Can a testicular ultrasound show infection?

A testicular ultrasound, also known as a scrotal ultrasound, is an imaging test that uses high-frequency sound waves to create detailed images of the scrotum and testicles. This non-invasive test can help diagnose various testicular conditions, including infections, tumors, cysts, torsion, and more.

Quick Answers:

– A testicular ultrasound may show signs of infection in the testicles, such as swelling, inflammation, and abnormal fluid collection. However, it cannot definitively diagnose a testicular infection on its own.

– Testicular infections often require further testing like bloodwork, urinalysis, and bacterial cultures to confirm the diagnosis and identify the specific pathogen involved.

– While a testicular ultrasound is useful for detecting potential abnormalities, a physician will typically need to synthesize its results with other clinical findings to determine if an infection is present.

How a Testicular Ultrasound Works

During a testicular ultrasound, the scrotum is first covered with a water-based lubricating gel. The ultrasound technician then presses a handheld probe, called a transducer, against the skin of the scrotum. The probe emits sound waves that bounce off tissues and organs, producing echoes that are converted into images on a computer screen.

These images allow the radiologist to evaluate the size, shape, and internal structure of the testicles and surrounding tissues. By comparing the ultrasound findings against baseline normal anatomy, certain patterns may indicate an infectious process.

However, ultrasound has limitations in its ability to identify specific microorganisms responsible for infection. It can only detect physical and structural changes to tissues. Additional testing is usually needed to pinpoint the pathogen and guide appropriate treatment.

Signs of Infection on Testicular Ultrasound

Although a testicular ultrasound cannot provide a definitive diagnosis of infection on its own, it may reveal certain findings suggestive of an infectious process. These include:

Swollen testicle/epididymis:

Many testicular infections cause inflammation and swelling of the testicle (orchitis) and/or epididymis (epididymitis). This appears on ultrasound as an enlarged, diffusely hypoechoic (dark) testicle and epididymis compared to the normal side. The presence of swollen testicular tissues indicates inflammation, often from infectious causes.


A hydrocele is an abnormal fluid collection around the testicle, which shows up on ultrasound as a dark space or “pocket” around the testicle. While hydroceles are sometimes idiopathic, infectious causes include filarial infections and epididymo-orchitis, particularly from sexually transmitted bacteria.

Echogenic debris:

Infectious fluid collections often contain echogenic (bright) debris, which may appear as moving dots or clumps within the scrotal sac. This represents pus, blood, tissue, and other products of infection floating in the hydrocele fluid.

Reduced blood flow:

Infection can impair testicular blood flow, detected on Doppler ultrasound as decreased or absent vascularity within the testicle. The testicle may also appear more hypoechoic than the normal side due to inflammation and edema.


A testicular abscess appears as a complex cystic mass with thick walls, internal echoes, and absent internal vascularity. Abscesses require drainage along with IV antibiotics to treat the infection.

Ultrasound Finding Potential Indication
Swollen testicle/epididymis Orchitis/epididymitis from infection
Hydrocele Infectious fluid collection
Echogenic debris in hydrocele Pus/products of infection
Decreased testicular blood flow Impaired flow from inflammation
Abscess Walled-off infection requiring drainage

Limitations of Testicular Ultrasound for Infection

Despite its ability to detect physical indicators of infection, a testicular ultrasound has some notable limitations:

Cannot identify specific organisms:

An ultrasound can only detect generalized inflammation and structural changes. It cannot identify the specific bacteria, viruses, or other pathogens causing infection. Definitive diagnosis requires microbial testing.

Non-infectious causes possible:

Findings like swelling, fluid, and reduced blood flow can also result from non-infectious processes like trauma, testicular torsion, or cancer. Clinical correlation is needed.

Early infection may have normal appearance:

The earliest stages of testicular infection may show no abnormalities on ultrasound. Follow-up imaging and clinical monitoring are often needed.

Adjacent structures not well visualized:

The ultrasound probe cannot penetrate bone or air-filled bowel loops obscuring parts of the scrotum. Infection in adjacent areas like the prostate or inguinal canals may go undetected.

