Table 1 Summary of statements and recommendations of OBA guidelines

Q.1. WHICH ARE THE “ALARMING" CLINICAL SIGNS AND SYMPTOMS FOR ACUTE SURGICAL ABDOMEN IN PATIENTS WITH A PREVIOUS HISTORY OF BARIATRIC SURGERY?

Statement 1.1

Tachycardia ≥ 110 beats per minute, fever ≥ 38 °C, hypotension, respiratory distress with tachypnea and hypoxia, and decreased urine output are alarming clinical signs in patients presenting with acute abdominal pain with a previous history of bariatric surgery (QoE: low)

Statement 1.2

 In the presence of respiratory distress and hypoxia, a pulmonary embolism must be systematically excluded (QoE: low)

Statement 1.3

 In the absence of fever and other signs of sepsis but in the presence of tachycardia (be aware of patients treated with beta blockers) and acute abdominal pain, patient requires immediate laboratory tests and imaging assessment for early and long-term complications following bariatric surgery (QoE: low)

Statement 1.4

 In the emergency setting, the combination of fever, tachycardia, and tachypnea are significant predictors of an anastomotic leak or staple line leak after sleeve gastrectomy and Roux-en-Y gastric bypass (QoE: low)

Statement 1.5

 Persisting vomiting and nausea are alarming clinical signs due to the high probability of complications such as internal hernia, volvulus, gastrointestinal stenosis, intestinal ischemia, or marginal ulcer after bariatric surgery (QoE: low)

Statement 1.6

 The most common clinical presentation of internal hernia after laparoscopic Roux-en-Y gastric bypass is acute onset, persistent crampy/colicky abdominal pain, mostly located in the epigastrium (QoE: low)

Statement 1.7

 The triad of persistent epigastric pain, pregnancy, and a history of laparoscopic Roux-en-Y gastric bypass should be warning signs for the prompt evaluation of the patient for the high suspicion of internal hernia (QoE: low)

Statement 1.8

 Any clinical signs of intestinal bleeding such as hematemesis, melena, and hematochezia after bariatric surgery are predictors signs of intra-abdominal complications (QoE: low)

Recommendation/1

 There are no absolute alarming clinical signs/symptoms for long-term complications after bariatric surgery. Clinical presentation can be non-specific. Any new onset abdominal symptoms should give rise to suspicion for long-term complications after bariatric surgery.

 We recommend against delaying prompt diagnostic work-up and laparoscopic surgical exploration in patients with a previous history of bariatric surgery, presenting with persistent abdominal pain and/or gastrointestinal symptoms, associated with fever, tachycardia, and tachypnea (Strong recommendation based on low level of evidence 1C)

Q.2. WHICH ARE THE MOST SENSITIVE AND SPECIFIC LABORATORY TESTS FOR DIAGNOSIS IN PATIENTS WITH A PREVIOUS HISTORY OF BARIATRIC SURGERY PRESENTING WITH ACUTE ABDOMEN?

Statement 2.1

 A detailed history, physical examination, laboratory tests, and imaging modalities are mandatory in decision-making algorithm for patients presenting with acute abdominal pain after a previous bariatric surgery, in the emergency setting (QoE: low)

Statement 2.2

 Laboratory tests including complete blood count cells, serum electrolytes, C-reactive protein (CRP), procalcitonin, serum lactate levels, renal and liver function tests, serum albumin and blood gas analysis are helpful in the emergency department assessment of this group of patients presenting with acute abdominal pain (QoE: low)

Statement 2.3

 High CRP level is predictive of both early and late postoperative complications after bariatric surgery (QoE: low)

Statement 2.4

 CRP has a remarkably higher sensitivity and specificity than white blood count cells or neutrophil count to rule out an abdominal surgical disease. However a normal CRP level alone does not rule out the possibility of a postoperative complication following a bariatric surgical procedure (QoE: low)

Statement 2.5

 Elevated serum lactates should not be used as a single marker to exclude internal herniation, because it can occur late in the presence of intestinal ischemia (QoE: low)

Statement 2.6

 Nutritional deficiencies in vitamins, minerals, and trace elements may follow bariatric surgery and are associated with clinical manifestations and diseases, including anemia, ataxia, hair loss, and Wernicke encephalopathy (QoE: low)

Recommendation/2

 There is not a biological marker for the diagnosis of long-term complications of bariatric surgery.

