Testicular scan

A testicular scan, also known as testicular scintigraphy or scrotal radionuclide imaging, is a specialized nuclear medicine imaging procedure used to evaluate blood flow to the testes and surrounding scrotal structures. This diagnostic test is most commonly performed in the setting of acute scrotal pain, where immediate and accurate diagnosis is essential for determining the proper treatment path. One of the most critical uses of this scan is to differentiate between testicular torsion and epididymitis or orchitis—two conditions that can present with similar symptoms but require vastly different treatments. Testicular torsion is a surgical emergency, while epididymitis is typically treated with medication. This distinction can prevent irreversible damage or loss of the testicle and avoid unnecessary surgery.

Due to its ability to detect vascular abnormalities and perfusion patterns, a testicular scan offers rapid, non-invasive, and accurate diagnosis, especially when ultrasound results are inconclusive or unavailable in emergency settings.

What is a Testicular Scan?

A testicular scan is a nuclear medicine procedure that uses a small amount of radiopharmaceutical (commonly 99mTechnetium-pertechnetate) to evaluate the blood supply to the scrotal contents, including the testes, epididymis, and spermatic cord. After the injection of the radiotracer into a vein, a gamma camera captures images of the scrotal region. The distribution of the radiotracer in the tissues reflects the level of blood flow, allowing physicians to identify ischemic (low blood flow) or hyperemic (increased blood flow) patterns, depending on the underlying pathology.

When is a Testicular Scan Performed?

This scan is primarily indicated in emergency or urgent settings where a patient presents with acute testicular or scrotal pain. It is especially helpful when a clinical examination is inconclusive, and the diagnosis needs to be established promptly to avoid testicular damage.

Common Indications Include:

• Acute onset scrotal or testicular pain
• Suspected testicular torsion
• Suspected epididymitis or orchitis
• Swelling or redness in the scrotal region
• Scrotal trauma or injury
• Inconclusive ultrasound Doppler study
• Suspected testicular infarction or ischemia
• Differentiation between testicular torsion and other causes of scrotal pain in children and adolescents

Understanding Testicular Torsion vs. Epididymitis

The ability to distinguish between testicular torsion and epididymitis is crucial, as the management of each is entirely different.

1. Testicular Torsion:

• Caused by twisting of the spermatic cord, leading to interrupted blood flow to the testis
• Presents with sudden, severe scrotal pain, swelling, nausea, and high-riding testis
• Requires immediate surgical intervention to untwist the cord and restore blood flow
• Delay in treatment can lead to testicular necrosis and infertility

2. Epididymitis/Orchitis:

• Caused by inflammation or infection of the epididymis (epididymitis) or testis (orchitis)
• Typically presents with gradual onset pain, fever, urinary symptoms, and tenderness
• Treated medically with antibiotics and anti-inflammatory medications
• Surgery is generally not required

In both cases, early diagnosis is key. A testicular scan helps clinicians make this distinction with high accuracy.

How is the Testicular Scan Performed?

The scan is non-invasive, quick, and safe. It involves the following steps:

1. The patient lies comfortably on an examination table.
2. A small intravenous injection of 99mTc-pertechnetate is administered.
3. Dynamic images are taken immediately to assess arterial blood flow into the scrotal region.
4. After the dynamic phase, static images are acquired for a more detailed evaluation of the testicular tissues.
5. The entire procedure takes around 30–45 minutes.

Patients can resume normal activities immediately after the test. There are no dietary or medication restrictions, although the referring physician may advise based on specific clinical needs.

Interpretation of the Testicular Scan

The images captured by the gamma camera are reviewed by a nuclear medicine specialist, who evaluates perfusion patterns and tracer uptake in the testicles.

Typical Findings:

• Normal Scan: Symmetrical, homogenous tracer uptake in both testicles indicating normal blood flow
• Testicular Torsion: Marked reduction or complete absence of uptake in the affected testis ("cold spot") due to lack of blood supply
• Epididymitis/Orchitis: Increased tracer uptake ("hot spot") indicating inflammation and hyperemia
• Missed or Late Torsion: May show surrounding increased uptake (rim sign) with central photopenia due to necrosis

Advantages of Testicular Scintigraphy

• Highly accurate in detecting vascular causes of scrotal pain
• Can distinguish between torsion and infection with high sensitivity
• Helps avoid unnecessary surgery in cases of non-torsion
• Useful when Doppler ultrasound is inconclusive
• Quick and easy to perform in emergency settings
• Radiation dose is minimal and considered safe
• Effective in pediatric and adolescent patients

Limitations of the Test

1. May not detect partial or intermittent torsion, especially if the blood flow is not fully blocked
2. Requires access to nuclear medicine facilities, which may not be available in all centers
3. In some cases, results may be ambiguous, requiring correlation with clinical findings or other imaging modalities
4. Interpretation must be done by experienced nuclear medicine physicians to avoid misdiagnosis

Preparation and Safety

There is no special preparation needed for the scan:

• No fasting required
• No need to stop any medications unless instructed
• Inform the physician if you are pregnant, breastfeeding, or allergic to any substances
• The radioactive tracer used is safe and quickly eliminated from the body
• Drink plenty of fluids after the scan to help flush the tracer out

When Should You Consider a Testicular Scan?

If you or your child experience any of the following symptoms, your doctor may recommend a testicular scan:

• Sudden or severe testicular pain
• Redness or swelling of the scrotum
• Trauma or injury to the groin area
• Pain that is not resolving with initial treatment
• Suspected testicular torsion or ischemia

Early imaging and diagnosis can be life-saving—especially in testicular torsion, where the window for surgical correction is within 4–6 hours to preserve testicular viability.

Conclusion

The Testicular Scan (Scrotal Scintigraphy) is a vital diagnostic tool in the evaluation of acute testicular pain, particularly for distinguishing between testicular torsion and epididymitis/orchitis. Its ability to assess real-time blood flow in the scrotal structures allows for prompt and accurate diagnosis, which is critical in preventing permanent damage or loss of the testicle. Quick, non-invasive, and highly reliable, the testicular scan is a go-to modality when clinical findings are unclear or when ultrasound is inconclusive. Whether in emergency situations or complex diagnostic cases, this test provides invaluable information that directly impacts patient management and outcomes.

If you are experiencing acute scrotal pain, seek immediate medical attention—timely imaging can make all the difference in preserving reproductive health and avoiding complications.