposed, partially separated from the surrounding tissues ("mobilized"), and brought into the scrotum. It is sutured to the scrotal tissue or enclosed in a "subdartos pouch." The associated passage back into the inguinal canal, an inguinal hernia, is closed to prevent re-ascent.

In patients with intraabdominal maldescended testis, laparoscopy is useful to see for oneself the pelvic structures, position of the testis and decide upon surgery ( single or staged procedure ).

Surgery becomes more complicated if the blood supply is not ample and elastic enough to be stretched into the scrotum. In these cases, the supply may be divided, some vessels sacrificed with expectation of adequate collateral circulation. In the worst case, the testis must be "auto-transplanted" into the scrotum, with all connecting blood vessels cut and reconnected ("anastomosed").

When the testis is in the abdomen, the first stage of surgery is exploration to locate it, assess its viability, and determine the safest way to maintain or establish the blood supply. Multi-stage surgeries, or autotransplantation and anastomosis, are more often necessary in these situations. Just as often, intra-abdominal exploration discovers that the testis is non-existent ("vanished"), or dysplastic and not salvageable.

The principal major complication of all types of orchiopexy is a loss of the blood supply to the testis, resulting in loss of the testis due to ischemic atrophy or fibrosis.

Surgery (orchiopexy) to retrieve the testes and position them in the scrotum is the primary treatment. Occasionally they are unsalvageable if located high in the retroperitoneum. During this surgery, the uterus is usually removed and attempts made to dissect away Müllerian tissue from the vas deferens and epididymis to improve the chance of fertility. If the person has male gender identity himself and the testes cannot be retrieved, testosterone replacement will be usually necessary at puberty should the affected individual choose to pursue medical attention. Lately, laparoscopic hysterectomy is offered to patients as a solution to both improve the chances of fertility and to prevent the occurrences of neoplastic tissue formation.

Testicular biopsy would confirm the absence of spermatozoa. Seminal plasma protein TEX101 was proposed for differentiation of Sertoli cell-only syndrome from maturation arrest and hypospermatogenesis. And a clinical trial at Mount Sinai Hospital, Canada started testing this hypothesis in 2016.

Some strategies suggested or proposed for avoiding male infertility include the following:

- Avoiding smoking as it damages sperm DNA

- Avoiding heavy marijuana and alcohol use.

- Avoiding excessive heat to the testes.

- Maintaining optimal frequency of coital activity: sperm counts can be depressed by daily coital activity and sperm motility may be depressed by coital activity that takes place too infrequently (abstinence 10–14 days or more).

- Wearing a protective cup and jockstrap to protect the testicles, in any sport such as baseball, football, cricket, lacrosse, hockey, softball, paintball, rodeo, motorcross, wrestling, soccer, karate or other martial arts or any sport where a ball, foot, arm, knee or bat can come into contact with the groin.

- Diet: Healthy diets (i.e. the Mediterranean diet) rich in such nutrients as omega-3 fatty acids, some antioxidants and vitamins, and low in saturated fatty acids (SFAs) and trans-fatty acids (TFAs) are inversely associated with low semen quality parameters. In terms of food groups, fish, shellfish and seafood, poultry, cereals, vegetables and fruits, and low-fat dairy products have been positively related to sperm quality. However, diets rich in processed meat, soy foods, potatoes, full-fat dairy products, coffee, alcohol and sugar-sweetened beverages and sweets have been inversely associated with the quality of semen in some studies. The few studies relating male nutrient or food intake and fecundability also suggest that diets rich in red meat, processed meat, tea and caffeine are associated with a lower rate of fecundability. This association is only controversial in the case of alcohol. The potential biological mechanisms linking diet with sperm function and fertility are largely unknown and require further study.

