Gastroenterology

·         It is necessary to auscultate the abdomen prior to percussion and palpation because percussion may alter the frequency and the intensity of bowel sounds. The absence of bowel sounds is not established unless no sounds are detected during 5 min of continuous auscultation. Percussion is an important means of assessing the size and density of abdominal organs as well as detecting fluid or air in the abdomen.

·         The HemOccult Slide Test (Smith-Kline Diagnostics) detects the presence of hemoglobin in feces. False-positive results can be produced by the dietary intake of rare beef or fruits and vegetables that contain peroxidases. This effect is seen mainly in tests performed on rehydrated stool specimens. Oral iron preparations also have been implicated in some studies but not in others. False-positive results can occur due to blood from sources other than colorectal carcinoma, such as gastric blood loss caused by nonsteroidal antiinflammatory drugs (NSAIDs).

·         AST is elevated by twice as much as ALT in alcoholic hepatitis because alcohol inhibits ALT synthesis more than AST synthesis.

·         Common MANEUVERS/SIGNS and their associations:

1. Cullen sign, Turner sign: hemorrhagic pancreatitis

2. Murphy sign: acute cholecystitis

3. Caput medusae: liver cirrhosis

4. Courvoisier gallbladder: cancer of the biliary tract or pancreatic head

5. Kehr sign: splenic rupture

6. Obturator test, reverse psoas maneuver: retrocecal appendicitis

7. Markle sign (jar tenderness): specific for peritonitis

8. Succussion splash: intestinal obstruction or gastric dilatation

·         CMV esophagitis often is only one component of a generalized CMV infection, and some 20% to 40% of patients with CMV esophagitis have systemic symptoms. In contrast, candidal and HSV esophagitis usually are not associated with infection in other organs, and systemic symptoms caused by these pathogens are uncommon.

·         Pancreatic necrosis is defined as an absence of enhancement of pancreatic parenchyma after the infusion of intravenous contrast on contrast-enhanced CT (CECT). Acute necrotizing pancreatitis is defined by the presence of necrosis on CECT; it is subclassified as either sterile necrosis or infected necrosis. Acute interstitial pancreatitis is defined by the absence of these CECT findings of necrosis. Finally, pancreatic abscess is defined as a circumscribed collection of pus containing little necrotic tissue. What was formerly called infected pseudocyst is now termed pancreatic abscess. The term phlegmon was abandoned, because no consensus could be reached as to its definition.

·         The serum amylase level may be normal in some patients with acute pancreatitis associated with alcohol use and in those with hyperlipidemic pancreatitis (marked elevations in the triglyceride level can interfere with the laboratory assay for amylase); the serum amylase level may be normal in patients with acute pancreatitis if the measurement is made several days after the onset of symptoms. Measurement of serum lipase is often used as an adjunct to or in place of serum amylase as a confirmatory test.

·         A low serum trypsinogen level (< 20 ng/ml) is highly specific for chronic pancreatitis, but the trypsinogen level only drops to this level in advanced disease. The bentiromide test utilizes the measurement in urine of a metabolite that can only be produced by the action of pancreatic enzymes. A 72-hour stool collection for fat is the gold standard to detect steatorrhea. Steatorrhea is only seen in far-advanced chronic pancreatitis. Fecal levels of elastase and chymotrypsin are reduced in more advanced cases of chronic pancreatitis. Direct pancreatic function tests involve placing a tube into the duodenum to collect pancreatic juice. This test directly measures pancreatic output of enzymes or bicarbonate after stimulation with a secretagogue. These tests are the most sensitive tests available and are able to detect chronic pancreatitis at an earlier stage than any other test.

·         Besides the commonly seen pseudocysts, a number of other cystic lesions may occur in the pancreas, including true cysts and cystic neoplasms. Serous cystic neoplasms are benign, but mucin-producing cystic neoplasms may follow a more malignant course. Mucinous cystic neoplasms present as large cystic collections (cystadenomas and cystadenocarcinomas) and may be relatively asymptomatic. Most cystic neoplasms occur in middle-aged patients, particularly women. They are often mistaken for pseudocysts and inappropriately treated as such. These cystic neoplasms may follow an initially benign course, but when they undergo malignant degeneration, outcomes are as poor as in patients with standard adenocarcinoma. The presence of a cystic collection of the pancreas in a middle-aged (particularly female) patient without a previous history of pancreatitis should immediately suggest a cystic neoplasm, not a pseudocyst.

