Parasites of the small intestine

This paper discusses the most important parasites that inhabit the human small intestine. Beginning with the protozoa and proceeding through the various species of cestodes, nematodes, and trematodes that inhabit the human small bowel, the most important organisms are presented. Possible future developments are discussed along with pathophysiology and treatment in this phylogenic approach. Zoonotic illnesses, those diseases that by their rarity are of little import, and diseases without significant clinical or social implications are beyond the scope of this article and are not discussed.     

Stents in the small intestine

Stents represent an exciting development in the field of gastroenterology. Their use to maintain luminal patency in the pancreatobiliary system has been well established. Stents have also found a place in maintaining the patency of the esophagus. Recent developments have led to an increasing role for their use to decompress both the small and large intestine. In the small intestine they are often placed to palliate proximal obstruction in the duodenum or the very proximal jejunum resulting from various malignancies. Self-expandable metal stents are an attractive alternative to surgery, especially in patients with compromised performance status, and can be done safely as outpatient procedures. However, one should be aware of the associated risks and complications. With a proper understanding of the principles involved in stent placement one can safely undertake this procedure.     

Neoplasms of the small intestine

Our experience with small intestinal neoplasms at the Medical College of Virginia has been reviewed. There were 78 benign and malignant neoplasms observed in our surgical pathology laboratory over a 20-year period. There were 34 benign small-bowel tumors, but the majority of these lesions were asymptomatic incidental findings at the time of surgery for other conditions. There were 21 patients with malignant neoplasms of the small bowel and 23 patients with carcinoid, a potentially malignant lesion. Clinical observations and the results of treatment are reviewed.Clinical Fellows of the American Cancer Society.     

Diverticulosis of the small intestine

Seven patients with small-intestinal diverticulosis were studied by means of intestinal absorptive tests, biopsies, and bacterial cultures of small-intestinal aspirates. Aerobic bacterial cultures were obtained in all patients, while anaerobic cultures with a modified Hungate roll-tube technic were performed in 3. Three of the patients manifested steatorrhea and were studied over prolonged periods of time. The bacterial flora varied over a wide quantitative range, with highest total counts in excess of 10⁹ colony-forming units per milliliter found in the 2 patients with the most severe malabsorption. Despite multiple diverticulosis, 1 patient without steatorrhea had no recoverable aerobic or anaerobic bacterial flora. E. coli predominated among the recovered aerobic organisms in this series, but A. aerogenes and various streptococci also were encountered repeatedly. Patients treated with antibiotics directed at the aerobic flora showed prompt improvement in absorption, and reduction in bacterial counts. Repeated short courses of antibiotics were needed to treat early bacteriologic and clinical relapses. After several such courses, all 3 patients treated maintained their clinical and metabolic improvement for periods of close observation ranging from 2 to 15 months without additional antibiotic treatment, and the clinical remissions were accompanied by gradual reductions in total bacterial counts to “borderline normal” limits. Of the 3 patients, 1 has now been followed for 5 years without relapse. It is apparent that the mere presence of diverticulosis does not lead necessarily to malabsorption. Malabsorption of fat, Vitamin B₁₂, and other nutrients was found only in patients with excessive bacterial flora, emphasizing the crucial role bacteria play in the pathogenesis of malabsorption in diverticulosis of the small intestine.     

Parasites of the small intestine

This paper discusses the most important parasites that inhabit the human small intestine. Beginning with the protozoa and proceeding through the various species of cestodes, nematodes, and trematodes that inhabit the human small bowel, the most important organisms are presented. Possible future developments are discussed along with pathophysiology and treatment in this phylogenic approach. Zoonotic illnesses, those diseases that by their rarity are of little import, and diseases without significant clinical or social implications are beyond the scope of this article and are not discussed.     

Adenocarcinoma of the small intestine

Opinion statement  

Sonography of the small intestine

In the last two decades, there has been substantial development in the diagnostic possibilities for examining the small intestine. Compared with computerized tomography, magnetic resonance imaging, capsule endoscopy and double-balloon endoscopy, ultrasonography has the advantage of being cheap, portable, flexible and user- and patient-friendly, while at the same time providing the clinician with image data of high temporal and spatial resolution. The method has limitations with penetration in obesity and with intestinal air impairing image quality. The flexibility ultrasonography offers the examiner also implies that a systematic approach during scanning is needed. This paper reviews the basic scanning techniques and new modalities such as contrast-enhanced ultrasound, elastography, strain rate imaging, hydrosonography, allergosonography, endoscopic sonography and nutritional imaging, and the literature on disease-specific findings in the small intestine. Some of these methods have shown clinical benefit, while others are under research and development to establish their role in the diagnostic repertoire. However, along with improved overall image quality of new ultrasound scanners, these methods have enabled more anatomical and physiological changes in the small intestine to be observed. Accordingly, ultrasound of the small intestine is an attractive clinical tool to study patients with a range of diseases.     

