DIGESTIVE SYSTEM PATHOLOGY

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Ascites Is the accumulation of fluid within the peritoneal cavity. Ascites may result from portal hypertension, chronic hepatitis, congestive heart failure, renal failure, and certain cancers. Abdominal sonography is commonly used in the detection or confirmation of ascites. Patients with ascites generally complain of nonspecific abdominal pain and dyspnea. Medical treatment of ascites includes bed rest, dietary restrictions of sodium, use of diuretics to avoid excess fluid accumulation, and treatment of the underlying cause. An underexposed image may result when patients have ascites. This is because sections of the abdomen that normally contain gas or fat do not, resulting in an increase in the density of the soft tissue. To compensate for this situation, increase the exposure (mAs) 30% to 50% or the kVp 5% to 8% from the routinely used technique before the image is taken. Radiographically, large amounts of ascitic fluid give the abdomen a dense, gray, ground-glass appearance. With the patient in a supine position, the fluid accumulates in the pelvis and ascends to either side of the bladder to give it a dog-eared appearance. Gradually the margins of the liver, spleen, kidneys, and psoas muscles become indistinct as the volume of fluid increases. Loops of bowel filled with gas float centrally, and a lateral decubitus radiograph demonstrates the fluid descending and the gas-filled loops of bowel floating on top.

Celiac Disease Is a hereditary disorder involving increased sensitivity to gluten, an agent found in wheat and rye products such as bread, which interferes with normal digestion and absorption of food through the small bowel. With such a condition, the bowel dilates, mucosal folds atrophy, and peristalsis slows or stops. Common symptoms include diarrhea, flatulence, weight loss, and abdominal distension. In addition, patients often present with nutritional deficiencies specific to the primary disease and the area of the GI system affected by the disorder.

Radiographic changes generally seen with celiac disease are; segmentation of the barium column, flocculation (resembling tufts of cotton), and edematous mucosal changes. Diagnosis is usually confirmed by biopsy of the small bowel. Treatment of celiac disease consists of avoidance of substances containing gluten and dietary substitution of other products. Vitamin therapy is also used to ensure adequate amounts of nutrients not available because of the malabsorption in the small bowel. Patients should be monitored because of an increased incidence of intestinal lymphoma.

Cirrhosis A chronic degenerative disease of the liver in which the lobes are covered with fibrous tissue, the parenchyma degenerates, and the lobules are infiltrated with fat. Functions of the liver deteriorate. Cirrhosis is most commonly the result of chronic alcohol abuse and sometimes nutritional deprivation, hepatitis, cardiac problems, or other causes. The symptoms are the same regardless of the cause. Early disease is often asymptomatic or may manifest as abdominal pain, diarrhea, nausea, vomiting, fatigue, and fever. As the disease progresses, manifestations such as chronic dyspepsia, constipation, anorexia, weight loss, pruritus, easy bruising, bleeding gums, nosebleeds, upper gastrointestinal bleeding, and enlarged liver are seen. Diagnosis is made definitively by biopsy, but radiographic and physical examinations and several blood tests of liver function are serially performed to monitor the course of the disease. Treatment depends on the cause. Liver transplantation may be the only hope for those with advanced disease.

Diabetes Mellitus Diabetes mellitus is a common endocrine disorder in which beta cells in the islets of Langerhans of the pancreas fail to secrete insulin, or target cells throughout the body fail to respond to this hormone. A lack of insulin prevents glucose from entering the cells, thus depriving them of the major nutrient needed for energy production. The blood glucose level increases (hyperglycemia).

The severity and age of onset of diabetes vary. Juvenile-onset diabetes, which develops in childhood, and insulin-dependent diabetes require the patient to undergo daily insulin injections. Non–insulin-dependent diabetes, which tends to develop later in life, is less severe and can often be controlled by diet alone. The precise cause of diabetes is unknown, although it is generally considered that heredity is an important factor.

Polyuria (excessive urination) and polydipsia (drinking large quantities of liquid) are common manifestations of diabetes. The large amount of sugar filtered through the kidneys exceeds the amount that the renal tubules can absorb. This leads to the excretion of glucose in the urine (glycosuria), which is a major sign of diabetes.

Glucose is the major fuel of the body. However, as glucose cannot enter the cells without the action of insulin, diabetic patients are forced to metabolize a large amount of fat. This produces a large number of fatty acids and ketones, which can be detected in the urine. Production of fatty acids lowers the body’s pH (acidosis). Severe acidosis and dehydration in a diabetic patient who fails to take enough insulin or eats a high-sugar diet can lead to diabetic coma, which may be fatal if not treated rapidly with fluids and a large dose of insulin.