Ultrasonography of the scrotum is useful when there is a suspicion of some particular diseases. It may detect signs of testicular dysgenesis, which is often related to an impaired spermatogenesis and to a higher risk of testicular cancer. Scrotum ultrasonography may also detect testicular lesions suggestive of malignancy. A decreased testicular vascularization is characteristic of testicular torsion, whereas hyperemia is often observed in epididymo-orchitis or in some malignant conditions such as lymphoma and leukemia. Doppler ultrasonography useful in assessing venous reflux in case of a varicocele, when palpation is unreliable or in detecting recurrence or persistence after surgery, although the impact of its detection and surgical correction on sperm parameters and overall fertility is debated.

Dilation of the head or tail of the epididymis is suggestive of obstruction or inflammation of the male reproductive tract. Such abnormalities are associated with abnormalities in sperm parameters, as are abnormalities in the texture of the epididymis. Scrotal and transrectal ultrasonography (TRUS) are useful in detecting uni- or bilateral congenital absence of the vas deferens (CBAVD), which may be associated with abnormalities or agenesis of the epididymis, seminal vesicles or kidneys, and indicate the need for testicular sperm extraction. TRUS plays a key role in assessing azoospermia caused by obstruction, and detecting distal CBAVD or anomalies related to obstruction of the ejaculatory duct, such as abnormalities within the duct itself, a median cyst of the prostate (indicating a need for cyst aspiration), or an impairment of the seminal vesicles to become enlarged or emptied.

Ultrasound is useful if the cause is not certain based on the above measures. If the diagnosis of torsion is certain, imaging should not delay definitive management such as physical maneuvers and surgery.

Useful tests that may help in the determination of the cause include a urinalysis (usually normal in testicular torsion). Pyuria and bacteriuria (white blood cells and bacteria in the urine) in patients with acute scrotum suggests an infectious cause such as epididymitis or orchitis and specific testing for gonorrhea and chlamydia should be done. All people with chronic pain should be tested for gonorrhea and chlamydia.

The most common presentation of testicular cancer is a hard, painless lump which can be felt on one of the testis. It is either noticed by a clinician during a routine examination, or the patient themselves. Risk factors for TC include:

- Cryptorchidism

- Family history

- Previous testicular cancer

- Being white

The diagnosis is confirmed in different ways. An ultrasound scan can be used to diagnose to a 90-95% accuracy. Bloods can also be taken to look for elevated tumour markers which is also used to analyse the patient’s response to treatment. 80% of testicular cancer cases are from the 20-34 year old age range

To some extent, it is possible to change testicular size. Short of direct injury or subjecting them to adverse conditions, e.g., higher temperature than they are normally accustomed to, they can be shrunk by competing against their intrinsic hormonal function through the use of externally administered steroidal hormones. Steroids taken for muscle enhancement (especially anabolic steroids) often have the undesired side effect of testicular shrinkage.

Similarly, stimulation of testicular functions via gonadotropic-like hormones may enlarge their size. Testes may shrink or atrophy during hormone replacement therapy or through chemical castration.

In all cases, the loss in testes volume corresponds with a loss of spermatogenesis.

Small cysts are best left alone, as are larger cysts that are an asymptomatic condition. Only when the cysts are causing discomfort and are enlarging in size, or the patient wants the spermatocele removed, should a spermatocelectomy be considered. Pain may persist even after removal.

Spermatocelectomy can be performed on an outpatient basis, with the use of local or general anesthesia.

A spermatocelectomy will not improve fertility.

Scrotal ultrasonography and transrectal ultrasonography (TRUS) are useful in detecting uni- or bilateral CBAVD, which may be associated with visible abnormalities or agenesis of the epididymis, seminal vesicles or kidneys.

Sertoli cell only syndrome is like other non-obstructive azoospermia (NOA) cases are managed by sperm retrieval through testicular sperm extraction (mTESE), micro-surgical testicular sperm extraction (mTESE), or testicular biopsy. On retrieval of viable sperm this could be used in Intracytoplasmic Sperm injection ICSI

In 1979, Levin described germinal cell aplasia with focal spermatogenesis where a variable percentage of seminiferous tubules contain germ cells. It is important to discriminate between both in view of ICSI.

