Major colorectal resection

10 min read Last updated April 8, 2026

Surgical approach

  • Typical operations: right/left hemicolectomy, sigmoid colectomy, subtotal/total colectomy, low anterior resection (LAR/TME), abdominoperineal resection (APR), Hartmann’s procedure
    • Indications: colorectal cancer, IBD (UC/Crohn’s), diverticular disease, ischaemia, obstruction/perforation, polyposis
  • Approach: laparoscopic/robotic vs open midline laparotomy
    • Laparoscopy: pneumoperitoneum (CO2), steep Trendelenburg and/or lithotomy (esp. pelvic dissection), longer set-up, less pain/ileus
    • Open: larger incision, greater fluid shifts/heat loss, higher pain burden
  • Key surgical steps (generic): mobilisation of colon/mesentery → vascular pedicle ligation → bowel resection → anastomosis or stoma formation
    • Pelvic surgery (TME/LAR/APR): prolonged deep pelvic dissection; risk of major bleeding; ureteric/nerve injury
    • Stoma: end colostomy/ileostomy; may be planned or due to contamination/instability
  • Potential intra-op events: pneumoperitoneum-related physiology, major haemorrhage (mesenteric/pelvic), anastomotic leak risk factors, bowel contamination/sepsis, ureteric injury

Anaesthetic management (overview)

  • Type of anaesthesia: GA with multimodal analgesia; neuraxial often beneficial for open surgery
    • Open: GA + thoracic epidural (commonly T8–T10) or alternative regional (TAP/rectus sheath) + PCA
    • Laparoscopic: GA + regional/LA infiltration (TAP/QL) + PCA; epidural selected cases (conversion risk, opioid-sparing, chronic pain)
  • Airway: cuffed ETT (RSI if obstruction/full stomach); SGA generally unsuitable for long laparoscopic colorectal resections
    • Consider arterial line if major comorbidity, expected blood loss, sepsis, or need for frequent gases
  • Duration: typically 2–6 hours (longer for pelvic dissection/robotic/complex re-do surgery)
  • Pain: moderate–severe (open > laparoscopic); pelvic/perineal pain significant in APR; shoulder tip pain possible after laparoscopy
  • Key goals: haemodynamic stability, avoid fluid overload, maintain perfusion to anastomosis, temperature control, PONV prophylaxis, early mobilisation/feeding (ERAS)

Preoperative assessment and optimisation

  • Assess indication and urgency: elective cancer vs emergency obstruction/perforation/sepsis (higher aspiration risk, haemodynamic instability, AKI)
  • Comorbidities: cardiovascular disease, COPD, CKD, diabetes, frailty; consider CPET/functional capacity for major elective resections
    • Cancer patients: anaemia, malnutrition, cachexia; chemo-related cardiomyopathy/neuropathy; VTE risk
    • IBD: steroid use (adrenal suppression), immunosuppressants/biologics (infection risk), electrolyte disturbances, anaemia, hypoalbuminaemia
  • Anaemia management: identify iron deficiency; consider IV iron ± transfusion depending on urgency and symptoms; optimise Hb to reduce transfusion
  • Medication considerations
    • Anticoagulants/antiplatelets: plan perioperative interruption/bridging; neuraxial timing per local/ASRA/ESAIC guidance
    • Steroids: if on long-term steroids or recent high-dose, consider perioperative steroid supplementation (institutional protocol)
    • ACEi/ARB: consider withholding on day of surgery if risk of refractory hypotension (local policy)
  • Bowel preparation: may cause dehydration/electrolyte disturbance; check U&E if high risk; ensure adequate pre-op hydration strategy
  • Aspiration risk: obstruction, ileus, emergency surgery, opioids; plan RSI and NG decompression if indicated
  • Consent/discussion: epidural risks/benefits, arterial/central access, blood transfusion, postoperative destination (HDU/ICU)

