The Curbsiders podcast

#275 Bariatric Surgery for the Internist with Dr. Vivian Sanchez

May 24, 2021 | By

Patient selection, perioperative management, and post-operative care

What if we told you there was a powerful tool that could help promote significant weight loss, correct uncontrolled diabetes, improve quality of life, and even improve patient mortality?  What if we told you it was offered less than 1% of the time to patients who qualify for it?  Listen as our esteemed guest Dr. Vivan Sanchez (Boston University) talks us through the patient selection, preoperative workup, and postoperative considerations for bariatric surgery, and how it might benefit your patients.


  • Written and Produced by: Paul Williams MD, FACP
  • Infographic: Edison Jyang
  • Cover Art: Edison Jyang
  • Hosts: Stuart Brigham MD; Matthew Watto MD, FACP; Paul Williams MD, FACP   
  • Editor: Molly Heublein, MD; Clair Morgan of
  • Guest: Vivian Sanchez, MD

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Show Segments

  • Intro, disclaimer, guest bio
  • Guest one-liner
  • Picks of the Week*
  • Case from Kashlak
  • Criteria for bariatric surgery
  • Benefits of bariatric surgery
  • Presurgical workup
  • Postoperative management
  • Complications
  • Outro

Bariatric Surgery Pearls

  1. Selection of bariatric surgery patients is largely based on a BMI > 40 or > 35 with major comorbidities
  2. Bariatric surgery has become increasingly recognized as an important tool in managing uncontrolled diabetes
  3. Under 1% of patients with morbid obesity undergo bariatric surgery, despite a perioperative mortality less than 1%
  4. While long-term success of medical weight loss is poor, metabolic surgery can lead to excess weight loss of 60-70%
  5. The American Society for Metabolic & Bariatric Surgery has clear guidelines for preoperative evaluation, including specific lab tests and specialist evaluation
  6. In the immediate postoperative period, extended release medications should be converted to immediate release, and dose adjustments may be needed for diabetes, thyroid, and blood pressure medications
  7. Oral NSAIDs should be avoided following bariatric surgery
  8. Postoperative complications of bariatric surgery include micronutrient deficiencies, symptomatic cholelithiasis, dumping syndrome, Barrett’s esophagus, and regain of weight

Bariatric Surgery Notes 

Candidates for Metabolic Surgery

  • Based primarily on BMI criteria
    • Originated in 1991 by NIH consensus panel
      • BMI > 40 or:
      • BMI > 35 with major comorbidities:
        • Diabetes, OSA, HTN, GERD, MAFLD, among others
    • In 2016, 2nd Diabetes Surgery Summit (DSS – II) recommended that patients with BMI 30-35 should be considered if diabetes is poorly controlled despite medication.
    • In Asian populations, could consider metabolic surgery at 2.5 points below these cutoffs
      • Same comorbidities appear to occur at a lower BMI point
  • Under 1% of patients who are morbidly obese undergo bariatric surgery
    • Patients may perceive elevated mortality risk
      • In centers of excellence, perioperative mortality under 1% (ASMBS 2018)
    • Patients may also be concerned that postoperative lifestyle changes are untenable
      • In under 3 months, most patients can eat majority of foods they ate pre-operatively

Benefits of Metabolic Surgery

  • Long-term success of medical weight loss is generally poor
    • Metabolic surgery has much better long-term efficacy for weight loss
      • Varies by procedure, but excess weight loss can range from 60-70%
  • Patients can expect improvements in quality of life and mortality
  • Can also see metabolic changes shortly after surgeries are performed
    • Exact mechanisms not well-understood
    • Patients with diabetes can sometimes be discharged off of diabetes medications

Preoperative evaluation for metabolic surgery

  • The American Society for Metabolic & Bariatric Surgery has clear guidelines for preoperative evaluation
    • Patient to see experienced surgeon, meet with a nutritionist and a behavioral psychologist, and will have their risk factors mitigated
  • Laparoscopic sleeve gastrectomy and roux-en-y bypass surgeries are the most commonly offered
    • Roux-en-y 
      • Usually done laparoscopically
      • Stomach divided into remnant and a smaller gastric pouch.  The small intestine is divided, with one limb connected to the gastric pouch and connected distally to a jejuno-jejunal anastomosis
    • Laparoscopic sleeve gastrectomy 
      • Stomach is divided using staples
      • Has metabolic effects beyond simple restriction
      • Severe reflux may be a contraindication for sleeve gastrectomy
  • Initial lab work usually includes CBC, BMP, iron studies, lipid panel, TSH, and Hgb A1c
  • Patients typically evaluated for OSA, and may be referred for Cardiology for risk stratification, Gastroenterology for endoscopic evaluation, or Endocrinology for optimization of diabetes
  • Nutrition can be viewed as the base of preoperative optimization
  • Behavioral health evaluation done to evaluate for substance use, disordered eating, or significant mood disorder that may impact care
    • High incidence of depression in patients with obesity
    • There is a somewhat controversial concept of “transference of addiction”
      • If food is used as a compensatory mechanism, this may be transferred to substance use or other outlets postoperatively
  • Preoperative weight loss often mandated by insurance companies
    • Idea is to improve intraoperative and postoperative outcomes
      • This is not supported by evidence and may serve as a barrier