A retrospective analysis performed in 2015 detailed the outcomes of N=148 men with non-obstructive azoospermia and diagnosed Sertoli cell-only syndrome:

- Men with SCOS: 148

- Testicular sperm was successfully retrieved: 35/148

- Successful ICSI: 20/148

- Clinical pregnancy: 4/148

This study considers the effect of FSH levels on clinical success, and it excludes abnormal karyotypes. All patients underwent MD-TESE in Iran. Ethnicity and genetic lineage may have an impact on treatment of azoospermia [citation needed].

The two most common surgical approaches are retroperitoneal (abdominal using laparoscopic surgery), infrainguinal/subinguinal (below the groin) and inguinal (groin using percutaneous embolization). Possible complications of this procedure include hematoma (bleeding into tissues), hydrocele (accumulation of fluid around the affected testicle), infection, or injury to the scrotal tissue or structures. In addition, injury to the artery that supplies the testicle may occur, resulting in a loss of a testicle.

Whether having variocele surgery or embolization improves male fertility is controversial, as good clinical data are lacking. There is tentative evidence that varicoceletomy may improve fertility in those with obvious findings and abnormal sperm; however, this has a number needed to treat of 7 for varicoceletomy and 17 for embolization. There are also studies showing that the regular surgery has no significant effect on infertility. A 2012 Cochrane review found tentative but unclear evidence of improved fertility among males treated for varicocele.

The fluid accumulation can be drained by aspiration, but this may be only temporary. A more permanent alternative is a surgical procedure, generally, an outpatient ambulatory (same-day) procedure, called a hydrocelectomy. There are two surgical techniques available for hydrocelectomy.

- Hydrocelectomy with Excision of the Hydrocele Sac: Incision of the hydrocele sac after complete mobilization of the hydrocele. Partial resection of the hydrocele sac, leaving a margin of 1–2 cm. Care is taken not to injure testicular vessels, epididymis or ductus deferens. The edge of the hydrocele sac is oversewn for hemostasis (von Bergmann's technique) or the edges are sewn together behind the spermatic cord (Winkelmann's or Jaboulay's technique). Hydrocele surgery with excision of the hydrocele sac is useful for large or thick-walled hydroceles and multilocular hydroceles.

- Hydrocele Surgery with Plication of the Hydrocele Sac: The hydrocele is opened with a small skin incision without further preparation. The hydrocele sac is reduced (plicated) by suture Hydrocele surgery: Lord's technique. The plication technique is suitable for medium-sized and thin-walled hydroceles. The advantage of the plication technique is the minimized dissection with a reduced complication rate.

If the hydrocele is not surgically removed, it may continue to grow. The hydrocele fluid can be aspirated. This procedure can be done in a urologist's office or clinic and is less invasive but, recurrence rates are high. Sclerotherapy, the injection of a solution following aspiration of the hydrocele fluid may increase success rates. In many patients, the procedure of aspiration and sclerotherapy is repeated as the hydrocele recurs.

Around 15% of all adult males, up to 35% of men who are evaluated for male infertility, and around 80% of men who are infertile due to some other cause, have varicocele.

A problem for people with penile agenesis is the absence of a urinary outlet. Before genital metamorphosis, the urethra runs down the anal wall, to be pulled away by the genital tubercle during male development. Without male development this does not occur. The urethra can be surgically redirected to the rim of the anus immediately after birth to enable urination and avoid consequent internal irritation from urea concentrate. In such cases, the perineum may be left devoid of any genitalia, male or female.

A working penis transplant on to an agenetic patient has never been successful. Only one major penis graft was successfully completed. This occurred in China and the patient shortly rejected it on psychological grounds. However a full female or agenetic to male transplant is not yet facilitated to fulfil full reproductive functions.

On March 18, 2013, it was announced that Andrew Wardle, a British man born without a penis, was going to receive a pioneering surgery to create a penis for him. The surgeons hope to "fold a large flap of skin from his arm — complete with its blood vessels and nerves — into a tube to graft onto his pubic area." If the surgery goes well, the odds of starting a family are very good.