A major complication of diabetes is the deposition of lipids within the walls of blood vessels (atherosclerosis). This causes arterial narrowing and even occlusion, resulting in myocardial infarction (coronary artery), stroke (carotid artery), or gangrene (peripheral artery). Atherosclerotic disease and subsequent ischemia involving the coronary, extracerebral, and peripheral circulations occur earlier and are more extensive in diabetics, especially those who smoke. Excess glucose in tissues provides an excellent bacterial culture medium and leads to the frequent development of infections, which tend to heal poorly because of the generally poor circulation in diabetic patients. This especially affects the feet and may lead to severe osteomyelitis, which produces bone destruction and can eventually lead to gangrene. The kidneys are always affected by long-standing diabetes, and kidney failure is frequently the cause of death. Another complication is narrowing and rupture of minute retinal blood vessels, which may lead to blindness. Poor circulation to the nervous system may produce intractable pain, tingling sensations, loss of feeling, and paralysis. Calcifications in peripheral vessels, especially those of the hands and feet, are virtually pathognomonic of the disease. Men with diabetes may demonstrate characteristic calcification of the vas deferens.

The purpose of therapy is to keep the blood glucose levels constant with a minimal variation. Insulin is used when proper diet and exercise cannot maintain normal levels. Recent advances in therapy include islet cell transplantation and insulin gene therapy.

Esophageal Varices Esophageal varices are dilated veins in the wall of the esophagus that are most commonly the result of increased pressure in the portal venous system (portal hypertension), which is in turn usually a result of cirrhosis of the liver. In patients with portal hypertension, much of the portal blood cannot flow along its normal pathway through the liver to the inferior vena cava and then on to the heart. Instead, it must go by a circuitous collateral route, and increased blood flow through these dilated veins causes the development of esophageal (and gastric) varices. Esophageal varices are infrequently demonstrated in the absence of portal hypertension. The characteristic radiographic appearance of esophageal varices is wavy border thickening of folds, which appear as round or oval filling defects resembling the beads of a rosary. A double-contrast barium swallow best demonstrates the wormlike filling defect. Upright and recumbent imaging may best demonstrate the varices dilated and empty, respectively.

The major complication of esophageal varices is bleeding. Vasoconstrictor drugs to constrict the dilated vessels are commonly used to treat esophageal varices. Active bleeding can be controlled by a technique called balloon tamponade, which creates pressure to stop the bleeding. If bleeding cannot be controlled, surgery is performed to tie off collateral vessels. Alternatively a TIPS (transjugular intrahepatic portal systemic shunt) procedure may be performed to reduce portal hypertension.


Hepatitis Is the most prevalent inflammatory disease of the liver. The most common causes are a viral infection or a reaction to drugs and toxins. The viral types of hepatitis include hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis E virus (HEV).

Hepatitis A virus, previously known as “infectious hepatitis,” is transmitted in the digestive tract from oral or fecal contact. In most cases the disease is self-contained and has a favorable prognosis.

Hepatitis B virus, previously known as “serum hepatitis,” is contracted by exposure to contaminated blood or blood products, or through sexual contact. Healthcare workers are more susceptible to this virus and are usually required to have been vaccinated or prove immunity.

Hepatitis C virus, formally known as “non-A, non-B hepatitis,” is the common cause of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Because it is contracted by blood transfusion or sexual contact, some believe healthcare workers are more susceptible; however, 40% of cases are of an unknown source found in the general population.

Hepatitis E virus is self-limited and acquired by the ingestion of food or water that has been contaminated with fecal material.

Viral hepatitis in the earliest stages is not visible on diagnostic images. The later stages resulting in cirrhosis or hepatocellular carcinoma can be demonstrated on ultrasound, computed tomography (CT), and MRI. CT demonstrates evidence of a fatty liver.

Routine Practices  for healthcare workers should include the use of PPE for all patients. Vaccines exist for hepatitis A virus and hepatitis B virus.

Hypoglycemia The diabetic patient who has taken insulin but no food may develop hypoglycemia, or low blood sugar. Symptoms include sudden onset of weakness, lightheadedness, fainting, trembling, hunger, perspiration and finally loss of consciousness. In the radiology department, this may occur in diabetic patients who have not eaten or drunk before gastrointestinal examination or other special procedures. It is essential that this condition be rapidly recognized and sugar given, usually in the form of orange juice or candy.


