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 late 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).

Discussion of evidence

Clinical signs and physical examination of patients who have undergone bariatric surgery presenting with AAP can be atypical, insidious, and often resulting in delayed management due to inconclusive clinical and radiological findings, with consequent poor outcomes and high morbidity and mortality rate.

Tachycardia is considered the main alarming sign in the early postoperative period [8]. Late postoperative complications can be revealed by hemodynamic instability, respiratory failure, or renal dysfunction, in the presence of sepsis. However, these signs may not always be present.

Several studies confirmed that acute and chronic abdominal pain is one of the most common and sometimes frustrating consequences after bariatric surgery. Some authors reported that 15–30% of these patients will visit the emergency room or require admission within three years after the bariatric surgical procedure especially LRYGB [9].

Correlation between the anatomical reconstruction and physiological effects and long-term outcomes of different bariatric surgical procedures are not yet fully understood. The altered physiology of various organs dictates a critical assessment of the patient and knowledge of the altered physiological response. This enables earlier detection of complications after surgery and prompt action [10]

In several case series, the most common symptoms identified in diagnosing an anastomotic leak after LSG were abdominal pain, tachycardia, and fever [8, 9].

Rapid weight loss has been associated with internal hernia (IH). Geubbels et al. [11] retrospectively analyzed data on 1583 LRYGB patients presenting with an abdominal pain. Forty patients (2.5%) had IH at explorative laparoscopy. In addition, it was reported that the median time between LRYGB and first onset of IH symptoms was 9 months (range 0–32). Ninety percent of all IH developed within 20 months. Most patients presented with complaints at regular checkups at the outpatient clinic (60%). All patients presented with abdominal complaints, mostly with an acute onset (80%), cramping/colicky nature (65%), and located in the epigastrium (45%). Laboratory studies were performed in majority of the patients, but did not reveal any major pathology.

Santos et al. [12] analyzed 38 patients during the postoperative period of LRYGB who presented with clinical manifestations suggestive of IH after an average of 24 months following the bariatric procedure. All patients presented with pain, 23 presented abdominal distension, 10 had nausea and 12 had vomiting; three of them had dysphagia, three had diarrhea and one had gastroesophageal reflux. The patients had symptoms for an average (range) of 15 (3–50) days. Seventeen (45.9%) patients were seen once, while the other 20 (54.1%) went to the emergency room twice or more.

More than 70% of the patients choosing weight loss surgery were females in child-bearing age [13].

Weight loss improves fertility in women. Nevertheless, pregnancy after LRYGB can increase the risk of IH and intestinal obstruction from associated increased intra-abdominal pressure during pregnancy.

Dave et al. [14] carried out a systematic review, including 27 articles, with a total of 59 patients, regarding internal herniation during pregnancy after LRYGB and showed that epigastric pain, nausea, and vomiting were the most common symptoms. In terms of serum and blood laboratory tests, white blood count was found to be normal in 22 out of 32 (68.75%) reported cases. Serum lactate levels were also found to be normal in 18 out of 20 (90%) of reported cases.

Torres-Villalobos et al. [15] reported in a systematic review that small-bowel obstruction (SBO) in pregnant women presents with signs and symptoms that are commonly found during pregnancy. Vomiting is uncommon after LRYGB because there is no large reservoir to accumulate secretions. The lack of specific signs and symptoms in this group of patients may lead to delayed diagnosis and intervention with an increase in overall morbidity. The evaluation of the post-RYGB pregnant patients with abdominal pain should include a detailed history, physical examination, laboratory work-up, and imaging work-up. Early involvement by the bariatric surgeon optimizes clinical outcomes, but it is not always possible, especially at night.

The OBA survey [4] reported that acute care and emergency surgeons are not confident in managing patients with a previous history of bariatric surgical procedure because of insidious clinical features. This survey, based on the personal experience of 117 international acute care and emergency surgeons, showed that the most common symptoms in the emergency presentation were generalized abdominal pain, vomiting, localized abdominal pain, and abnormal stools transit.

Another on line survey [https://www.1ka.si/admin/survey/index.php?anketa=286953&a=data] was done on members of various surgical bariatric associations. They considered tachycardia to be the most sensitive sign associated with surgical complications after bariatric surgery in the early postoperative period, and as a clinical alarm to closely investigate emergency surgical long-term complications.

Moreover, the combination of fever, tachycardia, and tachypnea in the emergency setting was identified as a significant predictor of an anastomotic leak or staple line leak [16].

Clinical examination of patients with obesity can be unreliable due to body habitus and the absence of the classic signs of peritoneal irritation. This means that postoperative tachycardia should be taken as a serious warning sign of surgical complications after bariatric surgery [8]. The classic signs of peritoneal irritation are usually absent [17].

