You are in: eMedicine Specialties > Radiology > GENITOURINARY EpididymitisArticle Last Updated: Dec 21, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 9
  Author: Vikram S Dogra, MD, Professor of Diagnostic Radiology, 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 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 Editors: Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Joshua A Becker, MD, Professor, Department of Radiology, New York University School of Medicine; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Eugene C Lin, MD, Consulting Staff, Department of Radiology, Virginia Mason Medical Center Author and Editor Disclosure Synonyms and related keywords: 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 INTRODUCTIONSection 2 of 9
  BackgroundAcute 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. PathophysiologyUsually, 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. FrequencyUnited StatesAcute epididymitis is the most common cause of acute scrotum in male adolescents. InternationalAs in the United States, acute epididymitis is the most common cause of acute scrotum in male adolescents. Mortality/MorbidityComplications of epididymitis and/or epididymo-orchitis include the following:
RaceNo racial predilection is reported. SexOnly males are affected. AgeAdolescents and adults can be affected. AnatomyNormal 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. Clinical DetailsPatients 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 ExaminationSonography, 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. DIFFERENTIALSSection 3 of 9
Testicle, Malignant Tumors Testicle, Trauma Testicular Torsion RADIOGRAPHSection 4 of 9
FindingsRadiography has no role in the evaluation of epididymitis. ULTRASOUNDSection 5 of 9
FindingsFindings 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. 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 ConfidenceUltrasonography 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/NegativesUsually, 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 MEDICINESection 6 of 9
FindingsNuclear 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/NegativesNuclear medicine studies help in the differentiation of epididymo-orchitis from acute torsion. Increased radionuclide uptake may be present in the setting of trauma. INTERVENTIONSection 7 of 9
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. Medical/Legal Pitfalls
MULTIMEDIASection 8 of 9
REFERENCESSection 9 of 9
Article Last Updated: Dec 21, 2006 | |||||||||||||||||||||