 We suggest performing a combination of complete blood count cells, serum electrolytes, serum albumin, liver and renal function tests, CRP, procalcitonin and serum lactate levels, blood gas analysis in assessing late complications following bariatric surgery in the emergency setting (Weak recommendation based on low level of evidence 2C)

 We suggest considering high CRP level and leukocytosis as predictors of abdominal emergencies following bariatric surgery (Weak recommendation based on low level of evidence 2C)

 We suggest assessing the nutritional status of patients undergoing bariatric procedures, including Vitamin D, folic acid, B12, B6, and B1 serum level, because of the high risk of vitamin B complex deficiency and malnutrition (Weak recommendation based on low level of evidence 2C)

Q.3: WHICH IS THE MOST SPECIFIC AND SENSITIVE RADIOLOGICAL STUDY FOR DIAGNOSIS IN ASSESSING PATIENTS AFTER BARIATRIC SURGERY PRESENTING WITH ABDOMINAL PAIN?

Statement 3.1

 The diagnostic value of imaging after bariatric surgery depends mostly on the knowledge of the anatomic changes and of the potential complications following bariatric surgery (QoE: low)

Statement 3.2

 Contrast-enhanced CT scan with oral contrast is the study of choice in patients with a previous history of bariatric surgery presenting with acute abdomen (QoE: moderate)

Statement 3.3

 Plain abdominal X-ray has a limited role, when CT scan is not available, in detecting bowel distension or/and fluid levels (QoE: low)

Statement 3.4

 Point-of-care ultrasound can be used by emergency physicians to rule out cholecystitis and biliary diseases, acute appendicitis, and the presence of free intraperitoneal fluid (QoE: low)

Statement 3.5

 The administration of oral and intravenous contrast is fundamental to find landmarks for the interpretation of images (QoE: low)

Statement 3.6

 In a pregnant woman with a history of bariatric surgery, US and magnetic resonance imaging (MRI) are preferred to assess acute abdominal pain with the aim of limiting ionizing radiation exposure. Low-dose CT could be performed in very selected cases (QoE: low)

Statement 3.7

 Diagnostic laparoscopy has higher sensitivity and specificity than any radiological assessment (QoE: moderate)

Statement 3.8

 The role of angiography and angioembolization in patients presenting with a gastrointestinal bleeding after bariatric surgery is marginal. They could be a valid tool to achieve bleeding control, in selected cases (QoE: very low)

Recommendations/3

 We recommend the use of contrast-enhanced computed tomography with oral contrast in the assessment of acute abdomen after bariatric surgery, whenever possible. The absence of oral and intravenous contrast can significantly decrease sensitivity and specificity of radiological assessment (Strong recommendation based on low level evidence 1C)

 We recommend assessing the acute abdomen in a pregnant woman by US and MRI to limit radiation exposure, though low-dose CT can be useful in selected cases (Strong recommendation based on low level evidence 1C)

 We recommend against delaying laparoscopic exploration if there is a high index of clinical suspicion and in the presence of alarming clinical signs/symptoms, even in situations of negative radiological assessment (Strong recommendation based on low level evidence 1C)

Q.4: WHAT IS THE ROLE OF ENDOSCOPY IN THE DIAGNOSIS AND TREATMENT OF LONG-TERM COMPLICATIONS FOLLOWING BARIATRIC SURGERY IN THE EMERGENCY SETTING?

