TESTICULAR TORSION

Torsion of the testis and attached spermatic cord occurs as a result of axial twisting which obstructs venous and then arterial circulation. This results in infarction and subsequent necrosis of the testicle. Torsion occurs most commonly around the age of two years, however it has been described in neonates (1) and antenatally (2).

TYPES OF TESTICULAR TORSION

1. Extravaginal type
• usually occurs in the neonatal period and the lactation phase.
• spermatic cord and tunica vaginalis twist as a single unit.
2. Intravaginal type
• later torsions are usually of this type.
• spermatic cord twists while suspended in the tunica vaginalis.

ULTRASOUND

1. Acute Phase
• Hypoechoic testicle (due to hypovascularization) (3)
• Heterogeneous pattern (due to necrosis) (2-4).
• Hydrocele (due to vascular alterations, mechanical obstruction or inflammation itself).
2. Chronic Phase
• Testis undergoes infarction and necrosis, decreases in size, becomes fibrotic and dense due to calcification. An echogenic halo may be seen on ultrasound (5).

Testicular torsion in utero appears to be an irreversible event. No case of a function testicle has been detected at birth after in utero torsion (6,7).

Postnatal ultrasonographic findings of testicular torsion occurring in utero include:

· An enlarged testis with an echogenic rim and inhomogeneous parenchymal pattern (8-10).

· Intrascrotal fluid collection (occasionally a contralateral hydrocele may be present) Stone et al (8) suggests these findings are due to hemorrhagic necrosis and the echogenic rim corresponds to edema or fibrosis of the tunica albuginea.

· Hubbard et al. (4) reported on testicular torsion that was diagnosed after birth and an antenatal ultrasound that had been performed 3 weeks earlier had shown a cystic swelling that was thought to represent a hydrocele.

· 'Double ring hemorrhage' - accumulation of hemorrhagic fluid between the visceral and parietal layers of the tunicae vaginalis and outside the tunica vaginalis, is explained by the mechanism of antenatal testicular torsion.

1. Intravaginal testicular torsion is typically seen in childhood or adolescence and refers to twisting of the testis and epididymis within the cavity created by the visceral and the parietal layers of the tunica vaginalis.

2. Extravaginal torsion is the predominant mechanism occurring in utero, resulting in torsion of the testis and both layers of the tunica vaginalis. The explanation of this mechanism is that during pregnancy the parietal layer of the tunica vaginalis is not yet firmly attached to the outer scrotal tissues. Microscopic examination confirmed that the inner fluid collection is produced by hemorrhage between the visceral and the parietal layers of the tunica vaginalis (cavum serosum tunicae vaginalis testis). The parietal layer of the tunica vaginalis separated the two hemorrhagic compartments. The outer fluid collection is therefore not a hydrocele, but rather hemorrhagic fluid outside the tunica vaginalis in the space created between the torted mass and the scrotal wall.

· Color Doppler of testicular torsion may be of limited value since Doppler signals are unreliable in such small vessels.

· Previous reports of the main postnatal ultrasound findings (4, 9-11) refer to a testis of variable size, heterogeneous appearance and with a peripheral echogenic rim. It is likely that the reason for these varying descriptions is the relatively long duration between the onset of the event and the subsequent ultrasound examination. A long-standing torsion may lead to the reabsorption of the fluid, decrease in the size of the testis and peripheral changes that produce the echogenic rim. This assumption is supported by reports indicating that in the vast majority of cases even early postnatal surgery is not helpful. Accordingly, Brandt et al (12) stated that antenatal torsion represents an irreversible intrauterine event.

· Scrotal wall thickness may serve as a clue as necrosis or torsion may cause inflammation that thickens the scrotal wall.

DIFFERENTIAL DIAGNOSIS

1. Scrotal inguinal hernias.
2. Scrotal tumor.
3. Epidydimitis - orchitis.
4. Torsion of testicular epididymal appendage.

REFERENCES

1. Weingarten JL, Garafolo FA, Cromie WJ. Bilateral synchronous neonatal tortion of the spermatic cord. Urology 1990;35:135-136.
2. Gross BR, Cohen HL, Schlessel J. Perinatal diagnosis of bilateral testicular tortion:beware of tortions simulating hydroceles. J Ultrasound Med 1993;12:479-481.
3. Rosenberg J, Zimmerman M. Case report: intrauterine testicular tortion. J Med Soc NJ 1984;81:320-321.
4. Hubbard AE, Ayers AB, MacDonald LM et.al. Br J Radiol 1984;57:644-646.
5. Devesa R, Munoz A, Torrents M et.al. Prenatal detection of testicular tortion. Ultrasound Obstet Gynecol 1998;11:286-288.
6. Brandt MT, Sheldon CA, Wacksman J et.al. Prenatal testicular tortion: principles of management. J Urol 1992;147:670-672.
7. Das S, Singer A. Controversies of perinatal tortion of the spermatic cord: a review, survey and recommendations. J Urol 1990;143:231-233.
8. Stone KT, Kass EJ, Cacciarelli AA, Gibson DP. Management of suspected antenatal torsion: what is the best strategy? J Urol 1995; 153: 782-784
9. Zerin JM, DiPietro MA, Grignon A, Shea D. Testicular infarction in the newborn: ultrasound findings. Pediatr Radiol 1990; 20: 329-330
10. Brown SM, Casillas VJ, Montalvo BM, Albores-Saavedra J. Intrauterine spermatic cord torsion in the newborn: sonographic and pathologic correlation. Pediatr Radiol 1990; 177: 755-757
11. Cartwright PC, Snow BW, Reid BS, Shultz PK. Color Doppler ultrasound in newborn testis torsion. Urology 1995; 45: 667-669
12. Brandt MT, Sheldon CA, Wacksman J, Matthews P. Prenatal testicular torsion: principles of management. J Urol 1992; 147: 670-672