Urinary evaluation after RYGBP: a lithogenic profile with early postoperative increase in the incidence of urolithiasis.

BACKGROUND: The objective of this study was to assess predictors for new-onset stone formers after Roux-en-Y gastric bypass (RYGBP). METHODS: One hundred and fifty-one obese patients underwent RYGBP and were followed for 1 year. The analysis comprised two study time points: preoperative (T0) and 1 year after surgery (T1). They were analyzed for urinary stones, blood tests, and 24-h urinary evaluation. Nonparametric tests, logistic regression, and multivariate analysis were conducted using SPSS 17. RESULTS: Median BMI decreased from 44.1 to 27.0 kg/m2 (p < 0.001) in the postoperative period. Urinary oxalate (24 versus 41 mg; p < 0.001) and urinary uric acid (545 versus 645 mg; p < 0.001) increased significantly postoperatively (preoperative versus postoperative, respectively). Urinary volume (1310 versus 930 ml; p < 0.001), pH (6.3 versus 6.2; p = 0.019), citrate (268 versus 170 mg; p < 0.001), calcium (195 versus 105 mg; p < 0.001), and magnesium (130 versus 95 mg; p = 0.004) decreased significantly postoperatively (preoperative versus postoperative, respectively). Stone formers increased from 16 (10.6 %) to 27 (17.8%) patients in the postoperative analysis (p = 0.001). Predictors for new stone formers after RYGBP were postoperative urinary oxalate (p = 0.015) and uric acid (p = 0.044). CONCLUSIONS: RYGBP determined profound changes in urinary composition which predisposed to a lithogenic profile. The prevalence of urinary lithiasis increased almost 70% in the postoperative period. Postoperative urinary oxalate and uric acid were the only predictors for new stone formers.

Esophageal motility after laparoscopic Roux-en-Y gastric bypass: the manometry should be preoperative examination routine?

BACKGROUND: Our goal was to identify the changes of esophageal motility, lower esophageal sphincter (LES) function, and eating adaptation before and after Roux-en-Y gastric bypass (RYGBP) and whether manometry should be a routine examination in patients who undergo this procedure. METHODS: A total of 81 patients underwent manometry before surgery and 1 year after surgery. The control group consisted of 10 nonobese volunteers. Patients were classified as presenting with vomiting and without vomiting 1 year after surgery. Manometric variables were compared before and after surgery. Statistical analysis was performed using Wilcoxon and Mann-Whitney test. RESULTS: The patients (45.6%) had preoperative manometric findings, 29.8% had LES hypertonia, 18.9% LES hypotonia, 43.2% increase in wave amplitude of contraction, and three 8.1% abnormal peristalsis. One year after surgery manometry was abnormal in 62.9% of patients, 11.7% with hypertonia and 15.7% with hypotonia of the LES, 53% with changes in amplitude contraction and 19.6% with abnormal peristalsis. The control group showed no manometric abnormalities. Chronic vomiting was noted in 21% of patients. When comparing all variables between the pre and postoperative periods, there was no significant difference for all of them except for peristalsis. Comparing the results of manometric findings between the vomiting and non-vomiting groups, no significant changes were found in the variables studied. CONCLUSIONS: There was an association between RYGBP and motor abnormalities in the esophagus but no differences in postoperative feeding adaptation. Thus, we conclude that esophageal manometry is not necessary as a routine preoperative examination.