Seminars in gastrointestinal disease最新文献

The management of severe ulcerative colitis and Crohn's colitis remains a challenge, despite significant advances in medical and surgical therapy. Optimal management of the patient with severe colitis requires close collaboration between the gastroenterologist and surgeon. All patients with severe colitis should be hospitalized and treated with intravenous corticosteroids. If significant improvement does not occur within 7 to 10 days, then intravenous cyclosporine therapy or surgery is appropriate. Newer medical therapies, including heparin, tacrolimus, and other immunomodulatory agents, show promise for the treatment of severe colitis. When surgery is necessary, a total abdominal colectomy with ileostomy is the appropriate surgical intervention in most cases. In patients presenting with fulminant colitis, toxic megacolon, or perforation, earlier surgical intervention is indicated. The evaluation of and approach to the medical and surgical management of severe colitis will be reviewed.

Crohn's disease is a panenteric, transmural inflammatory disease of unknown origin. Although primarily managed medically, 70% to 90% of patients will require surgical intervention. Surgery for small bowel Crohn's is usually necessary for unrelenting stenotic complications of the disease. Fistula, abscess, and perforation can also necessitate surgical intervention. Most patients benefit from resection or strictureplasty with an improved quality of life and remission of disease, but recurrence is common and 33% to 82% of patients will need a second operation, and 22% to 33% will require more than two resections. Short-bowel syndrome is unavoidable in a small percentage of Crohn's patients because of recurrent resection of affected small bowel and inflammatory destruction of the remaining mucosa. Although previously a lethal and unrelenting disease with death caused by malnutrition, patients with short-bowel syndrome today can lead productive lives with maintenance on total parenteral nutrition (TPN). This lifestyle, however, does not come without a price. Severe TPN-related complications, such as sepsis of indwelling central venous catheters and liver failure, do occur. Future developments will focus on more powerful and effective anti-inflammatory medication specifically targeting the immune mechanisms responsible for Crohn's disease. Successful medical management of the disease will alleviate the need for surgical resection and reduce the frequency of short-bowel syndrome. Improving the efficacy of immunosuppression and the understanding of tolerance induction should increase the safety and applicability of small-bowel transplant for those with short gut. Tissue engineering offers the potential to avoid immunosuppression altogether and supplement intestinal length using the patient's own tissues.

The causes of chronic malabsorption may be categorized as decreased intestinal absorption, most commonly caused by celiac sprue; or maldigestion caused by pancreatic insufficiency. The initial step in the evaluation of these patients should include stool studies to confirm fat malabsorption. If fat malabsorption is confirmed, endoscopy with small-bowel biopsies and aspirates for bacterial culture usually follows. A normal endoscopic examination should lead to assessment of pancreatic function. In the setting of normal pancreatic function and the absence of bile acid deficiency, a barium radiograph of the small bowel should be made, looking for anatomical abnormalities. Celiac sprue is an intolerance to gluten caused by a combination of genetic, environmental, and immunologic factors. It classically causes malabsorption. However, it is likely that many patients who exhibit only minor manifestations of the disease go unrecognized and untreated. A presumed diagnosis of celiac sprue is confirmed after a clinical and endoscopic response to a gluten-free diet. Serological markers are available with high degrees of sensitivity and specificity, but duodenal biopsy remains the gold standard for diagnosis. A minority of patients are unresponsive to a gluten-free diet, and intestinal lymphoma should be suspected in these cases.

The clinical example is one of diarrhea induced by the surreptitious use of laxatives. A 45-year-old man had a 3-year history of diarrhea, which had been fully investigated, without a cause having been identified. His general health appeared to be affected little, but he had the clinical features of an associated depressive illness. The diagnosis of laxative abuse was supported by the finding of abnormally high concentrations of magnesium in fecal water. He admitted initially, and later denied, the surreptitious ingestion of laxatives. This example is discussed with regard to features that were typical and atypical of the syndrome of laxative abuse. The significant points to be appreciated are 1) that any chronic, watery diarrhea that has eluded diagnosis after an adequate investigation is possibly self-induced, and 2) that awareness of this syndrome and its prevalence in selected cohorts can lead to direct and inexpensive documentation of the diagnosis.

Eight different neoplastic disorders can cause chronic diarrhea attributable to humoral-mediated diarrhea. These include pancreatic endocrine tumor (PET) syndromes (gastrinomas, VIPomas, glucagonomas, somatostatinomas, PET's releasing calcitonin), carcinoid syndrome, medullary thyroid cancer, and systemic mastocytosis. Because these disorders are an uncommon cause of all chronic diarrheas (<1%), they are not often considered in the differential diagnosis, leading to a delay in diagnosis. This is problematic not only because all are treatable, but also because the neoplasm is frequently malignant. In this article, the characteristics and pathogenesis of the diarrhea, important clinical and diagnostic laboratory features, and treatment of each disorder are briefly reviewed, with an emphasis on recent insights.

