The following investigations should be ordered for all patients:

Bedside glucose level (BGL)

A bedside glucose test helps rule out hypoglycaemia, although it is unlikely that you would make a quick recovery from hypoglycaemia induced LOC unless intervention was given.


ECG is an essential investigation into cardiac causes. Look for (amongst other things);Long / short QT, conduction blocks, pacemaker function, bradycardia, Brugada, WPW, LV hypertrophy (think about HOCM).


Measurement of haematocrit < 30%  is required to complete the San Francisco Rule to identify which patients can be safely discharged.

Learning bite

ECG is essential for picking up cardiac causes of collapse and should be done on all patients presenting with Syncope.

By this stage a history, examination and limited ED-based investigations will have allowed appropriate risk stratification. High-risk patients will require admission for further urgent investigation and appropriate intervention. Low-risk patients can be discharged, a proportion of whom may require further investigation which can appropriately be performed as an outpatient. The following investigations should be ordered where necessary:

Transthoracic echocardiogram

Echocardiography should be performed in any patient with a cardiac murmur and should be used to diagnose and quantify heart failure when this is suspected. If aortic stenosis is suspected, echocardiography should be performed urgently. This will commonly be done as an inpatient.

For people with a suspected cardiac arrhythmia cause of syncope, ambulatory ECG monitoring can be requested as an out patient. The type of monitor would depend on the frequency of symptoms.