Intraoperative monitoring, access, positioning

  • Monitoring: standard + temperature + neuromuscular monitoring; consider BIS if TIVA/long case
  • Vascular access: 2 large-bore cannulae; arterial line for major cases; consider CVC if poor access, vasoactive infusions, severe sepsis, or need for CVP/ScvO2 (selective)
  • Positioning: lithotomy/Trendelenburg common for pelvic surgery; protect nerves/pressure areas
    • Lithotomy risks: common peroneal nerve injury, compartment syndrome (prolonged), DVT; ensure padding and time checks
    • Trendelenburg + pneumoperitoneum: facial/airway oedema, raised IOP/ICP, reduced FRC; consider cuff leak/airway assessment before extubation if prolonged steep Trendelenburg
  • Urinary catheter: usually required (fluid balance, pelvic dissection); consider temperature-sensing catheter

Anaesthetic technique

  • Induction: tailor to physiology (sepsis/obstruction/elderly); consider RSI if full stomach; pre-oxygenation essential
    • Emergency obstruction/perforation: RSI + vasopressor readiness; consider ketamine/etomidate where appropriate; early antibiotics and source control
  • Maintenance: volatile or TIVA; aim for haemodynamic stability and normothermia; lung-protective ventilation
    • Ventilation (laparoscopy): pressure-controlled/volume-controlled with PEEP; accept mild hypercapnia if stable; manage raised airway pressures with recruitment/PEEP/position adjustments
    • Neuromuscular blockade: deep block may improve surgical conditions in laparoscopy; ensure full reversal (sugammadex/neostigmine) before extubation
  • Analgesia strategy (multimodal)
    • Epidural (open/pelvic): local anaesthetic + opioid infusion; anticipate hypotension; coordinate with fluid/vasopressors; monitor sensory level
    • Alternatives: spinal opioid (intrathecal diamorphine/morphine) + GA; TAP/QL blocks; rectus sheath for midline; wound infiltration/catheters
    • Systemic: paracetamol; NSAID/COX-2 (balance AKI/anastomotic risk and bleeding—follow local colorectal policy); low-dose ketamine or lidocaine infusion (where used); opioid PCA if no epidural
  • PONV prophylaxis: high risk (opioids, laparoscopy); use multimodal antiemetics (e.g., dexamethasone + ondansetron ± droperidol) and minimise opioids

Fluids, haemodynamics, blood management

  • Principle: avoid both hypovolaemia (risk organ hypoperfusion/anastomotic ischaemia) and fluid overload (ileus, pulmonary oedema, impaired wound healing)
  • Use balanced crystalloids; consider goal-directed therapy (stroke volume optimisation) in high-risk major surgery
    • Replace deficits from bowel prep/fasting cautiously; avoid large “third-space” assumptions
  • Vasopressors: treat vasodilation (anaesthesia/epidural/sepsis) with noradrenaline/metaraminol rather than excessive fluid; maintain MAP to patient-specific target
  • Blood loss: variable (often modest; can be major in pelvic re-do, inflammatory mass, cancer with vascular involvement)
    • Group & screen vs crossmatch based on risk; consider cell salvage (especially open/pelvic) per local policy (often acceptable in cancer with leukocyte depletion filters)
    • Tranexamic acid: consider if significant bleeding anticipated/occurring (balance thrombotic risk; follow local guidance)
  • Electrolytes/acid-base: monitor lactate, Hb, K+, Ca2+ (massive transfusion), glucose (diabetes/TPN/steroids)

Temperature management

  • High risk of hypothermia (large exposure, long duration, fluids); use forced-air warming, warmed fluids, minimise exposure

Antibiotics, sepsis, and aspiration

  • Antibiotic prophylaxis: broad spectrum covering Gram-negative and anaerobes; re-dose if prolonged surgery or major blood loss (local protocol)
  • Emergency contaminated surgery: treat as sepsis—early antibiotics, source control, lactate-guided resuscitation, vasopressors, consider ICU post-op
  • Aspiration prevention: RSI when indicated; NG decompression in obstruction; extubate awake with protective reflexes

