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Preoperative Evaluation

Disease specific approach to preoperative special investigations ASA category approach to preoperative special investigations Surgery or patient specific approach to preoperative special investigations Minimum pre-operative investigations American Society of Anaesthesiology grading Application of ASA grading Disease specific approach to preoperative special investigations Patient criter

Disease specific approach to preoperative special investigations

ASA category approach to preoperative special investigations

Surgery or patient specific approach to preoperative special investigations

Minimum pre-operative investigations

American Society of Anaesthesiology grading

Application of ASA grading

Disease specific approach to preoperative special investigations

Patient criteria  Investigations
Active, no documented medical illness, no medications  Finger prick Hb only 
Hypertension 

Formal Hb  
Creatinine
Na/K if using digoxin, diuretics, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs)
ECG  
Diabetes

Formal Hb 
Finger prick glucose in all
HBA1 C
Creatinine
Na/K if using digoxin, diuretics, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs)  
Ischaemic heart disease 

Formal Hb
Creatinine
Na/K if using digoxin, diuretics, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) ECG
Echo - Decision to perform an echo (formal or screening) should be decided on a case by case basis in consultation with an Anaesthetist 
Heart Failure 

Formal Hb
Creatinine
Na/K if using digoxin, diuretics, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs)  

Respiratory disease 

Well controlled, compliant, asymptomatic 

Poorly controlled/ uncharacterized dyspnoea or exercise intolerance that is unexplainable1 /Symptomatic COPD or asthma/ Admission for respiratory aetiology or oral steroid use in last year

Nil 

Lung function tests 


To avoid unnecessary re-testing prior to surgery, please follow the suggested “time since last investigation” column as recommended below in patients with stable disease and no change in symptoms.  Repeat investigations are only required if there is a change in the clinical symptoms.  

ASA category approach to preoperative special investigations 

Any level of surgery

Test Finger prick Hb
ASA 1 Routinely 
ASA 2  Routinely 
ASA 3 or 4 Routinely 
Time All patients

 

Test Formal Hb
ASA 1 Not routinely 
ASA 2  Not routinely 
ASA 3 or 4 CAD, liver disease, anaemia1,2,4 
Time 3 months unless recent bleeding documented 

 

Test Glucose –finger prick 
ASA 1 Not routinely 
ASA 2  All Diabetics2
ASA 3 or 4 All Diabetics2

 

Test Glucose formal
ASA 1 Not routinely 
ASA 2  Not routinely 
ASA 3 or 4 Not routinely 

 

Test HBA1c
ASA 1 Not routinely 
ASA 2  All Diabetics2
ASA 3 or 4 All Diabetics2
Time If not done within 3 months 

 

Test Creatinine
ASA 1 Not routinely 
ASA 2 

1. Patients age ≥45 years or 18-44 years with known cardiovascular risk factors. (CAD, Diabetes, Hypertension, CVD)1,2

2. History of renal impairment2
ASA 3 or 4
Time 6 months, earlier if on dialysis or previously documented Cr >177 or GFR <30ml/kg/min 

 

Test Urea
ASA 1 Not routinely 
ASA 2  Not routinely
ASA 3 or 4 Only if acutely indicated 

 

Test Na/K 
ASA 1 Not routinely 
ASA 2 

Patient is taking digoxin, diuretics, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs)2
History of Chronic Kidney Disease (CKD), CCF1,2,3
Endocrine disorders1
ASA 3 or 4
Time 6 months otherwise earlier if change in clinical symptoms  

 

Test

Thyroid function TSH/T4
ASA 2 

Patient on thyroid medication 
Screening for hypothyroidism in elderly if clinically indicated
ASA 3 or 4
Time 6 months

 

Test

INR/PTT
ASA 2 

All Patients on warfarin3, Chronic liver disease1, haemophilia4, inherited platelet disorder4
ASA 3 or 4
Time No time frame 

 

Test

ECG 
ASA 2 

Patients with known coronary heart disease, significant arrhythmia, peripheral arterial disease, cerebrovascular 
disease, or other significant structural heart disease1,2 
Hypertension 
ASA 3 or 4
Time Within 12 months unless onset of new symptoms 

 

Test CXR
ASA 1 Not routinely 
ASA 2  Not routinely 
ASA 3 or 4 Not routinely 

 

Test Pulmonary function test
ASA 2 

Obtained in patients with uncharacterized dyspnoea or exercise intolerance that is unexplainable1 
Symptomatic COPD or asthma, 
Admission for respiratory aetiology or oral steroid use in last year 
ASA 3 or 4
Time Within 12 months 

 

Test FATE Echo 
ASA 1 Not routinely 
ASA 2  Not routinely 
ASA 3 or 4

Consider in the following cases: 
VHD2
Unknown dyspnoea1
Worsening symptoms of cardiac failure 
“Decompensation” 
Documented pulmonary hypertension

 

