eMedicine Specialties > Radiology > Genitourinary

Epididymitis

Updated: Nov 13, 2009

Introduction

Background

Acute epididymitis, testicular torsion, and testicular tumors can have a common presentation of pain. Acute epididymitis is the most common condition that causes acute scrotal pain. Distinguishing between acute epididymitis and testicular torsion is important because their treatments differ significantly.^1,2

Transverse sonogram of the testis shows an enlarged and predominantly hypoechoic epididymis with a reactive hydrocele in a patient with acute epididymitis.

Color-flow sonogram shows increased vascularity in the epididymis. An enlarged epididymis with increased vascularity in the appropriate clinical setting is diagnostic of acute epididymitis.

Sonogram shows an enlarged epididymis with heterogeneous echotexture in a case of acute epididymitis.

CDC guidelines

According to the Centers for Disease Control and Prevention (CDC), the evaluation of men for epididymitis should include one of the following³:

Gram stain of urethral secretions demonstrating ≥5 WBC per oil immersion field. The Gram stain is the preferred rapid diagnostic test for evaluating urethritis. It is highly sensitive and specific for documenting both urethritis and the presence or absence of gonococcal infection. Gonococcal infection is established by documenting the presence of WBC containing intracellular gram-negative diplococci on urethral Gram stain.
Positive leukocyte esterase test on first-void urine or microscopic examination of first-void urine sediment demonstrating ≥10 WBC per high-power field.

The CDC provides the following treatment guidelines for epididymitis³:

For acute epididymitis most likely caused by gonococcal or chlamydial infection: Ceftriaxone 250 mg IM in a single dose PLUS doxycycline 100 mg orally twice a day for 10 days.
For acute epididymitis most likely caused by enteric organisms or for patients allergic to cephalosporins and/or tetracyclines: Ofloxacin 300 mg orally twice a day for 10 days OR levofloxacin 500 mg orally once daily for 10 days.

Recent studies

In a study by Tracy and Costabile, CDC guidelines for acute epididymitis were found to be followed in less than 35% of patients. They also noted that 97% of adult men were treated empirically with antibiotics often not in accordance with CDC guidelines. However, 50% of patients 18-35 years were prescribed an effective treatment according to CDC guidelines, as were 85% of patients older than 35 years.²

According to Karmazyn et al, children with epididymitis who have urinary tract abnormalities (UTAs) are more likely to have marked epididymal swelling, develop recurrent disease, and have a more protracted course. In 17 boys studied, the most common UTAs were hypospadias, neurogenic bladder, and functional bladder abnormality. Marked epididymal swelling occurred in 53% of children with UTAs, and epididymitis occurred in 53%. Chronic epididymitis, scrotal mass, and epididymal abscess occurred only in children with UTAs, when compared with controls.⁴

Pathophysiology

Usually, acute epididymitis is caused by Chlamydia trachomatis or Neisseria gonorrhoeae, which are sexually transmitted. In prepubertal boys and men older than 35 years, the disease is most frequently caused by Escherichia coli or Proteus mirabilis.

Other causes include tuberculosis (especially in patients with AIDS), sarcoidosis, brucellosis, and leprosy. Noninfectious causes include trauma and drugs such as amiodarone.

Mumps is the most common cause of orchitis and usually requires no intervention.

Frequency

United States

Acute epididymitis is the most common cause of acute scrotum in male adolescents.

International

As in the United States, acute epididymitis is the most common cause of acute scrotum in male adolescents.

Mortality/Morbidity

Complications of epididymitis and/or epididymo-orchitis include the following:

Chronic epididymitis
Infarction
Infertility
Abscess
Atrophy
Pyocele

Race

No racial predilection is reported.

Sex

Only males are affected.

Age

Adolescents and adults can be affected.

Anatomy

Normal testes develop in the celom and begin to descend into the scrotum at 36 weeks' gestation, guided by the contractile, cordlike structure called the gubernaculum testis. The epididymis and ductus deferens develop from the wolffian ducts.

