The blood supply to preputial island flaps.

The prepuce is formed by a combination of folding and epithelial proliferation, and separates from the glans after it has developed a blood supply. The arterial input, through 4 branches from the external pudendal arteries, is terminal and after birth supplies the outer and inner preputial surfaces in succession. Similarly, the venous return arises from small veins running transversely in the prepuce that connect to larger subcutaneous veins along the dorsal aspect of the shaft. Because the 2 preputial surfaces have a single blood supply they must be treated as 1 unit. Unfolding the prepuce leaves the former inner segment with only a terminal blood supply. The pedicle containing the superficial blood supply must remain attached to the skin flap or it will be devascularized. However, since this circulation goes exclusively to the flap, the more proximal portion of the prepuce that was raised to form the pedicle becomes ischemic when used as ventral cover. A double-faced flap avoids this complication.