Test Formal Echo  
ASA 1 Not routinely 
ASA 2  Not routinely 
ASA 3 or 4

Decision to perform an echo (formal or screening) should be decided on a case by case basis in consultation with an Anaesthetist 

 

Test Pacemaker assessment 
ASA 1 All pacemakers
ASA 2 
ASA 3 or 4
Time Within 12 months1 

 

Test Pregnancy test 
ASA 1 Females of child-bearing age 
ASA 2 
ASA 3 or 4


Intermediate surgery

Test Formal Hb 
ASA 1 Not routinely 
ASA 2  Major and intermediate risk surgery, recent bleeding4, expected blood loss of more than 300ml
ASA 3 or 4
Time 3 months unless recent bleeding documented 


Major surgery

Test Formal Hb 
ASA 1 Routinely 
ASA 2  Routinely 
ASA 3 or 4 Routinely 
Time 3 months unless recent bleeding documented 

 

Test ECG 
ASA 1 45 year old patients 
ASA 2  45 year old patients
ASA 3 or 4 45 year old patients 
Time Within 12 months unless onset of new symptoms  

 

Test Pulmonary function test  
ASA 2  Not recommended for abdominal or other high risk surgery1 except lung resection1,2
ASA 3 or 4
Time Within 12 months


Surgery or patient specific approach to preoperative special investigations

Investigation Finger prick Hb
Surgery specific Indication   All patients (screening)

 

Investigation Formal Hb
Time since last investigation  3 months unless recent bleeding documented 
Surgery specific Indication   Major and intermediate risk surgery, recent bleeding4, expected blood loss of more than 300ml
AND/OR  OR
Patient specific indication CAD, liver disease, anaemia1,2,4
Comment Definition of major and intermediate surgery: Vascular surgery, intraperitoneal and intrathoracic surgery, head and neck surgery, orthopaedic surgery and prostate surgery5

 

Investigation HBA1c
Time since last investigation  If not done within 3 months 
Patient specific indication Diabetic2

 

Investigation Glucose –finger prick 
Patient specific indication All Diabetic2

 

Investigation Glucose formal 
Surgery specific Indication   Not indicated

 

Investigation Creatinine
Time since last investigation  6 months
Patient specific indication

1. Patients age ≥45 years or 18-44 years with known cardiovascular risk factors. (CAD, Diabetes, Hypertension, CVD)1,2

2. History of renal impairment2
Comment Earlier if on dialysis or previously documented Cr >177 or GFR <30ml/kg/min

 

Investigation Urea
Surgery specific Indication   Only if acutely indicated

 

Investigation Na/K 
Time since last investigation  6 months otherwise earlier if change in clinical symptoms 
Patient specific indication

Patient is taking digoxin, diuretics, angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs)2
History of Chronic Kidney Disease (CKD), CCF1,2,3
Endocrine disorders1

 

Investigation

Thyroid function TSH/T4 
Time since last investigation  6 months 
Patient specific indication

Patient on thyroid medication 
Screening for hypothyroidism in elderly if clinically indicated

 

Investigation INR/PTT 
Time since last investigation  No time frame 
Patient specific indication All Patients on warfarin3, Chronic liver disease1, haemophilia4, inherited platelet disorder4

 

Investigation ECG 
Time since last investigation  Within 12 months unless onset of new symptoms 
Surgery specific Indication   45 year old patients undergoing high risk surgery3
AND/OR  OR
Patient specific indication

Patients with known coronary heart disease, significant arrhythmia, peripheral arterial disease, cerebrovascular
disease, or other significant structural heart disease1,2
Hypertension 

 

Investigation CXR 
Patient specific indication Not routinely recommended1,2

 

Investigation Pulmonary function test 
Time since last investigation  Within 12 months 
Surgery specific Indication   Not recommended for abdominal or other high risk surgery1 except lung resection1,2
AND/OR  OR
Patient specific indication

Obtained in patients with uncharacterized dyspnoea or exercise intolerance that is unexplainable1  
Symptomatic COPD or asthma,
Admission for respiratory aetiology or oral steroid use in last year

 

Investigation FATE Echo 
Patient specific indication

Consider in the following cases:
VHD2
Unknown dyspnoea1
Worsening symptoms of cardiac failure
“Decompensation”
Documented pulmonary hypertension 

 

Investigation Formal Echo
Patient specific indication

Decision to perform an echo (formal or screening) should be decided on a case by case basis in consultation with an Anaesthetist 

 

Investigation Pacemaker assessment 
Time since last investigation  Within 12 months1

 

Investigation Pregnancy test 
Patient specific indication

Females of child-bearing age 


Minimum pre-operative investigations 

Patient category Healthy patient for minor Sx Age > 60,  major surgery Procedure with expected blood loss > 600 ml
Ward Hb + +  
Hb WCC Platelets     +
Elecs + Creat      
CXR      
ECG   +  
Urine   + +
Blood Sugar     +
PFT’s      
Other      