In the presence of fever, hypotension, tachycardia, tachypnea associated with hypoxia and decreased urine output, signs of shock, and multi-organ failure, a surgical exploration is mandatory without delay. Knowledge of the type of surgery performed may indicate the specific cause of septic complications [18].

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).

Discussion of evidence

Clinical examination of patients with a previous history of bariatric surgery presenting with acute abdomen is challenging because of faded clinical symptoms and often chronic abdominal pain. Nevertheless, a detailed history, physical examination, laboratory tests, and imaging modalities are mandatory in decision-making algorithm in emergency setting.

Concerning laboratory tests, the OBA survey reported that a combination of complete blood cell count, serum electrolytes, C-reactive protein (CRP), and procalcitonin (PCT) concentrations are advised in ED [4].

Several meta-analyses and systematic reviews confirmed that the CRP has a high predictive value for postoperative complications in the early postoperative period after abdominal surgery [19, 20]. Several meta-analyses confirmed the usefulness of CRP level in the early diagnosis of postoperative infectious complications after bariatric procedures [21, 22]. In addition, it was demonstrated that bariatric surgery patients with elevated postoperative CRP level are at increased risk for 30-day complications. The low sensitivity of a CRP ≥ 5 mg/dL suggests that a normal CRP level alone does not rule out the possibility of a postoperative complication. However, with its high specificity, there should be an elevated clinical suspicion of a postoperative complication in patients with a CRP ≥ 5 mg/dL [23]. Several studies indicated that CRP is a useful negative predictive test for the development of anastomotic leakage and in detecting abscess formation after LSG and colorectal surgery with remarkably higher sensitivity and specificity than WBC or neutrophil count [24, 25].

PCT levels increase in bacterial infections, rising early in the course of infection, making it a useful biomarker for decision making regarding initiation of antibiotic therapy and management of sepsis when the results of blood culture are not available. Several studies systematically evaluated the clinical value of PCT and CRP in the diagnosis of adult patients with sepsis which demonstrated a higher diagnosis accuracy and specificity of PCT than CRP [26, 27].

A cross sectional study [28] was conducted to compare the performance of PCT, CRP, leukocyte count and lactate levels compared to blood culture in critically ill patients admitted with suspicion of sepsis. One hundred-twenty six patients were studied and it was reported that leukocyte count, CRP and lactate levels were higher in blood culture positive patients but the difference was not significant despite finding that PCT had higher negative predictive value in ruling out bacterial infection.

PCT dosage has its own limitations. It is expensive compared to CRP and WBC, and may falsely rise in cases of acute respiratory distress syndrome, chemical pneumonitis and severe falciparum malaria [29]. Nevertheless, it may have an important role in guiding the antibiotic therapy decision making and de-escalation [30].

Ambe et al. [31] reported that leukocytosis was found in 31.25%, and elevated serum lactate levels in 10% of patients having gastrointestinal obstruction and internal herniation. Therefore, leukocytosis and elevated serum lactate should not be used as markers for internal herniation. An explanation of these findings could be that multi-visceral involvement and ischemia needs to occur to increase systemic lactate. Furthermore, the amount of released lactate from ischemic regions of the bowel needs to exceed the metabolic capacity of the liver through the Cori cycle [32, 33].

People undergoing bariatric surgery are at high risk of developing neurological, cognitive and mental disabilities and cardiovascular disease due to deficiency of vitamin B. Early detection is important to prevent complications including Wernicke encephalopathy, peripheral neuropathy and bariatric beri beri [34, 35]. Vitamin B12 could be administered orally, intra-muscularly, intranasal, intravenous. In the emergency setting, the IV administration is preferred.

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).

Discussion of evidence

An accurate and early diagnosis is the cornerstone of the management of all patients presenting with AAP. Misdiagnosis or delay in diagnosis in patients with a previous history of bariatric surgery can have lethal consequences.

The clinical examination could be notoriously unreliable in this group of patients who often had high weight loss after a bariatric surgical procedure (excess of skin and flaccid abdomen, the absence of guarding sign, and abdominal rigidity).

Experienced emergency surgeons are aware that close monitoring and early diagnostic surgical intervention are mandatory in the management of bariatric surgery patients having persistent abdominal pain, even if stable [4]. Diagnostic radiological preoperative accuracy may influence the timing of the surgical exploration, the surgical technique and the outcomes.

The OBA survey showed that radiological exams performed to assess the acute abdomen after bariatric surgery were very useful in the decision making. This included a plain abdominal X-ray (AXR) and a contrast-enhanced computed tomography (CT) for 41.9% (49/117) of emergency surgeons; an abdominal CT with gastrointestinal opacification for 41.9% (49/117) of emergency surgeons, and AXR in standing position and abdominal ultrasound (US) for 13.7% (16/117) of emergency surgeons [4]. The diagnostic value of imaging studies depends mostly on the careful interpretation of the new anatomical landmarks and on the knowledge of the potential complications following bariatric surgery.

