Use of buccal mucosa grafts for urethral reconstruction in children: a retrospective cohort study

Urethral pathology in children is generally comprised of complex hypospadias cases and other causes of urethral stricture disease, which include traumatic, iatrogenic, and idiopathic etiologies. In many situations, these abnormalities can be reconstructed primarily. For hypospadias, most cases can be corrected via chordee release and local tissue rearrangement such as in the tubularized incised plate repair [1]. Short strictures less than 1–2 cm in length due to other causes are often amenable to direct visualization internal urethrotomy or primary anastomotic urethroplasty [2].

Hypospadias is most often repaired in the first 6–12 months of life with short-term success rates approaching 90% [3, 4]. However, long-term complication rates may be much higher, particularly for patients with severe hypospadias where complication rates approaching 30% have been reported [5]. Complications include urethrocutaneous fistula, diverticulum, residual chordee, breakdown of the repair, and urethral stricture, all requiring further surgical intervention. Subsequent attempts at repair are less likely to succeed than primary intervention due to tissue loss and scarred, hypovascular, immobile skin. Additionally, patients with strictures longer than 1–2 cm and/or multiple strictures may require augmentation or replacement of the diseased urethral tissue to achieve a successful surgical result.

Over the last 2 decades, the use of replacement grafts has become an increasingly popular choice for cases with complex urethral pathology. In particular, buccal mucosa grafting (BMG) is an attractive option because the buccal surface is non-hair bearing, it normally exists in a moist environment, and the tissue is abundant and readily accessible. There is a robust body of literature regarding the use of oral mucosa in the adult urethral stricture population [6‐8]. Both single and multi-staged approaches have been described with favorable outcomes thus far. However, less data exists for the use of BMG in the repair of complex urethral stricture disease pediatric patients. The aim of our study was to investigate and describe the Boston Children’s Hospital experience with BMG for urethral reconstruction.

In this report, we detail our institutional experience with the use of BMG for urethral reconstruction, which spans nearly 3 decades. The majority of our patients had an initial diagnosis of hypospadias and required multiple reconstructions prior to presentation at our institution. Nearly 2/3 of patients underwent a 2-stage repair, and we favored this approach over time. Tube grafts were abandoned relatively early in our experience due to an unacceptably high re-stricture rate, which we hypothesize is due to circumferential graft contracture. Long-term complications were seen in 47% of patients undergoing 2-stage repairs and 32% required at least 1 revision of their BMG. However, 68% were free of significant problems at the time of last follow-up.

Buccal mucosa first gained popularity as an option for complex urethral reconstructions in the early 1990s [9, 10]. BMG is an attractive option due to the fact that it is a mucosal, non-hair bearing surface with fast uptake and vascularization after free grafting for urethral substitution [10, 11]. BM tissue is abundant and accessible and the donor site morbidity is acceptably low [12, 13], although contractures have been reported with lip donor sites [14], as well as with large cheek grafts [15].

Multiple previous authors have reported their institutional experiences with buccal mucosa grafting for complex hypospadias. These reports have noted complication rates ranging from 14-57% [16‐20], with most complications occurring early (within 6–12 months) after buccal repair [19, 20]. Although our early experience with buccal grafts had a complication rate higher than the range previously noted in the literature, our more recent experience is congruent with that of other centers.

In addition to the learning curve inherent with a new technique, our suboptimal early results are reflective of the lack of success of tube grafting compared with other approaches. A consensus is forming in the literature that buccal tube grafts represent a less successful strategy than onlay BMG. Consistent with our experience, Hensle and colleagues’ report of a 50% complication rate with tube grafts [19], comparable to our rate of 100%. Surprisingly, Metro and colleagues noted opposite results in their series of 29 patients, where 42% of patients with onlay grafts developing postoperative strictures compared with only 6.3% of tube grafts [17].

Given our disappointing experience with tube grafts, we have adopted a philosophy of using onlay grafts for “simple” strictures, and have come to favor a 2-stage repair for the majority of patients requiring a revision urethroplasty. Newer approaches to onlay grafting, such as the widely anchored patch recently suggested by Djordjevic and colleagues may improve the results of a 1-stage approach for these complicated patients [21]. Thus far, we have found buccal mucosal grafting to be unnecessary for primary hypospadias repairs, although other authors have reported success with this technique for cases of hypospadias with severe chordee [22].

Alternatives to BMG do exist for patients with complex urethral stricture disease where local tissue is not available or suitable for reconstruction. For example, one alternative is to use a posterior auricular full-thickness skin graft as a material for urethral substitution. Our group has recently explored this concept for patients who require reconstruction of the distal penile urethra where buccal mucosa from the cheek might be thicker than desired. Additionally, the use of posterior auricular grafting has been reported in adults where the oral mucosa was unsuitable due to fibrotic changes [23].

Our study has several limitations that warrant mention. Although our experience spans a significant timeframe, it represents a single-institution, retrospective description that may have limited generalizability outside of the complex group of patients treated at our tertiary care academic pediatric hospital. Additionally, this series represents the experience of 11 different surgeons (average cases 2.6/surgeon), underscoring the fact that complex urethral pathology is relatively rare and difficult to manage even in a tertiary care setting. It is also difficult to make specific conclusions regarding the role of a specific surgeon on outcomes due to the small number of patients per surgeon. Also, our patient cohort was identified using billing data, so we could have unintentionally omitted patients undergoing buccal grafting at our institution. To mitigate this limitation, we were purposely broad in the initial billing codes included, and then manually screened patients to exclude them from the final study population. Due to the retrospective nature of our study, we were also limited in the outcome data that could be collected from the patient record; the same outcome measures were not necessarily reported in all encounters for each patient, and we were unable to systematically assess patient-reported outcomes such as quality of life (QOL) and sexual function, which have only been comprehensively reported by one previous group [14, 24]. Although these studies suggest that QOL and sexual function was favorable among patients at a single center, the incorporation of patient-reported outcome data from additional centers into future reports is paramount. In particular, assessment of post-pubertal outcomes will be of great interest. Finally, our series represents a heterogeneous group of patients, surgeons, and approaches. While this allowed a basic evaluation of several surgical approaches, this heterogeneity of our patients made a detailed determination of specific patient-and surgeon-level factors predicting complications after surgery challenging.

Despite these limitations, our study provides additional insight into the experience using BMG for reconstruction in patients with complex urethral pathology treated at a specialized academic center. Specifically, our series adds to the knowledge regarding complication rates and particular difficulties with tubularized 1-stage repairs. Our data should help to facilitate appropriate expectation setting for patients and families regarding complications and the potential for revision after buccal urethroplasty, and highlights the importance of long-term follow-up.

At our institution, we have found BMG to be a reasonable option for use in complex urethral reconstruction in children where local tissue is not available or suitable. Tubularized grafts had poor results in our series, and we no longer use them. Currently we favor a 2-stage approach for all patients except for those with “simple” urethral strictures due to causes other than hypospadias. Although many patients required revision procedures after BMG, the majority were free of long-term problems at the time of last follow-up.

This study was reviewed and approved by our hospital’s institutional review board. The results are reported in aggregate, and no individual case details were reported. Therefore a waiver of informed consent was granted for this study.