Statement 4.1

 After contrast-enhanced computed tomography with oral contrast administration, the endoscopic evaluation is the first tool to be considered for the diagnosis and management of leaks and fistulae related to bariatric surgery in stable patients (QoE: moderate)

Statement 4.2

 The endoscopic evaluation should be performed by an expert endoscopist aware of the new anatomy resulting from different surgical bariatric procedures (QoE: moderate)

Statement 4.3

 The endoscopic management of leaks and fistulae related to bariatric surgery in stable patients is effective and safe when performed in expert centers (QoE: moderate)

Statement 4.4

 Several endoscopic devices and techniques are available to manage bariatric surgery complications and they include internal drainage techniques and vacuum therapy, self-expanding metal (SEMS) and plastic stents, clipping techniques, including the use of through-the-scope clips (TTSC) and over-the-scope clips (OTSC), tissue sealants, suturing systems (OverStitch System®) (QoE: moderate)

Statement 4.5

 The endoscopic internal drainage by pigtail plastic stents is considered an effective alternative to fully covered SEMS in the treatment of late leaks and fistulae after LSG or RYGB providing higher success rates, shorter treatment duration, and lower adverse events rates compared to stenting (QoE: moderate)

Statement 4.6

 In the presence of gastric stricture after LSG or of anastomotic stricture after LRYGB, the endoscopic dilation performed by achalasia balloon in LSG or through-the-scope dilation hydrostatic balloon for LRYGB should be considered as the first-line treatment (QoE: low)

Statement 4.7

 Early endoscopic assessment should be performed in case of suspected active intra-gastric bleeding related to a marginal or stomal ulcer in stable patients. (QoE: low)

Statement 4.8

 Hemostasis of a bleeding ulcer, performed with injection of epinephrine or mechanical hemostasis with endoscopic clips and rubber band ligation are preferred over thermal hemostasis (QoE: moderate)

Statement 4.9

 Novel hemostatic powders may be considered as a valid therapeutic option in selected patients presenting with a bleeding ulcer (QoE: moderate)

Recommendation/4

 In the high suspicion and diagnosis of staple line leak, gastric fistula, delayed gastro-jejunal anastomotic leakage, marginal or stomal ulceration, gastro-gastric fistula, gastro-jejunal anastomotic stricture and intra-luminal bleeding after LSG and LRYGB, we recommend an urgent endoscopic assessment and management in hemodynamically stable patients, according to the availability of an endoscopist with expertise in bariatric surgery. We recommend against delaying surgical exploration in hemodynamically unstable patients (Strong recommendation based on low level of evidence 1C)

Q.5: HOW SHOULD ANTIBIOTICS BE USED IN THE MANAGEMENT OF THE ACUTE ABDOMEN IN PATIENTS WITH PREVIOUS HISTORY OF BARIATRIC SURGERY?

Statement 5.1

 The optimal management of patients presenting with sepsis requires early source control, adequate empiric antimicrobial therapy, and targeted fluid resuscitation (QoE: moderate)

Statement 5.2

 Complicated IAIs are multi bacterial mainly caused by Gram-negative bacilli and anaerobes. Broad-spectrum single-agent or combination drug regimens targeting these microorganisms are the mainstay of early empiric antimicrobial therapy (QoE: moderate)

Statement 5.3

 Obesity alone is not associated with antimicrobial treatment failure among patients with IAI. Obesity may not be an absolute indication for longer duration of antimicrobial therapy in treatment of IAI (QoE: moderate)

Statement 5.4

 A short (3–4 days of IV antibiotics) course of therapy may be effective even in critically ill surgical patients with complicated IAI, including fungal infection, after adequate source control (QoE: moderate)

Statement 5.5

 The empiric implementation of antifungal therapy due to perforated marginal ulcer (ulceration located on the jejunal side of the anastomosis) or stomal ulcer (ulceration on the gastric side) is not supported by the literature in community-acquired IAI (QoE: moderate)

Statement 5.6

 The dose of antibiotics must be adjusted to the weight and renal function of the patient (QoE: high)

Recommendations/5

 We recommend administering early empiric broad-spectrum antimicrobial therapy in patients presenting with intra-abdominal infections, in addiction to adequate source control. After surgical management, short-term antimicrobial therapy is preferred even in critically ill patients (Strong recommendation based on moderate quality of evidence 1B)

 We suggest administering antifungal therapy in frail, immunocompromised patients, presenting with biological and clinical signs of sepsis, and if fungal organisms are isolated in the intraperitoneal fluid (Weak recommendation based on low quality of evidence 2C)

Q.6: HOW CAN WE DECREASE THE RISK OF THROMBOEMBOLIC EVENTS IN SURGICAL PATIENTS WITH A PREVIOUS HISTORY OF BARIATRIC PROCEDURES AFTER EMERGENCY SURGERY?