Intussusception Is a major cause of bowel obstruction in children; it is much less common in adults. Intussusception is the telescoping of one part of the intestinal tract into another because of peristalsis, which forces the proximal segment of bowel to move distally within the ensheathing outer portion. Once such a lead point has been established, it gradually progresses forward and causes increased obstruction. This can compromise the vascular supply and produce ischemic necrosis of the intussuscepted bowel.

In children, intussusception is most common in the region of the ileocecal valve. In children it is idiopathic. The clinical onset tends to be abrupt, with severe abdominal pain, blood in the stool (“currant jelly”), and often a palpable right-sided mass. If the diagnosis is made early and therapy instituted promptly, the mortality of intussusception in children is less than 1%. However, if treatment is delayed more than 48 hours after the onset of symptoms, the mortality increases dramatically.

In adults, intussusception is often chronic or subacute and is characterized by irregular recurrent episodes of colicky pain, nausea, and vomiting. In adults, the leading cause is a pedunculated polypoid tumor or an inflammatory mass.

Radiographically, an intussusception produces the classic coiled-spring appearance of barium trapped between the intussusceptum and the surrounding portions of bowel. Reduction of a colonic intussusception can sometimes be accomplished by a barium enema examination, although great care must be exercised to prevent excessive intraluminal pressure, which may lead to perforation of the colon. On CT images, intussusception appears as three concentric circles forming a soft tissue mass.

Reduction of intussusceptions by rectal insufflation of air (instead of barium) has been reported to be an effective technique in children. In older children and adults, a repeat barium enema after reduction is necessary to determine whether an underlying polyp or a tumor caused the intussusception.

Hepatocellular Carcinoma (Liver Cancer) Primary liver cell carcinoma most commonly occurs in patients with underlying diffuse hepatocellular disease, especially alcoholic or postnecrotic cirrhosis. The clinical presentation varies from mild right upper quadrant discomfort and weight loss, to hemorrhagic shock from massive intraperitoneal bleeding, which reflects rupture of the tumor into the peritoneal cavity. Invasion of the biliary tree may produce obstructive jaundice.

CT is the modality of choice in the diagnosis of hepatocellular carcinoma. The tumor appears as a large mass that tends to alter the contour of the liver by projecting beyond its outer margin. After administration of IV contrast material, there is usually dense, diffuse, and nonuniform enhancement of the tumor. Hepatocellular carcinoma tends to be a solitary mass or multinodular.

Although the overall prognosis for patients with hepatocellular carcinoma remains bleak, radiographic studies can determine whether the tumor can be successfully removed surgically. If the tumor is confined to one lobe of the liver and there is no evidence of metastases. Surgery and chemotherapy are the treatments of choice. Metastases occur late and are usually not the cause of death. A common cause of death is catastrophic bleeding into the peritoneal cavity from hepatic failure or esophageal varices.

Pancreatic Cancer The most common pancreatic malignancy is adenocarcinoma (90%), which often is far advanced and has metastasized before it is detected and thus has an extremely poor survival rate. Of these malignancies, 60% occur in the head of the pancreas. Ultrasound is often the initial screening modality for a patient with suspected pancreatic carcinoma.

CT is the most effective modality for detecting pancreatic cancer in any portion of the gland and for defining its extent. CT can demonstrate the mass of the tumor, ductal dilatation, and invasion of neighboring structures and staging.

Carcinoma of the head of the pancreas often causes obstructive jaundice and the appearance of narrowing of the distal common bile duct on transhepatic cholangiography or ERCP. Percutaneous biliary drainage may represent an alternative to surgical intervention for relieving biliary obstruction in patients with pancreatic carcinoma who cannot be cured. Although the transhepatic insertion of biliary drainage tubes does not alter the dismal prognosis, it can reduce patient morbidity and the need for hospitalization.

Finding pancreatic cancer in the earliest stages can result in a cure (2%, 5-year survival rate). In most cases, the diagnosis of the disease occurs after metastasis and most patients die within 12 to 24 months of diagnosis. Nevertheless, treatment can improve the quality of life. Surgical resection, radiation therapy, chemotherapy, and biologic therapy help alleviate the patient’s symptoms.

Surgical resection (total pancreatectomy) includes the removal of the entire pancreas, duodenum, common bile duct, gallbladder, spleen, and surrounding lymph nodes. The Whipple procedure consists of removing only the head of the pancreas, the duodenum, a portion of the stomach, and other nearby tissue. In most cases, the purpose of the surgery is to alleviate biliary and small bowel obstruction.


Pneumoperitoneum Free air in the peritoneal cavity associated with significant abdominal pain and tenderness is often caused by perforation and indicates a surgical emergency. Less frequently, pneumoperitoneum results from abdominal, gynecologic, intrathoracic, or iatrogenic causes and does not require operative intervention.

