What are the three steps of the WHO analgesic ladder?

Step one is a non-opioid analgesic, step two adds a weak opioid such as codeine or tramadol for moderate pain, and step three uses a strong opioid such as morphine for severe and persistent pain, with adjuvants available at any step. The WHO 2018 cancer pain guideline describes the ladder as a teaching tool and general guide based on pain severity rather than a replacement for individualised planning.

Why is the ladder used in reverse for acute post-operative pain?

In acute pain the strongest analgesic appropriate to that intensity is the initial therapy, and it is then toned down as the pain settles, whereas chronic pain is usually approached stepwise from the bottom. Starting at step one in a patient with severe pain after a laparotomy simply delays effective analgesia.

What does NICE recommend as the base of post-operative analgesia?

NICE NG180 offers a multimodal approach combining analgesics from different classes, and offers oral paracetamol before and after surgery irrespective of pain severity. It also offers oral ibuprofen for immediate post-operative pain of all severities unless the person has had surgery for hip fracture.

When should an opioid be prescribed after surgery?

NICE NG180 offers an oral immediate-release opioid only if immediate post-operative pain is expected to be moderate to severe. It asks you to give it as soon as the person can eat and drink, and to adjust the dose so the person achieves functional recovery such as coughing and mobilising as soon as possible.

PCA or epidural after major surgery?

NICE NG180 offers a choice of patient-controlled analgesia or a continuous epidural for people who cannot take oral opioids. It asks you to take into account the benefits of a continuous epidural for people having major or complex open-torso surgery, those expected to have severe pain, and those with cognitive impairment.

What is the maximum daily dose of paracetamol in an adult?

The BNF gives adult oral paracetamol as 0.5 to 1 g every 4 to 6 hours, to a maximum of 4 g per day. Dose reduction applies at low body weight, and combination preparations containing paracetamol must be counted towards the same daily total.

When is post-operative pain a red flag rather than a prescribing problem?

When it is disproportionate to the findings, escalating, or no longer responding to analgesia that previously worked. That pattern points to ischaemia, compartment syndrome, a necrotising soft tissue infection or an anastomotic leak, and the correct response is to re-examine the patient and escalate rather than to increase the opioid.

Acute Pain Ladder — CST Interview Clinical Station Answer

The acute pain ladder is the WHO three-step analgesic ladder used downwards rather than upwards: in acute post-operative pain you start at the step that matches the pain and step down as it settles. According to NICE guideline NG180 on perioperative care in adults, published on 19 August 2020, the foundation is a multimodal approach in which analgesics from different classes are combined. At the CST station, analgesia is a test of safe prescribing and of whether you can spot pain that is a surgical warning sign.

Key takeaways

NICE NG180 offers oral paracetamol before and after surgery, including dental surgery, irrespective of pain severity
NG180 offers oral ibuprofen for immediate post-operative pain of all severities, unless the person has had surgery for hip fracture
NG180 offers an oral immediate-release opioid only if immediate post-operative pain is expected to be moderate to severe, and asks you to adjust the dose to achieve functional recovery such as coughing and mobilising
The WHO 2018 cancer pain guideline describes the three-step analgesic ladder as useful as a teaching tool and a general guide based on pain severity, but says it cannot replace individualised therapeutic planning
The three principles of the WHO ladder are by the clock, by the mouth and by the ladder, meaning regular timing, the oral route where possible, and titration by severity
The BNF gives adult oral paracetamol as 0.5 to 1 g every 4 to 6 hours to a maximum of 4 g per day

What is the WHO analgesic ladder, and how is it used in acute pain?

The WHO analgesic ladder is a three-step framework: a non-opioid at step one, a weak opioid such as codeine or tramadol for moderate pain at step two, and a strong opioid such as morphine for severe pain at step three, with adjuvants at any step.

The WHO 2018 guideline on cancer pain carries the ladder in Annex 1 and is careful about its status. It calls the ladder useful as a teaching tool and as a general guide based on pain severity, and says it cannot replace individualised planning.

In acute pain the ladder runs the other way. For acute pain the strongest analgesic appropriate to that intensity of pain is the initial therapy, which is then toned down as the pain settles, rather than climbed from the bottom.

The three principles to quote are by the clock, by the mouth and by the ladder: analgesia given at regular intervals rather than on demand, by the oral route wherever possible, and matched to assessed severity.

How do I assess pain in a post-operative surgical patient?

Assess pain in a post-operative surgical patient at rest and on movement, using the same scale each time, and treat the assessment as a clinical examination rather than a number on a chart.

Pain on movement is the number that matters surgically, because NICE NG180 asks you to adjust the opioid dose to help the person achieve functional recovery, such as coughing and mobilising, as soon as possible.

Assess non-verbal signs too. NICE CG103 on delirium asks clinicians to look for non-verbal signs of pain in people with communication difficulties, including those with dementia or a tracheostomy, and that applies on a surgical ward.

What is the first-line analgesia after surgery?

First-line analgesia after surgery is multimodal. NICE NG180 offers a multimodal approach in which analgesics from different classes are combined, and offers oral paracetamol before and after surgery irrespective of pain severity.

The BNF gives adult oral paracetamol as 0.5 to 1 g every 4 to 6 hours to a maximum of 4 g per day. NG180 says not to offer intravenous paracetamol unless the person cannot take oral medicine.

NG180 then offers oral ibuprofen for immediate post-operative pain of all severities, unless the person has had surgery for hip fracture, and asks you not to offer an intravenous NSAID unless the oral route is unavailable.