Postoperative care (ERAS-aligned)

  • Destination: ward vs HDU/ICU based on physiology, blood loss, sepsis, frailty, vasopressor requirement, epidural, and surgical complexity
  • Analgesia: continue epidural with regular review; otherwise PCA + multimodal; encourage early mobilisation and deep breathing
  • PONV/ileus: minimise opioids, maintain euvolaemia, correct electrolytes, consider chewing gum/early feeding per ERAS; avoid routine NG unless indicated
  • Fluids: aim for near-zero balance; early oral intake; stop IV fluids when tolerating; monitor stoma output (high-output ileostomy risk)
    • High-output ileostomy: risk of dehydration, hyponatraemia, hypomagnesaemia, AKI—early recognition and replacement plan
  • VTE prophylaxis: mechanical + pharmacological; extended prophylaxis often used after cancer surgery (follow local policy)
  • Glycaemic control and infection prevention: avoid hyperglycaemia; maintain normothermia; early mobilisation; wound care

Complications relevant to anaesthesia

  • Early: bleeding, sepsis, anastomotic leak, ileus, AKI, respiratory complications (atelectasis/pneumonia), myocardial injury, delirium
  • Procedure-specific: ureteric injury (haematuria/flank pain/AKI), pelvic nerve injury (urinary/sexual dysfunction), perineal wound issues (APR)
  • Epidural-related: hypotension, motor block, urinary retention, failure; rare haematoma/abscess
You are asked to anaesthetise a 72-year-old for elective open anterior resection. How do you assess and optimise them preoperatively?

Structure: patient factors, disease/surgery factors, optimisation, planning.

  • History/exam: functional capacity, cardiac symptoms, respiratory disease, frailty, cognition, nutrition, alcohol/smoking, previous abdominal surgery and anaesthetic issues
  • Investigations: FBC (anaemia), U&E (bowel prep/CKD), LFTs, coagulation if indicated, ECG; consider echo/CPET if poor exercise tolerance or significant cardiac disease
  • Optimisation: treat iron deficiency (often IV), manage HF/COPD, encourage prehabilitation, nutrition support, smoking cessation, review meds (anticoagulants, ACEi/ARB, diabetes drugs)
  • Plan: GA + epidural (benefits/risks), invasive monitoring, blood availability, postoperative HDU if high risk; ERAS expectations (early mobilisation/feeding)
Discuss your choice of analgesia for major colorectal surgery (open vs laparoscopic).

Compare neuraxial, regional, and systemic options; link to ERAS and side effects.

  • Open surgery: thoracic epidural provides excellent dynamic analgesia, reduces opioid requirement, may improve respiratory function; requires monitoring and hypotension management
  • Laparoscopic surgery: pain often less; consider intrathecal opioid, TAP/QL blocks, wound infiltration + PCA; epidural reserved for high pain risk or conversion likelihood
  • Multimodal baseline: paracetamol; NSAID/COX-2 if appropriate; minimise opioids; consider ketamine or lidocaine infusion where used locally
  • Procedure-specific: APR has perineal wound pain—may need additional local infiltration/blocks and careful sitting/mobilisation plan
How does pneumoperitoneum and Trendelenburg affect physiology and how do you manage it?

Cover cardiovascular, respiratory, and other effects; then practical management.

  • Cardiovascular: increased SVR and MAP; reduced venous return at high intra-abdominal pressures; arrhythmias possible from hypercapnia/vagal stimulation
  • Respiratory: reduced compliance and FRC, increased airway pressures, V/Q mismatch; CO2 absorption → hypercapnia
  • Other: reduced renal perfusion/urine output; increased IOP/ICP; facial/airway oedema with prolonged steep Trendelenburg
  • Management: limit insufflation pressure, optimise ventilation (PEEP/recruitment), adjust minute ventilation for CO2, ensure secure ETT, careful fluid/vasopressor balance, check eyes/pressure points, consider extubation strategy if airway oedema suspected
A patient presents with large bowel obstruction for emergency laparotomy. Outline your anaesthetic plan.