Microscopic colitis is a syndrome consisting of chronic watery diarrhea, a normal or near-normal gross appearance of the colonic lining, and a specific histological picture described as either lymphocytic colitis or collagenous colitis. Since its initial descriptions a quarter of a century ago, microscopic colitis has become a frequent diagnosis in patients with chronic diarrhea. Understanding of the cause and pathogenesis of microscopic colitis remain incomplete, but potentially important clues have been discovered that shed light on predisposing factors. In particular, specific HLA-DQ genotypes may be permissive for the development of microscopic colitis, and suggest a linkage to the pathogenesis of celiac sprue. Although the differential diagnosis of chronic watery diarrhea is broad, the diagnosis of microscopic colitis is straightforward, involving endoscopic inspection of the colonic mucosa and proper pathologic interpretation of biopsy specimens. As the limitations of drugs ordinarily used for other forms of inflammatory bowel disease are being recognized, new approaches, such as the use of bismuth subsalicylate, are being evaluated. The prognosis of patients with microscopic colitis syndrome remains good, and symptomatic improvement can be expected in most patients.

The role of surgical therapy in the management of gastroesophageal reflux disease (GERD) continues to evolve in the laparoscopic era. As the number of surgical procedures increases, so does the number of patients with postfundoplication complications. The most effective strategy is to prevent the complication in the first place. Patients who are most likely to have trouble after surgery are those with refractory, atypical, or complicated disease. Gastroenterologists should take care to make an accurate diagnosis, heal the esophagitis, and dilate any strictures before sending a patient to surgery. The surgeon should be a skilled laparoscopist. In patients with complicated GERD, the surgeon must be able to recognize severe disease and perform advanced procedures. Postoperatively, symptoms are usually the same (suggesting a failure of the operation or incorrect original diagnosis) or different (suggesting a complication) than before surgery. Most patients should have a barium swallow and an endoscopy to evaluate the integrity of the wrap. If intact, postoperative heartburn and dysphagia will usually resolve with conservative therapy. If the fundoplication is poorly oriented, too long, too tight, twisted, or herniated above the diaphragm, surgical revision is often necessary.

The esophagus is one of the most common sites of gastrointestinal involvement in human immunodeficiency virus (HIV)-infected patients, with at least 30% of the patients having esophageal symptoms at some point during the course of HIV infection. Esophageal ulcers are commonly caused by infections such as cytomegalovirus (CMV) or may be idiopathic. The clinical presentation of the various causes of esophageal ulcers are similar; therefore, a thorough endoscopic and histological workup is imperative to make a diagnosis and, consequently, to provide appropriate therapy. The widespread use of more effective antiretroviral therapy appears to have led to a decline in gastrointestinal opportunistic disorders in patients with acquired immunodeficiency syndrome (AIDS), including those involving the esophagus. Unfortunately, there are several reports of resistance of HIV-1 to multiple antiretroviral agents, and thus it is possible we will observe an increase in various opportunistic disorders again. The aim of this article is to provide a practical approach to the clinical, endoscopic, and histopathologic evaluation of esophageal ulcers in patients with AIDS.

Achalasia is a primary esophageal motor disorder of unknown cause that produces complaints of dysphagia, regurgitation, and chest pain. The current treatments for achalasia involve the reduction of lower esophageal sphincter (LES) pressure, resulting in improved esophageal emptying. Calcium channel blockers and nitrates, once used as an initial treatment strategy for early achalasia, are now used only in patients who are not candidates for pneumatic dilation or surgery, and in patients who do not respond to botulinum toxin injections. Because of the more rigid balloons, the current pneumatic dilators are more effective than the older, more compliant balloons. The graded approach to pneumatic dilation, using the Rigiflex (Boston Scientific Corp, Boston, MA) balloons (3.0, 3.5, and 4.0 cm) is now the most commonly used nonsurgical means of treating patients with achalasia, resulting in symptom improvement in up to 90% of patients. Surgical myotomy, once plagued by high morbidity and long hospital stay, can now be performed laparoscopically, with similar efficacy to the open surgical approach (94% versus 84%, respectively), reduced morbidity, and reduced hospitalization time. Because of the advances in both balloon dilation and laparoscopic myotomy, most patients with achalasia can now choose between these two equally efficacious treatment options. Botulinum toxin injection of the LES should be reserved for patients who can not undergo balloon dilation and are not surgical candidates.