Leaks occur with a reported incidence of 0–8 % in different series of laparoscopic BPD [31, 41–43]. Leaks are a serious source of morbidity and are a leading cause of mortality after bariatric procedures. Leakage has been implicated in mortality in up to 29 % of deaths after bariatric surgery [23]. Despite advancements in supportive care, mortality after intra-abdominal leakage is often due to delayed diagnosis, so a high index of suspicion allows for early detection and timely intervention.

Leaks at any staple or suture line can result from technical factors at the time of surgery. Such factors may include any or all of the following: division of blood supply during dissection, anastomotic tension, tissue injury from poor handling with laparoscopic instruments, or stapler misuse or malfunction. In a BPD ± DS, anastomotic leaks can occur at the following areas: (1) the gastric staple or suture line, (2) the gastroileostomy (Scopinaro procedure) or the duodenoileostomy (BPD-DS), (3) the duodenal stump, or (4) the ileoileostomy. Leaks, however, have also resulted from small bowel injuries due to intestinal handling with graspers during laparoscopic surgery, and this source of peritonitis should be considered when evaluating or treating postoperative patients.

The most common and serious site of leakage after a BPD ± DS is from the gastroileostomy/duodenoileostomy. The foot anastomosis, or ileoileostomy, leaks infrequently. When leakage occurs at this site, however, it tends to be high in output and associated with rapid deterioration of the patient, leading to potentially higher morbidity and mortality. In the BPD-DS with sleeve gastrectomy, another important (and often difficult to manage) area of leakage is the gastric staple line.

A leak can be immediate or may present up to 1–2 weeks postoperatively. A negative intraoperative leak test and an UGI swallow on the first postoperative day, if performed, offer some reassurance regarding the integrity of the upper anastomosis in a BPD, but these tests can be falsely negative, and a leak from ischemia at an anastomosis may take some time to manifest. We do not routinely perform an UGI swallow postoperatively in our patients after a BPD-DS. In addition, we do not routinely place drains intraoperatively. However, if a functioning drain had been appropriately positioned at the time of surgery, a change in the character of the drainage or an elevated amylase content of the drain fluid may be the first and only sign of anastomotic disruption in an otherwise well appearing patient.

Diagnosing postoperative peritonitis is often difficult in obese patients, and this is more so in the early postoperative state where pain and other cardiopulmonary conditions can cloud the presentation. Although fever, tachycardia, and abdominal pain are common, often the only sign is tachycardia in the absence of classic peritoneal signs such as guarding and rebound tenderness. A heart rate greater than 120 beats/min should alert the evaluating clinician to consider a leak, even if the patient feels and looks well [44]. Tachycardia alone, however, may not be a reliable early indicator of leakage [45]. A proximal gastric leak often results in left shoulder pain on deep inspiration. This is a sign of diaphragm irritation mediated by the phrenic nerve (C3–C5) and referred to the shoulder region (Kehr’s sign). Computed tomography (CT) can be very useful in all patients with unexplained tachycardia, fever, or abdominal pain after BPD ± DS. If a CT scan is unavailable, emergency re-laparoscopy should be offered for diagnosis and timely management.