Statement 6.1

 All patients needing an urgent surgical procedure should be risk stratified for venous thromboembolism (QoE: moderate)

Statement 6.2

 In the emergency setting, venous thromboembolism pharmacologic prophylaxis should be started as soon as possible, if there are no signs of active bleeding, to decrease the risk of venous thromboembolism (QoE: moderate)

Statement 6.3

 If contraindications to pharmacologic venous thromboembolism prophylaxis exist, mechanical venous thromboembolism prevention strategies such as compression stockings and foot pump should be considered even if the patient is ambulating, because of the high venous thromboembolism risk following emergency surgery (QoE: low)

Statement 6.4

 Pharmacologic venous thromboembolism prophylaxis with unfractionated heparin or low-molecular-weight heparin is highly effective for the prevention of venous thromboembolism in hospitalized patients (QoE: moderate)

Statement 6.5

 The venous thromboembolism prophylaxis should continue after discharge according to the thrombotic risk. This can be estimated based on patient- and procedure-specific factors, applying validated risk assessment models such as the Caprini score. Patients with a prolonged hospital stay, the presence of cancer, urinary tract infection, and postoperative sepsis are at high risk to present with venous thromboembolism (QoE: moderate)

Recommendation/6

 We recommend the administration of low-molecular-weight heparin for venous thromboembolism prophylaxis as soon as possible in patients presenting with an acute surgical abdomen after bariatric surgery. The LMWH dose should be adjusted to the patient’s weight, the thrombotic risk and creatinine clearance (Strong recommendation based on moderate level of evidence 1B)

 We suggest to continue venous thromboembolism prophylaxis at least 4 weeks after discharge (Weak recommendation based on moderate level evidence 2B)

 We suggest to use the monitoring of anti-Xa levels to adjust LMWH dose, particularly in elderly, pregnant, renally impaired, with BMI =  > 35 kg/m2 patients, at risk of suboptimal dosing (Weak recommendation based on moderate level of evidence 2B)

 In patients where pharmacologic venous thromboembolism prophylaxis is contraindicated, we recommend the use of mechanical prophylaxis, especially in high-risk patients (Strong recommendation based on moderate level evidence 1B)

Q.7: WHICH SURGICAL PROCEDURES ARE EFFECTIVE IN THE MANAGEMENT OF ACUTE ABDOMEN FOLLOWING BARIATRIC SURGERY?

Scenario 1: BLEEDING

Statement 7.1

 Intra-abdominal bleeding occurs very rarely as a late complication after bariatric surgery (QoE: low)

Statement 7.2

 The most common reason for late gastrointestinal bleeding is ulcer from gastric sleeve and gastro-jejunostomy, gastric pouch, bypassed stomach, or duodenum after LRYGB (QoE: moderate)

Statement 7.3

 Bleeding after LRYGB and LSG is self-limiting in many patients and can be managed conservatively, with medical treatment and close monitoring and observation (QoE: low)

Statement 7.4

 In hemodynamic stable patients presenting with intra-luminal intestinal bleeding after bariatric surgery, the endoscopic assessment (that must be performed after endotracheal intubation to protect airways) is a valid and safe tool after bariatric surgery (QoE: moderate)

Statement 7.5

 Angiography and angioembolization may be valid strategies to bleeding control (QoE: very low)

Statement 7.6

 If endoscopic and angiographic management fail, surgical exploration is indicated, if there are signs of persisting bleeding (QoE: low)

Statement 7.7

 In unstable patients not responding to aggressive resuscitation, diagnostic laparotomy and surgical hemostasis are mandatory (QoE: high)

Recommendations/7-BLEEDING

 Endoscopy is the first recommended diagnostic tool in stable patients presenting with gastrointestinal bleeding after SG and RYGB (Strong recommendation based on moderate quality of evidence 1B)

 We suggest performing an angio-CT and embolization in stable patients presenting with gastrointestinal and intraperitoneal extra-luminal bleeding, when skills are available (Weak recommendation based on low level of evidence 2C)

