[Medical education] Order of investigations

When you see a patient you should ideally:

1. Take a history
2. Perform a physical examination
3. Organise differential diagnosis
4. Request investigations

At stage 4, medical practitioners must learn to proceed in an ethical, practical and logical order. If a question can be answered by a low-risk, cheap, fast investigation, there is no need for invasive, high-risk, expensive, time-consuming investigations.

Physical examination

• Blood pressure measurement
• Dermatoscopy
• Fundoscopy
• Otoscopy

 

Point-of-care (bedside) investigations

• Pulse oximetry
• ECG 
• Pregnancy test
• Urine dipstick 
• BM test 
• Ultrasound scan (USS)  
• Echocardiography
• Electroencephalography 

Laboratory tests

• Blood tests
• Blood culture
• Faecal culture 
• Sputum culture 
• Swab culture
• Urine culture

Radiology tests (without ionising radiation)

• Ultrasound scan (USS)
• Magnetic resonance imaging (MRI) 
• Optic imaging

Radiology tests (with ionising radiation)

• Simple radiograph (X-ray imaging)
• Computed tomography (CT) scan
• Positron emission tomography (PET) scan

 

Unpleasant investigations

• Nerve conduction study

 

Invasive investigations

• Endoscopy 
• Laryngoscopy 
• Bronchoscopy
• Sigmoidoscopy
• Colonoscopy  
• Laparoscopy  
• Lumbar puncture
• Tissue biopsy 
• Lymph node clearance
• Exploratory surgery 

 

Post-mortem (after death)

• Forensic pathology 
• Autopsy (post-mortem examination) 
• Dissection
• Preservation of tissues and organs