Gastric leaks in a BPD-DS procedure tend to occur high on the neo-greater curve of the stomach near the GE junction, resulting in a perigastric collection or subphrenic abscess. Their treatment depends on the timing of presentation and patient stability [46]. Late gastric leaks are often more difficult to resolve than early ones, and to date a generally accepted algorithm for the management of gastric leaks is yet to be described [47]. Surgical or percutaneous drainage of leaks presenting in the early postoperative course is needed. In select stable patients, contained leaks can be managed nonoperatively with adequate percutaneous drainage, bowel rest, total parenteral nutrition, and antibiotics. A nasojejunal gavage tube may be temporarily utilized for nutritional support. When leaks are not contained, diffuse peritonitis results; and if left untreated, sepsis will follow with possible multisystem organ failure. Surgical treatment, on the other hand, involves early reoperation, copious irrigation, and wide drainage, while suture repair is avoided or reserved for cases where tissue is clearly amenable to manipulation without increasing the risk of further damage [48]. Omental patching may be helpful, but the key is effective drainage. For large gastric or upper anastomotic leaks requiring surgical drainage for sepsis, a jejunal feeding tube is best placed at the time surgery in the biliopancreatic limb for nutritional support. The feeding tube allows for outpatient management before complete healing of the leak site is achieved. For early leaks, endoscopically placed covered stents may be utilized to allow early oral intake, reduced hospitalization, and promote tissue healing [49, 50]. Any endoscopic treatment modality must be an adjunct to adequate drainage and broad-spectrum antibiotic therapy, as clinically indicated, along with appropriate nutritional support. For a late leak, which often manifests as a subphrenic abscess, percutaneous drainage is first performed. If the fistula does not heal after a few weeks (which is often the case), endoscopic placement of clips, stents, sutures, and glue products may be appealing options but are often unsuccessful. Eventually, surgical intervention may be required to treat chronic persistent fistulas. Many approaches have been attempted with varying success: (a) placement of a gastrostomy tube through the leak site, (b) a serosal patch with the small intestine pulled up to cover the leak, (c) a Roux-en-Y pull-up of the small bowel anastomosed to the leak site, (d) conversion from sleeve to gastric bypass with resection of the leak area, (e) a gastric seromyotomy, or (f) resection of the gastric sleeve with an esophagojejunostomy [51–53].

Pulmonary embolism is another common cause of mortality after bariatric surgery, and death from this condition can occur after discharge from hospital. Because of the type of resection and reconstruction involved in BPD ± DS, operative times are longer than other commonly performed bariatric procedures. Long times on the table and prolonged postoperative immobilization, along with the underlying state of obesity, place morbidly obese patients at elevated risk of deep venous thrombosis (DVT). The incidence of pulmonary emboli after bariatric surgery is about 1 %. A recent outcome study from the Michigan collaborative group establishes a baseline for the incidence of venous thromboembolic complications following bariatric surgery in recent years. In their multicenter review, the Michigan group reported that the prevalence of DVT not accompanied by pulmonary embolism (PE) was 6,480 events in 508,230 bariatric cases (1.3 %), and venous thromboembolism (VTE), either PE or DVT, occurred in 10,980 of 508,230 (2.2 %). The prevalence of PE was 0.9 %. The reported in-hospital mortality among patients with PE was 130 of 508,231 (0.03 %) in the same study [54].

Patients with a PE may become hypotensive and tachycardic with signs similar to those of sepsis. Nevertheless, in patients with signs of sepsis and hypoxia, the diagnosis of a PE and leak should be simultaneously considered, and appropriate imaging studies to guide diagnosis and treatment should be ordered promptly. An angio-CT of the thorax and a CT scan of the abdomen with oral contrast are helpful. In patients whose body size precludes them from undergoing diagnostic spiral CT imaging, a pulmonary V/Q scan may be helpful; but serious consideration should be given to immediate exploration in the operating room. If no intra-abdominal pathology is found at surgery, therapeutic anticoagulation can be initiated thereafter on clinical grounds.

Early ambulation is the key element of VTE prophylaxis. Difficult cases expected to require prolonged operative times due to poor exposure and difficult dissection are either better staged laparoscopically or converted to open to avoid unnecessary time on the OR table just to complete the procedure under laparoscopy. Sequential compression devices are used intraoperatively and in the early postoperative period to decrease VTE risk. This is often done in addition to pharmacologic prophylaxis with an appropriate dose of low molecular weight heparin (LMWH). It is our practice to discharge patients on subcutaneous LMWH injections for 20 additional days at a dose of 7,500 units of dalteparin.

