Download Preoperative and Postoperative Management of the Bariatric

Weight loss surgery
Preoperative and Postoperative Management of
the Bariatric Surgical Patient
Sara M. Pietras, MD, Lisa S. Usdan, MD, and Caroline M. Apovian, MD
Abstract
• Objective: To provide guidance for the primary care
practitioner when evaluating a patient for weight loss
surgery (WLS), to review commonly performed bariatric procedures, and to help guide management
during the pre- and postoperative periods.
• Methods: Review of existing literature and summary of current practices.
• Results: Appropriate candidates for WLS include
patients with a BMI of at least 40 kg/m2 or at least
35 kg/m2 with at least 1 significant comorbid condition. Obese patients require extensive screening
and multidisciplinary care prior to consideration for
WLS and during the postoperative period.
• Conclusions: While there is evidence for certain
routine evaluations before and after WLS, there are
areas that remain controversial and require further
study.
O
besity is a major public health problem in the United
States. Over the past few decades, the prevalence of
obesity in adults has increased sharply, from 15.0%
in 1976–1980 to 32.2% in 2003–2004 [1,2]. Approximately
5%, or 9 million Americans, are extremely obese [3,4].
Obesity contributes to and exacerbates numerous medical
conditions, including type 2 diabetes [5,6], hypertension [7],
obstructive sleep apnea (OSA) [8,9], osteoarthritis [10], and
certain cancers [11–13].
Nonsurgical approaches to treatment of obesity include
behavioral and pharmacologic intervention. Medications
currently approved for weight loss in the United States include sibutramine, orlistat, and phentermine. These drugs
promote modest weight loss when given along with recommendations for diet [14], but results are often insufficient
to alter the morbidity and mortality of extremely obese
patients. In contrast, surgical treatment of obesity has been
shown to induce substantial, long-term weight loss while
simultaneously improving comorbid conditions such as
diabetes, hypertriglyceridemia, sleep apnea, and hypertension [15,16]. Weight loss surgery (WLS) has become increasingly popular in the United States, increasing from 12,775
operations performed in 1998 to 140,000 in 2004 [17]. Given
262 JCOM May 2007 Vol. 14, No. 5
the increasing medical burden of obesity, the demand is
expected to increase.
WLS impacts all aspects of a patient’s life, and a multidisciplinary team should be involved in the patient’s care,
including a medical practitioner, nutritionist, mental health
professional, surgeon, and medical subspecialists as needed
[18]. However, as more patients have WLS, there is a growing role for the primary care physician, who should be
familiar with the procedures, recognize complications, and
manage changes in comorbid conditions. In this paper, we
review the preoperative and postoperative management of
patients seeking WLS.
Bariatric Surgery Procedures
WLS procedures may be classified into 3 types: those that
limit food intake (restrictive), those that alter nutrient absorption (malabsorptive), or combined restrictive/malabsorptive.
In general, choice of procedure depends on the experience
and preference of the surgeon and the characteristics and
goals of the patient. Algorithms have been proposed to help
broadly match patients to individual procedures [19]. A brief
review of WLS procedures follows.
Laparoscopic Adjustable Gastric Band
The laparoscopic adjustable gastric band (LAGB) was approved for use in the United States in 2001. In this purely
restrictive procedure, a band with an inflatable balloon is
placed around the upper portion of the stomach, creating
a small pouch to limit food ingestion (Figure 1). Sutures
are used to wrap the stomach wall around the band and
help hold it in place. The device is connected by tubing to a
subcutaneous injection port that allows saline to be injected
or removed to adjust the size of the balloon, thereby altering the size of the outlet between the new small pouch and
the remaining stomach. To encourage healing, the band is
not immediately inflated following surgery. Band adjustments take place in the clinic and are guided by patient
symptoms and weight loss. Unlike Roux-en-Y gastric by-
From the Section of Endocrinology, Diabetes and Nutrition, Boston Medical
Center and Boston University School of Medicine, Boston, MA.
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clinical review
Esophagus
Band
Small stomach pouch
Esophagus
Staples
Small stomach pouch
Band
Stomach
Duodenum
Figure 1. Adjustable gastric banding.
Stomach
Duodenum
Figure 2. Vertical banded gastroplasty.
pass (RYGB), where patients achieve maximal weight loss
at approximately 12 to 18 months following WLS, patients
who undergo LAGB usually continue to lose weight at 2
to 3 years postoperatively [20–22]. After 4 years, patients
generally experience an excess weight loss of 44% to 68%
[23]. Risks include bleeding, infection, leak or perforation,
slipping of the gastric band, band erosion, and malfunction
[22,24]. Hospital stay is usually between 1 to 2 days, and
the procedure is now being performed on an outpatient
basis in some centers [25–27]. LAGB offers the advantage of
low morbidity and mortality (mortality is usually less than
0.5%, with many studies documenting 0%) [28–31]. Despite
these advantages, LAGB is a relatively new technique and
therefore there is less long-term data to document sustained
weight loss and reversal of obesity-related comorbidities.
Vertical Banded Gastroplasty
Vertical banded gastroplasty (VBG) also is a restrictive
procedure. During the operation, a small pouch is created
in the upper part of the stomach with a narrow opening restricting the access of food to the distal stomach (Figure 2).
The pouch is usually stapled or cut from the remaining
stomach fundus. A piece of mesh placed around the stoma
lessens the likelihood that the stoma will expand over time.
