Introduction: Who Should Undergo Diagnostics
If you notice swelling in the scrotum, it’s important to see a healthcare provider for proper evaluation. Hydrocele, which is a painless buildup of fluid around one or both testicles, needs to be distinguished from other conditions that may cause similar symptoms.[1] While hydroceles are often harmless, especially in newborn babies, any scrotal swelling requires medical assessment to ensure nothing more serious is happening.
Parents should bring their baby for evaluation if they notice swelling in the scrotum, even though hydroceles in newborns often resolve on their own within the first year of life. However, if the swelling persists beyond age one or becomes larger over time, a doctor should examine the child again.[1] About 10% of newborn infants are born with a hydrocele, making it a relatively common finding that usually doesn’t cause concern.[8]
Adult men should seek medical attention if they develop scrotal swelling at any age. Although hydroceles in adults are less common than in infants, affecting only about 1% of adult males, they can occur spontaneously or following injury or infection to the scrotal area.[8] Sometimes the swelling may be small in the morning and larger later in the day, especially if fluid is moving between the abdomen and scrotum.[1]
It’s particularly important to have scrotal swelling evaluated if it causes discomfort, pain, or a feeling of heaviness in the scrotum or groin area. While hydroceles themselves are typically painless, they can sometimes be associated with other conditions such as inguinal hernia (when part of the intestine pushes through a weak spot in the abdominal muscles into the scrotum), which may require more urgent attention.[1]
In rare cases, a hydrocele may be an early sign of testicular cancer or indicate problems with the testicle, especially in men older than 40.[7] For this reason, any new scrotal swelling in an older child or adolescent should be examined by a physician, as it could be linked to infection, twisting of the testicles, or a tumor.[5]
Diagnostic Methods
Physical Examination
The diagnosis of hydrocele typically begins with a thorough physical examination by a healthcare provider. This is usually the most important step in identifying a hydrocele and distinguishing it from other causes of scrotal swelling. During the exam, the doctor will carefully feel the scrotum to check for swelling, tenderness, or other abnormalities.[9]
The provider will check for pain in the enlarged scrotum and press on both the stomach area and scrotum to look for signs of an inguinal hernia. An inguinal hernia can occur alongside a hydrocele, especially in babies, when the opening between the abdomen and scrotum doesn’t close properly.[9] The doctor may also ask you to cough while applying pressure to the groin area to better examine the swelling and rule out hernias.[12]
Transillumination Test
One of the most characteristic diagnostic procedures for hydrocele is called transillumination. During this simple test, the doctor shines a bright light through the scrotum from behind each testicle.[7] This technique helps determine what’s causing the swelling. If there’s a hydrocele filled with clear fluid, the light will shine through the scrotum, creating a glow. However, if the swelling is caused by a solid mass, such as a tumor or other tissue, the light will not pass through.[9]
Transillumination is a quick, painless, and very helpful way to confirm that the swelling is indeed fluid-filled. It can be performed right in the doctor’s office without any special preparation or discomfort to the patient. This test provides immediate information that guides the doctor’s next steps in care.
Ultrasound Imaging
If the physical examination and transillumination don’t provide clear answers, or if the doctor suspects other problems, an ultrasound may be ordered. Ultrasound is a type of imaging test that uses sound waves to create pictures of the inside of the scrotum.[9] It’s completely safe, painless, and doesn’t involve any radiation.
An ultrasound can confirm the diagnosis of hydrocele and help the doctor see exactly where the fluid is located. More importantly, it can check for other causes of scrotal swelling such as a hernia, tumor, or problems with the testicle itself.[9] This imaging test is especially useful when the doctor needs to rule out testicular cancer or other serious conditions, particularly in older men or when the hydrocele appears suddenly in an adolescent or adult.[5]
The ultrasound examination typically takes only a few minutes and can be performed in a radiology department or doctor’s office. The technician applies a special gel to the scrotal area and moves a handheld device across the skin to capture images. These images allow the doctor to see the fluid collection clearly and examine the testicles and surrounding structures for any abnormalities.
Blood and Urine Tests
In some situations, particularly when infection is suspected, the healthcare provider may order blood and urine tests. These laboratory tests help determine whether an infection is causing or contributing to the hydrocele.[9] Infections of the epididymis (the tube at the back of the testicle) or the testicle itself can lead to fluid accumulation in the scrotum.
Blood tests can check for signs of inflammation or infection in the body, while urine tests can identify urinary tract infections or other issues that might be related to scrotal swelling. These tests are particularly important in adults where hydroceles often develop due to underlying conditions rather than developmental issues as seen in babies.[2]
Diagnostics for Clinical Trial Qualification
When patients with hydrocele are being considered for participation in clinical trials, standard diagnostic procedures are typically required to confirm the diagnosis and assess the condition properly. Based on available information, these evaluations generally follow the same pattern as routine clinical diagnostics but may be more detailed and systematic.[10]
Clinical trials testing new treatments for hydrocele would typically require documentation of the hydrocele through physical examination and imaging studies. Ultrasound examination is especially important for clinical trials as it provides objective, measurable data about the size and characteristics of the hydrocele. This baseline information allows researchers to accurately track changes over time and assess whether a treatment is effective.
Trial participants would need to undergo comprehensive evaluation to ensure they meet specific criteria. This might include confirming that the hydrocele is indeed present, determining its type (communicating or noncommunicating), measuring its size, and ruling out other conditions that might make the patient unsuitable for the study. The diagnostic workup would also help identify any complications or associated conditions that could affect participation or require special monitoring during the trial.
Patients being screened for clinical trials may also need additional blood tests or imaging studies beyond what’s typically done in routine care. These extra tests help researchers collect complete information about each participant’s health status and ensure that any changes observed during the trial can be properly understood and attributed to the treatment being studied rather than other factors.



