Original article| Volume 19, ISSUE 3, P187-193, March 2023

The role of preoperative toxicology screening in patients undergoing bariatric surgery

Published:October 31, 2022DOI:


      • 12.7% of patients who underwent bariatric surgery tested positive on toxicology screening.
      • There was no association between a positive toxicology screening and outcomes of preoperative length, 30-day complications, 30-day readmissions, and 1-year weight loss.
      • This calls into question the utility of routine preoperative toxicology screening.



      Some programs and insurers may require patients to undergo toxicology screening despite lack of evidence that this practice affects postoperative outcomes.


      To understand the prevalence of screening positive on toxicology testing in the bariatric surgical population and to examine the association between testing positive and important surgical outcomes.


      We performed a retrospective review of patients who underwent laparoscopic sleeve gastrectomy or Roux-en-Y gastric bypass from an academic health system from 2017–2020. We described the rate of preoperative toxicology positivity as determined by serum and urine testing. We examined the association between toxicology positivity and outcomes of preoperative length, 30-day complications (bleeding, venous thromboembolism, leak, wound infection, pneumonia, urinary tract infection, and myocardial infarction), readmissions, and 1-year weight loss using chi-square and t-test analysis.


      Of 1057 patients, there were 134 patients (12.7%) who had positive toxicology testing. Of these, 37 (28%) were positive for opiates and 21 (16%) were positive for cotinine. Mean preoperative length was 381.8 days (standard deviation [SD], 222.5) for patients with positive testing versus 287.8 days (SD, 151.5; P = 1.00) for negative testing. Toxicology positivity was not associated with readmissions (5.2% versus 4.3%, X2 = 0.22; P = .64). The loss to follow-up at 1 year was 32.5%. There was no association with 1-year mean change in body mass index (mean of loss 12.23kg/m2 [SD, 5.61]) versus mean of loss 12.74 (SD, 6.44; P = .20)].


      Our study is the first to describe preoperative toxicology positivity rates. We found no association between toxicology positivity and preoperative length, readmissions, or weight loss. Given its lack of impact on outcomes, toxicology testing prior to bariatric surgery may be an unnecessary burden on patients and healthcare, with regard to cost and wait times.

      Graphical abstract


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