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Preoperative Assessment: The Tools

When patients sign their consent forms for surgery, part of the paperwork involves a health questionnaire. The questions involve a thorough exploration of the patient’s medical & surgical history along with medications & any relevant family history. This can help identify patients who may need to visit the preadmission clinic.

The Preadmission Clinic [PAC] consists of gathering a detailed history, collecting preoperative data such as vital signs & completing preoperative investigations such as scans & pathology. Input from multi-disciplinary team is required for most patients with results of investigations being reviewed by the anaesthetist & any other requirements discussed & organised prior to admission.

Verbal education along with plain language take home materials are provided to patients. Care is continued in the community in consultation with the patient’s GP which comprises of a formalised risk assessment & patient discharge checklist.


There are several validated assessment tools applied preoperatively to identify potential risks for patients. Many of these tools are utilised by the anaesthetist to assess the suitability of anaesthetic technique & to notify the surgical team of any issues they foresee.

These tools assess the following:

Physical Status

The American Society of Anesthesiologists [ASA] Physical Status score is one of the most prominent assessment tools used to identify high risk patients. There are 6 different scores ranging from number 1 (healthy patient) to number 6 (patient for organ procurement). There is also the option to add P for pregnancy & E for emergency.

Please use the following link to the ASA website to view some examples associated with each ASA-PS score

Airway Risk

If a thorough airway assessment is not performed preoperatively, the risk of an unanticipated difficult intubation & the potential for associated complications increases. The tools used during assessment of the airway help to identify if the patient’s airway may provide difficulties with bag-mask ventilation [BMV] &/or the placement of supraglottic airway devices [SADs] or endotracheal tubes [ETTs].

The following methods are only a few used & most of the these use a scoring system. The higher the number, the higher the anticipated difficulty.

Mallampati Score (assessing the posterior pharyngeal wall)

Upper Lip Bite Test (assessing the mobility of the jaw)

Wilson Score (a summative score of multiple assessment methods)

STOP BANG (assessing Obstructive Sleep Apnoea [OSA] risk)

Pressure Risk

Waterlow & Braden Scales which you should be familiar with from basic nursing practice & form part of our National Standards

Thrombosis Risk

These tools are highly specialised tools to assess clotting risk along with the risk versus benefit of continuing or ceasing antiplatelet & antithrombotics. The CHA₂DS₂VASc is one of the common tools used here.

Next week, we will explore what happens with high risk patients preoperatively by expanding alittle more on the outcomes of these assessment tools.

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