Gastrointestinal Conditions: Acute Infectious Gastroenteritis and Colitis.

Gastroenteritis is inflammation of the stomach and intestines; colitis is inflammation of the colon. Viruses are the most common cause, followed by bacteria and parasites. Incidence of the various infections varies by age, sex, location, and vaccine availability; vaccination has reduced rotavirus infections by as much as 90% in children. Postinfectious complications include irritable bowel syndrome (IBS) and lactose intolerance. Approximately 9% of patients with acute gastroenteritis or colitis develop postinfectious IBS, which accounts for more than 50% of all IBS cases. The diagnostic approach to gastroenteritis and colitis varies with symptom severity. Microbial studies are not needed with mild symptoms that resolve within a week, but longer-lasting or more severe symptoms (including bloody stool) warrant microbial studies. In addition, recent antibiotic exposure should prompt testing for Clostridioides difficile. Multiplex antimicrobial testing is preferred; stool cultures and microscopic stool examinations are no longer first-line tests. Management depends on severity. Patients with mild or moderate symptoms are treated with oral hydration if tolerated; nasogastric or intravenous hydration are used for those with more severe illness. In addition, antiemetic, antimotility, and/or antisecretory drugs can be used for symptom control. Antimicrobial therapy is indicated for C difficile infections, travel-related diarrhea, other bacterial infections with severe symptoms, and parasitic infections.

Gastrointestinal Conditions: Pancreatitis.

Acute pancreatitis is among the most common gastrointestinal disorders requiring hospitalization. The main causes are gallstones and alcohol use. Patients typically present with upper abdominal pain radiating to the back, worse with eating, plus nausea and vomiting. Diagnosis requires meeting two of three criteria: upper abdominal pain, an elevated serum lipase or amylase level greater than 3 times the normal limit, and imaging findings consistent with pancreatitis. After pancreatitis is diagnosed, the Atlanta classification and identification of the systemic inflammatory response syndrome can identify patients at high risk of complications. Management includes fluid resuscitation and hydration maintenance, pain control that may require opioids, and early feeding. Feeding recommendations have changed and "nothing by mouth" is no longer recommended. Rather, oral feeding should be initiated, as tolerated, within the first 24 hours. If it is not tolerated, enteral feeding via nasogastric or nasojejunal tubes should be initiated. Antibiotics are indicated only with radiologically confirmed infection or systemic infection symptoms. Surgical or endoscopic interventions are needed for biliary pancreatitis or obstructive pancreatitis with cholangitis. One in five patients will have recurrent episodes of pancreatitis; alcohol and smoking are major risk factors. Some develop chronic pancreatitis, associated with chronic pain plus pancreatic dysfunction, including endocrine failure (insulin insufficiency) and/or exocrine failure that requires long-term vitamin supplementation.

Gastrointestinal Conditions: Gastroesophageal Reflux Disease.

Gastroesophageal reflux disease (GERD) affects more than 20% of adults. Risk factors include older age, obesity, smoking, and sedentary lifestyle. Lower esophageal sphincter (LES) dysfunction is a primary cause. Classic symptoms include heartburn and regurgitation. With classic symptoms, proton pump inhibitors (PPIs) can be prescribed without further testing; PPIs should be taken on an empty stomach. Patients with atypical symptoms and those not benefiting from management should undergo esophagogastroduodenoscopy (EGD), and potentially pH and impedance testing to confirm GERD or identify other conditions. This is important because GERD increases risk of esophageal erosions/stricture, Barrett esophagus, and esophageal adenocarcinoma. However, a large percentage of adults taking PPIs have no clear indication for treatment, and PPIs and other antisecretory therapy should be tapered off if possible. Of note, vonoprazan, a new drug approved by the Food and Drug Administration (FDA), has shown superiority to PPIs. In addition to pharmacotherapy, lifestyle changes are indicated, including losing weight if overweight, not lying down after meals, and ceasing tobacco use. Procedural interventions, including fundoplication and magnetic sphincter augmentation, can be considered for patients wishing to discontinue drugs or with symptoms unresponsive to PPIs. Procedural interventions are effective for the first 1 to 3 years, but effectiveness decreases over time.

Gastrointestinal Conditions: Peptic Ulcer Disease.

Peptic ulcer disease (PUD) involves ulceration of the mucosa in the stomach and/or proximal duodenum. The main causes are Helicobacter pylori infection and nonsteroidal anti-inflammatory drug (NSAID) use. PUD occurs in 5% to 10% of people worldwide, but rates have decreased by more than half during the past 20 years. This reduction is thought to be because of H pylori management, more conservative use of NSAIDs, and/or widespread use of proton pump inhibitors (PPIs). Common symptoms include postprandial abdominal pain, nausea, vomiting, and weight loss. These symptoms have broad overlap with those of other conditions, making clinical diagnosis difficult. Endoscopy is the gold standard for diagnosis, especially in older patients and those with alarm symptoms, but a test-and-treat strategy (noninvasive test for H pylori and treat if positive) can be used for younger patients with no alarm symptoms. Numerous treatment regimens are available, all of which include PPIs plus antibiotics. As an alternative to PPIs, a new triple therapy with vonoprazan (which blocks acid production) plus antibiotics has been approved and appears to be superior to conventional therapy with PPIs plus antibiotics. At least 4 weeks after treatment, repeat testing for H pylori should be obtained to confirm cure. When possible, NSAIDs should be discontinued; when not possible, antisecretory cotherapy should be considered.