Operator dependence:

Image quality and diagnostic accuracy depend on the skill and experience of the ultrasound technician. Results can vary between different operators.

Role in Diagnosis of Testicular Infection

Given its advantages and drawbacks, how should physicians use testicular ultrasound in the clinical assessment for possible infection?

Initial test to identify abnormalities requiring further evaluation

When infection is suspected, ultrasound provides an accessible first-line test to identify any gross abnormalities in the scrotum that warrant more extensive diagnostic workup. Findings like swelling, debris, and reduced vascularity are “red flags” for infection.

Guide for more definitive diagnostic testing

By localizing any lesions, inflammation, fluid collections, or other irregularities, ultrasound helps target subsequent testing like blood draws or bacterial cultures to the affected area. Ultrasound also assesses for abscesses needing drainage procedures.

Correlation with clinical signs and symptoms

Testicular ultrasound results must be interpreted in context with the patient’s clinical presentation, risk factors, lab tests, and other imaging modalities to reach the most accurate diagnostic conclusion regarding infection.

Monitor response to treatment

Follow-up ultrasound during and after antibiotic treatment helps evaluate whether infectious abnormalities like swelling, debris, and abscesses are improving with appropriate therapy.

In summary, testicular ultrasound serves as a useful initial test for identifying suspicious structural irregularities that may indicate infection. However, given its limitations in specificity, ultrasound should not be relied upon alone to definitively diagnose testicular infections. A multi-pronged diagnostic approach with correlation of ultrasound findings and clinical features is required for optimal diagnostic accuracy and treatment planning.

Common Causes of Testicular Infection

A number of pathogens can infect the testicles, with typical routes of transmission and risk factors. Common infectious causes to consider include:

Sexually transmitted infections

Chlamydia and gonorrhea bacteria frequently cause epididymitis/epididymo-orchitis from urethral infection spreading to the scrotum. Men under 35 sexually active are most at risk.

Urinary tract infections

Bacteria like E. coli can ascend the urinary tract to infect the prostate and testicles. Common in older men with prostatic enlargement or urinary catheters.


The mumps virus has a known affinity for the testes. Orchitis occurs in up to 1/3 of postpubertal males with mumps parotitis. Vaccination has greatly reduced incidence.


Mycobacterium tuberculosis is a rare cause of tuberculous epididymo-orchitis. Most cases result from hematogenous spread from active pulmonary TB infection.

Fungal infections

Candida and other fungi can sometimes infect the testicle in immunocompromised patients, particularly after long courses of antibiotics. Diabetics at highest risk.

Parasitic infections

Filariasis from mosquito-borne parasites Wuchereria and Brugia can obstruct testicular lymphatics, causing fluid collection and inflammation. Endemic in tropical regions.

Pathogen Transmission Risk Factors
Chlamydia/Gonorrhea bacteria Sexual contact Sexually active males under 35
E. coli and urinary bacteria Ascending UTI Older males, urinary catheters, prostatic enlargement
Mumps virus Respiratory droplets Unvaccinated postpubertal males
Tuberculosis bacteria Hematogenous spread from lungs Active pulmonary TB infection
Candida fungi Endogenous overgrowth Immunocompromised states, diabetes, antibiotics
Filariasis parasites Mosquito vectors Endemic in tropical regions

Treatment of Testicular Infections

Once the causative organism is identified, testicular infections can usually be effectively treated with appropriate antimicrobial therapy:

Bacterial infections

Bacterial epididymitis and orchitis are treated with antibiotics targeting common urinary pathogens like fluoroquinolones (eg, ciprofloxacin) or cephalosporins (eg, ceftriaxone). Several weeks of therapy may be needed to eradicate stubborn bacterial infections.

Viral infections

Supportive care for viral orchitis includes scrotal elevation, NSAIDs, and possibly steroids for severe swelling. Antivirals provide little benefit for mumps orchitis once established but can be considered in very early illness.

Fungal infections

Anti-fungal medications like fluconazole are first-line for susceptible fungal pathogens. Removal of infected prostheses or shunts may be necessary.

Parasitic infections

Antiparasitic drugs like diethylcarbamazine or ivermectin, combined with analgesics/anti-inflammatories, effectively treat filariasis and other parasitic orchitis.