 In selected cases of hemodynamically stable bleeding peptic ulcer patients, after failure to attempt endoscopic hemostasis, we suggest the use of angiography with angioembolization if technical skills and equipment are available (Weak recommendation based on very low level of evidence 2D)

 We recommend against delaying surgical exploration in unstable patients presenting with ongoing gastrointestinal bleeding after endoscopic assessment and negative angio-CT scan for bleeding source localization (Strong recommendation based on low level evidence 1C)

 In patients selected for surgical exploration for a bleeding ulcer, we suggest planning intra-operative endoscopy to facilitate the localization of the bleeding site, using a surgical gastrostomy in case of patient with LRYGB to assess the gastric remnant and duodenum (Weak recommendation based on very low quality of evidence, 2D)

 We recommend against delaying diagnostic laparoscopy/laparotomy in patients presenting with ongoing intraperitoneal, extra-luminal bleeding, after angioembolization (Strong recommendation based on low level of evidence 1C)

 A biopsy of the bleeding ulcer is recommended to exclude malignancy (Strong recommendation based on low level of evidence, 1C)

Scenario 2: INTESTINAL OBSTRUCTION

Statement 7.8

 Stenosis after LSG in stable patients presenting with gastrointestinal symptoms should be assessed by endoscopy and the treatment must be tailored according to the clinical status of the patient and endoscopic findings (QoE: low)

Statement 7.9

 Endoscopic pneumatic dilation is a safe and effective first-line treatment of gastric stenosis after SG and gastro-jejunostomy strictures after RYGB. Perforation is a potential complication of this treatment and may necessitate surgical intervention (QoE: moderate)

Statement 7.10

 After RYGB, the most common causes of small-bowel obstruction (SBO) are internal hernia, adhesions, incisional hernia/trocar site hernia, intussusception, volvulus, obstruction localized at the jejuno-jejunostomy (JJ), twisted alimentary limb, alimentary limb mesenteric ischemia, and adhesions proximal to the JJ (QoE: low)

Statement 7.11

 In case of SBO after RYGB, an exploratory laparoscopy is mandatory in the first 12–24 h in stable patients presenting with persistent abdominal pain and inconclusive clinical and radiological findings (QoE: low)

Statement 7.12

 Diagnostic laparoscopy in pregnant women with SBO after bariatric surgery is effective and is associated with a good maternal and fetal outcome (QoE: very low)

Statement 7.13

 Surgical exploration in patients after LRYGB should start from the ileocecal junction (distally to the obstruction) toward the inspection of the jejuno-jejunostomy and of the 3 potential site locations of internal hernia: the traverse mesocolon (in retrocolic bypasses), Petersen’s space (Petersen’s hernia) and the jejuno-jejunostomy mesenteric defect (mesojejunal hernia), and then the remnant stomach. (QoE: very low)

Statement 7.14

 If an internal hernia is found, an assessment of intestinal viability should be undertaken; if intestinal ischemia is present, surgical resection is performed. The closure of the mesenteric defect should be performed with non-absorbable material in running or interrupted suture (QoE: very low)

Statement 7.15

 Indocyanine green (ICG) fluorescence angiography may be a valid tool in the evaluation of the extent of bowel resection and anastomosis perfusion, when it is available (QoE: very low)

Statement 7.16

 If no internal hernia or other evident causes of SBO are found, the entire small intestine should be assessed given that there are other causes of intestinal obstruction (adhesions, intussusception, volvulus) (QoE: very low)

Statement 7.17

 In case of intra-operative findings of intussusception, the surgical treatment may be limited to reduction if the small bowel is viable, but resection of the affected segment is recommended since it seems to result in fewer recurrences (QoE: very low)

Statement 7.18

 In the emergency setting, when SBO is due to a bezoar located in the stomach, the first approach could be endoscopy. If the bezoar is located distally in the small bowel, surgical intervention is required to milk the bezoar into the cecum or remove it by creating an enterotomy (QoE: very low)

Recommendations/7-INTESTINAL OBSTRUCTION

 In the presence of symptoms of proximal SBO after LSG and LRYGB, endoscopic assessment is recommended in stable patients (Strong recommendation based on low level of evidence 1C)

