Core Surgery Knowledge Library
Condition-by-condition guides with a management focus — the evidence behind each decision, mapped to the core surgery interview stations.
Acute surgical conditions
Acute Appendicitis: Assessment and Management
The WSES 2020 Jerusalem update recommends the AIR and AAS scores rather than the Alvarado score to predict acute appendicitis in adults, ultrasound as the first-line imaging, and laparoscopic appendicectomy on the next available list within 24 hours of admission.
Acute Limb Ischaemia: the Six Ps and Time to Theatre
Acute limb ischaemia is graded by the Rutherford classification, anticoagulated at once with intravenous unfractionated heparin, and revascularised promptly when the limb is threatened; a Rutherford IIb limb with motor loss goes to theatre immediately, and a class III limb is irreversible.
Cauda Equina Syndrome: Red Flags and Emergency MRI
The GIRFT national pathway says suspected cauda equina syndrome with symptoms of under two weeks is an emergency referral for an MRI at the presenting hospital as soon as possible and certainly within four hours of request, in and out of hours, with incomplete CES decompressed as an NCEPOD E1/E2 emergency.
Compartment Syndrome and the BOAST Standard
The BOAST standard on compartment syndrome says the diagnosis is clinical, on pain out of proportion and pain on passive movement; that dressings are released, the limb elevated and the patient re-evaluated within 30 minutes; and that immediate surgical decompression should follow the diagnosis.
Head Injury and the NICE CT Criteria
NICE NG232 sets the CT head criteria for adults: within 1 hour for GCS 12 or less on arrival, GCS under 15 at 2 hours, suspected open or depressed skull fracture, basal skull fracture signs, post-traumatic seizure, focal deficit or more than one episode of vomiting; within 8 hours for loss of consciousness or amnesia with age 65 or over, a clotting disorder, a dangerous mechanism or more than 30 minutes of retrograde amnesia.
Hip Fracture and the 36-hour Target
NICE CG124 says to operate on a hip fracture on the day of, or the day after, admission, and the NHFD Best Practice Tariff measures that as surgery within 36 hours from arrival in the emergency department to the start of anaesthesia, with orthogeriatric assessment within 72 hours.
Necrotising Fasciitis: the Rapidly Spreading Painful Limb
Necrotising fasciitis is a surgical emergency diagnosed on suspicion: pain out of proportion, rapid spread and systemic toxicity mean immediate senior review, broad-spectrum antibiotics and urgent debridement. The LRINEC score supports the decision at a cut-off of 6 but never replaces it.
Open Fractures and the BOAST Standards
The BOAST and NICE NG37 standards for open fractures: intravenous antibiotics ideally within 1 hour of injury, photograph then cover with saline-soaked gauze, realign and splint, debride immediately if highly contaminated or ischaemic, within 12 hours for high-energy and 24 hours for other injuries, and definitive soft tissue cover within 72 hours.
Perforated Peptic Ulcer: Sudden Severe Epigastric Pain
The WSES guidelines on perforated peptic ulcer recommend CT as the imaging of choice, operative treatment for significant pneumoperitoneum, contrast extravasation or peritonitis, and surgery as soon as possible, because each hour of surgical delay in the first 24 hours after admission carried an adjusted 2.4% fall in the probability of survival.
RUQ Pain: Cholecystitis, Cholangitis and Pancreatitis
Right upper quadrant pain separates into acute cholecystitis, acute cholangitis and acute pancreatitis, and NICE CG188 offers early laparoscopic cholecystectomy within one week of diagnosis for acute cholecystitis while the Tokyo Guidelines grade cholangitis by organ dysfunction to decide how urgently the bile duct must be drained.
Ruptured AAA: Collapse with Abdominal and Back Pain
NICE NG156 says to think of a ruptured AAA in anyone with new abdominal or back pain, collapse or loss of consciousness, to do an immediate bedside aortic ultrasound, to discuss immediately with the regional vascular service, and to use permissive hypotension during transfer.