After VBG, patients generally experience an excess weight
loss of 40% to 77% at 4 years postoperatively [23]. Mortality
following the procedure is less than 1% [23]. Risks of this
procedure include bleeding, infection, leak or perforation,
anastomotic stenosis, hernia, and small bowel obstruction
[24]. If the stoma becomes dilated or if the pouch is not
completely separated from the fundus (or if a fistula forms
between the 2), the patient may experience weight regain.
Severe symptomatic complications from reflux or stomal
stenosis may necessitate revisional procedures [32,33]. This
fairly frequent complication and the inferior weight loss
when compared with RYGB have made VBG a less popular
option for WLS [22].
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Roux-en-Y-Gastric Bypass
RYGB is a combined restrictive/malabsorptive procedure.
The surgeon first creates a small gastric pouch. A biliopancreatic limb of bowel is then created to bring digestive
secretions to the distal small bowel. The jejunum is attached
to the newly created gastric pouch (this is the alimentary, or
Roux limb) to bring food the distal anastomosis (Figure 3).
This arrangement of the bowel delays the mixing of food
with digestive enzymes and results in malabsorption. At
1 year postoperatively, patients experience an average of
62% excess weight loss after open RYGB, and a 68% excess
weight loss after laparoscopic RYGB [34]. Complications include bleeding, infection, incisional hernia, leak, anastomotic
stenosis or ulceration, nutrient and calorie malnutrition,
hernia, and small bowel obstruction [24]. Hospital stay is
generally shorter if the approach is laparoscopic (3 vs. 4 days)
[34]. Mortality is low, ranging between 0 to 1.9% in various
studies [35,36]. The RYGB has the advantage of established
long-term efficacy for sustained weight loss and reduction
of obesity-related comorbidities. In a large prospective study,
the percentage of patients achieving at least 20% weight loss
at 10 years was 74% following gastric bypass, 35% following
VBG, and 28% following gastric banding [15].
Biliopancreatic Diversion and Biliopancreatic Diversion
with Duodenal Switch
Biliopancreatic diversion (BPD) and BPD with duodenal
switch (BPD/DS) have both restrictive and malabsorptive
components, although the malabsorptive component is
more significant. The restrictive component is created via
partial gastrectomy (either distal gastrectomy or “sleeve”
gastrectomy). The alimentary limb is formed with 150 to
200 cm of ileum, which is either anastomosed to the proximal stomach after distal gastrectomy (the BPD) or to the
duodenal stump, preserving the pylorus (the BPD/DS).
The biliopancreatic limb is anastomosed to the distal ileum
Vol. 14, No. 5 May 2007 JCOM 263
Weight loss surgery
Gallbladder
removed
Esophagus
Small pouch
Duodenal
switch
Partially
resected
stomach
Staples
Stomach
Digestive loop
Duodenum
Figure 3. Roux-en-Y gastric bypass.
creating a short (50–100 cm) common channel for digestion (Figure 4). Long-term weight loss with this procedure
is excellent, estimated at 61% to 73% excess weight loss at
2 years postoperatively [37]. Risks of the procedure include
bleeding, infection, hernia, leak, anastomotic stenosis, nutrient and calorie malnutrition, and small bowel obstruction
[24]. Mortality following this procedure is less than 2%
[38,39]. BPD and BPD/DS cause significant malabsorption,
and these patients are at higher risk for protein malnutrition
and nutritional and micronutrient deficiencies.
Appropriate Candidates for Weight Loss Surgery
The current classification of obesity is based on body mass
index (BMI) (Table 1), with extreme obesity defined as a BMI
of 40 kg/m2 or greater. The BMI provides the basis for selection of appropriate candidates for WLS, as outlined by the
1991 National Institutes of Health Consensus Development
Conference Panel and the National Heart, Lung, and Blood
Institute guidelines [40,41], which provide the generally accepted eligibility requirements for WLS. These guidelines
recommend that WLS be considered for patients with a BMI
greater than 40 kg/m2, or patients with a BMI between 35
and 40 kg/m2 if they have at least 1 significant comorbid
condition (eg, severe sleep apnea, Pickwickian syndrome,
obesity-related cardiomyopathy, severe diabetes mellitus,
or obesity-related physical problems [such as joint disease]
interfering with activities of daily life).
Patients who are candidates for WLS must be well informed as to the nature, risks, and potential complications of
the procedure; motivated in their desire to achieve a healthier
weight; and provide an acceptable operative risk. They also
must be willing to commit to lifetime medical follow-up, as
it is critical to monitor for nutritional deficiencies and ensure
optimal long-term weight loss [42–44]. Appropriate candidates should have demonstrated prior nonsurgical weight
loss attempts [40].
264 JCOM May 2007 Vol. 14, No. 5
Biliopancreatic
loop
Common loop
Figure 4. Biliopancreatic diversion/duodenal switch.
There are few absolute contraindications to WLS. In general, patients would not be considered for WLS if they have
unstable coronary artery disease, an irreversible illness that
will likely significantly shorten the patient’s lifespan, portal hypertension with gastric or intestinal varices, active
substance abuse, an untreated psychiatric disorder, or a history of poor adherence to medical therapies [45–48] (Table 2).
