How Accurate can we Estimate the Length of the Limbs in Gastric Bypass Surgery? An Ex Vivo Experiment

Special Article - Bariatric Surgery

Ann Obes Disord. 2016; 1(3): 1016.

How Accurate can we Estimate the Length of the Limbs in Gastric Bypass Surgery? An Ex Vivo Experiment

Kaijser MA¹*, Emous M¹, Dijkstra FA², Apers JA³ and Totte ER¹

¹Department of Bariatric and Metabolic Surgery, Medical Centre Leeuwarden, Netherlands

²Department of Surgery, University of Medical Centre Groningen, Netherlands

³Department of Bariatric and Metabolic Surgery, Sint Fransiscus Gasthuis, Netherlands

*Corresponding author: Mirjam A Kaijser, Department of Bariatric and Metabolic Surgery, Medical Centre Leeuwarden, P.O. Box 888, 8901 BR Leeuwarden, Netherlands

Received: September 23, 2016; Accepted: November 20, 2016; Published: November 14, 2016


Background: The role of limb length in Roux-en-Y gastric bypass is the subject of several studies. The results of multicenter and multiple surgeon studies could be influenced by the technique used to determine limb length. We conducted an ex vivo experiment to compare results between surgeons estimating the limb length without a measuring device.

Objectives: We measured intra- and inter-observer differences in determining limb length in order to ensure comparability.

Setting: European teaching hospital staff conducted the experiment in an ex-vivo lab.

Methods: In a laparoscopic box trainer three participants estimated lengths of 80, 120 or 200 centimeters on a segment of devascularized pork gut with thirty repetitions. The results were analyzed for intra- and inter-observer differences with a power of 91% to detect non-inferiority.

Results: One participant estimated within a 10 per cent margin on all three tasks. The other participants underestimated the length of their segments overall, with a larger difference on the longer tasks. This resulted in significant inter-observer differences.

Conclusion: The participants were able to estimate limb lengths within a ten per cent margin on the 80-cm task, but we found intra-observer variance and significant inter-observer differences especially in the long limb tasks. The presented box model can be used to specify this variation.

Keywords: Gastric bypass; Technique; Limb lengths; Box model


Obesity is one of the largest global health problems, with over 600.000 million obese adults worldwide [1]. In the Netherlands ten percent of all adults are obese. Obesity and obesity related illness account for 2.2% of all healthcare costs in the Netherlands, which in 2012 corresponded to 1.6 billion Euros [2]. For morbidly obese patients with a Body-Mass-Index (BMI) > 40kg/m2, or above 35kg/ m2 with associated comorbidities, bariatric surgery is the most efficacious treatment. The Roux-en-Y gastric bypass is an established safe and effective procedure in the treatment of morbid obesity [3]. The length of the alimentary limb, biliopancreatic limb and common channel, and their influence on weight reduction and weight regain are widely discussed. In variants of the classic Roux-en-Y gastric bypass longer limb length may lead to extra weight loss, but has malnutrition as a potential threat. In these procedures accurate limb length measurement is especially important.

In laparoscopic Roux-en-Y gastric bypass surgery multiple techniques to determine the length of a limb are used. Different operating techniques may explain some of the discrepancies in the results of studies on limb length [4]. Some bariatric surgeons try to measure the length exactly, using a rope or tape measure [5]. Others estimate the length on sound judgment or compare their steps with an object with fixed length, like a grasper or other laparoscopic instrument. This study aims to determine whether this estimation technique results in reproducible lengths of the gastric bypass limbs.


Study design

Since 2012, a tailored Roux-en-Y gastric bypass is performed in our bariatric center. The surgeons construct the biliopancreatic limb with a variable length of 80, 120 or 200 centimeters, based on the patient’s Body-Mass-Index (BMI) (< 40, 40-50, and > 50 kg/m2 respectively). Using graspers as reference points, the length of the bypassed bowel is estimated. The alimentary limb has a standard length of 150 centimeters. Anatomic variations like mesenteric fat deposition may influence the exact place of the anastomosis.

This study aims to determine if different bariatric surgeons in a single center can estimate the length laparoscopically with interchangeable results and without variation in their own series. As no comparable studies are found in literature, a variation of 10% (e.g. a biliopancreatic limb of 108 to 132 centimeter for morbidly obese patients with a BMI between 40-50 kg/m2) is assumed to cause no significant differences in weight loss, awaiting more research on the ideal limb lengths. With this 10% margin a sample size of 26 measurements for each surgeon would achieve a power of 91% to detect non-inferiority (both under and over-estimation) in the inter- observer variation [6]. Moreover, the intra-observer differences can be determined.

In an ex vivo experiment, the estimation of the biliopancreatic limb was simulated in a laparoscopic box trainer. A four-meter segment of cleansed and devascularized pork gut was attached at one end to a Styrofoam board, simulating the fixated ligament of Treitz. Three participants were selected, two bariatric surgeons (5 and 2.5 years of experience in bariatric surgery each, operating on 250 and 200 gastric bypass cases each year) and a chief resident from the same center (portfolio includes over 250 solo or supervised laparoscopic cases including 50 gastric bypass surgeries). Each participant completed three rounds of 10 measurements, estimating lengths of 80, 120 and 200 centimeters in random order. These lengths correspond to the standard limb lengths for the tailored bypass. A 30 degree Karl Storz® camera fixed in position and two Karl Storz® fenestrated fixation forceps were used. The obtained length was measured twice outside the box by a single observer using a tape measure. The participants did not receive any feedback on their results until after the experiment, eliminating any influence of learning.

Statistical analysis

The values were analyzed with SAS/STAT® software. The individual scores of the participants are expressed as mean and standard deviation. The separate variances (i.e. proportional differences between obtained and intended length) were analyzed by means of a mixed model, using a 95% confidence interval, testing for non-inferiority in all three samples and comparing the inter-observer differences.


Individual results

In the 80-centimeter task all participants scored a mean of their repetitive measurements within the expected 10% deviation. The standard deviations were 7.88 cm, 4.90 cm and 5.48cm.Participant a estimated between the upper and lower limit 8 out of 10 times, participant B 7 out of 10 times and the third participant 4 out of 10 times (Table 1).

Citation: Tai CM, Tsai MS and Yu ML. Endoscopic Diagnosis of Gastric Fold Herniation. Ann Obes Disord. 2016; 1(3): 1015.