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Diagnostic tests
Reasons for medical tests
To confirm or exclude a proposed diagnosis
To screen for disease
To screen for the presence of risk factors
To monitor the course of al illness
To monitor the effect of treatment
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Categories of patients
Those with signs and symptoms of a specific illness or condition and the test will either confirm or exclude a diagnosis.Broad screening tests for patients who have non specific symptoms or present with vague signs of illness eg FBE.Screening tests for patients with no signs or symptoms . The test aims to detect the presence of disease before it has manifested (eg PSA) or identify risk factors (eg elevated cholesterol).
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pathology
Is the collection of specimens such as blood, tissue, body fluids and using laboratory tests to find the abnormal values/ structure etc.Histology of tissueSystem / organ functionsImmunity , infection, autoimmunity Genetics- chromosomal DNADrug monitoringCancer markers
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Diagnostic imaging
X –Ray- with or without contrast, videoScans.
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MRI- combination of large magnets, radiofrequencies and a computer
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Ultrasound – high frequency sound waves and a computer are used to create an image.
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Scans-Nuclear – small amounts of radioactive substances are used.
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ECG – study the hearts electrical activity
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EEG-study of the brain’s electrical activity
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scopes
Many of the scopes today are fiber optics which allows the catheter to be flexible
These instruments can be inserted into organs and cavities.
The structure/s are either observed directly or viewed on a screen.
Dyes and X-Rays can also be used
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Respiratory system diagnostic testshttp://mips.stanford.edu/research/quon/
Bronchoscopy
A fiber optic endoscope is inserted into the bronchus
The patient is fasted and sedated
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bronchoscopy
Tumors or bronchial cancerAirway obstructions and or stricturesInflammation and infections such as tuberculosis, pneumonia, or fungal or parasitic lung infections.Interstitial pulmonary diseasePersistent cough or haemoptysisBiopsy of tissue or collection of other specimens, such as sputumVocal cord analysis
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Bronchoscopy -therapeutic
Removal of secretions, blood, mucus plugs, or polyps (growths) to clear airways.Control bleeding in the bronchiRemoval of foreign objects or other obstructionsLaser therapy or brachytherapy (radiation treatment) for bronchial tumors. Stent placement ( a device used to keep the airway open)Draining of an abscess
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Bronchoscopy complications
Bleeding
Infection
Bronchial perforation
Bronchospasm or laryngospasm
Pneumothorax
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Lung biopsies
TypesNeedle biopsy- under CT or fluoroscopy guidanceTransbronchial biopsy- via bronchoscopeThoracoscopic biopsy or video – assisted thoracic surgery (VATS) biopsy- after a general anesthetic is given, an endoscope is inserted through the chest wall into the chest cavity.In addition therapeutic procedures such as the removal of a nodule or other tissue lesion my be performed. Open biopsy- after a general anesthetic is given, the physician makes an incision in the skin on the chest and surgically removes a piece of lung tissue.
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Lung perfusion and / or ventilation scansA dye is either
Injected into a vein and the blood flow to the lungs and the alveoli is observed (perfusion)
This test shows pulmonary embolism or
Inhaled into the lungs to assess the ventilation capabilities of the lungs.
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Thoracentesis
Is the removal of effusion from the pleural space for Diagnosis purposes- infection, malignancy Therapeutic purposes – remove excess fluid, to re-expand the lung Performed under local anesthetic Post Procedure checkVital signs especially respiratory rate and coughWatch for signs of distress , shock and bleeding dressing
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Thoracentesis photo
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Cardiovascular diagnostic procedures
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bloods
FBE
U&E’s
Tropinin levels
Group and cross match
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FBE
Haemoglobin (Hb)Red CellsNumberShape – eg sickle cell, spherocytes, pencil cells, ovalocytesSize – normo- micro- macro-cyticColour –normo- hypo- chromicWhite cell count and differentiationPlatelet count
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Urea and electrolytes
Urea is formed in the liver from the by products of protein metabolism.The levels will be raised if the kidney filtration rate is less than 50 % of normal.Other causes of raised urea are Diet high in proteinLoss of salt and water eg vomiting , diarrhoeaDecreased blood flow to the kidneys eg CCFLow levels can be due to Severe liver damage Poisoning
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electrolytes
Acid –base balanceNormal 7.4Acidic 7.36Alkaline 7.44Water sodium balanceElectrolytesSodium potassiumChloride BicarbonateCalcium Magnesium
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Tropinin
Tropinin is a part of muscleThere are two types that are found only in cardiac muscle.If the level of these is raised then there has been some damage to the myocardium –AMIThere may be mild elevation in severe unstable angina
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Bone marrow biopsy
Reasons for doingDiagnose certain conditionsAssess the stage or progression of certain conditionsmonitor treatment of certain conditionsProcedureIntravenous (IV) sedationLocal aesthesia Complications Bleeding Infection
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Cardiac catheter
A cardiac catheter is performed to view the obstructed coronary blood vessels.The patient is awake but sedated.A dye is injected to show the blood vessels.Complications Bleeding Angina AMI
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Electrocardiograph - ECG
Views the conduction of the heart
The tracing shows PQRST formation
P wave = depolarization of the atria
QRS = depolarization of the ventricle
T wave = depolarization of the ventricle
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Echocardiograph
Uses ultrasound and computer technology to crate an image of blood flow through the heart.It can be done through the chest wall or via the oesophagus ( posterior view of the heart).If done via the oesophagus the patient is to be fasted and sedated.
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Electrocardiograph - ECG
One small square is 0.04 seconds.
One large square ( 5 small squares) is 0.2
Damage or malfunction of the heart can be observed in an ECG.
