Obesity is one of the most significant health problems worldwide, and the prevalence has been increasing over the past decade. Despite improvement in the performance of bariatric surgery, complications are not uncommon. These complications vary according to baseline patient characteristics, the duration of time since the operation, and the type of bariatric surgery performed. Endoscopy is the cornerstone in the diagnosis of postoperative complications after bariatric surgery, and may even be performed in the early postoperative course. With an increasing number of patients being referred for endoscopic evaluation following bariatric surgery, it is essential to develop an understanding of the anatomic changes for optimal assessment and appropriate treatment of these patients.
Early and late dumping syndrome occurs not uncommonly in patients who have undergone gastric bypass surgery when large quantities of simple carbohydrates are ingested. Early dumping typically occurs within 15 minutes of ingestion and has been attributed to rapid fluid shifts from the plasma into the bowel from hyperosmolality of the food. Late dumping occurs hours after eating and results from hyperglycemia and the subsequent insulin response leading to hypoglycemia. When hypoglycemia is severe, treatment with a low carbohydrate diet and an alphaglucosidase inhibitor may be effective. Furthermore, restoration of gastric restriction using an endoscopic approach to reduce the aperture of the GJA has also demonstrated to be effective in management of this condition.
The initial management of dumping syndrome is dietary modifications. Recommendations include consuming smaller meals by dividing daily calorie intake into six meals and delaying liquids at least 30 min after meals Rapidly absorbable simple carbohydrates should also be avoided. Adjuncts to diet modification include pectin and guar gum, which slow down gastric emptying by increasing food viscosity. Acarbose, which interferes with carbohydrate absorption in the small intestines, has also proven to relieve symptoms in small studies. After dietary modifications, medications such as somatostatin analogs (e.g., octreotide) alleviate symptoms by delaying gastric emptying and small bowel transit time, as well as inhibiting gastric hormones and insulin secretion. Multiple studies have evaluated both short- and longterm somatostatin therapies, with results showing sustained symptom control in patients refractory to dietary modifications. In severe cases refractory to medical management, surgical interventions, such as narrowing of the anastomosis, conversion of the prior bariatric surgery, and using jejunostomy parenteral feeding, may help. Follow-up with gastrointestinal specialists and the patient’s bariatric surgeon is strongly recommended if dumping syndrome is suspected.
An important metabolic complication which is attracting increasing interest is postprandial hyperinsulinemic hypoglycemia (PHH), characterized by hypoglycemic symptoms developing 1–3 h after a meal accompanied by a low blood glucose level. This condition should be distinguished from early dumping syndrome where symptoms develop within minutes to 1 h after a meal of caloric dense food, caused by the rapid and unregulated emptying of food into the jejunum, which induces rapid fluid entry into the small bowel. Early dumping often occurs early in the postoperative period, most commonly after Roux-en-Y gastric bypass, whereas PHH may develop months to years after surgery.
Symptoms related to post-PHH usually develop late after surgery in contrast to early dumping. Symptoms are wide ranging, but are usually related to Whipple’s triad: symptomatic hypoglycemia, a low plasma glucose level, and resolution of symptoms after the administration of glucose. Symptoms of hypoglycemia may include anxiety, sweating, tremors, palpitations, confusion, weakness, lightheadedness, dizziness, blurred vision, disorientation, and possibly loss of consciousness.
Because of variability in degree of symptoms and the absence of a clear pathophysiology, management of this condition can be challenging. Fortunately, a significant percentage of patients with milder forms of the condition can be managed with dietary modifications consisting of frequent small meals with a low glycemic index. This requires supervision by a dietitian and long-term patient compliance. Additional benefit has been obtained by the addition of acarbose, an α glucosidase inhibitor in doses 100–300 mg. Successful management has been also reported in case reports or small case series with diazoxide, calcium channel blockers, and somatostatin analogues. The role of GLP-1 in the pathogenesis of this condition is supported by the observation that infusions of GLP-1 antagonists corrected hypoglycemia in these patients. These agents are investigational at present, but provide opportunity for additional future treatment approaches. For patients with persistent symptoms despite medical treatment, reversal of the bariatric procedure should be considered. Partial pancreatectomy, although used in the past, is now not recommended because of the significant morbidity and poor long-term symptom control. Postprandial hyperinsulinemic hypoglycemia is an important, potentially dangerous late complication of metabolic surgery. Successful diagnosis and management of this condition requires multidisciplinary specialty resources and essential long-term follow-up capabilities.