At sonography, a normal adult testis has medium-level echoes and measures 5 x 3 x 2 cm. Septa extend from the tunica albuginea into the testicle, dividing the testes into lobules. The posterior surface of the tunica albuginea is reflected into the interior of the gland to form the incomplete septum known as the mediastinum of the testis. Each lobule is composed of many seminiferous tubules that open, via tubules (tubuli recti), into dilated spaces called the rete testes in the mediastinum. These, in turn, communicate via efferent ductules in the epididymal head.

The epididymis is composed of a head, body, and tail, the ducts of which continue as the vas deferens in the spermatic cord. The epididymis lies superior and lateral, along the posterior aspect of the testis; the head of epididymis is the most cephalic part.

Four testicular appendages have been described; however, only 2 are clinically relevant: the appendix of the testis (müllerian duct remnant) and the appendix of the epididymis, a wolffian duct remnant. Sonographically, the head of the epididymis is better depicted in the longitudinal view than in others. It is an isoechoic or slightly hypoechoic structure with medium-level echoes. Usually, the body of the epididymis is not identified at sonography in healthy adults. Sometimes, the epididymal tail is seen.

Presentation

Patients present with acute pain in the scrotum, which may be associated with fever and pyuria. Physical examination reveals an enlarged and tender epididymis that can be separated from the scrotum. The pain is relieved by elevating the scrotum to the symphysis pubis (Prehn sign). Usually, the cremasteric reflex is present.

Regarding the differential diagnosis, testicular torsion has a similar presentation. Torsion of the appendix of the testis also causes pain, but systemic symptoms are usually absent. Physical examination reveals the blue dot sign, which occurs in patients with torsion of the appendix of the testis. The Prehn sign is positive in patients with acute epididymitis and negative in patients with testicular torsion. The cremasteric reflex is present in patients with acute epididymitis and absent in patients with testicular torsion. Approximately 10% of the tumors may cause acute pain.

Preferred Examination

Sonography, clinical history taking, and physical examination are the mainstays in diagnosing acute epididymitis. The preferred imaging examination is ultrasonography, which is very useful in the detection of the epididymitis and/or epididymo-orchitis. Ultrasonography is helpful in excluding testicular torsion.^5,6

Differential Diagnoses

Testicle, Malignant Tumors
Testicle, Trauma
Testicular Torsion

Radiography

Findings

Radiography has no role in the evaluation of epididymitis.

Ultrasonography

Transverse sonogram of the testis shows an enlarged and predominantly hypoechoic epididymis with a reactive hydrocele in a patient with acute epididymitis.

Color-flow sonogram shows increased vascularity in the epididymis. An enlarged epididymis with increased vascularity in the appropriate clinical setting is diagnostic of acute epididymitis.

Sonogram shows an enlarged epididymis with heterogeneous echotexture in a case of acute epididymitis.

Findings

Findings considered diagnostic of acute epididymitis include an enlarged (>17 mm) epididymis with a hypoechoic, hyperechoic, or heterogeneous echotexture at gray-scale sonography and increased blood flow at color or power Doppler sonography. Associated reactive hydrocele and scrotal wall thickening may be present. Blood flow can be seen in a normal epididymis; therefore, the mere presence of blood flow should not be considered the sine qua non of epididymitis. It is the asymmetrical increase (more in the affected epididymis) that is important.⁷

The epididymis is primarily involved in epididymo-orchitis, with orchitis developing in about 20-40% of cases by means of direct spread. Diffuse testicular involvement is confirmed with testicular enlargement and an inhomogeneous echotexture. These findings are nonspecific, but acute epididymo-orchitis is the most common disease with this pattern. This pattern of heterogeneous echotexture can also occur in patients with tumors, metastasis, and infarction. Therefore, patients with these conditions should be followed up with sonography to demonstrate complete resolution.

The readily detectable intratesticular venous flow is highly suggestive of orchitis. Analysis of the spectral waveform also can provide useful information. In the testes of a healthy volunteer, the resistive index (RI) is rarely less than 0.5, but more than half of the patients with epididymo-orchitis have an RI of less than 0.5.

Degree of Confidence

Ultrasonography is the first-line imaging modality for evaluating a patient with suspected acute epididymo-orchitis. The sensitivity of color Doppler ultrasonography in detecting scrotal inflammation is almost 100%.

