Torsion of testicular appendages can result in the clinical presentation of acute scrotum. Two such appendages are the appendix testis, a remnant of the paramesonephric (müllerian) duct, and the appendix epididymis, a remnant of the mesonephric (wolffian) duct.
The appendix testis is present in 92% of all testes and is usually located at the superior testicular pole in the groove between the testicle and the epididymis. The appendix epididymis is present in 23% of testes and usually projects from the head of the epididymis, but its location may vary. Most acute presentations of scrotal pain and swelling can be attributed to epididymitis, testicular torsion, or torsion of a testicular appendage. The presentations of these conditions can typically be distinguished by history and examination. However, in many cases, torsion of a testicular appendage, although a benign condition, may present identically to testicular torsion, a true urologic emergency.
Testicular torsion must be diagnosed quickly and accurately, because delay of the diagnosis and subsequent delay of surgery, if needed, can lead to loss of testicular viability and orchidectomy.[1]
The vestigial tissues forming the appendices are commonly pedunculated and are structurally predisposed to torsion. Torsion of an appendage leads to ischemia and infarction. Necrosis of appendices causes pain and local inflammation of surrounding the tunica vaginalis and epididymis (acute hemiscrotum). Torsion of the testicular appendage may also be accompanied by presence of a thickened scrotal wall, a reactive hydrocele, and enlargement of the head of the epididymis.
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Torsion of testicular appendices is one of the most common causes of acute scrotum; it is the leading cause of acute scrotum in children.
In several retrospective reviews of pediatric patients who presented to the emergency department with acute scrotal pain, the incidence of torsed testicular appendage ranged from 46-71% and represented the most common cause of scrotal pain.
In one study of 155 scrotal explorations that were performed for acute scrotal pain, the pathology was testicular torsion in 46.5% (N = 72); torsion of a testicular appendage in 30.3% (N = 47); epididymitis in 16.1% (N = 25); no obvious pathology in 3.3% (N = 5); and other pathology in 4%. The mean age was 9.1 years (range 0-15 years), and there was a significant difference in age of presentation between those with testicular torsion and those with torsion of a testicular appendage (9 vs 10 years, P = 0.0074).[2] In another, retrospective study of 76 patients younger than 15 years with acute scrotal pain, 59 (78%) had acute spermatic cord torsion, 16 (21%) had torsion of the testicular appendage, and 1 (1%) had orchitis. In patients with acute spermatic cord torsion, the median age was 13 years (range: 0.18-14.97).[3]
Torsion of the testicular appendices is virtually a benign condition, but again, must be distinguished from testicular torsion, which can have permanent consequences on testicular viability.
Age ranges vary from infancy to adulthood with more than 80% of cases occurring in children aged 7-14 years. Mean age is 10.6 years. This condition rarely presents in adulthood (probably due to local fibrosis). Torsion of testicular appendices is the leading cause of acute scrotum in children.[2, 3, 5, 6]
The prognosis is excellent. Long-term sequelae to this condition do not exist. Virtually all patients have uneventful recoveries.
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The patient's history is important in distinguishing torsion of the testicular appendages from testicular torsion and other causes of acute scrotum.
The most common cause of acute scrotum in prepubertal boys is torsion of the testicular or epididymal appendages.[7]
Pain may be present. Onset is usually acute, but pain may develop over time. Typically, it has a more gradual onset than testicular torsion. Intensity ranges from mild to severe. Patients may endure pain for several days before seeking medical attention. The pain is located in the superior pole of the testicle. This is a key distinguishing factor from testicular torsion. A focal point of pain on the testicle is uncommon in complete testicular torsion.
Systemic symptoms are absent. Nausea and vomiting (frequently seen in testicular torsion) are usually not associated with this condition.
Urinary symptoms are absent. Dysuria and pyuria are not associated with torsion of the testicular appendages. Their presence is more indicative of epididymitis.
Physical examination may reveal the following findings[5] :
Ultrasonography can be useful in distinguishing torsion of a testicle and torsion of an appendix testis. Testicular appendage torsion appears as a lesion of low echogenicity with a central hypoechogenic area. The presence of a large appendix adjacent to the epididymis (in the absence of clinically detectable inflammation) may signify testicular involvement. If the edematous appendix and the head of the epididymis are close enough, this condition will have the "Mickey Mouse" appearance on transverse view.