AXR has a limited role when a CT scan is not available. It may reveal bowel distension or/and fluid levels. Specific indications for ordering a plain radiography in assessing acute include suspicion of perforated viscus, urinary tract stones, bowel obstruction, and an ingested foreign body [36].

Point-of-care ultrasound (POCUS) is useful in the evaluation of gallbladder pathology, acute appendicitis, free fluid, or intestinal distention.

The contrast-enhanced CT with oral contrast administration is the study of choice in patients with a previous history of bariatric surgery [37,38,39].

In several studies, the new radiological anatomy in this group of patients at CT was described. The administration of oral and IV contrast is fundamental to identify landmarks for the interpretation of findings [40,41,42,43,44,45]. If this is not possible in case of allergy to IV or oral hydrosoluble contrast or acute kidney failure, then laparoscopic exploration is mandatory due to the low sensitivity of radiological studies.

After LRYGB, the identification on CT of the gastric pouch, gastro-jejunal anastomosis, jejunal Roux limb, jejuno-jejunal anastomosis, and biliopancreatic limb is essential for detecting potential complications such as internal hernias (IH), small-bowel obstruction (SBO), anastomotic stenosis, perforation, and gastro-gastric fistula.

In LRYGB, oral contrast administered just prior to image acquisition helps to differentiate the gastric pouch and Roux limb from the excluded stomach and biliopancreatic limb, which are not opacified. The Roux limb should be followed along its antecolic or retrocolic course to the jejuno-jejunal anastomosis, typically in the left mid-abdomen. The excluded stomach should be visualized on CT images and is normally collapsed [41].

According to CT scan findings, SBO following LRYGB is classified based on the features of the Roux-alimentary limb, biliopancreatic limb and the involvement of the common distal channel [46].

Moreover, the abdominal CT is an important tool in diagnosing internal herniation, with a high specificity 87.1 (81.7–91.2) % and a high negative predictive value 96.8 (92.9–98.7) % [38].

Garza et al. [47] examined 1000 LRYGB patients for signs of internal hernia (IH). Of the 34 patients that had an IH, 22 (64%) had signs of IH in the CT scan.

Geubbels et al. [11] reported that 40% of the IH patients had signs of an IH on CT scanning. Therefore, a negative CT scan should not rule out an IH.

Agaba et al. [48] suggested that the work-up for LRYGB patient presenting with abdominal complaints should be as follows: Those presenting with acute signs of SBO (vomiting, acute abdomen) should be considered a surgical emergency and require immediate diagnostic laparoscopy. A low threshold for elective re-laparoscopy should be set for these patients to prevent small-bowel ischemia. The algorithm presented by Agaba et al. included an abdominal CT.

After LSG, CT scan is the best radiological exam to diagnose abscesses, perforations, staple line dehiscence, and other complications such as splenic injury or infarction [41].

Alharbi et al. [49] retrospectively analyzed data of 152 consecutive patients who underwent CT for suspected post-SG gastric leak and reported that CT findings sensitivity and specificity of perigastric collection without oral contrast leak were 61% and 88.8%, for oral contrast leak were 28% and 100%, and for gas leak were 10% and 77.7%, respectively. Therefore, indirect sign such as perigastric fluid collection without contrast leak and with variable wall enhancement and extra-luminal gas are the most common CT findings of post-sleeve gastrectomy gastric leak.

In pregnant women with a history of bariatric surgery, US and magnetic resonance imaging (MRI) are preferred to assess acute abdominal pain with the aim of limiting radiation exposure to the embryo or fetus.

Specific sonographic findings associated with SBO include diameter of the small bowel > 25 mm, small-bowel wall edema, “to and fro” peristalsis, free intra-abdominal fluid, and the presence of a sonographic transition point (defined as the location between dilated small bowel proximal to the obstruction and decompressed small bowel distal to the obstruction) despite the gravid uterus [50].

MRI may be considered an alternative to CT which eliminates the risk of radiation exposure of the embryo or fetus. One of the limitations of MR imaging is the use of gadolinium. The current American College of Radiology guidance document for safe MRI practices suggests that MRI contrast agents should not be routinely used in pregnant patients and this decision should be made on a case by case basis accompanied by a risk–benefit analysis. The restricted availability of MRI imaging limits its utility in the emergency setting [51,52,53,54].

The radiation exposure of a CT scan is a major concern and the risks and benefits should be evaluated. The absolute risks of fetal effects, are small at doses of 100 mGy and negligible at doses of less than 50 mGy [55]. CT examinations of the abdomen and pelvis rarely exceed 25 mGy. Because the dose from a single-acquisition CT examination of the abdomen and pelvis poses a small risk to fetal health, CT may be appropriate depending on the clinical situation [15,16,17,18,19,20,21,22,23,24,25,