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Post-bariatric gastric outlet

New endoscopic measurement of post-bariatric gastric outlet

They report that diameters greater than 14mm are associated with weight regain

A new guidewire has demonstrated a high degree of observer reliability presenting similar results between expert endoscopists and trainees, according to a Brazilian study. The researchers said that between 10 and 20% of all patients undergoing bariatric surgery procedures regain weight secondary to a gastrojejunostomy enlargement. The aim of the study, ‘Validation of a new method for the endoscopic measurement of post-bariatric gastric outlet using a standard guidewire: an observer agreement study’, published BMC Research Notes, was to validate the inter-observer agreement while measuring gastric outlet diameters using a new standard guidewire.

The authors explain that although there are a multitude of possible factors associated with weight regain, gastric outlet dilation occurs when its diameter exceeds 14–20mm, ultimately leading patients back to obesity. A number of therapeutic options have been developed to reduce the anastomotic diameter, including endoscopic suturing devices and gastrojejunostomy. Abnormal anatomical findings are found in 71.2% of all patients, 58.9% of which have a dilated anastomosis, 28.8% present a dilated pouch, and 12.3% with both conditions.

However, there seems to be no consensus on how to best measure anastomosis diameter. Indeed, devices designed to measure these dimensions frequently differ in both units and mechanisms, including balloons, clamps and spacers.

“While most authors use gaging through a grasper-type forceps connected to the endoscope working channel, no consensus exists on which differences might exist when different measurement tools might be used. In addition, grasper-type forceps are both expensive and hard to find in developing countries,” the authors write. “The objective of this study was therefore to validate a novel, efficient and inexpensive method to measure gastric outlet diameter, evaluating its agreement reliability.”

In the study, the researchers selected thirty-five videos of consecutive endoscopic procedures on patients undergoing esophagogastroduodenoscopy after a Roux-en-Y gastric bypass procedure. All videos were evaluated by four raters: two expert endoscopists and two trainees. The researchers excluded videos having a slipped Fobi ring or a strictured gastric outlet.

The anastomosis diameter was measured using a novel device with standardised markings on a guidewire (Hydra jagwire, Boston Scientific) as well as the current gold standard defined as a calibrated endoscopic measuring instrument (Olympus America).

Figure 1: Diameter measurement of the gastrojejunal anastomosis through the guidewire (A, B) and gold standard method (C, D)

All patient identifiers were stripped from the video in order to ensure patient confidentiality. The anastomosis diameter was initially measured through an articulated device for anastomosis scouting with distal markings at every 0.2mm by 0.2mm (Figure 1).

A second measurement was then conducted with the experimental guidewire, custom manufactured from a Wire Guide Hydra Jagwire with a hydrophilic flexible tip painted in black and additional black stripes every 0.5mm.


The researchers obtained 272 measurements of the gastric outlet. There were no injuries or complications occurred during any of the measurements. Patients’ average age was 38.46±10.61, with 77.14% (n=27) of them being women.

When visually inspecting the correlation among different raters, there was a higher correlation in ratings within experts as well as within novice raters. In addition, the agreement using the guidewire and the gold standard made by the same rater were higher than across other raters.

Overall, agreement measured through intra-class correlation coefficients for the gold standard was 0.84 (p<0.01) and 0.83 (p<0.01) for the new guidewire. Agreement among experts was 0.699 (p<0.01), while among trainees it was 0.822 (p<0.01). When evaluating subgroups, intra-class correlation coefficients for trainees evaluating the gold standard was 0.877 (p<0.01), trainees evaluating the new guidewire was 0.865 (p<0.01), experts evaluating the gold standard was 0.795 (p < 0.01), and experts evaluating the guidewire was 0.843 (p < 0.001).

“Our results are clinically relevant to clinical practice since approximately 20–30% of all bariatric patients regain weight, many of these being addressed through an endoscopic procedure,” the authors write. “The precision in these procedures is essential, in that an anastomosis with a diameter smaller than 5mm would prevent patients from digesting liquids, a diameter smaller than 10mm would prevent patients from digesting solid food, while diameters greater than 14mm are associated with weight regain.”

“These findings are relevant in that the gold standard Olympus calibration device is not only of difficult access in a number of countries, but also expensive,” the authors conclude. “Given that we have demonstrated equivalent measurement reliability between the Olympus device and our new guidewire, both with experienced endoscopists and trainees, we recommend its use in clinical and research practice.”

To access this paper, please click here

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