The physiology of gastrocystoplasty: once a stomach, always a stomach.

To determine the physiology of acid secretion after gastrocystoplasty with the body of the stomach we performed a prospective standardized 3-day study in 13 children (median age 12.5 years) who had undergone bladder augmentation/replacement (median postoperative period 2 years). Urinary pH and titratable acid, and serum gastrin levels were measured after gastric distention with a meal and bladder distention with urethral filling at baseline and after medication with a histamine-2 receptor antagonist or an anticholinergic agent. Five children underwent cystoscopy and biopsy of the gastric and native segments of the gastrocystoplasty. In the fasting state pH was neutral, there was no titratable acid in the urine and serum gastrin level was normal in all cases. After a meal urinary acid secretion and serum gastrin level increased markedly. After each medication half of the patients demonstrated marked inhibition of urinary acid secretion after a meal while response was partial in the remainder. In none of the patients was there significant alteration in the pattern of gastrin secretion. Bladder distention did not result in urinary acid secretion or gastrin secretion. The cystoscopic and histological appearance of the native bladder and stomach segment of the gastrocystoplasty in the 5 patients was normal. We conclude that the gastric body segment used in gastrocystoplasty continues to secrete acid as though it were part of the stomach. The secretion of acid in the urine can be decreased with histamine-2 receptor antagonist or anticholinergic medication.