False Positives/Negatives

Usually, no false-positive or false-negative findings occur. However, the epididymis may be involved in some patients with testicular torsion. Hence, in every case of epididymitis, intratesticular blood flow should be carefully evaluated to exclude the possibility of acute testicular torsion.

Nuclear Imaging

Findings

Nuclear medicine study is an alternative method for evaluating epididymitis. However, because of the improved capability of color and power Doppler sonography in the evaluation of testicular perfusion, this modality is no longer favored. The most common scenario in which epididymitis appears on scintigrams is in patients who undergo imaging for suspected torsion.

The radionuclide angiogram obtained with technetium-99m pertechnetate reveals increased spermatic cord blood flow. Static images reveal increased radiotracer uptake, which may be focal (as in epididymitis) or diffuse (as in epididymo-orchitis), in the involved hemiscrotum. These findings should easily differentiate epididymitis from acute torsion. However, if an abscess or hydrocele formation is present, a photopenic area with a hypervascular rim (halo sign) can be apparent. This finding could potentially mimic late, missed torsion.

False Positives/Negatives

Nuclear medicine studies help in the differentiation of epididymo-orchitis from acute torsion. Increased radionuclide uptake may be present in the setting of trauma.

Intervention

No radiologic intervention is required.

Patient Education: For excellent patient education resources, visit eMedicine's Men's Health Center, Bacterial and Viral Infections Center, and Sexually Transmitted Diseases Center. Also, see eMedicine's patient education articles Testicle Infection (Epididymitis), Inflammation of the Testicle (Orchitis), Mumps, and Sexually Transmitted Diseases.

Medicolegal Pitfalls

Acute epididymitis and testicular torsion have similar presentations with regard to pain.
Differentiating acute epididymitis and testicular torsion is important because their treatments and outcomes differ.

Multimedia

Media file 1: Transverse sonogram of the testis shows an enlarged and predominantly hypoechoic epididymis with a reactive hydrocele in a patient with acute epididymitis.

Media file 2: Color-flow sonogram shows increased vascularity in the epididymis. An enlarged epididymis with increased vascularity in the appropriate clinical setting is diagnostic of acute epididymitis.

Media file 3: Sonogram shows an enlarged epididymis with heterogeneous echotexture in a case of acute epididymitis.

