The Evaluation of Gastric Emptying Using Nuclear Scintigraphy Compared to Three-Dimensional Multi-detector Computed Tomography (3D-MDCT) Gastric Volumetry in the Assessment of Poor Weight Loss Following Sleeve Gastrectomy

BACKGROUND

Poor weight loss and weight regain are principal challenges following laparoscopic sleeve gastrectomy (LSG). There is a lack of standardised assessments and diagnostic tests to stratify the status post-LSG and determine whether anatomical or physiological problem exists. We aimed to compare nuclear scintigraphy gastric emptying with CT volumetric analysis of sleeve anatomy and determine the impact of anatomy on physiological function and its correlation with weight loss.

MATERIALS AND METHODS

Patients greater than 12 months post-LSG were categorised into optimal weight loss (OWL) (n = 29) and poor weight loss groups (PWL) (n = 50). All patients underwent a protocolised nuclear scintigraphy and three-dimensional multi-detector computed tomography (3D-MDCT) gastric volumetry imaging.

RESULTS

Post-operative % total weight loss in OWL was 26.2 ± 10.5% vs. 14.2 ± 10.7% in the PWL group (p value < 0.0001). The PWL group had significantly more delayed gastric emptying half-time than OWL (34.1 ± 18.8 vs. 19.5 ± 4.7, p value < 0.0001). Gastric emptying half-time showed statistically significant correlations with weight loss parameters (BMI; r = 0.215, p value 0.048, %EWL; r =  - 0.336, p value 0.002 and %TWL; r =  - 0.379, p value < 0.001). The median gastric volume on 3D-MDCT did not differ between the OWL (246 (IQR 50) ml) and PWL group (262 (IQR 129.5) ml), p value 0.515. Nuclear scintigraphy gastric emptying half-time was the most highly discriminant measure. A threshold of 21.2 min distinguished OWL from PWL patients with 86.4% sensitivity and 68.4% specificity.

CONCLUSION

Nuclear scintigraphy is a potentially highly accurate tool in the functional assessment of sleeve gastrectomy physiology. It appears to perform better as a diagnostic test than volumetric assessment. Gastric volume did not correlate with weight loss outcomes. We have established diagnostic criteria of greater than 21 min to assess sleeve failure, which is linked to suboptimal weight loss outcomes.

The Role of the Gut Microbiota in Sustained Weight Loss Following Roux-en-Y Gastric Bypass Surgery

BACKGROUND

The aim of the study was to investigate the role of the gut microbiota in weight regain or suboptimal weight loss following Roux-en-Y gastric bypass (RYGB).

MATERIALS AND METHODS

The gut microbiota composition in post-RYGB patients who experienced successful weight loss (SWL, n = 6), post-RYGB patients who experienced poor weight loss (PWL, n = 6), and non-surgical controls (NSC, n = 6) who were age- and BMI-matched to the SWL group (NSC, n = 6) were characterized through 16S rRNA gene sequencing. To further investigate the impact of the gut microbiota on weight profile, human fecal samples were transplanted into antibiotic-treated mice.

RESULTS

Orders of Micrococcales and Lactobacillales were enriched in SWL and PWL groups compared to the NSC group. No significant difference was observed in the gut microbiota composition between PWL and SWL patients. However, transfer of the gut microbiota from human patients into antibiotic-treated mice resulted in significantly greater weight gain in PWL recipient mice compared to SWL recipient mice. A few genera that were effectively transferred from humans to mice were associated with weight gain in mice. Among them, Barnesiella was significantly higher in PWL recipient mice compared to SWL and NSC recipient mice.

CONCLUSION

These results indicate that the gut microbiota are at least functionally, if not compositionally, different between PWL and SWL patients. Some taxa may contribute to weight gain after surgery. Future studies will need to determine the molecular mechanisms behind the effects of the gut bacteria on weight regain after RYGB.