Seromuscular gastrocystoplasty in rats

Bladder augmentation with an omental pedicled gastric seromuscular flap without the necessity of gastric resection

Bladder augmentation using gastrointestinal segments requires gastric or intestinal resection. This has several risks. In a rat model, we aimed to test the efficacy of a new procedure in which a gastric seromuscular (GSM) flap is separated from the gastric mucosa without the necessity of gastric resection, and this GSM flap, based on an omentum pedicle, is transferred to the bladder. A GSM flap based on an omental leaf was dissected from the gastric mucosa and rotated 180 degrees counter-clockwise, after ligation of the vessels relating to the omentum, until the mid-duodenum. After urodynamic analysis for control levels of bladder capacity and pressure, the GSM flap was anastomosed to the bladder with a continuous suture. Because four rats died due to bladder calculi, only 21 of 25 rats were killed at 1 month (n = 10) and 4 months (n = 11) for histopathological and urodynamic evaluations of the augmented bladder. Bladder capacity increased significantly in the augmented bladders compared to preaugmentation (P < 0.001). There was no significant difference between end-filling pressures of the augmented bladders and preaugmentation. Histopathological findings demonstrated that the muscular surface of the flap was completely re-epithelialized in all rats. Squamous metaplasia was detected in 30% (3/10) of the 1 month group rats, and in 55% (6/11) of 4 month rats (P > 0.05). Gross calculi formation appeared in 20% (2/10) of the 1 month group rats, and in 34% (4/11) of 4 month rats (P > 0.05). Our data show that the use of the GSM flap in the bladder of a rat resulted in the complete re-epithelialization of the flap and sufficient bladder capacity. Despite significant complications such as death, metaplasia and calculi, this technique may be considered as an alternative experimental model to traditional full-thickness patching, which needs gastric or intestinal resection.

The use of silver nitrate for chemical de-epithelialization and urothelialization of intestine in a rabbit model of augmentation cystoplasty

Urinary tract reconstruction using bowel segments can result in complications such as electrolyte abnormalities, infections, stones and cancer. Intestinal mucosa is the primary site responsible for these complications. De-epithelialization of the mucosa and subsequent urothelialization might alleviate these problems. We recently reported our success in de-epithelialization and subsequent uroepithelialization of intestinal segments using 10 g/100 ml AgNO(3) solution in a rat model of augmentation. In this study, chemical de-epithelialization of a colonic segment was attempted using 10 g/100 ml AgNO(3) solution in a rabbit model of augmentation. Sigmoid cystoplasty was performed in 20 male New Zealand rabbits using a 6 cm patch of sigmoid colon. There were two groups, including one group of five rabbits (control, group 1) that underwent augmentation alone, while another group (15 rabbits, treatment group or group 2) was treated with 10 g/100 ml AgNO(3 )solution before augmentation. Control rabbits were killed at the week 8 of experimentation. Treatment rabbits were killed at 2-, 4-, 6- and 8-week intervals. Immediately before augmentation and at the end of the 8 week experimental period each rabbit underwent cystometry. De-epithelialization of the bowel epithelium without urothelialization was apparent in the treatment rabbits killed at 2 and 4 weeks. Histological analysis revealed almost complete urothelialization of the augmented sections treated with 10 g/100 ml AgNO(3 )solution at the end of the 6 and 8 week of experimental periods. The preoperative and postoperative bladder capacities increased substantially in all groups. There was no obvious histologic difference in the amount of collagen present in the augmented tissues in any of the experimental groups. The present study confirmed that the treatment of intestinal segments with 10 g/100 ml AgNO(3 )solution led to chemical de-epithelialization and urothelialization of the augmented segments. This procedure could, theoretically, have applications to human surgery.

Urothelial ingrowth over demucosalized gastrocystoplasty: an experimental study

OBJECTIVE

To evaluate histopathologically the ingrowth of urothelium over a demucosalized gastric flap used for augmentation, as such flaps increase the capacity of the bladder if the urothelium can cover the seromuscular patch.

MATERIALS AND METHODS

The study included eight male dogs; the urinary bladder was widely divided at its dome anteroposteriorly to receive a seromuscular gastric flap, sutured to the edges of the urinary bladder. Before and 1 month after surgery the changes in bladder capacity and pressure were recorded, and urothelial ingrowth assessed histopathologically.

RESULTS

Two of the eight dogs died; the increase in mean bladder capacity in the remaining dogs was 20% and the decrease in mean intravesical pressure 34%. Gross pathological examination of the urinary bladder showed good 'take' of the gastric flap by the urinary bladder. Histopathologically, there was good healing of the flap, active ingrowth of urothelium, and no mucosal re-growth.

CONCLUSION

Bladder augmentation with a demucosalized gastrocystoplasty allows the creation of a large compliant urinary bladder with few complications caused by the incorporation of the enteric or gastric epithelium into the urinary bladder. The stomach has a rich blood supply, allowing the harvesting of a well-vascularized flap, and urothelial ingrowth over this flap in the present study was significant.

Functional outcome and specific complications of gastrocystoplasty for failed bladder exstrophy closure

PURPOSE

The encouraging initial results of gastrocystoplasty led us to perform it for failed bladder exstrophy closure. We assess the functional outcome of the augmented bladder and evaluate complications related directly to use of the stomach in this specific group of children.

MATERIALS AND METHODS

We performed gastrocystoplasty in 22 children an average of 9.5 years old with a small, poorly compliant bladder after staged reconstruction of bladder exstrophy failed. Followup ranged from 6 months to 6 years (mean 3 years).

RESULTS

Complete urinary continence was achieved in 14 children (64%). Voiding via the urethra was possible in 13 patients (60%) but post-voiding residual urine was significant in 12. Bladder capacity increased from a mean of 77 to 270 ml. Bladder capacity decreased during followup in 3 children, requiring repeat augmentation. Six children had isolated dysuria and 2 had dysuria with hematuria. Perforation of the gastric patch and a bleeding gastric ulcer occurred in 1 patient each.

CONCLUSIONS

The disadvantages of gastrocystoplasty outnumber its advantages after failed bladder exstrophy closure. Urethral sensation makes dysuria a major discomfort. Safety is not optimal, since perforation may occur. Voiding is not efficient because gastrocystoplasty provides continence only when it is associated with intermittent catheterization. Bladder capacity is insufficiently augmented and inconsistent during followup. We believe that the use of gastrocystoplasty in cases of failed bladder exstrophy closure should be reconsidered.