References

Tracy CR, Steers WD, Costabile R. Diagnosis and management of epididymitis. Urol Clin North Am. Feb 2008;35(1):101-8; vii. [Medline].
Tracy CR, Costabile RA. The evaluation and treatment of acute epididymitis in a large university based population: are CDC guidelines being followed?. World J Urol. Apr 2009;27(2):259-63. [Medline].
Center for Disease Control and Prevention. Sexually Transmitted Diseases Treatment Guidelines 2006: Epididymitis. Centers for Disease Control and Prevention. Department of Health and Human Services. Available at http://www.cdc.gov/std/Treatment/2006/epididymitis.htm. Accessed November 6, 2009.
Karmazyn B, Kaefer M, Kauffman S, Jennings SG. Ultrasonography and clinical findings in children with epididymitis, with and without associated lower urinary tract abnormalities. Pediatr Radiol. Oct 2009;39(10):1054-8. [Medline].
Lee JC, Bhatt S, Dogra VS. Imaging of the epididymis. Ultrasound Q. Mar 2008;24(1):3-16. [Medline].
Al-Taheini KM, Pike J, Leonard M. Acute epididymitis in children: the role of radiologic studies. Urology. May 2008;71(5):826-9; discussion 829. [Medline].
Pearl MS, Hill MC. Ultrasound of the scrotum. Semin Ultrasound CT MR. Aug 2007;28(4):225-48. [Medline].
Bree RL, Hoang DT. Scrotal ultrasound. Radiol Clin North Am. Nov 1996;34(6):1183-205. [Medline].
Brown JM, Hammers LW, Barton JW. Quantitative Doppler assessment of acute scrotal inflammation. Radiology. Nov 1995;197(2):427-31. [Medline].
Burks DD, Markey BJ, Burkhard TK. Suspected testicular torsion and ischemia: evaluation with color Doppler sonography. Radiology. Jun 1990;175(3):815-21. [Medline].
Chou YH, Chan HK, Huang CN. [Torsion of the appendix testis]. Kaohsiung J Med Sci. Jun 1999;15(6):322-5. [Medline].
Dogra V, Bhatt S. Acute painful scrotum. Radiol Clin North Am. Mar 2004;42(2):349-63. [Medline].
Dogra VS, Gottlieb RH, Oka M. Sonography of the scrotum. Radiology. Apr 2003;227(1):18-36.
Dogra VS, Rubens DJ, Gottlieb RH. Torsion and beyond: new twists in spectral Doppler evaluation of the scrotum. J Ultrasound Med. Aug 2004;23(8):1077-85.
Dogra VS, Sessions A, Mevorach RA. Reversal of diastolic plateau in partial testicular torsion. J Clin Ultrasound. Feb 2001;29(2):105-8. [Medline].
Gordon LM, Stein SM, Ralls PW. Traumatic epididymitis: evaluation with color Doppler sonography. AJR Am J Roentgenol. Jun 1996;166(6):1323-5. [Medline].
Gronski M, Hollman AS. The acute paediatric scrotum: the role of colour doppler ultrasound. Eur J Radiol. Jan 1998;26(2):183-93. [Medline].
Hawtrey CE. Assessment of acute scrotal symptoms and findings. A clinician''s dilemma. Urol Clin North Am. Nov 1998;25(4):715-23, x. [Medline].
Herbener TE. Ultrasound in the assessment of the acute scrotum. J Clin Ultrasound. Oct 1996;24(8):405-21. [Medline].
Horstman WG. Scrotal imaging. Urol Clin North Am. Aug 1997;24(3):653-71. [Medline].
Lerner RM, Mevorach RA, Hulbert WC. Color Doppler US in the evaluation of acute scrotal disease. Radiology. Aug 1990;176(2):355-8. [Medline].
Mevorach RA, Lerner RM, Greenspan BS. Color Doppler ultrasound compared to a radionuclide scanning of spermatic cord torsion in a canine model. J Urol. Feb 1991;145(2):428-33. [Medline].
Noske HD, Kraus SW, Altinkilic BM. Historical milestones regarding torsion of the scrotal organs. J Urol. Jan 1998;159(1):13-6. [Medline].

Keywords

epididymitis, epididymis, acute epididymitis, epididymo-orchitis, acute scrotum, acute scrotal pain, testicular torsion, Chlamydia trachomatis, C trachomatis, Neisseria gonorrhoeae, N gonorrhoeae, Escherichia coli, E coli, Proteus mirabilis, P mirabilis, Prehn sign

Contributor Information and Disclosures

Author

Vikram S Dogra, MD, Professor of Diagnostic Radiology, Urology, and Biomedical Engineering, University of Rochester School of Medicine; Director, Division of Ultrasound, Associate Chair of Education and Research, Department of Imaging Sciences, University of Rochester Medical Center
Vikram S Dogra, MD is a member of the following medical societies: American College of Radiology, American Institute of Ultrasound in Medicine, American Roentgen Ray Society, Association of Program Directors in Radiology, Radiological Society of North America, Society of Radiologists in Ultrasound, and Society of Uroradiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

Joshua A Becker, MD, Professor, Department of Radiology, New York University School of Medicine
Joshua A Becker, MD is a member of the following medical societies: Society of Uroradiology
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Resolution Imaging Medical Corporation
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Eugene C Lin, MD, Consulting Radiologist, Virginia Mason Medical Center; Clinical Assistant Professor of Radiology, University of Washington School of Medicine
Eugene C Lin, MD is a member of the following medical societies: American College of Nuclear Medicine, American College of Radiology, Radiological Society of North America, and Society of Nuclear Medicine
Disclosure: Nothing to disclose.

Further Reading

Related eMedicine topics

Epididymitis (from Urology)

Epididymitis (from Emergency Medicine)

Testicular Torsion

Testicular Choriocarcinoma

Bedside Ultrasonography, Testicular Evaluation

Guidelines

Epididymitis and Orchitis. In: Guidelines on the Management of Urinary and Male Genital Tract Infections

ACR Appropriateness Criteria Acute Onset of Scrotal Pain (Without Trauma, Without Antecedent Mass)