 

Patient category Diabetes, well controlled
< 40 years, minor surgery		 Major abdominal surgery Major vascular surgery
Ward Hb +    
Hb WCC Platelets   + +
Elecs + Creat +   +
CXR     +
ECG +   +
Urine +    
Blood Sugar +   +
PFT’s     ±
Other      

 

Patient category Cardiovascular disease

Respiratory disease with significant functional
impairment

 Renal impairment
Ward Hb      
Hb WCC Platelets + + +
Elecs + Creat +   +
CXR + +  
ECG + + +
Urine     +
Blood Sugar      
PFT’s   +  
Other      

 

Patient category Liver disease and Right Heart failure Thoracotomy Morbid obesity
(B.M.I. > 35)
Ward Hb      
Hb WCC Platelets + + +
Elecs + Creat +   +
CXR + + +
ECG +   +
Urine +    
Blood Sugar +   +
PFT’s   + +
Other LFTs +  INR  + Albumin    

 

Patient category Steroids (prednisone > 10mg/day) Females of child-bearing age
Ward Hb + +
Hb WCC Platelets +  
Elecs + Creat    
CXR    
ECG    
Urine    
Blood Sugar    
PFT’s    
Other   Pregnancy test


Additional Notes:

  • All cases must be fully clerked. Further tests may be necessary on clinical grounds.
  • CXRs < 1 year old need not be repeated unless there is a change in symptoms.
  • ECG < 6 months old need not be repeated if symptoms are stable.
  • Elecs & creatinine need not be repeated if normal in previous 3 months and no new diuretic prescription.
  • RESPIRATORY DISEASE:
    • Asthmatic – young, well controlled: Nil
    • Asthmatic – symptomatic: Spirometry (Pre and post bronchodilator)
    • Severe COAD: Spirometry (Pre and post bronchodilator) Blood gases: Anaesthetic consultation
    • Previous lung surgery: Anaesthetic consultation
  • CARDIOVASCULAR DISEASE:
    • Hypertension: Hb, U&E, ECG, Urinalysis
      • Diastolic BP >115mm Hg on:Refer to physicians at least 2 weeks
      • > 1 occasion prior to elective surgery
      • Urgent surgery with DBP >115mmHg: Anaesthetic consultation
    • Pacemakers: Review of pacemaker within past year
    • Previous cardiac surgery: Anaesthetic consultation
    • Ischaemic Heart Disease:
      • Unstable or frequent angina: Physician and Anaesthetic consultation
      • MI in past 6 months: Anaesthetic consultation
  • AIRWAY PROBLEMS - Anaesthetic consultation
  • HIV +ve - stable with no recent deterioration     No additional tests
  • Ordering Group and Screen (G + S) preoperatively
    • Ordering a Group and Screen is a clinical decision dependent upon:
    • Patient.
      • Baseline Haemoglobin level
      • Presence of co-morbid disease (e.g. cardiac, respiratory,etc)
    • Extent and duration of surgery
    • Surgical technique

It should be considered when it is likely that the intraoperative Hb level will fall below 7.5g% in an otherwise healthy patient, or below 10g% in a patient with significant cardiac / respiratory disease. Surgery likely to fall into these categories includes cardiac surgery, major thoracic surgery, major vascular surgery, major orthopaedic surgery (corrective spinal surgery, revision arthroplasties and primary lower limb arthroplasties), liver surgery and major oncological surgery with or without reconstruction.

Patients who have had previous blood transfusions, at risk of intraoperative bleeding, need a G + S to detect possible antibodies from the previous transfusion which may make cross-matching difficult.

Patients with chronic anaemia (eg chronic renal failure) do not need a G + S for surgery where blood loss is unlikely.

Where possible all G + S requests should be ordered during normal working hours.

If a registrar or intern is uncertain about whether to order one for the proposed surgery please ask the anaesthetic consultant concerned.

American Society of Anaesthesiology grading 

ASA Grade Definition Post op mortality (%)
I Normal healthy individual 0.5
II Mild systemic disease not limiting activity 0.4
III Severe systemic disease limits activity but not incapacitating 4.5
IV Incapacitating constantly life threatening disease 25
V Moribund not expected to survive >24 hrs without intervention 50

 
APPLICATION OF ASA GRADING

Cardiovascular disease

  Grade II Grade III
Angina Occasional use of GTN Regular use of GTN, or unstable angina
Hypertension Well controlled, single agent Poor control, multiple agents
Diabetes Well controlled, no complications Poorly controlled, complications


Respiratory disease

  Grade II Grade III
COPD Cough or wheeze, well controlled Breathless on minimal exertion
Asthma Well controlled with inhalers Poor control, limiting lifestyle

Version: Preoperative investigation for elective surgery 18_03_2019_revision[11] (Last checked for updates: May 2023)

Drugs mentioned

NeoHealth® ID 19911 · updated 8/10/2023