Patients who are elderly are not necessarily excluded from
consideration, although this is controversial. There is still only
limited experience with WLS in the elderly, and studies have
suggested an increase in both morbidity and mortality in this
population [49,50]. One review found a 30-day mortality rate
of 4.8% in patients aged 65 years or older compared with a
30-day mortality of 1.7% in younger patients [50]. However,
there is also evidence that WLS can induce weight loss and reverse obesity-related comorbidities in the elderly [51,52]. There
is no consensus at this time as to whether or not older patients
should undergo WLS.
Choice of Surgeon and Facility
It is recommended that the surgeon performing the procedure be experienced in WLS, be certified in general or
gastrointestinal surgery, and have additional training in
WLS [45]. In order to maintain credentialing in WLS, the
surgeon should have performed at least 100 WLS in the preceding 2 years [48]. Surgical experience has been shown to
impact morbidity and mortality following WLS. In 1 review,
surgeons who performed less than 10 bariatric procedures
per year had a 28% morbidity rate and a 5% mortality rate,
while surgeons who performed more than 100 procedures
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Table 1. Classification of Obesity
Table 2. Contraindications to Weight Loss Surgery
Body Mass Index (kg/m2)
Unstable coronary artery disease
Cirrhosis with gastric or intestinal varices
Active substance abuse
Untreated psychiatric disorder
History of poor adherence to medical therapies
History of an irreversible medical condition that will likely significantly shorten the patient’s lifespan
Unrealistic expectations or failure to understand risks and consequences of the procedure
Classification
< 18.5
Underweight
18.5–24.9
Healthy weight
25–29.9
Overweight
30–34.9
Class 1 obesity
35–39.9
Class 2 obesity
≥ 40
Class 3 (or extreme ) obesity
per year had a 14% morbidity rate and a 0.3% mortality rate
[53]. In particular, the incidence of postoperative anastomotic leaks (a potentially life-threatening complication) has
been found to correlate with surgical experience. It has been
estimated that a surgeon may need to perform 100 to 150 lap­
aroscopic bypass procedures before reaching an acceptable
morbidity rate [54–56]. Patients should be encouraged to ask
their surgeon how may bariatric procedures he or she has
performed and what their complication rate is.
Another factor influencing mortality is choice of hospital.
One review found that high-volume hospitals (> 100 cases/
year) had a lower complication rate and shorter length of
stay (10% vs. 15% and 3.8 vs. 5.1 days, respectively) compared
with low-volume hospitals (< 50 cases/year) [57]. In patients
aged older than 55 years, the mortality rate was 0.9% at highvolume hospitals and 3.1% at low-volume hospitals [57].
of obesity and an understanding of the adjustments that
will need to be made after surgery. A dietician, preferably
experienced with WLS patients, should be involved in the
evaluation [18,45] and can provide preoperative education
on postoperative nutritional requirements.
The patient’s expectations regarding WLS should be
examined to see if they are realistic. Patients should be informed that most people remain obese after WLS and that
very few will achieve a normal body weight.
Preoperative Medical Assessment
A comprehensive patient evaluation should be performed in
patients considering WLS. Patient assessment has not been
completely standardized and patients seeking WLS should
be cared for in conjunction with medical and surgical physicians specializing in the treatment of obesity.
Screening for Underlying Medical Causes of Obesity
Preoperative evaluation should include screening for underlying medical causes of obesity. As hypothyroidism is common and symptoms of thyroid dysfunction are nonspecific, it
is recommended that all patients have a thyroid-stimulating
hormone measurement. The history should be reviewed
for evidence of Cushing’s syndrome, and a 24-hour urine
collection for cortisol should be obtained if there is a clinical
suspicion for this syndrome. Although endocrine disorders
alone generally do not cause severe obesity, preoperative
identification and treatment is nonetheless appropriate [46].
Weight History and Knowledge Assessment
A detailed weight history should be obtained, including
patterns of weight gain and loss as well as prior weight loss
attempts with dietary and medical therapies. A graph plotting the patient’s lifetime weight can be a useful tool; the
clinician and the patient can correlate the graph to life events
and determine significant emotional, social, and medical
factors contributing to the patient’s obesity. The number and
duration of medical weight loss attempts and compliance
with prior therapies should be reviewed. At this time, there
is no accepted definition as to what constitutes a “weight
loss attempt.” Most patients who present for evaluation of
WLS have a history of extensive dieting.
The practitioner should evaluate the patient’s existing
knowledge regarding healthy diet and exercise habits. Caloric intake should be reviewed. The patient should demonstrate appropriate insight into the causes and consequences
Assessment for Comorbid Medical Conditions
Cardiovascular. Cardiovascular evaluation should be guided by current practice guidelines for noncardiac surgery
[58,59]. The history should focus on assessment of coronary
risk factors, physical exercise capacity, and symptoms of
unstable cardiac disease. This should include a physical
examination for valvular abnormalities that may warrant
further characterization prior to surgery and signs of decompensated cardiac function, such as congestive failure.
An electrocardiogram (ECG) is recommended to screen for
ischemia and prior infarction. The need for testing beyond
an ECG is determined by individual patient risk factors and
exercise capacity [2]. At our facility, we usually perform preoperative stress tests on patients with known heart disease,
those older than 55 years, patients who have had diabetes for
more than 10 years, and those with atypical chest pain. It is
generally recommended that a cardiologist evaluate patients
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Vol. 14, No. 5 May 2007 JCOM 265
Weight loss surgery
with a history of heart disease prior to WLS. Prophylactic
b blockade should be considered in moderate- to high-risk
patients, including those with 2 or more cardiac risk factors
[59]. Major risk factors include a prior history of heart disease, heart failure, cerebrovascular disease, type 1 diabetes,
and chronic renal insufficiency [59].
