Teaching Case

A 54-year-old man presented with unilateral right testicular pain and swelling 5 days post hernia repair. On examination he had a markedly swollen right hemiscrotum with tenderness, the testis remained palpable. The patient was referred for an ultrasound to exclude a recurrent hernia.

Biochemical markers showed raised inflammatory markers, but were otherwise unremarkable. Greyscale ultrasound demonstrated a heterogenous, enlarged right testis (Fig. 1) with a mildly thickened epididymis and thickened spermatic canal to the inguinal region. There was small volume intratesticular signal on colour Doppler imaging (Fig. 2). Contrast-enhanced ultrasound (CEUS) was performed with 4.8 ml SonoVue (Bracco, Milan) intravenously in contrast specific mode on Logiq E9 utilising 9L linear transducer (GE Healthcare). CEUS showed minimal peripheral enhancement of the testis with less than 10% viable tissue (Fig. 2). The patient proceeded to orchidectomy and developed abscess formation, treated with incision and drainage, but had no further complication. Pathological specimen confirmed a completely infarcted testis with no remaining seminiferous tubules identified.

Inguinal hernia repair is a common procedure with infrequent complications. Testicular ischaemia is estimated to occur in 0.2-1.1% of hernia repairs, however clinical diagnosis may be difficult as oedema, haematoma, hernia recurrence occur more frequently and ultrasound is essential. [1] Testicular infarction is critical to exclude as there is the risk of recurrent infection and testicular preserving treatments may need to be undertaken, especially as autoimmunity to spermatozoa can occur. [2] Colour Doppler imaging has been criticised for lack of sensitivity within the testis – particularly within the paediatric population and can lead to uncertainty over testicular viability. [3]

CEUS utilises low mechanical index imaging to resonate microbubbles of sulphur hexoflourine encased in a phospholipid shell. The non-linear signal produced can be isolated after linear signal cancellation from static tissue. The truly intravascular nature of the contrast results in imaging of both the micro and macrovasculature. CEUS gained widespread popularity in liver lesion characterisation due to the real time nature of the imaging along with the lack of radiation and nephrotoxic contrast. [4] EFUSMB (European Federation of Ultrasound in Medicine and Biology) have also released guidelines on non-hepatic uses, including the testis. [5] The testis, unlike many organs, lacks other imaging modalities; MRI (magnetic resonance imaging) requires prolonged imaging and is impractical, whilst CT (computed tomography) is undesirable given radiosensitivity and lack of spatial resolution. Testicular CEUS has been used to demonstrate intralesional vascularity, particularly Leydig cell tumours which show characteristic enhancement and may allow testicular sparing surgery. [5,6] Conversely as CEUS has the ability to definitively identify vascularity, the absence of enhancement can be useful in characterising epidermoid lesions, haematoma or testicular infarction.

CEUS has been used to describe global testicular infarction secondary to missed torsion or rarely epididymo-orchitis. [5,6,7] Typically global testicular infarction is from arterial compromise from torsion of the spermatic cord. It is thought that post-hernia repair testicular infarction occurs secondary to occlusion of the pampiniform plexus resulting in venous infarction. [1] Initially venous infarction may be compensated by hyperaemia from collaterals from the cremasteric or deferential artery. With progression there is central testicular infarction and peripheral sparing, which may not be immediately obvious on conventional ultrasound. In our case, the presence of minimal colour Doppler-signal is misleading as it is the sole spared area of parenchyma, which is difficult to determine on B-mode and Doppler imaging, but is shown unequivocally on CEUS and can expedite surgical management.

Written informed patient consent for publication has been obtained.