Alternative ileal flap for bladder augmentation if mesentery is short

Purpose: To date the clam ileocystoplasty is the preferred method of bladder augmentation in children when the urodynamic problem is non-compliance and/or detrusor overactivity. The key to this technique is the incision of the bladder wall deep into the pelvis down to the trigone in order to avoid a diverticulum like neobladder and to provide adequate margin for augmentation. The detubularised ileum flap therefore has to reach to the bottom of the divided bladder on a reliable vascular pedicle without significant tension. A short ileal mesentery caused by previous surgery, peritonitis, peritoneal dialysis or ventriculo-peritoneal shunt may complicate surgery and compromise outcome. We hypothesized we can rely on the communication of the intramural vessels within the intestine and can detubularise the ileum adjacent to the mesentery rather than along the antimesenteric line and this could be combined with ligation of some vasa recta (VR) in order to create alternative ileum flaps, which reach further into the pelvis. Our aim was to assess the viability of the alternative flaps detubularised along the paramesenteric line and measure how many VR could be sacrificed beyond the tertiary arcades.

Materials and methods: After ethical approval adjacent ileal segments were detubulirased along the antimesenteric line (Group 1) and along the paramesenteric line (Group 2) in 5 minipigs in general anaesthesia. Ligation of 0,1,2,3 and 4 VR has been performed starting from the free end of the segments. The length of the ileal flaps was recorded. The microcirculation of flap edges was detected by in vivo microscopy using orthogonal polarising spectral imaging (Cytoscan A/R Cytometrics, PA, USA). Clam ileocystoplasty was performed with the ileum detubularised along the paramesenteric line without ligation of VR. Specimens of the augmented bladder were obtained after 4 weeks and stained with Hematoxilin + Eosin.

Results: No alteration in capillary red blood cell velocity (RBCV) and perfusion rate (PR) was observed after paramesenteric detubularisation. The flaps in Group 2 reached 20.25 ± 0.5 mm longer vs.

Control: This is 98% of the mean bowel width (20.5 ± 0.57 mm) measured in the animals. Ligation of each VR further increased the length of both flaps (mean: 10.59 ± 3.18 mm) however ligation of more than 2 VR gradually decreased the microcirculation in both groups. All animals augmented with alternative flap survived, there was no urine leak or suture break down. Histology confirmed viable bowel flaps.

Conclusion: Paramesenteric detubularisation of the ileum is fully tolerated and results in longer reaching ileal flap vs.

Control: Only limited ligation of VR is tolerated.

Discussion: This study showed the first time that clam ileocystoplasty is feasible with ileal flap detubularised along the paramesenteric line. The use of the animal model and the relative short postoperative observation are the main limitations of this study.