Spontaneous perforation of the small intestine due to scleroderma

Summary We have described a 42-year-old black woman with scleroderma who developed spontaneous perforation of the terminal ileum due to complete collagenous involvement of the bowel wall. Spontaneous intestinal perforation represents a rare complication of scleroderma which can be initially mistaken for pseudoobstruction.     

Adenomyoma of the small intestine

Adenomyoma of the gastrointestinal tract is a rare benign tumor-like lesion.The small intestine is the second most frequent location,usually in the periampullary area,but the lesion also occurs in the jejunum and ileum.While adenomyoma of the Vaterian system is primarily diagnosed in adults,more than half of reported cases of jejunal and ileal adenomyoma have been diagnosed in pediatric patients.Adenomyoma of the periampullary area usually presents with biliary obstruction or abdominal pain,whereas jejunal and ileal adenomyoma usually presents with intussusception or is incidentally discovered during surgery or autopsy.Since endoscopic and radiological examination yields uncharacteristic findings,histopathological evaluation is important in adenomyoma diagnosis.Pathologically,adenomyoma consists of glandular structures of various sizes and interlacing smooth muscle bundles that surround the glandular elements.The pathogenesis of adenomyoma is generally considered to be either a form of hamartoma or a pancreatic heterotopia.Although limited resection is considered the most effective treatment,pancreaticoduodenectomy is often performed when the lesion occurs in the periampullary area due to preoperative misdiagnosis as a carcinoma.It is,therefore,important that clinicians and pathologists maintain current knowledge of the disease to avoid inaccurate diagnosis,which could lead to unnecessary surgery.     

Ontogeny of the small intestine

During development the gastrointestinal tract undergoes marked changes in many physiological and anatomic properties. The remarkable degree of coordination between the development of the gastrointestinal function suggests that the processes may be signalled by some factors, such as weaning, nutrient intake, growth and hormones. The interactions between nutrition and intestinal development begin when fetuses start swallowing amniotic fluid and extend past weaning. Hormonal control plays a major role in the ontogeny of the small intestine. There are late effects of early nutrition, and the normal progress of ontogeny may be important to ensure that the intestine is capable of adaptation in later life.     

Acute exposure of small intestine to ethanol

Digestive Diseases and Sciences -     

Alcohol and the small intestine

Several alterations of the small-intestinal morphology and function have been documented after alcohol ingestion. There are morphologic changes macroscopically and microscopically after acute alcohol administration in the proximal part of the small intestine, which are quickly reversible. There are no macroscopic changes and, in most patients, very discrete light microscopic changes in the small intestine after chronic alcohol ingestion. The ultrastructural changes are, however, profound, as seen by both transmission and scanning electron microscopy. The permeability is probably increased, permitting entrance of possible noxious agents, which may explain some of the extraintestinal tissue damage observed in chronic alcoholism. The transit is increased, at least after acute alcohol administration, perhaps contributing to the diarrhea commonly seen after heavy drinking. Several of the enzymes located in the brush border are affected; lactase activity can be depressed and perhaps result in a transient milk intolerance in predisposed individuals. The activity of GGT is increased and may partly account for the GGT elevation in serum after heavy drinking. Other enzymes, such as Na(+)-K(+)-ATPase, can be inhibited and result in a decreased absorption of substances that require active, energy-dependent transport mechanisms. The secretion of water and electrolytes may be increased (an effect on cAMP?). The absorption of several nutrients, vitamins, and other elements is disturbed. The bacterial flora is increased and changed, which may give rise to symptoms and also increase the production of acetaldehyde by bacterial metabolism of ethanol. Acetaldehyde is more toxic than ethanol, and an increased concentration of acetaldehyde can possibly accentuate the damage to the liver and other organs. The bacterial overgrowth can possibly cause endotoxinemia. Although studies on alcohol-related intestinal alterations have been relatively sparse, the acute and chronic effects of alcohol thus seem to be considerable. From available results it is, however, difficult to draw any definite conclusions about the clinical importance of many of the findings. Future research will need to study the relationship between, for example, the chronic morphologic changes, the absorptive dysfunction, and permeability alterations, on the one hand, and the gastrointestinal symptoms, the extraintestinal damage, and various deficiencies, on the other hand.