Is colorectal mucosa a reasonable graft alternative to buccal grafts for urethroplasty?: A comparison of graft histology and stretch

OBJECTIVE: To compare the histological properties and stretch of colorectal mucosal grafts (CMG) and buccal mucosal grafts (BMG) and to evaluate the impact of age, medical comorbidity and tobacco use on these metrics. MATERIALS AND METHODS: Samples of BMGs from patients undergoing augmentation urethroplasty were sent for pathologic review. CMGs were collected from patients undergoing elective colectomy. CMGs were harvested fresh, at full thickness from normal rectum/sigmoid. Patients with inflammatory bowel disease, prior radiation, or chemotherapy were excluded. RESULTS: Seventy two BMGs and 53 CMGs were reviewed. While BMGs and CMGs were both histologically composed of mucosal (epithelium + lamina propria) and submucosal layers, the mucosal layer in CMG had crypts. The outer epithelial layers differed significantly in mean thickness (BMG 573μm vs. CMG 430μm, p=0.0001). Mean lamina propria thickness and submucosal layer thickness also differed significantly (BMG 135μm vs. CMG 400μm, p<0.0001; BMG 1090μm vs. CMG 808μm, p = 0.007, respectively). Mean delta stretch, as to length and width, was greater for CMG (118% x 72%) compared to BMGs (22% x 8%), both p<0.001. CONCLUSION: CMGs and BMGs significantly differ histologically in layer composition, width and architecture, as well as graft stretch. Given its elastic properties, CMG may be useful in covering large surface areas, but its thin epithelium, thick lamina propria and additional muscularis mucosal layer could impact graft take and contracture.