Pulmonary. The extent of preoperative pulmonary evaluation varies among institutions. Chest radiographs are routinely recommended because of the increased risk of postoperative pulmonary complications [45] even though the yield
of a chest radiograph in an asymptomatic patient is low [60].
Obesity alone has not been shown to increase postoperative
pulmonary complications [60]. Patients should be screened
for symptoms of OSA, which is relatively common in this
population; it is estimated that 40% of obese men have OSA
[61]. The practitioner should look for a crowded oropharynx,
which may predispose to OSA. If OSA is suspected, the
patient should be referred for polysomnography. Although
there are no data demonstrating that untreated OSA increases perioperative risk, it may influence perioperative
pulmonary management with the use of continuous positive
airway pressure (CPAP) [62–64]. Some practitioners have recommended preoperative spirometry in all patients seeking
WLS [45], but there is no evidence demonstrating that this is
universally beneficial [65].
Venous thromboembolism. Perioperative venous thromboembolism remains an important complication of WLS,
and diligent perioperative prophylaxis is critical [18]. At this
time, there is insufficient evidence to recommend screening
with a preoperative lower extremity Doppler ultrasound
in patients who do not have a prior history of deep venous
thrombosis (DVT) [66]. However, patients with a prior history of venous stasis disease, pulmonary embolism (PE),
or a hypercoagulable disorder should be considered for
prophylactic inferior vena cava filter placement to minimize
the risk postoperative PE [66–68].
Gastrointestinal. Rapid weight loss following WLS places
patients at risk for gallstone formation and symptomatic
gallbladder disease [69], and patients suspected of having
gallstones should receive a preoperative ultrasound. It is
recommended that patients with documented gallstones
have a prophylactic cholecystectomy at the time of WLS [47].
Given the frequency of stone formation after WLS, screening
and prophylactic cholecystectomy in all patients undergoing
WLS has been proposed; however, this remains controversial [70–73]. At our facility, all patients receive preoperative
ultrasounds; however, only those patients with an abnormal
gallbladder and those patients who will have an extensive
malabsorptive surgery undergo concomitant cholecystec266 JCOM May 2007 Vol. 14, No. 5
tomy. Those patients who do not undergo cholecystectomy
at the time of surgery should be treated with ursodiol for
at least 6 months after surgery to prevent gallstones [74].
Patients should also be evaluated with preoperative liver
function tests. Many obese patients will have asymptomatic
elevations of liver enzymes due to nonalcoholic fatty liver
disease (NAFLD). NAFLD is estimated to occur in 70%
to 80% of the obese population [75]. Patients with transaminitis should undergo standard workup, including hepatic
imaging, prior to surgery. There are several modalities available for liver imaging, including ultrasound, computed tomography, and magnetic resonance imaging [76], and there
is little benefit of 1 modality versus another. Ultrasound is
the most cost-effective and was found in 1 study to be more
sensitive for fatty changes when compared with computed
tomography [77]. Patients with evidence of liver dysfunction
should have a liver biopsy done at the time of surgery to
determine the extent of hepatic damage and the prognosis
[48,78]. Upper gastrointestinal contrast studies are often performed prior to surgery to evaluate for peptic ulcer disease,
however, some centers have replaced this with testing and
treatment for Helicobacter pylori infection [47].
Metabolic. As previously mentioned, patients should have
a thyroid-stimulating hormone measurement and be evaluated for Cushing’s syndrome if clinically warranted. Patients should also have a fasting lipid panel to evaluate for
hypertriglyceridemia and hypercholesterolemia. A fasting
glucose (and hemoglobin A1c if the patient is diabetic)
should be done to assess for undiagnosed diabetes and level
of glycemic control. Blood glucose should be optimized
as recommended by the American Diabetes Association,
with a goal hemoglobin A1c of less than 7% [79]. This can be
achieved either with medications or insulin, depending on
the individual patient. Good preoperative glycemic control
is associated with a decreased rate of postoperative infections following noncardiac surgery [80]. Patients should be
screened for risk factors of osteoporosis, as there is evidence
that WLS causes a decrease in bone density [81]. It is felt that
low bone density is probably uncommon in obese, premenopausal women without other risk factors, and a preoperative
bone density test should be considered only for patients who
meet standard criteria for screening, including those who
are postmenopausal or have other significant risk factors
such as long-term corticosteroid use.
Psychiatric. The practitioner should probe for evidence
of an eating disorder or other psychiatric condition. This
should include questions targeted at untreated depression,
personality disorders, and substance abuse. It is estimated
that more than 50% of patients referred for WLS have a
psychiatric disorder [82]. A history of psychiatric problems
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usually does not preclude surgery. There is no standardized
preoperative psychologic assessment, although an evaluation by a clinician experienced with patients undergoing
WLS is generally recommended [48] and often required
prior to insurance approval.
Other. Other routine preoperative tests include a complete
blood count, vitamin B12 level, folate level, iron studies, renal
function tests, and in patients considering malabsorptive procedures, measurement of fat-soluble vitamins [47] (Table 3).
These tests are generally considered appropriate despite no
clear data that they change postoperative outcomes.
