GASTROINTESTINAL 2 Flashcards
what is the function of the large intestine?
absorbs water from indigestible material; expulsion of waste products; site of vitamin production by bacteria
what are common pathologies seen in large intestine?
obstruction/dilation, tumour, inflammation
what is a large intestinal obstruction?
less common than SBO- gastrointestinal obstruction- secondary to neoplasia (typically of colon, ovary, pancreas & lymphoma)
what causes large bowel obstruction?
may be due to volvulus, post-operative adhesions, strictures, hernia, intussusception, faecal impaction
how is large bowel obstruction radiographed?
site of obstruction can be easily visualised by transition from dilated to non-dilated- plain radiographs offer limited value in diagnoses- upright chest image helpful in diagnosing perforation- CT is optimal
what is ileus?
low gut motility in absence of obstruction- can occur after abdominal surgery & normal surgeries- resolves in 2 to 3 days
how does ileus appear in radiographs?
gets copious gas dilation of small intestine & colon- CT is modaility of choice
what is volvulus?
sigmoid colon twists on its mesentery, resulting in acute, subacute or chronic obstruction- usually impacts elderly, debilitated & bedridden
what is volvulus caused by?
over filling of sigmoid colon due to constipation & excessive fibre in colon
how does volvulus appear in radiographs?
massive dilation of sigmoud colon extending from pelvis to diaphragm & caecal volvulus produces large & intestinal obstructions
what are most colorectal cancers?
adenomatous polyps- present in 30 to 50% of people but less than 1% of polps become malignant
what population is colonic cancer incident increased?
patients with long-standing inflammatory bowel disease
what are symptoms of colonic cancer?
often associated with non-regenerative anaemia
how is screening for colon can done?
colonoscopy
what do tumours in tranverse & descending colon result in?
occasional obstruction & perforation
what do radiographs reveal on abdomen about colon cancer?
characteristic annular constricting lesions (apple core or napkin ring)
what is ulcerative colitis (UC)?
mucosal disease that usually involves the rectum & extends proximally to involve all or part- of colon - unknown aetilogy- occurs in continuous pattern (compared with chronic disease)
with UC, how many patients have disease limited to rectum & sigmoid colon?
40-50%
with UC, how many patients have disease extending beyond the sigmoid but not whole colon?
30-40%
with UC, how many patients have colitis?
20%
how is diagnoses made in UC?
endoscopy, plain radiographs show colonic dilation, contrast enema shows mucosal damage, CT shows complications of UC
what is the appendix?
blind ending tubular structure arising in the caecum- normally not visible only on US or CT in appendicitis- rarely tumours
what is the function of the liver?
filtration of blood draining digestive tract; metabolism of protein, carbs, lipid, chemicals; production of plasma proteins, bile salts; excretion of cholesterol & bilirubin
what is blood supply of the liver?
portal vein
what is the role of portal vein?
carries blood from GI tract & spleen to liver, delivers blood to hepatic sinusoids
what are the common pathologies of liver?
primary tumour, metastatic tumour, trauma, vascular obstruction, infections/abscesses
how does normal imaging of CT/MRI show liver?
assess outline of capsule, liver should be uniformlu contrasts, portal vein should fill with contrast, dilation of bile ducts
what type of primary tumours appear in liver?
hepatocellular carcinoma is most common- increasing & occurs in patients with cirrhosis
what cause liver primary tumours?
hep C, alcohol use, nonalcoholic fatty liver disease
what is diagnosis based on for liver tumours?
ultrasound for screening & CT for determining surgical approach for treatment (usually see hypervascular pattern)
is liver a common site for metastasis?
yes- CT is modality of choice due to differential enhancemen of metastases compared with normal tissue
what is severe liver trauma?
most severe injuries associated with laceration & damage to major vessels- most common cause of death due to abdominal trauma- cause haemodynamic changes
how is liver trauma diagnosed?
plain radiographs may show skeletal damage, contrast enhanced CT scaning is modality of choice
what is portal vein obstruction due to?
primary thrombosis (occurs in cirrhosis & hepatic malignancy) & occlusion by neoplasm
what happens due to portal vein obstruction?
collateral circulation develops resulting in oesophageal varices
how is portal vein obstruction diagnosed?
ultrasound & CT (shows varuces & intrahepatic vascular abnormalities)
what are varices?
veins are enlarged or swollen- develop in 50% of pateint with cirrhosis (mostly in oesophagus)- cause significant haemorrhage
what is the function of the gallbladder?
storage, concentration & release of bile
what does the right & left hepatic duct drain into?
common hepatic duct
what does the common hepatic duct & cystic duct form?
common bile duct