Testicular abscesses require surgical drainage in addition to tailored antibiotic therapy based on culture results.

In refractory cases, sonographic or surgical guidance can target treatment directly into affected areas. Severe, untreatable infections may ultimately require removal of the severely damaged testicle (orchiectomy).

Preventing Testicular Infections

Certain preventative measures can help reduce the risk of developing testicular infections:

Safe sexual practices

Using condoms, limiting partners, and prompt STI testing/treatment in high-risk individuals helps prevent sexually acquired epididymitis.

Good hygiene

Practicing proper hygiene, especially before and after sex, helps avoid introducing pathogens into the urinary tract that could reach the testicles.

Appropriate urethral catheter usage

Avoiding unnecessary catheters and shortening duration of use where possible limits ascending UTIs leading to infectious complications.

UTI treatment

Prompt diagnosis and antibiotic treatment of urinary infections can prevent ascending spread to the prostate and testicles.

Mumps vaccination

The MMR vaccine provides effective immunity against mumps orchitis in childhood. Booster doses in outbreaks may benefit at-risk adults.

Avoiding immunosuppression where possible

Preventing immunocompromised states, when medically appropriate, reduces susceptibility to atypical fungal/parasitic infections. Careful antibiotic use also helps maintain normal microbiota.

Travel precautions in endemic regions

When traveling in tropical areas with parasites like filarial worms, use insect repellants, bed nets, and protective clothing to avoid mosquito bites that transmit infection.

Preventative Measure Purpose
Safe sexual practices Avoid STIs causing epididymitis
Proper hygiene Prevent pathogens entering urinary tract
Judicious catheter use Avoid ascending UTIs
Prompt UTI treatment Prevent spread to testicles
Mumps vaccination Prevent viral orchitis
Avoiding immunosuppression Reduce risk of atypical infections
Insect precautions in tropics Prevent filarial infection

When to See a Doctor

Any men experiencing testicular pain, swelling, lumps, or other abnormalities should see a physician promptly for evaluation. Possible urgent reasons to seek medical care include:

Significant scrotal pain/swelling

Sudden onset and progressive pain or enlargement of a testicle warrant urgent assessment to rule out dangerous causes like testicular torsion or rapidly worsening infection.

Fever, chills, and acute scrotal tenderness

These classic systemic symptoms accompanying testicle pain indicate probable infection requiring antibiotics and drainage if an abscess is present.

Trauma to the scrotum

Any injury to the genitals puts a man at higher risk for delayed complications like testicular hematoma or rupture if not assessed soon after the incident.

Difficulty urinating

Infectious prostate swelling compressing the urethra along with testicular inflammation can cause urinary retention needing catheterization.

Recent antibiotic use without improvement

Failure to respond to initial antibiotic therapy for suspected infectious epididymitis or orchitis warrants re-evaluation to confirm an appropriate antibiotic choice and dosage.

High-risk sexual contact or UTI

Known exposure to STIs or recent urinary infection should prompt lower threshold for scrotal evaluation if any new bumps, lesions, or swelling appear.

Immunocompromised state

Immunosuppressed patients are at increased risk for atypical fungal/parasitic infections and should have scrotal symptoms assessed urgently.

While many scrotal abnormalities can be managed electively, sudden, severe testicular pain and systemic symptoms require prompt evaluation to minimize long-term repercussions like infertility or testicular loss in cases of delayed diagnosis.


In summary, while a testicular ultrasound provides helpful visual information about the scrotum’s anatomy and pathology, it has significant limitations in its ability to definitively diagnose testicular infections. Ultrasound cannot pinpoint specific microorganisms or always discriminate infectious versus non-infectious causes of abnormalities. However, it remains a useful initial test for identifying “red flag” irregularities that warrant further diagnostic workup when infection is suspected based on risk factors and clinical presentation. Ultimately, the ultrasound results must be carefully integrated with the patient’s full clinical picture to guide appropriate treatment and follow up. Combining ultrasound’s imaging capabilities with more advanced microbiological testing provides the optimal approach to accurately diagnosing and managing testicular infections.

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