In a retrospective study of 241 boys with acute scrotal pain, the best predictors for epididymitis were dysuria, a painful epididymis on palpation, and altered epididymal echogenicity and increased peritesticular perfusion on ultrasound studies; for appendix testis (AT), the best predictor was a positive blue dot sign.[9]
Color Doppler sonography (CDS) is the imaging modality of choice for evaluation of the acute scrotum.[10, 11, 7] In torsion of the testicular appendage, CDS shows normal blood flow to the testis, with an occasional increase on the affected side that possibly is due to inflammation. In prepubertal patients, this method of imaging is somewhat controversial because the prepubertal testis has low-velocity blood flow, and CDS is less accurate in these instances.
Standard US of the scrotum should include both grayscale and Doppler studies. Linear high-resolution transducers should be used, and te studies should include both the scrotum and inguinal areas. In patients with torsion, a normal homogeneous echo pattern is likely to indicate a viable testis, whereas a hypoechoic or inhomogeneous testis is likely to be nonviable.[12]
Some studies suggest that CDS has 90% sensitivity and 98% specificity in diagnosing acute testicular torsion. However, variability exists in the sensitivity of color Doppler ultrasonography. As a result, a negative ultrasonographic result does not necessarily exclude testicular torsion.
A study by Pepe et al demonstrated that CDS specificity may not be as high as previously reported for testicular torsion.[13] In a subset analysis of 42 adolescents with diagnostic suspicion of testicular torsion by CDS, only 22 had surgical confirmation of this diagnosis, while 16 were found to be normal and 4 had torsion of the testicular appendage. In fact, clinical examination alone had sensitivity and specificity of 100% and 50%, respectively, while CDS had sensitivity and specificity of 95.7% and 48.7%, respectively. In a patient presenting with an acute scrotum, a negative CDS result may provide supportive evidence that the patient has a benign condition like torsion of an appendage, but it does not exclude the diagnosis of testicular torsion. In high clinical suspicion, surgical exploration may still be warranted.
Since the acceptance of Doppler US as the primary imaging for evaluation of acute scrotum, radionuclide scrotal imaging (RNSI) is uncommonly used.[12] The positive sign for testicular appendix torsion is the hot-dot sign, which is an area of increased tracer uptake. This sign is pathognomonic for testicular appendix torsion. Radionuclide images do not show a positive result if symptoms have been present for fewer than 5 hours. Positive results are seen in only 45% of patients whose symptoms have lasted 5-24 hours.[14] The test is reported to be 68% sensitive and 79% accurate.[14]
MRI techniques are not typically used for the acute scrotum because of the limited availability of equipment and the long examination time involved. However, the use of MRI in scrotal diseases is increasing, and future studies are necessary to help determine the role of MRI in patients who have acute scrotal pain but equivocal CDU findings.[12]
Necrotic tissue of the testicular appendices causes no damage other than damage to itself. Most cases, therefore, are treated conservatively. Pain usually resolves within 1 week but may persist for several weeks. Uncontrolled pain can be relieved by surgical excision of the appendix.
NSAIDs and ice are the mainstays of therapy for inflammation, and reduced activity and scrotal support are indicated.
If the diagnosis is unclear and testicular torsion cannot be ruled out or if pain persists, surgical exploration is warranted.[15]
The following guidelines have been published by the American College of Radiology[12] :
The goals of pharmacotherapy are to reduce morbidity and prevent complications.
Clinical Context: DOC for patients with mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing prostaglandin synthesis.
Clinical Context: For relief of mild to moderate pain and inflammation.
Small dosages initially are indicated in small and elderly patients and in those with renal or liver disease.
Doses over 75 mg do not increase therapeutic effects. Administer high doses with caution and closely observe patient for response.
Clinical Context: For relief of mild to moderate pain; inhibits inflammatory reactions and pain by decreasing activity of cyclooxygenase, which results in a decrease of prostaglandin synthesis.
These agents have anti-inflammatory and antipyretic activities. Their mechanism of action is not known, but they may inhibit cyclooxygenase activity and prostaglandin synthesis. Other mechanisms may exist as well, such as inhibition of leukotriene synthesis, lysosomal enzyme release, lipoxygenase activity, neutrophil aggregation, and various cell-membrane functions.