Postoperative management after metabolic surgery

  • In the short term, typically advanced from clear liquids to full liquids to soft foods
    • Often program-specific and dependent upon procedure
  • Alcohol intake should be restricted, as should carbonated beverages
  • Extended release medications should be switched to immediate release
    • Often done preoperatively
  • Antihypertensives, diabetes medications, and thyroid medications may need adjusted postoperatively
  • NSAIDs must be avoided postoperatively due to the increased risk of marginal ulceration
  • Pregnancy should be avoided for the first year or two after the procedure
    • Contraceptive counseling should be provided
    • Underlying endocrinopathies may be corrected by surgery and lead to increased fertility
    • The weight loss and potential vitamin deficiencies may lead to pregnancy complications
  • Multivitamin with iron, calcium, and B12 supplementation recommended postoperatively
    • Often part of an order set, but patients can take child’s multivitamin
    • With gastric bypass, may use vitamin C to aid absorption of iron, which is impaired due to changes in gastric pH and surgical changes of the duodenum
      • Bypass surgeries can also lead to other micronutrient deficiencies
        • With the sleeve gastrectomy, anemia is most common nutritional complication
    • Nutritional labs may eventually fall to the primary care physician
      • Include B12, folic acid (RBC folic acid optional), iron studies, 25-vitamin D, iPTH, and Vitamin A (Mechanik 2020)
      • Thiamine, copper, zinc, and selenium evaluation are recommended if there are findings consistent with deficiency

Potential complications of metabolic surgery

  • Postoperative patients are at increased risk for symptomatic cholelithiasis
  • Gastric bypass in the postoperative period with acute onset abdominal pain should be referred for urgent evaluation
    • Can herald hernia, dilated remnant, or ulcer
  • Gastric sleeve patients can develop worsening reflux or de novo Barrett’s esophagus (Qumseya 2021)
    • Dr. Sanchez recommends upper endoscopy 3 years after the sleeve procedure even in the absence of reflux symptoms
  • Dumping syndrome can also occur postoperatively with gastric bypass 
    • Generally occurs after high carbohydrate intake
    • Early dumping (30-60 minutes after eating) is associated with cramping, nausea, flushing, and palpitations
      • Attributed to fluid shifts and gut hormonal changes
    • Late dumping (1-3 hours after eating) is associated with fatigue, flushing, dizziness and palpitations
      • Thought to be due to blood sugar changes
    • Managed by eating more complex carbohydrates, increasing fiber and hydration, and eating small meals
  • Patients with weight regain postoperatively should be re-connected to Nutrition and Behavioral Health


Listeners will recognize appropriate indications for metabolic surgery, as well as preoperative and postoperative management of commonly offered bariatric surgeries.

Learning objectives

After listening to this episode listeners will…  

  1. Outline the potential indications for bariatric surgery
  2. Explain the potential patient benefits of bariatric surgery
  3. Discuss the recommended preoperative evaluation for patients considering metabolic surgery
  4. Recognize the most common types of bariatric surgery offered to patients
  5. Describe the key elements of postoperative medication and diet management of bariatric surgery management
  6. Identify potential postoperative complications of bariatric surgery


Dr. Sanchez reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 


Sanchez V, Williams PN, Watto MF, Brigham S. “#275 Bariatric Surgery with Vivian Sanchez”. The Curbsiders Internal Medicine Podcast. May 24, 2021.


  1. May 25, 2021, 2:11pm Hector Arreaza writes:

    What a great coincidence. I am teaching a lecture on Bariatric Surgery for Family Medicine to my residents tomorrow. Your episode on bariatric surgery was really helpful. Thanks!

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The Curbsiders are partnering with VCU Health Continuing Education to offer FREE continuing education credits for physicians and other healthcare professionals. Visit and search for this episode to claim credit.

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