If an intravenous NSAID is used, NG180 asks for a traditional NSAID rather than a COX-2 inhibitor. NG180 also suggests considering pre-emptive analgesia for use when the local anaesthetic wears off.

When do I add an opioid after surgery, and how?

Add an opioid after surgery only when the immediate post-operative pain is expected to be moderate to severe, which is the threshold NICE NG180 sets for an oral immediate-release opioid.

NG180 asks you to give the opioid as soon as the person can eat and drink after surgery, and to adjust the dose to help them achieve functional recovery, such as coughing and mobilising, as soon as possible.

For people who cannot take oral opioids, NG180 offers a choice of patient-controlled analgesia or a continuous epidural, taking into account the benefits of an epidural for major or complex open-torso surgery, expected severe pain, or cognitive impairment.

Prescribe the consequences at the same time. An anti-emetic, a laxative, a stool softener where appropriate, and observations that will detect sedation and respiratory depression before they become an emergency.

What adjuncts and regional options should I mention?

The adjuncts worth naming in post-operative analgesia are regional and local anaesthetic techniques, ketamine and the neuropathic agents, alongside the non-drug measures that reduce opioid requirement.

NICE NG180 suggests considering a single dose of intravenous ketamine, at 0.25 mg/kg to 1 mg/kg, given during or immediately after surgery to supplement other pain relief when pain is expected to be moderate to severe and an intravenous opioid alone is not enough, or where there is opioid sensitivity.

On gabapentin, NG180 is deliberately non-committal: the evidence that it can help was there, but the evidence on when to give it and how much was inconclusive, so the committee made a research recommendation instead.

In major trauma, NICE NG39 uses intravenous morphine as the first-line analgesic, adjusted to achieve adequate pain relief, with ketamine in analgesic doses as a second-line agent, and the intranasal route if there is no intravenous access.

How do I prescribe analgesia safely in the surgical patient?

Prescribe analgesia safely by choosing one drug at a full therapeutic dose before adding another, which is the principle NICE Clinical Knowledge Summaries set out and which prevents the accidental double-dosing of paracetamol.

NICE CKS advises against combination analgesics as first-line treatment, because prescribing single-constituent analgesics allows each drug to be titrated independently. It also asks for regular analgesia, not as-required alone, where pain is continuous.

Check renal function, gastrointestinal risk and cardiovascular risk before any NSAID, and avoid it after hip fracture surgery as NG180 directs
Beware paracetamol in low body weight and hepatic impairment, and beware duplicate paracetamol inside combination preparations
Reduce opioid doses in renal impairment, in older patients and in obstructive sleep apnoea
Give opioid-sparing analgesia deliberately, because opioid load drives ileus, delirium, nausea and respiratory depression
Counsel on driving, dependence and the risk of respiratory depression in overdose, as NICE CKS asks

When is post-operative pain a surgical emergency rather than an analgesia problem?

Post-operative pain becomes a surgical emergency when it is disproportionate, escalating, or no longer responding to analgesia that was working, because that pattern is a complication announcing itself.

Pain out of keeping with the findings is the classic warning in ischaemia, in compartment syndrome and in necrotising soft tissue infection. New severe abdominal pain after a bowel anastomosis is a leak until proven otherwise.

Say the rule out loud at interview. Escalating opioid requirement is a reason to re-examine the patient and to call the registrar, not a reason to write a bigger dose.

Who do I escalate post-operative pain problems to, and when?

Escalate post-operative pain to the acute pain team when a standard multimodal regimen is not working, and to your surgical registrar whenever the pain itself suggests a complication.

Escalate to anaesthetics for epidural and patient-controlled analgesia problems, for a block that has failed or is regressing abnormally, and for any suspicion of local anaesthetic toxicity or an epidural complication.

Escalate immediately for sedation with a falling respiratory rate on opioids, for new neurological signs in a patient with an epidural, and for uncontrolled pain in a patient whose observations are deteriorating.

What is the interviewer listening for in an analgesia scenario?

The interviewer in an analgesia scenario is listening for multimodal prescribing, a named ladder used in the right direction, safe dose limits, and the instinct to re-examine before escalating the opioid.

Assessment of pain at rest and on movement before any prescription
Regular paracetamol and, where safe, an NSAID as the base of the regimen
Opioids reserved for moderate to severe pain, titrated to function rather than to a score
Anti-emetic, laxative and monitoring prescribed alongside every opioid
An explicit statement that disproportionate pain is a reason to examine the patient and call for help

What are the common mistakes in an analgesia answer?

The commonest mistake in an analgesia answer is climbing the ladder from the bottom in a patient with severe acute pain, when acute pain starts at the step that matches the severity and steps down.

The second is prescribing an NSAID reflexively. NICE NG180 excludes hip fracture surgery, and renal impairment, gastrointestinal bleeding risk and cardiovascular disease all change the calculation on a surgical ward.

The third is treating rising analgesia requirement as a prescribing question. The answer the panel wants is that you go back to the patient and examine the wound, the abdomen and the limb.

How this comes up at the CST interview

Analgesia usually arrives at the CST station inside another scenario: a patient in pain after a laparotomy, a patient whose epidural has stopped working, or a patient asking for more morphine on day one.

The panel then pushes on safety, on the opioid-sparing plan, or on the moment when pain stops being a symptom to treat and becomes a sign to investigate.

The coresurgeryinterview question bank includes scored analgesia and prescribing scenarios among its 299 questions, with AI-marked spoken practice for the structure: /Question-Bank/Sample-Questions.

Analgesia and the Acute Pain Ladder