Name: Pre-operative assessment
Creator: Dr. Mohammed Maree
Published: 2026-11-02

Written and clinically reviewed by Dr. Mohammed Maree, consultant minimally invasive and bariatric surgeon, Al-Makassed Hospital, Jerusalem, and Assistant Professor of Surgery, Al-Quds University. Last updated 2 November 2026.

Pre-operative assessment answers three questions: how risky is this operation for this patient, can we make the patient safer before it, and what needs to be in place on the day. Work through the same seven steps for every patient — from a hernia repair to a Whipple.

Calculator · 9 scoresPre-operative risk scoresASA, RCRI, functional capacity, STOP-BANG, ARISCAT, frailty, Caprini and Wells in one place. Guide · Caprini · WellsVTE risk and prophylaxisScore the clot risk, weigh the bleeding risk, prescribe the prophylaxis. GuideAntibiotic prophylaxisWound classes, which drug, when, and for how long. Practice · 8 patientsPre-operative ordersDecide what each patient needs, then check every decision. Worked exampleA 74-year-old for a hemicolectomyAll seven steps applied to one patient.

1The operation and its urgency

Risk belongs to the patient and the operation. Before you see the patient, know what is planned and how soon.

Surgical grade	Examples
Minor	Excision of a skin lesion, drainage of a breast abscess
Intermediate	Inguinal hernia repair, varicose veins, tonsillectomy, knee arthroscopy
Major or complex	Laparoscopic cholecystectomy*, bowel resection, thyroidectomy, joint replacement, bariatric surgery, major vascular or thoracic surgery

*Grades follow the NICE NG45 examples; a laparoscopic cholecystectomy is graded major.

Urgency (NCEPOD)	Timing	Example
Immediate	Within minutes, alongside resuscitation	Ruptured aortic aneurysm
Urgent	Within hours	Perforated viscus, strangulated hernia
Expedited	Within days	Cancer causing obstruction that is not complete
Elective	Planned	Hernia repair, cholecystectomy, cancer resection

Why it matters

Elective surgery can wait for optimisation; an emergency cannot. In an emergency the assessment is shorter and focuses on resuscitation, risk prediction and the level of post-operative care.

2History: a focused systems review

You are looking for conditions that change the anaesthetic, the operation or the recovery.

System	Ask about
Cardiac	Chest pain, breathlessness, palpitations, fainting, previous MI or stents, heart failure, valve disease, pacemaker. Functional capacity: can they climb two flights of stairs without stopping?
Respiratory	COPD, asthma (how often do they need steroids?), recent chest infection, home oxygen, smoking (pack-years), snoring and daytime sleepiness
Endocrine	Diabetes: type, treatment, control (HbA1c), hypoglycaemia. Thyroid disease. Steroid use in the last 3 months
Renal and liver	Chronic kidney disease, dialysis; liver disease, alcohol intake
Neurological	Stroke or TIA (when?), epilepsy, cognitive impairment
Bleeding	Easy bruising, bleeding after dental extraction or previous surgery, family history of bleeding
Anaesthetic history	Previous anaesthetics and problems; nausea and vomiting; difficult airway; family history of malignant hyperthermia or suxamethonium apnoea
Drugs and allergies	Every medicine, including anticoagulants, antiplatelets, diabetic drugs, steroids, herbal remedies. Allergies and what actually happened (latex, antibiotics, chlorhexidine)
Social	Smoking, alcohol, who is at home, mobility, frailty, who will look after them after discharge

3Examination

Observations: blood pressure, heart rate and rhythm, oxygen saturation on air, temperature, weight, height and BMI.
Airway: mouth opening, Mallampati class, teeth (loose, crowns, dentures), jaw protrusion and neck movement. The anaesthetist will repeat this, but flag a likely difficult airway early.
Cardiovascular: listen for a murmur. An ejection systolic murmur may be aortic stenosis, which needs an echocardiogram before major surgery. Look for signs of heart failure.
Respiratory: wheeze, crackles, signs of infection.
Frailty: how they walk into the room; grip strength; the Clinical Frailty Scale.
The surgical site: previous scars, stomas, skin condition and infection.

4Investigations: targeted, not routine

Order a test only if it could change the decision to operate, the anaesthetic or the post-operative care. This table summarises the approach in NICE guideline NG45.

