Dr Prabhjot Singh, Pen State Health Hershey Medical Center, USA
Preputial skin graft (PSG) for urethral reconstruction was first reported by Presman and Greenfield in 1953.(1) In 1963, Devine et al. popularized this technique in urethral strictures and hypospadias repair.(2) Currently, PSG is the second most used graft in substitution urethroplasty for penile and bulbar urethral strictures not amenable for end-to-end anastomosis. PSG is hairless, elastic, and can withstand wet environments like the BMG. PSG is readily available and versatile to use in the management of anterior urethral strictures. However, it remains underutilized compared to buccal mucosal grafts (BMG). PSG can be harvested from the same operative site, unlike BMG which requires an additional operative field and preparation of the oral cavity (Figure 1). Harvesting a BMG can result in donor site morbidities like post operative pain, oral tightness, perioral numbness, alteration in saliva production and has the risk of lower lip retraction in large grafts. A PSG avoids this morbidity with limited risk to donor area which is closed with interrupted sutures. However, prerequisite for PSG includes a normal prepuce with no evidence of Balanitis xerotica obliterans (BXO).
Graft “take” and contracture are the two main variables which determine successful outcomes in addition to the quality of graft bed. The microscopic structure of PSG and BMG are distinct from each other. PSG is a full-thickness skin graft which includes the epidermis and the deep dermis. The intradermal vascular plexus, part of the subdermal vascular plexus and the dermal collagen are components of this graft. In general, full thickness grafts have suboptimal uptake due to their bulky graft mass. However, PSG has the unique property of having a lesser graft mass. This thin architecture of PSG results in good graft uptake compared to non-genital full thickness skin grafts. PSG is less prone to contraction as it contains dermal collagen which maintains tissue structure. BMG on the other hand has a non-keratinized epithelium. The graft includes the epithelium along with the lamina propria. Since the vascularity is pan-laminar, BMG has good graft take. Nevertheless, BMG can contract over time and 10% extra donor tissue is harvested to tackle this issue. BMG also needs to be de-fatted to increase the graft take. This is sometimes time consuming and needs meticulous handling to prevent graft loss.
Long term success rates of PSG urethroplasty can reach upto 87% at five years which is comparable to BMG urethroplasty. In an RCT comparing PSG vs BMG urethroplasty by Tyagi et al. 2022, it was found that there was no statistical difference between the two groups.(3) The utility of PSG was further expanded by Kulkarni et al. 2023 in their novel spiral PSG technique where a long spiral graft can be employed for pan urethral stricture disease.(4) PSG is a valid and easy alternative to BMG and can be utilized in all patients who have an intact prepuce without BXO changes.
Figure 1: Harvesting preputial graft & dorsolateral substitution urethroplasty