GIT investigation

GASTROINTESTINAL INVESTIGATION

المحاضر: الدكتور خلدون ذنون- كلية طب نينوى- طلبة المرحله الرابعه

Objectives

1. To know different types of GIT investigations, the indications , contraindications, and limitations of each test.
2. To know the best and diagnostic test which establishes the diagnosis of each GIT disease.
3. Imaging, endoscopy, and biochemical tests are used basically to diagnose GIT diseases.
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Plain radiograph of the abdomen

Show gas distribution within the small and large bowel , helpful in the diagnosis of intestinal obstruction & paralytic ileus ( dilated bowel loops and fluid level in the erect posture .
outline of liver,spleen &kidneys .
Calcification of above organs and pancreas,blood vessels,lymph nodes and calculi .

Chest radiograph

subdiaphragmatic free air in perforated viscus or associated pleural effusion
Show diaphragm in case of diaphragmatic hernia & abdominal
viscera in the chest .


Contrast studies
Barium sulfate : inert substance .
Water soluble contrast : opacify bowel prior to CT & in suspected perforation .
With fluoroscopy : assess motility of the bowel .
Double contrast with air, better mucosal visualization.
Detect filling defects e.g food , faeces , carcinoma or lymph node compression,stricture,erosions,ulcer,motility disorders .

Barium swallow

Indications: dysphagia , heart burn , chest pain , motility disorders.
Major uses: stricture , hiatus hernia , GERD , achalasia .
Limitation: aspiration, poor mucosal detail , no biopsy .

Barium meal

Indications:dyspepsia,epigastric pain,anaemia,vomiting,perforation
major uses : GU , DU , CA stomach , gastric outlet obstruction .
Limitations : low sensitivity for early cancer, may miss ulcers and erosions .

Barium follow-through

Indications : diarrhoea and abdominal pain of small bowel , obstruction by strictures .
Uses : malabsorption , Crohns disease .
limitations : time-consuming , radiations .


Barium enema
Indications : altered bowel habit , rectal bleeding , anaemia .
Uses : neoplasia , diverticulosis , strictures , megacolon .
Limitations : difficult in frial elderly , uncomfortable , miss polyp <1cm , less useful in inflammatory bowel disease .

Ultrasound

Uses : abdominal masses and cysts , organomegaly , ascites , biliary tract dilatation , gall stones , guided needle aspiration and biopsy of lesions .
Limitations : low sensitivity for small lesions , operator-dependent, gas and obesity obscure view .

CT scan

Uses : pancreatic and hepatic tumors with secondaries , staging of tumors , vascularity of lesions .
Limitations : high radiations .
CT-PET: detects metastasis not seen on U/S or CT, depends on metabolic activity of the tumor.

MRI

Uses : stage of hepatic tumors , MRCP , pelvic and peritoneal Crohns fistulae .
Limitations : limited availability , time consuming , metallic prosthesis and cardiac pacemakers .

Upper GIT endoscopy

Fibreoptic and videoscopy .
Examine oesophagus , stomach , 1st two parts of the doudenum .
Indications : dyspepsia especially>55y,upper abdominal pain, atypical chest pain,dysphagia,vomiting,weight loss,acute and chronic upper GIT bleeding,suspicious barium meal,duodenal biopsy in malabsorption.


Therapeutic indications: control of bleeding , treatment of tumors , treatment of strictures (stent),balloon dilatation.

Enteroscopy

Visualization of small intestine , assessment of recurrent bleeding .

Capsule endoscopy

26 mm capsule, swollen, after 8 hours excreted, recorder carried in a belt.
Indications: obscure GIT bleeding, small bowel Crohns disease, celiac disease, screen familial polyposis
Contraindication: small bowel stricture, pacemaker or defibrillator.
Complication: capsule retention <1%.

Double balloon endoscopy

Indications: obscure GIT bleeding, unexplained diarrhea, suspicious small bowel tumor, polyposis syndrome.
Therapeutic: stop bleeding, placement of jejunostomy.
Complication: abdominal pain, pancreatitis, perforation.

Sigmoidoscopy and colonoscopy

Indications : IBD , altered bowel habits , rectal bleeding or anaemia , abnormal barium enema , colorectal cancer surveillance , therapeut- tic procedures e.g bleeding , tumor therapy ,polypectomy , stenting.

Endoscopic retrograde cholangiopancreatography ERCP

Side viewing duodenoscope , canulate CBD & pancreatic duct .
Indications : obstructive jaundice , biliary pain , pancreatic disease e.g chronic pancreatitis and CA pancreas . Therapeutic : sphincterotomy and removal of stones in CBD , stenting of strictures .
Complications : 3-5%pancreatitis , 4%haemorrhage after sphincterotomy ,1% perforation.diagnostic ERCP is being replaced by MRCP.
Histology
Biopsy obtained during endoscopy.
Indications : ( malignancy ( mucosal abnormality e.g malabsorption . ( diagnosis of infection e.g candida , H.pylori , giardia. ( Measurement of enzyme contents e.g disaccharidase. ( Analysis of genetic mutations e.g oncogens,tumor suppressor gene.


Bacterial cultures
Stool culture in diarrhoea .
Stool examination
RBC,pus cells,parasites,eggs of worms ,toxin of clostridium difficile.
Occult blood in the stool
Assess minor bleeding from lower GIT e.g CA colon .
Serology
Antibodies against H.pylori , salmonella , E.histolytica .
Breath test H.pylori , small intestinal bacterial overgrowth .
Blood tests
Blood count , ESR , s.folate , s.BI2 , iron state , s.albumin , calcium , phosphorus ,s.amylase , s.lipase etc.

Test of function

1.Absorption
A-fat : C14-triolein breath test , 3days feacal fat .
B-lactose : lactose H2 breath test e.g hypolactasia .
C- bile acids : using labelled selenium .
2.Pancreatic exocrine function
Faecal chymotrypsin or elastase , pancreolauryl test for p.esterases
3.Mucosal inflammation
Using quantification of label after oral dose .
Sugar test e.g lactulose (urinary excretion)
Calprotectin : protein secreted by neutrophil in to the colon in response to inflammation or neoplasia of colonic disease .


Gastrointestinal motility tests
Oesophageal motility
Barium swallow .
Videofluoroscopy .
Oesophageal manometry with PH measurement .
Useful in GERD , achalasia , chest pain .
Gastric emptying
In delayed gastric emptying (gastroparesis) , radioisotope retained in the stomach after a test meal. Gastric emptying is ( by fat and high osmolality .

Small intestinal transit
Barium follow through : contrast reach terminal ileum in < 90 min.
Lactulose-hydrogen breath test . Colonic bacteria digest lactulose, H+ is liberated & measured in breath , time calculated .
Colonic & anorectal motility
Plain radiograph of the abdomen taken 5 days after ingestion of plastic pellets of day 1-3 e.g chronic constipation .
Anorectal manometry , defeacating proctography , both assess anorectal function .
Radio-isotope tests
Gastric emptying e.g gastroparesis in e.g DM .
Urea breath test: for H.pylori( urea( C02 + ammonia by bac.urease)
Meckels scan : for M.diverticular bleeding which contain ectopic parietal mucosa .
Labelled RBC scan : recurrent GIT bleeding .
Labelled leukocyte scan : localise abscess , IBD activity .










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