出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/07/01 21:02:29」(JST)
| Testicular torsion | |
|---|---|
| Classification and external resources | |
1. Epididymis 2. Head of epididymis 3. Lobules of epididymis 4. Body of epididymis 5. Tail of epididymis 6. Duct of epididymis 7. Deferent duct (ductus deferens or vas deferens) |
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| ICD-10 | N44 |
| ICD-9 | 608.2 |
| OMIM | 187400 |
| DiseasesDB | 12984 |
| MedlinePlus | 000517 |
| eMedicine | med/2780 |
| MeSH | D013086 |
Testicular torsion occurs when the spermatic cord (from which the testicle is suspended) twists, cutting off the testicle's blood supply, a condition called ischemia. The principal symptom is rapid onset of testicular pain. The most common underlying cause is a congenital malformation known as a "bell-clapper deformity" wherein the testis is inadequately affixed to the scrotum allowing it to move freely on its axis and susceptible to induced twisting of the cord and its vessels. The diagnosis can be made clinically but an urgent ultrasound is helpful in evaluation. Irreversible ischemia begins around six hours after onset and emergency diagnosis and treatment is required within this time in order to minimize necrosis and to improve the chance of salvaging the testicle.
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Testicular torsion usually presents with acute, diffuse, testicular pain and tenderness. There is often an absent or decreased cremasteric reflex.[1] Many of the symptoms are similar to epididymitis though epididymitis may be characterized by discoloration and swelling of the testis, often with fever, while the cremasteric reflex is not affected. Both conditions can, of course, co-occur. Testicular torsion, or more probably impending testicular infarction, can also produce a low-grade fever.[2]:p.314
Conditions that allow the testicle to rotate predispose to torsion.[3] A congenital malformation of the processus vaginalis known as the "bell-clapper deformity" accounts for 90% of all cases.[4] In this condition, rather than the testes attaching posteriorly to the inner lining of the scrotum by the mesorchium, the mesorchium terminates early and the testis is free floating in the tunica vaginalis.
Torsions are sometimes called "winter syndrome" because they are more frequent in cold conditions, specifically decreasing atmospheric temperature and humidity.[5]
Immediate testing for torsion is indicated when the onset of testicular pain is sudden and/or severe. In general a doppler ultrasound should be obtained in low suspicion cases to rule out torsion while in those cases with a convincing history and physical exam immediate surgical detorsion (derotation) is reasonable.[3]
Prehn's sign, a classic physical exam finding, has not been reliable in distinguishing torsion from other causes of testicular pain such as epididymitis.[6] In cases of true torsion the cremasteric reflex is typically absent (the twisted cords of the testicle make reflexive responses all but impossible), the scrotum is generally neither swollen nor discolored, and the affected testis may have a horizontal lie.[3] The individual will not usually have a fever, though nausea is common.
A doppler ultrasound scan, also called a high-frequency transducer sonography and including pulsed color Doppler imaging, of the scrotum is nearly 100% accurate at detecting torsion.[3] It is identified by the absence of blood flow in the twisted testicle, which distinguishes the condition from epididymitis.[7]
Radionuclide scanning of the scrotum is the most accurate, diagnostic, imaging technique, but it is not routinely available, particularly with the urgency that might be required.[8] The agent of choice for this purpose is technetium-99m pertechnetate.[9] Initially it provides a radionuclide angiogram, followed by a static image after the radionuclide has perfused the tissue. In the healthy patient, initial images show symmetric flow to the testes, and delayed images show uniformly symmetric activity.[9]
Torsion is due to a mechanical twisting process. It is also believed that torsion occurring during fetal development can lead to so-called neonatal torsion or vanishing testis, and is one of the causes of an infant being born with monorchism (one testicle)[10] .
With prompt diagnosis and treatment the testicle can usually be preserved.[3] Typically, when a torsion takes place, the surface of the testicle has rotated towards the midline of the body. Non-surgical correction can sometimes be accomplished by manually rotating the testicle in the opposite direction (i.e., outward, towards the thigh); if this is initially unsuccessful, a forced manual rotation in the other direction may correct the problem.[11]:p.149 The success rate of manual detorsion is not known with confidence.
Testicular torsion is a surgical emergency that requires immediate intervention to restore the flow of blood.[3] If treated either manually or surgically within six hours, there is a high chance (approx. 90%) of preserving the testicle. At 12 hours the rate decreases to 50%; at 24 hours it drops to 10%, and after 24 hours the rate of preservation approaches 0.[3]
Torsion is most frequent among adolescents with about 65% of cases presenting between 12 – 18 years of age.[12] It occurs in about 1 in 160 males before 25 years of age;[3][4] but it can occur at any age, including infancy.[11]:p.149
A variant is a less serious but chronic condition called intermittent testicular torsion (ITT), characterized by the symptoms of torsion but followed by eventual spontaneous detortion and resolution of pain. Nausea or vomiting may also occur.[11]:p.150 Though less pressing, such individuals are at significant risk of complete torsion and possible subsequent orchiectomy and the recommended treatment is elective bilateral orchiopexy. Ninety-seven percent of patients who undergo such surgery experience complete relief from their symptoms. [2]:p.316
A torsion which occurs outside of the tunica vaginalis, when the testis and gubernaculum can rotate freely, is termed an extravaginal testicular torsion. This type occurs exclusively in newborns. Neonates experiencing such a torsion present with scrotal swelling, discoloration, and a firm, painless mass in the scrotum. Such testes are usually necrotic from birth and must be removed surgically.[2]:p.315
This type of torsion is the most common cause of acute scrotal pain in boys ages 7–14. Its appearance is similar to that of testicular torsion but the onset of pain is more gradual. Palpation reveals a small firm nodule on the upper portion of the testis which displays a characteristic "blue dot sign." This is the appendix of the testis which has become discolored and is noticeably blue through the skin. Unlike other torsions, however, the cremasteric reflex is still active. Typical treatment involves the use of over-the-counter analgesics and the condition resolves within 2–3 days.[2]:p.316
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| リンク元 | 「精巣捻転」「精巣回転症」「spermatic cord torsion」 |
| 関連記事 | 「testicular」「torsion」 |