Ultrasound For The Win! Case – 64M with Fever and Scrotal Pain #US4TW

Welcome to another ultrasound-based case, part of the “Ultrasound For The Win!” (#US4TW) Case Series. In this series, we focus on a real clinical case where point-of-care ultrasound changed the management or aided in the diagnosis. In this case, a 64-year-old man presents with acute onset scrotal pain and fever.

Learning Objectives

1. List the differential diagnosis for a patient presenting with acute scrotal pain.
2. Differentiate various scrotal fluid collections (hydrocele, hematocele, and pyocele) based on their sonographic features.
3. Discuss the appropriate Emergency Department workup and managment of a scrotal pyocele.

Case Presentation

A 64-year-old man with a history of poorly-controlled diabetes and hypertension presents to the Emergency Department with acute onset left-sided scrotal pain and swelling. He reports fever and dysuria for the past 4 days. He denies any urethral discharge or any past history of sexually-transmitted infections. He is not currently sexually active and there is no history of trauma.

On physical examination, you find a well-appearing man in no acute distress. His abdomen is soft and non-tender without any palpable masses, and there is no rebound tenderness or guarding. His genito-urinary examination reveals a mildly enlarged and tender left testicle. The cremasteric reflex is intact. The scrotum is mildly erythematous and edematous without lesions or drainage. There is no erythema of the perineum and no crepitus.

Vital Signs

• BP 171/89 mmHg
• P 104 bpm
• RR 22 breaths/min
• O2 96% room air
• T 39.4 C

Differential Diagnosis

• Epididymitis/epididymo-orchitis
• Hematocele
• Hydrocele
• Scrotal abscess
• Scrotal pyocele
• Testicular malignancy
• Testicular torsion
• Varicocele

Laboratory Investigations

• Urinalysis: 3+ leukocyte esterase, 3+ nitrite
• Urine microscopy: 30-40 white blood cells/high-powered field
• White blood cell count: 16.3 x10^9 cells/L
• Lactate: 2.5 mmol/L

The emergency physician performs a point-of-care ultrasound.

Point-of-Care Ultrasound:

Figure 1. Ultrasound of the left hemi-scrotum reveals a mildly enlarged testicle with good vascular flow with color Doppler. A complex heterogenous fluid collection and a thickened scrotal wall is also seen.

Figure 2. A complex heterogenous fluid collection (*) and scrotal wall thickening (arrow).

Figure 3. Hyperemic epididymis and a complex heterogenous fluid collection with septations within the scrotum.

Figure 4. Hyperemic epididymis suggestive of epididymitis (E) and a complex fluid collection with internal echoes and septations (arrow) concerning for a scrotal pyocele.

Figure 5. Another view of the patient’s hyperemic epididymis and scrotal pyocele.

Ultrasound Image Quality Assurance (QA)

When performing a point-of-care ultrasound of the scrotum, patient positioning and comfort are key [Fig. 6]. Have the patient lie in a frog-leg position with the head of the bed elevated and a towel draped under the scrotum to provide support. Another towel can be used to drape the penis.

Figure 6. Ideal patient positioning when performing a point-of-care ultrasound of the scrotum. (Image: https://abdominalkey.com/scrotal-ultrasound/)

A high frequency linear transducer is used to scan each hemi-scrotum in 2 planes (longitudinal and transverse) and examine the echotexture, size, and vascularity of each testicle. Identifying the epididymis and assessing for hyperemia with color Doppler can be useful in identifying epididymitis. Sonographic findings of epididymitis include an enlarged and hyperemic epididymis, and visualization of associated secondary findings such as a thickened scrotal wall or a reactive hydrocele.¹ Orchitis is identified on ultrasound with testicular enlargement when compared to the non-affected testicle, and hyperemia with color Doppler.

For further reading on patient positioning and technique for performing a scrotal ultrasound, refer to a prior #US4TW case.

Scrotal fluid collections can be categorized into 1 of 3 distinct types:²

Table 1. Sonographic Findings of Scrotal Fluid Collections

Disposition and Case Conclusion

Given the findings on the point-of-care ultrasound concerning for pyocele, intravenous broad spectrum antibiotics were started and urology was consulted. The patient was admitted to the urology service, where surgical drainage of the pyocele was performed. He was subsequently discharged on antibiotics with no complications.

A scrotal pyocele is an uncommonly encountered urologic emergency that typically arises secondary to a severe or untreated epididymo-orchitis, but may also result from trauma or surgery. The presentation of scrotal pyocele is an acute to sub-acute onset of testicular pain and swelling. Unfortunately, this presentation is non-specific and can be seen in many other pathologies (see Differential Diagnosis above) providing a difficult diagnostic challenge for the emergency physician.

A pyocele is formed when purulent fluid from a testicular infection communicates with a hydrocele via the tunica vaginalis.³ This purulent fluid collection surrounds the testicle and often contains debris, loculations, and septations.¹ If left untreated, it can progress to Fournier gangrene.

Pathogenesis

Typically, the common pathogens of epididymo-orchitis in men aged ≤35 are sexually-transmitted Chlamydia trachomatis and Neisseria gonorrhoea. In men aged >35 and young children, the common pathogens include Escherichia coli or Pseudomonas.¹ Patients with diabetes, HIV, or other immunosuppressed states are at increased risk for developing scrotal pyoceles.²

The management of scrotal pyoceles includes treatment with broad-spectrum antibiotics and urology consultation for potential surgical drainage or debridement.

Take-Home Points

1. Ultrasound is the diagnostic imaging modality of choice for evaluating a patient presenting with acute scrotal pain or swelling.
2. Scrotal fluid collections can be categorized into 1 of 3 types: hydrocele, hematocele, and pyocele.
3. A scrotal pyocele is an uncommon complication of epidiymo-orchitis, but is considered a urologic emergency and may require surgical intervention to prevent potential complications including Fournier gangrene.
4. Sonographic findings of scrotal pyoceles include a heterogeneous fluid collection within the scrotum with septations +/- gas and air-fluid levels.

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