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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