The vasal injection is given deep to external spermatic fascia, but superficial to internal spermatic fascia
which encloses testicular arteries and veins.
The scrotal wall consists of the following layers (from superficial to deep): skin, superficial fascia, dartos muscle, external spermatic fascia, cremasteric fascia, and internal spermatic fascia
. The tunica vaginalis, covering the tunica albuginea, is double-layered and has an outer parietal layer lining the inner scrotal wall to form the mediastinum.
As shown in Figure 1, these layers include the skin, superficial scrotal fascia, external spermatic fascia, cremaster muscle, and internal spermatic fascia
. These scrotal tissue layers bunch up and surround the loop of vas just above the level of the skin, potentially confusing the vasectomist.