Test	When to order it
Full blood count	Major or complex surgery; intermediate surgery in ASA III–IV; symptoms of anaemia
Kidney function	Major surgery; ASA II or more with a risk of acute kidney injury (diabetes, hypertension, heart failure, ACE inhibitors, diuretics)
HbA1c	Every patient with diabetes not tested in the last 3 months
ECG	Cardiovascular, renal or diabetic disease, or age over 65 before major surgery
Clotting screen	Anticoagulants, liver disease, or a bleeding history
Group and save or crossmatch	According to the expected blood loss of the operation
Pregnancy test	Any woman who could be pregnant, with her consent
Echocardiogram	A new murmur, unexplained breathlessness, or signs of heart failure
NT-proBNP	Age 65 or more, or RCRI 1 or more, before major non-cardiac surgery (Canadian guideline) — a high value predicts cardiac complications
CPET	Major surgery when functional capacity is uncertain, if available

Not routine

Chest X-ray, lung function tests and arterial blood gases are not routine pre-operative tests. Order them for a specific clinical reason.

5Risk scores: put a number on the risk

Each score answers a different question. Use the ones that fit the patient in front of you — all six are in the pre-operative risk scores calculator.

How unwell is the patient overall?ASA physical statusI to VI, plus E for emergency. Every patient. Risk of a major cardiac event?RCRI (Lee index)Six yes/no items. Non-cardiac surgery in adults. Can the heart and lungs cope?Functional capacity (METs)Can they manage 4 METs, such as two flights of stairs? Undiagnosed sleep apnoea?STOP-BANGEight items. Matters for opioids and the airway. Risk of a post-operative chest complication?ARISCATSeven items, including the incision and duration. Is the patient frail?Clinical Frailty Scale1 to 9. Age 65 and over.

Predicting mortality

For major and emergency surgery, estimate the risk of death with a validated model: P-POSSUM, the ACS NSQIP surgical risk calculator, or the NELA score for emergency laparotomy. In the UK, a predicted mortality of 5% or more after emergency laparotomy should bring a consultant surgeon and a consultant anaesthetist to theatre, and a planned critical care bed after the operation.

Blood clots (VTE)

Risk of a blood clot after surgery?Caprini scoreGuides VTE prophylaxis. Every surgical inpatient.Is this swollen leg a DVT?Wells DVTDiagnostic. Leads to D-dimer or ultrasound.Is this breathless patient a PE?Wells PEDiagnostic. Leads to D-dimer or CTPA.

Read the full VTE risk and prophylaxis guide.

6Optimise the patient

Reasons to postpone elective surgery

Myocardial infarction within 60 days, or unstable angina
Decompensated heart failure, symptomatic severe aortic stenosis, or an uncontrolled arrhythmia
Blood pressure of 180/110 mmHg or more in the pre-assessment clinic
Stroke or TIA in the last 3 months
Active chest infection
Anaemia not yet investigated before major surgery
Very poorly controlled diabetes (HbA1c above about 69 mmol/mol, 8.5%) — for elective surgery

For cancer surgery, weigh the delay against the risk of the cancer progressing: optimise quickly, not indefinitely.

Problem	What to do
Anaemia	Investigate. Iron deficiency before major surgery is treated with iron — intravenous if surgery is less than about 6 weeks away.
Diabetes	Improve control where time allows. Plan the day: first on the list, dose adjustments, and a variable-rate insulin infusion if more than one meal will be missed.
Smoking	Stopping at any point helps; 4 to 8 weeks before surgery reduces wound and chest complications.
Alcohol	Ask, and plan for withdrawal.
Nutrition	Screen with MUST. Malnourished patients need dietitian input and nutritional support before major surgery.
Fitness	Prehabilitation: exercise, nutrition and psychological support in the weeks before major surgery.
Sleep apnoea	Bring CPAP on the day; caution with opioids and sedatives.

The medicines plan

Write down what to stop, when, and what to continue. Timings vary between drugs and hospitals: always check local guidance.