Also the heart can be calculated.
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Doppler
A Doppler uses sound waves to study the flow and rate of blood through vessels .
It can depict alterations to the flow of blood through vessels (blockages)
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Angiograms and venograms
Dyes are injected into arteries or veins to highlight the flow of blood through the vessels.The vessels can be anywhere in the body. http://www.ohioheartandvascular.com/cvprocedures/cardiac-catheterization.php(great site to view the dye in arteries of heart)
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Nervous system diagnostic procedures
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Lumbar puncture (spinal tap)
Reasons for performing Meningitis and encephalitisMetastatic tumors and central nervous system tumors.SyphilisBleeding (hemorrhaging) in the brain and spinal cord.Multiple sclerosis.Guillain-Barre, a demyleinating disease involving peripheral sensory and motor nerves
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Lumbar puncture
Post procedureLay flat for 4-6 hoursNeurological observations and Check wound site (dressing)Lumbar puncture headaches typically begin within two days after the procedure and persist form a few days to several weeks or months.ComplicationsInfectionBleeding or CSF discharge from site of entry Numbness to legs and lower back pain
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myelogram
During a lumbar puncture a dye is injected into the subarachnoid spaceReasons for procedureHerniated discsSpinal cord or brain tumorsAnkylosing spondylisisBone spursArthritic discsCysts – benign capsules that may be filled with fluid or solid matter tearing away or injury of spinal nerve rootsAracnoiditis – inflammation of arachnoid mater.http://video.about.com/backandneck/Myelography.htm
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Electroencephalograph (EEG)
Observes the electrical activity of the brain.
Reasons for procedure
Diagnosis of epilepsy or brain injury
To assess conditions and diseases that affect the brain.
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Urinary system diagnostic proceduresGlomerular filtration rate measures the volume of blood filtered by the Glomerular membrane to form the Glomerular filtrate .Blood flowBlood pressureThe number of functioning glomeruliPermeability of the glomerular membraneBack pressure in the tubules.Still most used to determine kidney function.Declines as we get older
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Glomerular filtration rate (GFR)
is the amount of filtrate formed by both kidneys per minute; in a normal adult, it is about 125 ml/minute. This amounts to 180 liters per day.
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Glomerular filtration rate (GFR)
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Serum urate
Uric acid is the breakdown of purine components (guanidine and adenine) of the nucleic acids1/3 derived from the diet (meat and meat products)2/3 derived from turnover of body cellsCan also be measured from 24 hour urinary specimen.
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urea
Urea is the end product of protein metabolism.
Urea levels rise with
High protein diets
Excessive tissue breakdown
GI bleeding
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creatinine
Creatinine is the product of creatine metabolism in muscle
Blood levels depend closely on GFR
Creatinine levels are proportionate to muscle mass
If the blood value doubles then renal function has probably fallen to half normal state
Can also be measured by doing a 24 hour urine creatinine clearance test.
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Cystoscopy
Internal view of the bladder.
The patient is sedated.
Often a biopsy is taken
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Retrograde pyelogram
Performed during a Cystoscopy.
A dye is inserted into the ureters via a small catheter
X-ray is taken to view the kidneys , ureters and bladder
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Retrograde pyleogram
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Intravenous pyelogram (IVP)
A dye is inserted into a vein.As the dye passes through the urinary system X- Rays are taken.To ensure clarity of the X-ray images the bowel needs to be empty.
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Gastrointestinal diagnostic procedures
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Barium
Barium is a radio-opaque substance that is used to highlight the gastrointestinal tractIt can be given as a swallow, meal or enemaTo enhance the X- Rays the patient usually needs to have an empty gastrointestinal system.The introduction of air into the area with the barium also improves the X-Ray image
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Barium enema
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Endoscope - gastroscopy
Are used to perform diagnostic procedures and also therapeutic procedures.Gastroscopy The patient is to fastLight anesthetic givenReasons for procedureAnemia – bleeding from unknown sourceEpigastric pain or indigestionSwallowing difficultiesBiliary tree disease
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Endoscope
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Colonoscopy reason for procedureDiagnosis of disease process eg, ulcerative colitis, diverticulitis
Checking condition of polyps – biopsy
Assessing possible cause of anaemia (GI bleeding)
Investigate cause of frequent diarrhoea, bleeding , change in bowel habits - biopsy
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Preparation for procedure
No consuming of solid food for 24-48 hours prior to procedure . Can have clear fluids such as broth, jellies,
Fast 8-10 hours prior to procedure
Bowel cleansing day before procedure –cathartic (eg. Fleet, politely) may be required.
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Colonoscopy
Complications
Perforation of intestinal wall
Heavy bleeding due to the removal of the polyp or from the biopsy site (rare)
Infections (extremely rare)
Patients with artificial or abnormal heart valves are usually given antibiotics before and after the procedure to prevent an infection.
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colonoscopy
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Endoscopy
Find photos of
Reflux oesophagitis
Angio – dysplasia
Pseudo- polyposis
Colon cancer
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Endoscopic retrograde cholangiopancratography ERCP
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Endoscopic retrograde cholangiopancreatography ERCPIs used for diagnosing and treating disease of the pancreas, gallbladder, liver, and bile ducts.
An endoscope is inserted to the duodenum and a dye injected into the pancreatic duct and common bile duct.
Then an X-ray is taken
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Abdominal paracentesis
Is the removal of accumulated fluid form the peritoneal cavity.A needle is inserted into the abdominal cavity and it may be connected to a collecting bag.Done under local anesthetic. A sedative may be needed.The drainage of fluid may take time. It should not be removed too quickly as it may cause shock and collapse.
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