To appreciate the radiological appearance of the “dancing megasperm” phenomenon Discuss the clinical context for this incidental finding

The “dancing megasperm” phenomenon is hypothesised to represent clusters of agglutinated spermatozoa within a dilated epidydimal tubule, occurring as a result of an obstructed spermatic duct1. The most common cause of an obstructed spermatic duct is a vasectomy, but other causes include orchidopexy or hernia repair (iatrogenic), mumps (infection), and chronic epididymitis (inflammation)2. It is an incidental finding on scrotal ultrasound. The differential for dancing megasperm is the “filarial dance sign”3. This is caused by an infection of microfiliarae (Wuchereria bancrofti, also known as the...

‘Dancing megasperm’ are an incidental finding during ultrasound of the scrotum. In the following cases, the patients presented for unrelated testicular pain in the contralateral side to the dancing megasperm. On cine loop, there are oscillating (mobile), hyperechoic foci within the epididymis - in the setting of a previous vasectomy, this was favoured to reflect dancing megasperm. [Fig 1] These may appear like debris (Figure 2), a focal echogenic region (a ‘clump’ of agglutinated spermatozoa) (Figure 3), or multiple echogenic foci (Figure 4).

The ‘dancing megasperm’ phenomenon is an incidental finding and thought to occur as a result of an obstructed spermatic duct. This is most commonly associated with vasectomy but can also occur with prior infection or chronic inflammation. As the differential of this finding is the ‘filarial dance sign’ (representing parasitic infection), it is important to understand the clinical context in which the patient presents for ultrasound. With Australia’s high vasectomy prevalence and advances in ultrasound technology, it is likely that this phenomenon will be encountered...

Leenknegt B, Diss L, Sidhu PS. Dancing Megasperm. J Belg Soc Radiol. 103(1):5. Frates MC, Benson CB, Stober SL. Mobile Echogenicities on Scrotal Sonography. Journal of Ultrasound in Medicine. 2011;30(10):1387–90. Shetty A. Filarial dance sign | Radiology Reference Article | Radiopaedia.org [Internet]. Radiopaedia. [cited 2023 Mar 28]. Available from: https://radiopaedia.org/articles/filarial-dance-sign?lang=gb Zulfiqar H, Malik A. Bancroftian Filariasis. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Mar 28]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK547682/ Jacobstein R, Radloff S, Khan F, Mimno K, Pal M, Snell J, et...