Preoperative Management
It is usually recommended that patients lose weight prior
to WLS. Preoperative weight loss has been associated with
greater long-term weight loss and shorter operative times
[83]. There is a concern that patients who are unable to
lose some amount of weight prior to WLS will be unable
to comply with medical advice and the necessary dietary
restrictions after surgery. Patients who cannot lose weight
should be evaluated on a case-by-case basis to determine if
proceeding to WLS is appropriate [18].
Patients who smoke should be encouraged to quit as soon
as possible, but at a minimum they should stop 8 weeks
prior to surgery to minimize postoperative pulmonary
complications and decrease the risk of stomach ulceration
[84,85]. Many surgeons will not perform WLS on active
smokers. Patients taking hormone therapies that increase
the risk of thrombotic complications should be advised to
discontinue this medication. Premenopausal women should
stop oral contraceptive pills 6 weeks before surgery, and
postmenopausal women on hormone replacement therapy
should be tapered off the medication 4 to 6 weeks before
surgery. These medications should not be restarted until at
least 90 days after surgery.
Postoperative Management
Depending on the type of procedure, patients may initially
be monitored in the intensive care unit. There is no standard
criteria for which patients should receive intensive care
monitoring after surgery; however, it may be reasonable to
consider an intensive care setting for patients who are older
than age 50 years; have a history of congestive heart failure, OSA, venous thromboembolism, metabolic syndrome,
chronic respiratory failure, pulmonary hypertension, or
pseudotumor cerebri; and those who have had intraoperative complications or hemodynamic instability [47,86].
Before the patient leaves the hospital, the clinician should
provide general expectations for the postoperative course.
During the first 30 days after surgery, complications are usu-
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Table 3. Routine Laboratory Testing Prior to Weight
Loss Surgery
Complete blood count
Fasting glucose (and hemoglobin A1c if diabetic)
Basic metabolic panel including kidney function
Liver function tests
Thyroid-stimulating hormone
Lipid panel
Electrocardiogram
Chest radiograph
Vitamin B12, iron studies, folate
In some patients: gallbladder ultrasound, spirometry, fat-soluble
vitamins (ADEK), polysomnography
ally related to the operative procedure. Patients experiencing
severe vomiting, wound infections, and blood clots should
be referred back to the surgical team. Patients should be encouraged to see the surgeon for routine postsurgical care.
Complications in the Immediate Postoperative Period
WLS has a major complication rate of approximately 10%
[87]. One of the most frequently encountered postoperative
complications is pneumonia or aspiration, occurring in 0.14%
to 2.6% of patients [87,88]. Pulmonary complications are less
common after laparoscopic bypass procedures than after
open procedures [89]. Such complications can be minimized
by the use of incentive spirometry, early ambulation, and adequate pain control [90]. PE causes up to 50% of deaths after
WLS [88]. This reenforces the importance of diligent DVT
prophylaxis during hospitalization, although there is currently no consensus as to a standard regimen [91] and there are
only a few trials that compare different treatments. In 1 study,
patients receiving a higher dose of low-molecular-weight heparin for prophylaxis perioperatively did not have a decrease
in thrombotic events, although they did have more bleeding
complications [92]. In another study, patients were treated
with compression stocking and either enoxaparin 30 mg
every 12 hours or enoxaparin 40 mg every 12 hours [93]. The
rate of DVT in the group receiving 40 mg of enoxaparin was
0.6% compared with 5.4% in the group receiving the lower
dose. No difference in bleeding complications was observed.
Most physicians employ subcutaneous heparin or intermittent compression stockings, and both of these in combination
with early ambulation is likely optimal [48,66,94].
Another serious postoperative complication is anastomotic leak. Leaks are the second most common cause of
death following WLS and account for 38% of deaths after
laparoscopic gastric bypass, and 12.5% of deaths after open
bypass [88]. Anastomotic leaks can lead to sepsis, organ
failure, and death and may be difficult to diagnose [95].
Vol. 14, No. 5 May 2007 JCOM 267
Weight loss surgery
Table 4. Dietary Stages Following Weight Loss Surgery
Stage
Food Type
Duration
Intake Goals
1
Water only
0–1 day, beginning postoperative day 1
14–32 oz fluid/day
2
Clear liquids
1–2 days, begin postoperative days 1–2
32–48 oz fluid/day
3
Full liquids, including milk, low-fat creamed
soups, cottage cheese
2–3 weeks
48–72 oz fluid/day
Protein goal: 60–80 g/day
4
Pureed or soft/ground food, including meat,
fish, and dairy. Starches, fruits and vegetables usually excluded
3–6 weeks
48–72 oz fluid/day
Protein goal: 60–80 g/day
5
Small meals and snacks of low-fat foods
Beginning 4–10 weeks postoperatively,
continuing indefinitely
Adapted from Anderson WA, Foresta L. Nutritional consequences following bariatric surgery. In: Farraye FA, Forse RA, editors. Bariatric
surgery: a primer for your medical practice. Thorofare (NJ): SLACK Inc; 2006:141–55.
Symptoms include nausea, vomiting, abdominal pain, fever,
and hypotension; however, signs may be limited to respiratory distress and tachycardia [96]. Less severe cases can be
managed with antibiotics and drainage; however, reoperation is necessary in some cases [97].