Small and Large Bowel Obstruction
Bowel obstruction at the CST station is resuscitation, a prompt CT with intravenous contrast, nasogastric decompression, and a decision: strangulation, peritonitis or ischaemia means theatre, and an uncomplicated adhesive obstruction earns a trial of up to 72 hours of non-operative care.
The Acute Scrotum: Torsion until Proven Otherwise
Acute severe testicular pain is torsion until proven otherwise and goes to theatre on clinical suspicion. According to BAUS, salvage is 90 to 100% under 6 hours, around 50% at 12 hours and under 10% beyond 24 hours, and imaging must not delay surgery.
The Trauma Primary Survey for the Non-trauma SHO
NICE NG39 asks you to record catastrophic haemorrhage, airway with in-line spinal immobilisation, breathing, circulation, disability and exposure as the primary survey, to give intravenous tranexamic acid as soon as possible in active or suspected active bleeding, and not to give it more than three hours after injury unless there is evidence of hyperfibrinolysis.
Management, ethics and the portfolio
Audit vs QI vs Research, and How the Portfolio Grades Them
HQIP defines clinical audit as a quality improvement cycle that measures the effectiveness of healthcare against agreed standards and takes action to bring practice in line with them; the HRA's Defining Research table separates research, which generates generalisable new knowledge, from audit, which measures against a standard, and service evaluation, which measures current care without one; NHS England's 2025/26 CST portfolio grades audit and QI together, with level A for leading all aspects of a surgically themed project that demonstrated change.
Breaking Bad News and Disclosing Complications: Duty of Candour
The professional duty of candour, in joint GMC and NMC guidance, requires you to tell the patient when something has gone wrong, apologise, offer an appropriate remedy or support, and explain fully the short and long term effects; the statutory duty in Regulation 20 of the 2014 Regulations obliges the organisation to notify a notifiable safety incident in person, give a true account and an apology, and follow up in writing.
Consent and Capacity, Including Consent beyond Your Competence
Under the Mental Capacity Act 2005 an adult is presumed to have capacity, and lacks it only if an impairment or disturbance of the mind or brain leaves them unable to understand, retain, use or weigh the information, or communicate a decision; GMC Decision Making and Consent 2020 adds that a doctor asked to take consent must be satisfied they have the knowledge and skills to do so, and should otherwise say so and seek support.
The Struggling or Impaired Colleague: SPIES and the GMC Duties
A struggling colleague is handled with SPIES, seek information, patient safety, initiative, escalate, support, and the professional duty underneath it is the one RCS Good Surgical Practice 3.6 states: raise concerns at the earliest opportunity when you reasonably believe the care or wellbeing of patients or colleagues may be in jeopardy, including because of a colleague's conduct, performance or health.
The WHO Checklist, Never Events and Human Factors
NHS England defines Never Events as patient safety incidents that are wholly preventable because national guidance providing strong systemic protective barriers exists and has been implemented; the surgical ones are wrong site surgery, wrong implant or prosthesis and retained foreign object, and the barriers are the WHO Surgical Safety Checklist and the NatSSIPs 2 sequential standards known as the NatSSIPs Eight.
Three Calls at Once: Prioritisation Frameworks
When three calls come at once, prioritise by physiological threat rather than by who called first: CCrISP teaches prioritising the patients most at risk, and the RCP NEWS2 chart fixes the thresholds, with an aggregate of 5 or 6 as the key threshold for urgent response and 7 or more needing an urgent or emergency response from a team with critical care skills.
The approach
Acute Kidney Injury in Surgical Patients: Prevention, Staging and Management
According to NICE NG148, acute kidney injury is a rise in serum creatinine of 26 micromol/L or more within 48 hours, a rise of 50% or more within 7 days, or a urine output under 0.5 ml/kg/hour for more than 6 hours, and stage 3 means a creatinine ratio of 3.0 or more or a value over 354 micromol/L.