To date, there are no high quality data favoring one DVT prophylaxis approach over another. In early 2013, the American Society for Metabolic and Bariatric Surgery (ASMBS) Clinical Issues Committee released its recommendations for VTE prophylaxis [55]. The committee considers all bariatric surgery patients as being at elevated risk for VTE. Factors that increase risk include high BMI, advanced age, immobility, prior VTE, known hypercoagulable condition, hormonal therapy, expected long operative time or open approach, and male gender. In the absence of evidence supporting any one regimen for VTE prophylaxis and recognizing that the risk cannot be completely eliminated, the committee recommended that individual bariatric practices should develop and adhere to a protocol for prophylaxis to reduce the risk of thromboembolic disease. While mechanical compression devices and early postoperative ambulation are encouraged, the combination of mechanical prophylaxis and chemoprophylaxis is to be considered based on clinical judgment and risk of bleeding. Although there is some low-level evidence to support using only mechanical prophylaxis, the weight of the data supports using a combination of chemoprophylaxis and mechanical prophylaxis in bariatric patients to lower overall VTE rates to less than 0.5 %. In the absence of contraindications, extended post-discharge VTE prophylaxis for patients deemed to be at high risk should be considered; evidence to support a dose and duration of therapy remains lacking, however.

Bleeding is not an infrequent complication after laparoscopic BPD ± DS surgery. It is often self-limited, and life-threatening hemorrhage is rare. In a series of 1,000 patients, gastrointestinal hemorrhage after BPD-DS was reported at a rate of 0.5 % [31]. Higher rates, however, have been reported after laparoscopic bariatric procedures involving anastomoses [56]. Bleeding can occur at port sites, intra-abdominally, or intraluminally in the gastrointestinal tract. Intraoperative and postoperative bleeding can be minimized and prevented with measures that include deliberate port placement and removal techniques, careful dissection, and appropriate utilization of energy sources for controlling blood vessels.

Carefully placed single absorbable stitches are recommended to close laparoscopic port sites greater than 10 mm in size, and all port sites should be removed under vision at the end of the procedure. Postoperatively, any significant port site bleed will either result in discoloration around the port site on the first or second postoperative day or abdominal pain with or without hypotension or a drop in hemoglobin (Hb). If a port site bleeds intra-abdominally, a hematoma requiring surgical evacuation may result. A postoperative drop in Hb associated with bruising around a port site or abdominal pain may indicate a significant bleed, but such bleeds are often self-limited and do not require a transfusion.

The gastrosplenic area can pose a hemostatic challenge, especially in cases where the gastric fundus is large, posterior, and sometimes closely intimate with the spleen near its upper pole. Bleeding from short gastric vessels or the splenic capsule can be difficult to control. It is best to avoid bleeding in this area by carefully using laparoscopic energy sources such as ultrasonic or bipolar devices with the judicious aid of metallic clips.

After performing a sleeve gastrectomy in a BPD-DS, the long staple line on the vascular stomach is prone to bleeding, and this can be exacerbated by subcutaneous heparin. Oozing from the staple line can be controlled with clips or suturing. Some surgeons use suture or biosynthetic strips to reinforce the gastric staple line and reduce hemorrhage [57, 58]. Fortunately, staple-line bleeding is usually self-limited, but any large intra-abdominal hematomas resulting from such bleeds may require evacuation to reduce the risk of gastric obstruction and/or leak formation due to a compressive effect of a large hematoma and to facilitate recovery and discharge from hospital.

Postoperative bleeding may cause tachycardia, hypotension, oliguria, persistent hypothermia, a decrease in hematocrit (late sign), or possibly blood collecting in the drains placed at the time of surgery. Intraluminal gastrointestinal hemorrhage can present with hematemesis or melena. The source can be from the gastric mucosa or the upper or lower anastomosis. Upper endoscopy may enable direct visualization and coagulation of the bleeding point. Managing hemorrhage after bariatric surgery depends on the cause and persistence of bleeding, and sometimes endoscopy or surgical exploration is needed for definitive diagnosis and treatment [59]. Bleeding at the mesentery can occur but is often self-limited. It may, however, contribute to a prolonged postoperative ileus or an early small bowel obstruction.

BPD ± DS can result in surgical complications long after the procedure is performed. With appropriate recognition and management, these potential complications can be resolved without significant morbidity or mortality. Common delayed gastrointestinal complications after BPD ± DS include marginal ulcers, anastomotic stenosis, intestinal obstruction, dumping syndrome, cholelithiasis, changes in bowel habits, and intestinal bacterial overgrowth.