Wound infections are another concern after WLS. They
are more common after open procedures than those done
laparoscopically (an incidence of 7% vs. 3%) [88]. Patients
should be managed with prophylactic antibiotics and drainage as needed. While wound infections rarely cause death,
they cause significant morbidity and increase the length of
hospital stay.
Nutritional Considerations
Nutritional support after WLS is designed to ensure adequate
hydration, promote wound healing, preserve lean body mass,
and minimize gastrointestinal distress. Nutritional counseling provided by a dietician is critical for success. The patient’s
diet after surgery progresses through 5 stages (Table 4) [98].
Once cleared to eat, patients begin with water for 24 hours,
progressing to 24 hours of clear liquids, followed by 24 hours
of full liquids. The patient usually is considered stable for
discharge after successful completion of this stage. Three
weeks after surgery, the patient begins a high-protein, softsolid diet and continues this for approximately 1 month. The
patient then advances to the final stage, the low-fat solid diet,
and continues with this indefinitely [98].
There are some general principles that can help patients
adjust to digestion with their new anatomy. Patients should
chew food very thoroughly to facilitate swallowing and prevent vomiting. During the progression through early food
stages, patients should not drink liquids at the same time
as they are eating their regular small meals. Protein should
be consumed at the onset of the meal to help prevent protein malnutrition and to preserve lean body mass. Patients
should keep a food log to help identify food intolerances
268 JCOM May 2007 Vol. 14, No. 5
and monitor compliance. It is common for patients to have
difficulty with several types of food during the first several
months after surgery, most commonly dry meats, breads,
pasta, milk, and nuts [98,99].
Dumping syndrome also can occur; this is most commonly encountered after RYGB due to the loss of the
physiologic sphincter at the stomach outlet. If the patient
consumes a bolus of high-sugar or high-fat food, its arrival
into the small intestine will cause a release of gut hormones
and an influx of intraluminal fluid. The patient may experience nausea, vomiting, diarrhea, flushing, and palpitations.
This syndrome can usually be managed with nutritional
counseling. Patients should be encouraged to see a dietician
periodically to manage these issues, however, there is no
standard recommended frequency for these visits.
Postoperative Medical Management
The timing of visits with the medical practitioner depends
on the type of surgery as well as the patient’s comorbidities
and overall health. At a minimum, the patient should return
for visits 3 times during the first postoperative year [45].
At our center, patients are routinely seen 2 to 6 weeks after
surgery, and at 3, 6, and 12 months postoperatively. Patients
with serious comorbidities or complications should be seen
more frequently. After the first year, visits may usually be
spaced out to every 6 to 12 months [45]. All patients should
be reminded that they must visit a medical practitioner at
least annually after WLS for the remainder of their lives to
monitor for complications and nutritional deficiencies. Generally patients are able to start a walking exercise program
1 week postoperatively. Most patients should not do more
vigorous exercise than walking until 6 to 12 weeks postoperatively. Most patients who successfully lose weight after
bariatric surgery exercise a minimum of 40 minutes per day,
4 times per week after recovery.
There are several broad areas that the clinician should
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clinical review
address during follow-up visits, including the management
of comorbidities following surgery, monitoring and treating
nutritional deficits, and complications from the procedure. Patients need continued enforcement regarding the importance
of a healthy lifestyle and guidance as to what to expect for
their future health. During routine visits, the main comorbidities the clinician should assess include diabetes, hypertension,
hyperlipidemia, OSA, and abnormal liver function tests [100].
Management of comorbidities. After WLS, patients demonstrate a dramatic change in insulin sensitivity and glucose
tolerance. WLS has been shown to dramatically improve diabetes, and more than 70% of patients will be normoglycemic
and off medication 2 years after surgery [15]. In the immediate
postoperative period, the patient’s medications may need to
undergo significant adjustment. Due to the risk of hypovolemia and liver function abnormalities, metformin and thiazolidinediones should be discontinued [100]. If a patient is taking
a sulfonylurea, this medication should be reduced by half
and given only in the morning, and the medication should
be discontinued if the patient’s blood glucose is relatively low
(< 90 ng/dL fasting or < 110 ng/dL before bedtime) [100]. Patients who were taking insulin prior to surgery should have
their basal insulin dosage decreased by half and discontinued
for low glucose levels. Patients taking prandial insulin should
not resume this practice until postprandial glucose values rise
above 150 ng/dL [100]. The most important factor in assuring
safety is frequent monitoring, and patients should check their
blood glucose 3 to 4 times daily and if needed discuss these
values several times per week with their clinician. Because of
the risk of future diabetes, patients who have been weaned off
all of their medications should be checked at regular intervals
for recurrent hyperglycemia. It is unclear if patients who have
had resolution of their diabetes should continue other aspects
of preventive diabetic care.
Hypertension also improves following WLS, and approximately 30% of patients with prior hypertension will
not require medication at 2 years postoperatively [15].
Diur­etics should be discontinued during the immediate
postoperative period when patients are at risk for dehydration and electrolyte abnormalities. Most patients should
have antihypertensive medications held in the postoperative
period, as there can be a dramatic drop in blood pressure
during this time [100].