Arterial Blood Gases and Acid-Base for the Surgical SHO: Reading the Gas Out Loud
Read a gas in a fixed order: oxygenation against the inspired oxygen, then pH, then whether the primary problem is respiratory or metabolic, then compensation, then lactate and electrolytes; a raised lactate in a surgical patient is hypoperfusion until proven otherwise.
Fluids and Electrolytes: Assessment, Resuscitation versus Maintenance and NICE CG174
CG174 separates resuscitation from maintenance: resuscitate with 500 ml of a sodium-containing crystalloid over less than 15 minutes when the indicators of hypovolaemia are present, and prescribe maintenance at 25 to 30 ml/kg/day of water with about 1 mmol/kg/day of sodium, potassium and chloride and 50 to 100 g/day of glucose.
Post-operative Respiratory Compromise: Atelectasis, Pneumonia, PE and Oxygen Targets
According to the BTS oxygen guideline, a breathless post-operative patient is given oxygen to a target saturation of 94 to 98%, or 88 to 92% if at risk of hypercapnic respiratory failure, while a two-level Wells score above 4 points, which surgery in the previous 4 weeks helps reach, means an immediate CTPA under NICE NG158.
Sepsis and Septic Shock: Sepsis Six, Source Control and NICE NG253
According to NICE NG253, a surgical patient at high risk of sepsis (NEWS2 of 7 or more) needs broad-spectrum intravenous antibiotics and a 250 ml fluid bolus within 1 hour of the score being calculated, with the senior decision maker attending in person if there is no response within 1 hour.
Shock and Haemorrhage: Recognition, Massive Transfusion and Damage Control
According to NICE NG39, a bleeding patient in hospital is resuscitated with blood components at a ratio of 1 unit of plasma to 1 unit of red cells rather than crystalloid, given tranexamic acid as soon as possible and not more than 3 hours after injury, and taken for damage control surgery if haemodynamic instability does not respond to volume.
The CCrISP Three-Stage Assessment: Immediate Management, Full Assessment, Decide and Plan
CCrISP structures every deteriorating surgical patient into three stages: immediate management by ABCDE, a full assessment of chart, history, examination and results, then a decision to treat or investigate with a plan and a named escalation.
The Deteriorating Surgical Patient: NEWS2, Escalation and When to Call Critical Care
NEWS2 aggregates six observations into a score with fixed triggers: 5 or more needs an urgent review by a clinician with acute-care competencies, 7 or more needs an emergency response from a team with critical care skills and consideration of level 2 or 3 care.
Ward and post-operative emergencies
Analgesia and the Acute Pain Ladder
NICE NG180 offers oral paracetamol before and after surgery irrespective of pain severity, oral ibuprofen for immediate post-operative pain of all severities except after hip fracture surgery, and an oral immediate-release opioid only when pain is expected to be moderate to severe.
DKA in the Surgical Patient
The Joint British Diabetes Societies guideline diagnoses diabetic ketoacidosis when all three of known or new diabetes, capillary ketones of 3 mmol/L or more (or ketonuria of ++ or more), and a venous bicarbonate below 15 mmol/L and/or a venous pH below 7.3 are present, and treats it with 0.9% sodium chloride first and a fixed rate insulin infusion at 0.1 units/kg/hr second.
Hyperkalaemia and the Critical Electrolytes
The UK Kidney Association 2023 guideline grades hyperkalaemia as mild at 5.5 to 5.9, moderate at 6.0 to 6.4 and severe at 6.5 mmol/L or more, and treats it in five steps: protect the heart with 30 ml of 10% calcium gluconate over 10 minutes if the ECG has changed, shift potassium with 10 units of soluble insulin in 25 g of glucose plus nebulised salbutamol 10 to 20 mg, remove it with sodium zirconium cyclosilicate, monitor potassium at 1, 2, 4, 6 and 24 hours, and prevent recurrence.
