Influence of the Resected Gastric Volume on the Weight Loss After Laparoscopic Sleeve Gastrectomy

The relation between the resected gastric volume and the weight loss after laparoscopic sleeve gastrectomy appears conflicting in the literature. Both the residual and the resected volumes represent the total gastric volume, and if the weight loss is related to one of the two volumes, it should be related to the other. While some reports indicate that the weight loss is related to the resected gastric volume, others state that the weight loss is not related to the residual volume. The aim is to investigate the influence of the resected gastric volume on the weight loss after surgery.

The study included 287 consecutive patients. Gastrectomy was performed encroaching over a 38-Fr calibrating tube all the way to the angle of His. Filling volume of the resected stomach, with tap water, was measured. Patients were analyzed into group 1 with BMI ≤50 kg/m(2) and group 2 >50 kg/m(2).

Females represented 74 % of cases. Mean age was 32.9 ± 9.5 years; preoperative BMI = 48.7 ± 7.9 kg/m(2). The mean resected gastric volume was 1525 ± 408 ml, and it was significantly lower in females compared to that in males (1443 ± 311 vs 1824 ± 502 ml, p < 0.001). Data were analyzed in two groups: group 1 with BMI ≤5050 kg/m(2) and group 2 >50 kg/m(2). Both groups were similar in preoperative BMI (p = 0.399) and excess weight percent (EW%) (p = 0.33). Group 2 had a resected gastric volume (1663 ± 424.7 ml) greater than that of group 1 (1440 ± 347 ml; p < 0.001). The percentage of excess weight loss (EWL%) was 57.9 ± 14.5 % at 6 months (62.7 ± 13.5 % vs 48.34 ± 11.29 %, p < 0.001), 77 ± 19 % at 12 months (84 ± 19.6 % vs 68 ± 14.2 %, p = 0.001), 76.6 ± 7.4 % at 18 months (79.7 ± 4.8 vs 74.7 ± 8.2 %, p = 0.5), and 75.8 ± 11.5 % at 24 months (81.7 ± 11.17 vs 70 ± 11 %, p = 0.8) (group 1 vs group 2, respectively). At 12 months, 86 % patients achieved more than 50 % EWL% (100 % of group 1 vs 60 % of group 2). Preoperative BMI correlated with resected gastric volume (r = 0.239, p = 0.004). In multiple regression, the initial BMI was a predictor of EWL% at 6 and 12 months (r partial = -0.65, p < 0.0001) while the resected gastric volume was not.

The resected gastric volume is related to the total gastric volume when the technique is standardized and the residual volume is calibrated using a consistent technique. It is not in itself a predictor of weight loss, but it is related to the initial BMI which predicts the weight loss.