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To What Extent Buccal Mucosal Graft Can Shrink Immediately after Harvesting during Substitutional Urethroplasty for Stricture Urethra?

Introduction: Long segment stricture urethra is a difficult urological disease to treat. Substitutional urethroplasty utilising the Buccal Mucosal Graft (BMG) has shown promising results. Still up to one fourth of the patients can develop recurrence in the long term. Shrinkage of BMG immediately after harvesting, is a less studied phenomenon. It may compromise the tension free placement of BMG over the urethral defect, especially in long strictures. This may ultimately affect the final outcome. Aim: To study postharvest shrinkage of the BMG in patients undergoing substitutional urethroplasty. Materials and Methods: A prospective observational study was conducted during the study period from 2018 to 2020. All 18 patients of substitutional urethroplasty with BMG were enrolled. The baseline clinical profile was noted. Preharvest size of BMG was calculated and marked over the Buccal Mucosa (BM). Postharvest size was measured immediately after graft removal from the oral cavity. Changes in the donor area were also assessed. Alteration in BMG size and donor site area was analysed using paired t-test. Alterations in tobacco and non-tobacco users were compared using an unpaired t-test. Descriptive data were presented in the form of mean, range, percentage and standard deviation. Statistical analysis was completed using SPSS software, version 21.0 (IBM Corp, NY, USA). Statistical significance was kept below 0.05. Results: There were 18 cases which were finally available for analysis. Mean age was 32.9±14.2 years. Balanitis Xerotica Obliterans (BXO) was the most common aetiology. Pan-anterior stricture was found in 9/18 of cases. Mean pre and postharvest BMG size was 7.7×1.8 and 6.9×1.6 cm, respectively. An 8.8% decrease in length (p<0.001**) and 10.8% decrease in width of BMG (p<0.001**) occurred after harvesting, which were statistically significant. A significant Increase in the donor site area was also seen (18.5%, p<0.001**). Conclusion: A shrinkage of around 9% in the length and 11% of the width was seen in BMG after harvesting. The study suggests taking an extra 10% of measured size of BMG, in order to compensate for the expected shrinkage. The donor site area also increases and can be left open to heal by itself.