Comparison of Two Types of Liver Retractors in Laparoscopic Roux-en-Y Gastric Bypass for Morbid Obesity

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Retraction of the left lobe of the liver is an important step in most bariatric surgical procedures. Bariatric patients may have enlarged, fatty livers and retraction can be complicated with injuries, haematoma, or necrosis. The aim of this study was to compare the effects of two standard liver retractors, Nathanson and PretzelFlex on patients undergoing laparoscopic Roux-en-Y gastric bypass (LRYGB).


All consecutive patients undergoing LRYGB in our center from April 2017 to January 2019 were analysed. The type of retractor used was dependent on the surgeon’s preference and the availability of instruments. Patients were divided into two groups, based on the type of liver retraction device used. Each group was assessed and compared for postoperative pain score, presence of nausea or vomiting, blood test results (liver function tests and C-reactive protein), and length of hospital stay.


LRYGB was performed on 167 patients in which Nathanson was used in 93 patients and PretzelFlex in 74 patients. The duration of surgery was similar in both groups. Alanine transaminase (ALT) levels and C-reactive protein (CRP) were significantly higher in the group where Nathanson’s retractor was used. The postoperative pain score and length of stay were also higher when Nathanson’s retractor was used but it did not reach statistical significance.


The PretzelFlex liver retractor causes significantly less measurable liver damage and is associated with less postoperative pain and nausea when compared with Nathanson’s retractor.

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The authors would like to thank Dr. J Toombs, Ms. S Katswere, and Mr. MI Booth for their help and advice.

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Correspondence to Sumit Midya.

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This is a retrospective study and hence, ethical approval is not required.

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Midya, S., Ramus, J., Hakim, A. et al. Comparison of Two Types of Liver Retractors in Laparoscopic Roux-en-Y Gastric Bypass for Morbid Obesity. OBES SURG 30, 233–237 (2020).

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  • Liver retraction
  • Nathanson retractor
  • PretzelFlex retractor
  • Bariatric surgery
  • Laparoscopic Roux-en-Y gastric bypass