·         The organisms that most commonly cause cholangitis are Escherichia coli, Klebsiella, enterococci, and Bacteroides fragilis. Ceftriaxone is not recommended in this case because it does not cover enterococci and has been associated with the development of gallbladder sludge. Treat with ampicillin-sulbactam.

·         Although sclerosing cholangitis usually develops in younger men (aged 20 to 50 years), it is often associated with ulcerative colitis. About 60% of patients will also have a positive perinuclear antineutrophil cytoplasmic antibody (p-ANCA) test result. The hallmark finding on ERCP is segmental stenosis of the biliary tree. Primary biliary cirrhosis is an autoimmune disease that typically affects women. About 95% of patients have antimitochondrial antibodies. Both primary biliary cirrhosis and drug-induced cholestasis cause intrahepatic cholestasis without extrahepatic duct dilatation.

·         Collagenous sprue is a rare, devastating disease in which there is a layer of collagen underneath the enterocytes of the small bowel. The origin of collagenous colitis is unknown, but it develops in approximately half the patients who have refractory celiac disease. The symptoms are severe and include obvious malabsorption. The diagnosis is made on the basis of the classic histologic picture of villous atrophy and subepithelial collagen deposition. Therapy for collagenous sprue is uncertain; some patients respond to steroids. Poor adherence to gluten-exclusion diet is common.

·         Congenital intestinal lymphangiectasia: Intestinal lymphangiectasia is often a congenital condition in which deformed lymphatics impair the transport of chylomicrons from the enterocytes to the mesenteric lymph duct. The blockage of lymphatic drainage may result in chylous ascites. Protein-losing enteropathy and lymphopenia are prominent features. Modest steatorrhea is also present. In the congenital form of the disease, lymphedema of the legs or of one leg and one arm is seen. With endoscopic examination, white villi, white nodules, and submucosal elevations may be noted. The white appearance of the mucosa is undoubtedly caused by retained chylomicron triacylglycerol. Double-contrast barium x-ray examination shows smooth nodular protrusions and thick mucosal folds without ulceration. On histologic examination, dilated lymphatics with club-shaped villi are seen.

·         Pancreas transplantation has been shown to prevent or reduce the nephropathy that often develops in kidney grafts in diabetic patients. The favored placement of the graft is the right lower quadrant, with vascular anastomoses to the common iliac artery and the common iliac vein or portal vein; in simultaneous pancreas and kidney transplantations, the preferred placement is the left lower quadrant.

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SKIN FINDINGS IN CONDITIONS THAT CAUSE GI BLEEDING

Disease	Associated skin findings
Peutz-Jeghers	Pigmented macules on lips, palms, soles
Malignant melanoma	Melanoma
Hereditary hemorrhagic telangiectasias	Telangiectasias on lips, mouth, palms, soles (Osler-Weber-Rendu)
Blue rubber bleb nevus	Dark, blue soft nodules
Bullous pemphigoid	Oral and skin bullae
Neurofibromatosis	Café-au-lait spots, axillary freckles, neurofibromas
Cronkhite-Canada	Alopecia; hyperpigmentation of creases, hands, and face
Cirrhosis	Spider angiomata, Dupuytren's contracture
Neoplasm	Acanthosis nigricans
Kaposi's sarcoma	Cutaneous Kaposi's sarcoma
Ehlers-Danlos	Skin fragility, keloids, paper thin scars
Pseudoxanthoma elasticum	Yellow "chicken fat" papules and plaques in flexural areas
Turner's	Webbing of neck, purpura, skin nodules

·         Basic stool studies, including bacterial culture and sensitivity, Sudan stain for fat, Wright's stain for WBCs, test for occult blood, and a phenolphthalein test for the presence of laxative ingestion, are simple and quickly obtainable tests that may give valuable results.