Teaching Case

A gentleman presented to his general practitioner (GP) with a painful & swollen right testicle. Antibiotics were prescribed by GP for suspected epididymo-orchitis, however, the pain progressed and worsened. The patient was referred to the urologists who requested ultrasound (US) to further elucidate the cause of testicular pain.

An urgent ultrasound revealed significant infarction of the lower pole of the right testis. Imaging also showed a swollen right testicle with no colour Doppler flow within a 3 x 3 x 5 cm parenchymal area. A ‘twirling’ was seen in the region of the right epididymis at the upper pole of the right testis within the spermatic cord, in keeping with testicular torsion. The left testis was otherwise normal in size, echo-texture and Doppler flow.

Background

Testicular torsion (TT) is a surgical emergency presenting with acute testicular pain, swelling and scrotal redness. The majority are teenagers and children (1/4000 <25-years-old), but rarely it is encountered in adults or the elderly [1]. The term 'spermatic cord torsion or twist', is a common surgical term used to describe a spiral twist of spermatic cord causing testicular ischaemia due to testicular hypo-perfusion. A well-known predisposing risk factor is bell-clapper deformity (12% of men, bilateral in 80%) [2].

Clinical Perspective

In adults and the elderly testicular pain may seem tolerable enough to allow physical examination, especially if given sufficient analgesia. Other relatively reliable clinical signs are: high testicular position, abnormal cremasteric reflex, nausea & vomiting [3, 4]. Clinicians must act promptly with children/teenagers, while manifestations in adults may present later.

Imaging Perspective

US provides a useful comparative assessment of anatomical details of ipsilateral affected testis to contra-lateral (control) testis. Doppler evaluation of intra-extra testicular perfusion, whether fully restricted or partially diminished, can be also performed [6].

The venous component of colour Doppler is usually affected first (congestion) which subsequently obstructs the arterial flow causing ischaemia. Therefore, dependency on colour Doppler in order to rule out TT has a false negative result, quite misleading and hazardous [5]. Whilst the imaging of choice, Doppler US reported sensitivity ranges from 64–100% & specificity 97–100% [3-6, 8].

In this case we have demonstrated by ultrasound the “twirling sign” of the spermatic cord. A sign that can directly illustrate the occult to explain the hypoechoic and hypovascular ultrasound of the affected testis. Recently, a multi-centre study on the 'twirling sign' showed that routine US only diagnosed 76% of cases while a higher positive predictive value (96%) was observed when the sign was consistently identified, called 'snail shell-shaped' [9].

However, the study neither described the exact technique nor included a graphical US image of the sign. Therefore, this can be considered the first report to describe the technique and illustrate the 'twirling sign' in motion. Experience and training years were reported as significant factors in identifying this confirmatory sign [9].

Outcome

Salvaging the testis is crucial, as 100% recovery in the first 6-12 hours after symptoms onset is achievable by restoring anatomical position and prophylactic contra-lateral orchidopexy [7]. In this case, orchidectomy was necessary and patient was discharged and followed-up with no further complications.

Teaching Points

Currently, modern US equipment is capable of motion/cine recording with a high-frame-rate to demonstrate the 'twirling sign' showing spiral rotations of the spermatic cord.