What is the differential for unilateral scrotal swelling in a neonate?
Hydrocele, inguinal hernia (indirect), testicular torsion, tumour (teratoma, yolk sac tumour)
What is the aetiology of testicular torsion in a neonate, and how does it differ from torsion in later life?
Neonatal - extravaginal torsion: occurs prior to testicular fixation by the tunica vaginalis (ie a physiological predisposition in the process of testicular descent). Usually occurs antenatally and diagnosed after birth. In contrast, in older children/adults - intravaginal torsion: occurs after testicular fixation, but when fixation is incomplete (ie an anatomical predisposition - bell clapper deformity).
The left testis is smaller than the right, with no internal vascularity. It has a rim of peripheral calcification. Right testis has normal appearance and vascularity, no calcification. Incidentally, there is a right hydrocele.