 In the presence of SBO after RYGB, we recommend performing an exploratory laparoscopy in the first 12–24 h in stable patients with a history of bariatric surgery presenting with persisting acute abdominal pain after inconclusive laboratory, radiological and endoscopic results in the emergency setting (Strong recommendation based on low level of evidence 1C)

 We suggest considering limited intestinal resection and anastomosis in case of clear intestinal segmental ischemia in hemodynamically stable patients, or damage control and open abdomen approach in cases of extended intestinal ischemia/peritonitis in hemodynamic unstable patients (Weak recommendation based on low level evidence 2C)

Scenario 3: Localized or Generalized PERITONITIS

Statement 7.19

 Stable patients with perforated gastro-jejunal ulcer after LRYGB should be managed with laparoscopic primary repair by suturing and omental patch which are safe and feasible and associated with decreased operative time, blood loss, and length of stay (QoE: low)

Statement 7.20

 In patients presenting with marginal ulceration and perforation at the jejuno-jejunal anastomosis, laparoscopic primary suturing is a valid option in selected patients (young patients, early presentation, no other serious comorbidities, hemodynamic stability) (QoE: low)

Statement 7.21

 If a gastro-gastric fistula is found at surgical exploration for a perforated ulcer, surgical options include simple resection of the fistula, resection of the fistula with revision of the gastro-jejunal anastomosis (GJA), resection of the fistula with remnant gastrectomy ± revision of GJA, or gastrectomy of the remnant stomach (QoE: very low)

Statement 7.22

 After LRYGB, a perforated remnant stomach may be managed by primary suture and omental patch or stapled resection, If there is concern for significant postoperative ileus due to peritonitis, a gastrostomy tube could be placed in the gastric remnant proximal to the site of the perforation to decompress the stomach and allow a postoperative endoscopic access (QoE: low)

Statement 7.23

 If diffuse peritonitis is due to a perforated excluded gastrointestinal segment (stomach or duodenum), it is recommended to explore the jejuno-jejunostomy (stenosis) or the gastric remnant (gastro-gastric fistula) (QoE: low)

Statement 7.24

 Surgical treatment of a duodenal perforation depends on the hemodynamic stability of the patient, size of the perforation and extent of native tissue loss (QoE: very low)

Recommendations/7-PERITONITIS

 We recommend performing immediate surgical exploration in unstable patients presenting with peritonitis without delay (Strong recommendation based on low level evidence 1C)

 We recommend assessing all anastomoses after LRYGB, the remnant stomach and the excluded duodenum (Strong recommendation based on low level evidence 1C)

 We recommend performing biopsies of the perforated ulceration to exclude malignancy (Strong recommendation based on low level evidence 1C)

 We recommend performing primary suture with omental patch in laparoscopic approach in stable patients presenting with a perforated marginal ulcer or gastric remnant or duodenal perforation of less than1cm, whenever technically possible (Strong recommendation based on low level evidence 1C)

 We suggest considering damage control surgery and open abdomen in hemodynamically unstable patients (Weak recommendation based on low level evidence 2C)

Q.8: WHAT IS THE ROLE OF DAMAGE CONTROL SURGERY IN THE MANAGEMENT OF PATIENTS WITH ACUTE ABDOMEN DUE TO LATE COMPLICATIONS OF BARIATRIC SURGERY?

Statement 8.1

 Damage control surgery may be a tool to consider in the management of the acute abdomen in patients presenting with persistent hemodynamic instability because of severe peritonitis and septic shock (QoE: low)

Statement 8.2

 The open abdomen is an option for emergency surgery patients with severe peritonitis and severe sepsis/septic shock in the context of an abbreviated laparotomy due to severe physiological derangement, the need for a deferred intestinal anastomosis, a planned second look for intestinal ischemia, persistent source of peritonitis (failure of source control), or extensive visceral edema with concerns for the development of abdominal compartment syndrome (QoE: low)

Recommendation/8

 We suggest the use of damage control surgery with open abdomen in hemodynamic unstable patients secondary to an intra-abdominal source of infection, to extensive intestinal ischemia and massive hemoperitoneum (Weak recommendation based on low level evidence 2C)