Ehab Elzayat ¹, Gilles Karsenty ¹, Tarek Bismar ² and Jacques Corcos ¹

Urology ¹ and Pathology² departments, Gewish General Hospital, McGillUniversity, Montreal (Quebec), Canada

Introduction: Urinary incontinence is a prevalent clinical problem affecting a high proportion of women and men at any age. Periurethral injection of bulking agents is commonly used in the treatment of urinary incontinence. Durability of the treatment of urinary incontinence depends on stability of the injected bulk.

Objectives: To investigate the volume changes and local tissue reaction of dextranomer/hyaluronic acid implants with Collagen implants.

Methods: A total of 57 rats were included in this study. The rats were divided into 3 groups, control group (9 rats) Collagen injected group (24 rats) and Dx/HA copolymer injected group (24 rats). Under anaesthesia 0.35 ml a bulking agents were injected subcutaneously in the abdominal area (collagen and Dx/HA copolymer group). Nine rats were injected with normal saline to act as controls. At 1,6, and12 months, 8 animals of the 2 implant groups and 3 animals of the control group were sacrificed using an overdose of anaesthesia. The area of the injected material was carefully dissected in order to recuperate the bulking material without any surrounding tissue. The volume changes of the bulking agents was measured by putting the implant in a graded tube containing saline and measuring the increase in volume. Surrounding tissues was also resected for histopathological examination.

Results: No postoperative complications were observed and no one of the animals died during the study period. The injected bulking agents were easily palpated at the injected site with no distant migration. No tumours were detected at implant site or at the surrounding tissues. The bulking material was well capsulated and dissected easily.

Mean volume changes in the Dx/HA copolymer group were 0.56±0.12, 0.43±0.08, and 0.28±0.26 ml at 1,6, and 12 months respectively. Mean volume changes in the collagen group were 0.25±0.03, 0.21±0.08 and 0.21±0.01at 1,6, and 12 months respectively. There is a significant change in volume at each time points in each group. Also there is a significant difference between volume changes in collagen and Dx/HA copolymer groups.

The histological examination showed fibroblast, inflammatory cell and foreign body giant cell reaction inside the implanted material. The degree of tissue reactions and fibrosis are more in the Dx/HA copolymer group at each time points of the study.

The difference between the volume changes in collagen and Dx/HA copolymer groups (-20% vs-40%) was significant at 12 months after injection (P< 0.002).

Conclusions: The volume of injected Dx/HA copolymer incraesed up to 6 months after injection however at 12 months it shows 20% reduction of volume. Boths material showed decraese in volume after 12 months with more volume reduction in collagen group.

UroToday.com Coverage of SUFU 2007

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