After WLS, patients can anticipate a gradual improvement in total cholesterol, triglycerides, and high-density
lipoprotein cholesterol. In the 6 months following surgery,
a reduction of more than 15% in total cholesterol and a
triglyceride reduction of more than 50% can be observed
[101]. High-density lipoprotein improvement is usually more
gradual. Depending the severity of the patient’s preoperative
hyperlipidemia and whether or not the patient has cardiowww.turner-white.com
vascular disease, the practitioner may wish to continue a
low-dose of an HMG-CoA reductase inhibitor [100]. The
practitioner may discontinue any medications, such as fibrates, for hypertriglyceridemia [100]. Patients should then
have their cholesterol levels remeasured 3 months postoperatively.
Over 80% of patients with OSA can expect resolution or
improvement of their disease following WLS [39]. At this
time, there are no standing recommendations for discontinuing of CPAP therapy after WLS. However, it may be
reasonable to seek repeat polysomnography after the patient
has achieved 30% loss of excess body weight [100].
Patients with NAFLD generally see improvement following WLS [102]. Liver biopsies obtained at the time of surgery
are useful in predicting the likelihood of regression. A small
cohort of patients has developed liver failure and cirrhosis
after WLS; the etiology for this is unclear, however, the
practitioner should avoid potentially hepatotoxic medications
during the first 6 months postoperatively [100].
Management of long-term complications.
GI complaints. Vomiting after bariatric surgery is multifactorial and occurs in most patients for the first several months.
Patients who continue to have severe vomiting or persistent
vomiting for longer than 6 months should undergo further
workup for obstruction, ulceration, stenosis, or dysmotility.
During all types of WLS, a new “stoma” will be created, and
this region of intestine can develop stenosis and ulcerations.
Patients suspected of having stenosis (often presenting
as persistent vomiting and inability to tolerate nutrition)
should be referred for possible dilation. Stenosis can present
acutely or several months after surgery. Patients with bloating, abdominal pain, and bleeding should be evaluated for
marginal ulceration. If uncomplicated, marginal ulceration
can usually be managed medically. Diarrhea is another
common complaint in the immediate postoperative period,
and the differential diagnosis should include dumping syndrome, lactose intolerance, sprue, and bacterial overgrowth.
Hernia. Incisional hernias are fairly common after bariatric
surgery, particularly in patients who have undergone open
surgical procedures. If the patient is asymptomatic, it is
usually recommended that surgical repair be deferred until
maximal weight loss has been achieved. In contrast, internal
hernias are more common after laparascopic surgery [103].
These patients will often complain of postprandial abdominal pain, nausea, and vomiting [100]. When an internal
hernia is suspected, patients should be referred back to the
surgeon for diagnostic imaging and exploratory surgery.
Inadequate weight loss. Patients will often lose up to ½ to 1 lb
per day for the first 3 months after surgery. Maximal weight
Vol. 14, No. 5 May 2007 JCOM 269
Weight loss surgery
loss after RYGB usually occurs between 12 to 18 months
after WLS but may be more gradual in patients after LAGB.
During the period of rapid weight loss, it is common for
patients to complain of fatigue and cold intolerance. After
patients achieve peak weight loss, there is usually a period of
weight stabilization followed by gradual weight regain. When
a patient complains of weight regain, the practitioner should
document weight patterns and carefully review dietary habits.
The most common cause of weight regain is maladaptive eating habits. Due to improved surgical techniques, a ruptured
staple line is now a rare cause of weight regain. Patients with
a ruptured staple line often complain of an increased appetite
and ability to consume food and decreased satiety [100].
Kidney stones. Patients who have had malabsorptive procedures are at risk for renal oxalate stones because of impaired
oxalate binding in the small intestine. This is most commonly
seen after BPD/BPD-DS but may be seen after RYGB [104].
These patients should consume a moderate calcium diet; have
periodic urine testing for calcium, oxalate, and citrate; and
have careful monitoring of calcium and vitamin D status.
Neurologic complications. Although rare, some patients have
been hospitalized with persistent vomiting, weakness, and
hyporeflexia after WLS. This syndrome is known as acute
postgastric reduction surgery neuropathy and remains poorly
understood. When suspected, these patients should undergo
testing for vitamin deficiencies, especially vitamin B12 and
thiamine, as they have been linked to the syndrome [105].
Hair loss. Hair loss commonly occurs in the 3 to 6 months
following surgery. The exact mechanism is unclear. Patients
should be reassured that this should reverse with time and
weight stabilization.
Excess soft tissue. After significant weight loss, patients may
be faced with large amounts of sagging skin. Not only is this
distressing to the patient because it is cosmetically unpleasant, but skin folds can harbor infection and impair mobility.
Unfortunately, insurance companies often consider corrective plastic surgery cosmetic and it may be difficult or impossible to obtain insurance coverage.
Psychological problems. In general, most patients will have improved psychological functioning after surgery. However, a
subset of patients will experience difficulties adjusting to
their new lifestyles and changing interpersonal relationships. The clinician should periodically screen for this and
refer to a mental health professional as needed.
Vitamin Supplementation
Routine vitamin supplementation will vary from patient
270 JCOM May 2007 Vol. 14, No. 5
to patient, with the most important determinant being the
type of WLS performed. Patients undergoing purely restrictive procedures rarely experience significant nutritional
deficiencies; however, those undergoing BPD or BPD/DS are
at greater risk. It is recommended that patients be routinely
screened for micronutritent deficiencies 6 and 12 months
after surgery and annually thereafter [48]. At our facility, all
patients are supplemented with a multivitamin and calcium
tablets containing vitamin D and monitored carefully for
deficiencies in iron, vitamin B12, and thiamine.