As little as 1 cc of free intraperitoneal gas can be identified by examination of the patient in the upright position with a horizontal beam. The gas rises to the highest point in the peritoneal cavity, it accumulates beneath the domes of the diaphragm and appears as a sickle-shaped lucency that is easiest to recognize on the right side between the diaphragm and the liver. The free air is shown to best advantage if the patient remains in an upright (or lateral decubitus) position for 10 minutes before a radiograph is obtained.

If the patient is too ill to sit or stand, a lateral decubitus view (preferably with the patient on the left side) can be used. In this position, free air moves to the right side and collects between the lateral margin of the liver and the abdominal wall. When the patient is in the supine position, The demonstration of distinct inner and outer contours of the bowel wall is often the only sign of pneumoperitoneum.

In children, pneumoperitoneum can be manifest as a generalized greater-than-normal lucency of the entire abdomen. An important sign of pneumoperitoneum on the supine radiograph is demonstration of the falciform ligament. This almost vertical, curvilinear, water-density shadow in the upper abdomen to the right of the spine is outlined only when there is gas on both sides of it, as in pneumoperitoneum.

The most common cause of pneumoperitoneum with associated inflammation is perforation of a peptic ulcer, either gastric or duodenal. Colonic perforations, especially those involving the cecum, give the most abundant quantities of free intraperitoneal gas. Septic infection of the peritoneal cavity by gas- forming organisms can result in the production of a substantial amount of gas and the radiographic appearance of pneumoperitoneum. Pneumoperitoneum can also develop after penetrating injuries of the abdominal wall and after blunt trauma causing rupture of a hollow viscus.

Iatrogenic pneumoperitoneum is generally asymptomatic and usually follows abdominal surgery. Postoperative pneumoperitoneum can be radiographically detectable for up to 3 weeks after surgery, but usually it can no longer be demonstrated after the first postoperative week. Rarely, free air in the peritoneal cavity may be the result of perforation during an endoscopic procedure.

Immediate surgical repair of a perforation is required to reduce the risk of peritonitis and sepsis. IV antibiotics help control infection.

Ulcerative Colitis Is one of the major inflammatory bowel diseases. It primarily affects young adults and is highly variable in severity, clinical course, and ultimate prognosis. The cause is unknown, although an autoimmune cause has been suggested and a psychogenic factor may be involved because the condition is often aggravated by stress. The onset of the disease and subsequent exacerbations can be insidious or abrupt. The main symptoms include bloody diarrhea, abdominal pain, fever, and weight loss. A characteristic feature of ulcerative colitis is alternating periods of remission and relapse. Ulcerative colitis can lead to toxic megacolon and perforation. Usually, ulcerative colitis involves only the mucosal layer of the colon.

Plain abdominal radiographs are essential for diagnosis. Large nodular protrusions of hyperplastic mucosa, deep ulcers outlined by intraluminal gas, or polypoid changes along with a loss of haustral markings and toxic megacolon may indicate the diagnosis. Ulcerative colitis has a strong tendency to begin in the rectosigmoid area. Ulcerative colitis may spread to involve the entire colon (pancolitis). The disease is almost always continuous, without evidence of the skip areas seen in Crohn’s disease. Except for “backwash ileitis” (minimal inflammatory changes involving a short segment of terminal ileum), ulcerative colitis does not involve the small bowel, a feature distinguishing it from Crohn’s disease. On double-contrast studies, the earliest detectable radiographic abnormality in ulcerative colitis is fine granularity of the mucosa. Once superficial ulcers develop, small flecks of adherent barium produce a stippled mucosal pattern. As the disease progresses, the ulcerations become deeper. Extension into the submucosa may produce broad-based ulcers with a collar-button appearance. When the disease is chronic, fibrosis and muscular spasm cause progressive shortening and rigidity of the colon. The haustral pattern is absent, eventually appearing as a symmetric, rigid, tubular structure (lead-pipe colon).

Carcinoma of the colon is about 10 times more frequent in patients with ulcerative colitis than in the general population.

 

Vancomycin Resistant Enterococcus (VRE) Enteroccoci are bacteria naturally present in the intestinal tract. Vancomycin is an antibiotic to which some strains of enteroccoci become resistant; these strains are referred to as VRE. However, when VRE infects urinary tract, bloodstream, or surgical wounds, it can be difficult to treat and may be life threatening. Serious VRE infections usually occur in hospitalized patients with serious underlying illnesses such as cancer, blood disorders, kidney disease or immune deficiencies. VRE is transmitted via direct contact (enteric isolation precautions – gown, glove).

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