UROLOGICAL SURVEY   ( Download pdf )

 

RECONSTRUCTIVE UROLOGY

Porcine Small Intestinal Submucosa Graft for Repair of Anterior Urethral Strictures
Fiala R, Vidlar A, Vrtal R, Belej K, Student V
Department of Urology, University Hospital, Olomouc, Czech Republic
Eur Urol. 2007; 51: 1702-8

  • Objectives: We evaluated porcine small intestinal submucosa (SIS) used in the treatment of inflammatory, iatrogenic, posttraumatic, and idiopathic strictures of bulbar and penile urethra. Midterm maintenance of urethral patency was assessed.
  • Methods: Fifty patients aged 45-73 yr with anterior urethral stricture underwent urethroplasty using a porcine SIS collagen-based matrix for urethral reconstruction. Stricture was localized in the bulbar urethra in 10 patients, the bulbopenile area in 31 cases, and in the distal penile urethra in nine patients. All patients received a four-layered SIS patch graft in an onlay fashion. A voiding history, retrograde and antegrade urethrography, and cystoscopy were performed preoperatively and postoperatively. Failure was defined as stricture confirmed on urethrogram.
  • Results: After a mean follow-up of 31.2 mo (range: 24-36 mo), the clinical, radiological, and cosmetic findings were excellent in 40 (80%) patients. Restricture developed in one of 10 bulbar, five of 31 bulbopenile, and four of nine penile strictures. These all occurred in the first 6 mo postoperatively. All patients with recurrences needed further therapy, but there has been no additional recurrence observed to date. No complications such as fistula, wound infection, UTI, or rejection were observed.
  • Conclusions: Use of inert porcine SIS matrix appears to be beneficial for patients with bulbar and bulbopenile strictures. Midterm results are comparable to skin flaps and mucosal grafts.

  • Editorial Comment
    Several recent reports have used porcine small intestinal submucosa (SIS) produced either commercially or by individual laboratories as a substitute for autologous flaps in urethral stricture surgery. The initial experimental results were promising (1,2), however, clinical results were mixed (3).
    When using porcine acellular matrix, it might be applied either alone functioning as a scaffold for the ingrowths of the neighboring healthy urethra or together with cultivated urothelial cells as urethral wall substitute.
    The authors of this contribution used commercially available porcine SIS in an onlay fashion for bulbar, bulbopenile, and distal penile urethral defects after careful excision of strictured urethral segments. The results were acceptable for bulbar strictures but clearly unsatisfactory for penile and bulbopenile strictures. One should be cautious with the interpretation of the results in bulbar strictures: one of ten patients with bulbar stricture surgery recurred after 24 – 36 months. Considering the small number in this subgroup and the possibility of further recurrences with longer follow-up one has to question the use of xenogenic acellular matrices over autologous free flaps such as buccal mucosa. Recent experimental studies have shown that at least in commercial products there are nuclear remnants identifiable within the matrix of the presumably acellular small intestinal submucosa suggesting possible remnant donor DNA (4). Under in vitro conditions, it was also seen that human urothelial cell growths was grossly impaired. Furthermore, SIS so far did not yield any other obvious benefit for patients nor does it help to reduce any surgical costs. We therefore have to continue our search for suitable biomaterials in urethral reconstructive surgery. Until we succeed to find something current standard techniques such as buccal mucosa are the best and safest choice.

References

1. Kropp BP, Ludlow JK, Spicer D, Rippy MK, Badylak SF, Adams MC, et al.: Rabbit urethral regeneration using small intestinal submucosa onlay grafts. Urology. 1998; 52: 138-142.
2. Sievert KD, Bakircioglu ME, Nunes L, Tu R, Dahiya R, Tanagho EA: Homologous acellular matrix graft for urethral reconstruction in the rabbit: histological and functional evaluation. J Urol. 2000; 163: 1958-1965.
3. Santucci RA, Barber TD: Resorbable extracellular matrix grafts in urologic reconstruction. Int Braz J Urol. 2005; 31: 192-203.
4. Feil G, Christ-Adler M, Maurer S, Corvin S, Rennekampff HO, Krug J, et al.: Investigations of urothelial cells seeded on commercially available small intestine submucosa. Eur Urol. 2006; 50: 1330-7.

Dr. Karl-Dietrich Sievert &
Dr. Arnulf Stenzl
Department of Urology
Eberhard-Karls-University Tuebingen
Tuebingen, Germany
E-mail: Arnulf.Stenzl@med.uni-tuebingen.de