Experimental rectus abdominis myocutaneous and rectus abdominis myoperitoneal flaps as urinary bladder wall substitutes in miniature swine.

An experiment was performed in Yucatan miniature swine to determine the feasibility and characteristics of musculocutaneous or musculoperitoneal flaps as urinary bladder wall substitutes. In five swine, a single-pedicle skin island flap (rectus abdominis myocutaneous, RAM/C) was sutured into the bladder. In five other swine the flap was a peritoneum island (rectus abdominis myoperitoneal, RAM/P). Three swine were sham-operated controls. The patches were in place for 20 weeks, remaining viable and elastic. Inflammation, maceration, and infection were absent. Skin patch histology was unchanged. The peritoneal patches became resurfaced with uroepithelium. The sham bladder volume (ml/kg body weight) did not differ significantly from RAM/P bladder volume (p = 0.54). RAM/C bladders were slightly smaller than shams (p = 0.11) and significantly smaller than RAM/P bladders (p = 0.03). Substitution of the bladder wall with RAM patch flaps is feasible. This is an important preliminary step toward our goal of nonenteral urinary bladder wall substitution.