All patients should be encouraged to consume 1 to 2
mul­tivitamins per day after surgery. Patients may initially
tolerate a chewable children’s tablet more easily. A multivitamin containing folate will generally provide sufficient folic
acid after surgery [106]. Patients consuming a multivitamin
after RYGB also generally maintain adequate levels of the
fat-soluble vitamins A, E, and K. Deficiencies may be more
common after BPD/BPD-DS; however, there is currently insufficient evidence to recommend routine supplementation.
Patients should have levels monitored every 6 to 12 months
and supplemented as necessary [107].
Following WLS, there is a significant increase in markers
of bone turnover associated with a decrease in bone mass
[81]. As there are currently no evidence-based recommendations for WLS patients, most clinicians recommend routine
supplementation with 1200 to 1500 mg of calcium per day.
Patients who have undergone BPD/BPD-DS may require
more calcium. Calcium citrate tablets may be more easily
absorbed than calcium carbonate tablets, but more pills are
required to reach the recommended daily amount. Most
calcium tablets also contain vitamin D, but this may not
provide adequate supplementation, and vitamin D levels
should be assessed. Vitamin D deficiency is more prevalent
in the obese, and this may be partially due to sequestration of vitamin D in body fat [108]. In patients with 25-OH
vitamin D levels less than 30 ng/mL, additional vitamin D
in the form of 50,000 IU by mouth weekly should be added
for 8 weeks. Levels should then be rechecked. Patients may
require chronic supplementation with 50,000 IU every week
to maintain adequate stores [109]. Because of the complexity
of calcium and vitamin D regulation, it is recommended
that several parameters of bone health be monitored, including parathyroid hormone, total calcium, albumin, 25-OH
vitamin D, 24-hour urinary calcium, bone-specific alkaline
phosphatase levels, and bone mineral density (DEXA).
Iron deficiency is multifactorial after bariatric surgery.
Contributing factors include low intake of red meat, bypass
of the duodenum and proximal jejunum where most of the
absorption occurs, and a decrease in gastric acid needed for
adequate iron absorption. Following RYGB and BPD/BPDDS, patients should be considered for prophylactic iron
supplementation due to the frequency of low iron levels
www.turner-white.com
clinical review
following surgery. Ferrous sulfate supplementation in the
form of 320 mg twice per day has been shown to prevent
iron deficiency in patients after RYGB [110]. Vitamin C may
also be used to facilitate absorption. Patients who remain
iron deficient despite oral supplementation should undergo
a workup for gastrointestinal blood loss (including marginal
ulceration) and be considered for intravenous iron therapy.
Serum ferritin is the most sensitive marker of early iron deficiency [111] and should be included in the evaluation.
At this time, there are no evidence-based recommendations for routine vitamin B12 replacement after surgery. It
is estimated that a third of patients will be vitamin B12–
deficient after gastric bypass if not supplemented beyond
a multivitamin [112], and therefore periodic monitoring is
indicated. Treatment with oral crystalline B12 at doses of at
least 350 mg per day has been shown to maintain normal
plasma vitamin B12 levels [113]. Subcutaneous or intramuscular injections may be used in patients not responding to
oral therapy. When assessing vitamin B12 deficiency, levels
of homocysteine and methylmalonic acid should also be
obtained as these are more sensitive markers of vitamin B12
deficiency [114].
Thiamine deficiency after WLS is rare although the exact
prevalence is unknown. It can be prevented in the majority
of patients with the administration of a multivitamin. Thiamine supplementation should be considered in patients who
have persistent vomiting or inadequate nutrient intake after
surgery in order to prevent neurologic complications [18]. In
our center, patients presenting to the emergency department
with vomiting after WLS receive 100 mg of thiamine, 1 mg
of folate, and 10 mL of liquid multivitamin in normal saline
to prevent Wernicke Korsakoff syndrome.
Some WLS patients have been documented to have low
levels of selenium, copper, zinc, and carnitine. Of these, zinc
deficiency may be the most common, particularly after BPD/
BDP-DS. Symptoms of zinc deficiency include impaired
immune function, hair loss, and rash. Unfortunately, zinc
deficiency is difficult to diagnose, as serum levels represent
less than 0.1% of total zinc stores, and during periods of inflammation this level will be artificially low due to increased
zinc uptake in the liver [115]. At this time, there is insufficient
evidence to recommend routine zinc supplementation after
bariatric surgery. Practitioners should rely on the clinical picture and laboratory data to assess the need for supplemental
zinc. Clinically relevant deficiencies of selenium, copper, and
carnitine are poorly studied and seem to be rare. There are
currently no evidence-based recommendations for routine
testing or supplementation of these elements.
Conclusion
Over the past several decades, major strides have been made
in the surgical treatment of obesity. Careful pre- and postwww.turner-white.com
operative assessment is necessary for optimizing patient
outcomes after WLS. While much has been learned, many
gaps in our knowledge remain. It is likely that the rising
popularity of WLS will lead to increased understanding of
how to best manage WLS patients.
Corresponding author: Caroline Apovian, MD, Robinson Bldg. 4400,
88 E. Newton St., Boston Medical Center, Boston, MA 02118, caroline.
[email protected].
Financial disclosures: None.
Author contributions: conception and design, SMP, LSU, CMA;
analysis and interpretation of data, SMP; drafting of the article, SMP;
critical revision of the article, LSU, CMA.
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