Medicine	Usual plan
Aspirin (secondary prevention)	Usually continued
Clopidogrel, ticagrelor	Usually stopped 5–7 days before. Never stop after a recent coronary stent without asking cardiology.
Warfarin	Stopped 5 days before; INR checked the day before. Bridging with heparin only for high thrombotic risk (for example a mechanical mitral valve).
DOACs (apixaban, rivaroxaban, dabigatran)	Stopped 1–3 days before, depending on the drug, kidney function and bleeding risk
SGLT2 inhibitors (empagliflozin, dapagliflozin)	Stopped 3 days before surgery (ertugliflozin 4 days): risk of euglycaemic ketoacidosis
Metformin	Usually omitted on the day if a meal will be missed or kidney function is impaired
Insulin	Long-acting dose usually reduced by about 20% the night before and on the day
GLP-1 agonists (semaglutide)	Delay stomach emptying: aspiration risk. Follow current local guidance on holding the dose or a clear-fluid diet beforehand.
ACE inhibitors and ARBs	Often withheld on the morning of surgery (hypotension)
Beta-blockers and statins	Continued. Do not start a beta-blocker just before surgery.
Long-term steroids	Continued, with extra steroid cover for major surgery
Combined pill and HRT	Consider stopping 4 weeks before major surgery (VTE risk)

7Plan the day and take consent

Fasting: no food for 6 hours; clear fluids until 2 hours before (many units now allow sips until called); breast milk 4 hours. Carbohydrate drinks are part of enhanced recovery.
Level of care: ward, enhanced care, HDU or ICU — decided from the risk scores, not after the operation.
VTE prophylaxis: based on the Caprini score and the bleeding risk; extended for 28 days after major abdominal or pelvic cancer surgery. VTE guide.
Antibiotic prophylaxis: decided by the wound class; usually a single dose within 60 minutes before the incision. Antibiotic guide.
Enhanced recovery (ERAS): carbohydrate loading, minimal fasting, early eating and mobilisation.
Consent: the benefits, the material risks (those this patient would want to know), the alternatives including doing nothing, and time to decide. Document it.
On the day: site marking and the WHO surgical safety checklist.

✓Worked example

Mr A, 74, for an elective laparoscopic right hemicolectomy for caecal cancer

Hypertension; type 2 diabetes on insulin (HbA1c 64 mmol/mol); myocardial infarction 4 years ago, no symptoms since. Breathless after one flight of stairs. Smokes 10 a day. Snores loudly. BMI 31. On air his saturation is 95%. Hb 9.8 g/dL with a low ferritin; creatinine 115 µmol/L (1.3 mg/dL). Lives with his wife and walks to the shop daily.

Score	Working	Result
ASA	Severe systemic disease: insulin-treated diabetes, previous MI more than 3 months ago	ASA III
RCRI	Intraperitoneal surgery 1 + ischaemic heart disease 1 + insulin 1	3 points: about 15% risk of a major cardiac event
Functional capacity	Stops after one flight of stairs	Below 4 METs
STOP-BANG	Snoring, high blood pressure, age over 50, male	4: high risk of sleep apnoea, because two STOP items are present in a man
ARISCAT	Age 3 + SpO₂ 95% 8 + anaemia 11 + upper abdominal 15 + 2–3 hours 16	53: high risk of a chest complication
Clinical Frailty Scale	Independent, slowed by his breathlessness	4: living with very mild frailty

The plan

Heart: ECG and NT-proBNP; echocardiogram if there is a murmur or the BNP is high. Continue aspirin, beta-blocker and statin.
Anaemia: iron deficiency with surgery in about 3 weeks, so intravenous iron now.
Diabetes: first on the list; reduce the long-acting insulin; variable-rate infusion if he cannot eat after surgery.
Chest: stop smoking now; prehabilitation exercises; incentive spirometry and early mobilisation after surgery.
Sleep apnoea: refer for a sleep study if time allows; minimise opioids; monitor saturation overnight.
The day: enhanced recovery pathway; book an HDU or enhanced-care bed; VTE prophylaxis for 28 days; consent including leak, bleeding, chest infection and cardiac complications.

Practise

Practice · 8 patientsPre-operative ordersDecide what each patient needs, then check every decision.CalculatorPre-operative risk scoresScore Mr A yourself.OSCE stationVTE prophylaxis after cancer surgeryA prescribing station.OSCE stationPost-operative analgesiaA prescribing station.OSCE stationMaintenance intravenous fluidsA prescribing station.OSCE stationObservation chartRecognise the deteriorating patient.TopicAcid–base & blood gasesFor the sick surgical patient.

Sources and local practice

This page summarises widely used guidance, including NICE NG45 (routine pre-operative tests), the 2017 Canadian Cardiovascular Society perioperative guideline, the ASA physical status classification, and UK Centre for Perioperative Care guidance. Hospitals differ, particularly on stopping medicines: follow your own hospital’s policy.

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Pre-operative assessment