New Atrial Fibrillation after Surgery
NICE NG196 says to carry out emergency electrical cardioversion without delaying to achieve anticoagulation in anyone with life-threatening haemodynamic instability from new-onset atrial fibrillation, and otherwise to offer rate or rhythm control if onset is under 48 hours and rate control if onset is over 48 hours or uncertain.
Post-operative Abdominal Pain and Anastomotic Leak
The ACPGBI and ASGBI define an anastomotic leak as a leak of luminal contents from a surgical join between two hollow viscera, with a prevalence of 1% to 19%, and require source control within 18 hours without organ dysfunction, 6 hours with organ dysfunction and 3 hours in septic shock.
Post-operative Chest Pain: ACS, PE and the Surgical Differential
According to NICE NG185, a patient with a suspected acute coronary syndrome receives a single 300 mg loading dose of aspirin as soon as possible, no dual antiplatelet therapy until the diagnosis is made, and a GRACE score to decide whether coronary angiography is needed within 72 hours; a two-level Wells score above 4 points sends the same patient for an immediate CTPA under NG158.
Post-operative Confusion and Delirium
NICE CG103 asks you to assess a post-operative patient with indicators of delirium using the 4AT, or the CAM-ICU or ICDSC in critical care and in the recovery room after surgery, and to use verbal and non-verbal de-escalation before any consideration of short-term haloperidol.
Post-operative Hypotension: the Structured Approach
Post-operative hypotension is hypovolaemia until proven otherwise, and NICE CG174 gives the response: a 500 ml bolus of sodium-containing crystalloid over less than 15 minutes when the systolic is under 100 mmHg, the heart rate over 90 or the capillary refill over 2 seconds, then reassess, while blood loss is replaced with blood under NICE NG39 and suspected sepsis follows NG253's 250 ml boluses.
Post-operative Pyrexia: the Five Ws
The five Ws of post-operative pyrexia (wind, water, wound, walking and wonder drugs) are a teaching heuristic for the source; the decision that matters is the NEWS2, where a temperature of 38.1 to 39.0 scores 1, 39.1 or more scores 2, and an aggregate of 7 or more with suspected infection puts the patient at high risk under NICE NG253.
The Airway-Compromising Neck Swelling after Thyroid or Neck Surgery
A neck haematoma after thyroid surgery occurs in 0.45% to 4.2% of cases, most within 24 hours and about half within 6 hours; the DAS, BAETS and ENT UK guideline says to recognise it by DESATS, call for senior surgical and anaesthetic help immediately, and if the airway is compromised open the wound at the bedside with SCOOP: skin exposure, cut sutures, open skin, open muscles, pack wound.
Upper GI Bleeding: Glasgow-Blatchford, Resuscitation and Endoscopy
NICE CG141 recommends the Blatchford score at first assessment and the full Rockall score after endoscopy, early discharge for a pre-endoscopy Blatchford score of 0, endoscopy immediately after resuscitation for unstable patients and within 24 hours of admission for everyone else, and no proton pump inhibitor before endoscopy in suspected non-variceal bleeding.
VTE Prophylaxis and the Swollen Leg
NICE NG89 requires a VTE and bleeding risk assessment on admission, mechanical prophylaxis from admission for abdominal surgery and pharmacological prophylaxis for a minimum of 7 days, extended to 28 days after major abdominal cancer surgery; NICE NG158 then uses a two-level Wells score, with 2 points or more meaning a proximal leg vein ultrasound within 4 hours or interim anticoagulation and a scan within 24 hours.
FAQ
What is the Core Surgery Knowledge Library?
Free condition-by-condition guides for the core surgical training interview, with a management focus: assessment, the evidence and the management for the conditions the clinical questions draw on. No account is needed.
How does it help with the CST interview?
The guides cover the clinical knowledge behind the interview's scenarios. The question bank turns the same topics into full practice stations with model answers.