Priorities: resuscitation, aspiration prevention, sepsis management, and postoperative critical care.

  • Resuscitation: ABC, IV access, bloods (FBC/U&E/VBG/ABG, lactate), crossmatch; treat hypovolaemia and electrolyte disturbance; early antibiotics if perforation/sepsis suspected
  • Aspiration risk: full stomach—RSI; consider NG decompression pre-induction if safe; head-up preoxygenation
  • Induction/maintenance: haemodynamically cautious induction, vasopressors ready; invasive monitoring (arterial line); lung-protective ventilation; temperature management
  • Analgesia: consider epidural only if stable and coagulation normal (often not in emergencies); otherwise multimodal + opioid infusion/PCA; consider regional blocks
  • Post-op: likely HDU/ICU if sepsis, vasopressors, significant lactate/AKI, or major physiological derangement; ongoing fluid balance and early complication surveillance
Discuss fluid therapy and haemodynamic targets in major colorectal surgery.

Aim for adequate perfusion without overload; use monitoring to guide therapy.

  • Targets: patient-specific MAP (often ≥65 mmHg, higher if chronic hypertension), adequate urine output trend (not sole endpoint), normalising lactate, stable stroke volume where monitored
  • Strategy: balanced crystalloids; avoid large empiric replacement; consider goal-directed fluid therapy in high-risk patients
  • Vasopressors: treat vasodilation (GA/epidural/sepsis) with noradrenaline/metaraminol rather than repeated fluid boluses; ensure adequate intravascular volume first
  • Avoid overload: reduces gut oedema, ileus, pulmonary complications; important in ERAS
You have an epidural running and the patient becomes hypotensive after incision. How do you manage this?

Differentiate causes; treat promptly; maintain organ perfusion.

  • Immediate actions: check depth of anaesthesia, surgical bleeding, ECG rhythm, capnography, airway pressures; assess epidural level and recent boluses
  • Treat: vasopressor bolus (metaraminol/phenylephrine) and/or start noradrenaline infusion; cautious fluid bolus if hypovolaemic; reduce volatile/propofol if excessive
  • Epidural management: reduce rate/LA concentration if high block; consider opioid-only epidural temporarily; ensure no intrathecal/intravascular migration if unexpectedly high block
  • Escalate: arterial line if not already; ABG/lactate/Hb; communicate with surgeon re bleeding and progress
What are the key postoperative complications after major colorectal resection and how would you recognise an anastomotic leak?

Focus on early recognition and escalation.

  • General complications: bleeding, sepsis, respiratory complications, AKI, ileus, myocardial injury, delirium, VTE
  • Anastomotic leak: tachycardia, fever, increasing abdominal pain, ileus, rising inflammatory markers, metabolic acidosis/lactate, sepsis, unexpected drain output; may be subtle in elderly/immunosuppressed
  • Actions: urgent senior surgical review, cultures/antibiotics, imaging (CT with contrast), resuscitation and critical care involvement; source control may require re-operation
How do you manage a patient with a high-output ileostomy postoperatively?

Common FRCA-style postoperative physiology question.

  • Recognise: large stoma losses → dehydration, hypotension, AKI; electrolyte losses (Na+, Mg2+, sometimes K+), metabolic acidosis
  • Monitor: strict fluid balance, daily weights, U&E/Mg, urine output, orthostatic BP; consider urinary sodium if unclear
  • Treat: IV balanced crystalloid guided by losses; replace magnesium; restrict hypotonic oral fluids and use oral rehydration solutions; liaise with surgeons for anti-motility/anti-secretory agents (e.g., loperamide) and dietetic input
  • Escalate: HDU if ongoing large losses, AKI, or haemodynamic instability
Describe an ERAS pathway for colorectal surgery and the anaesthetist’s role.

Expect perioperative measures that reduce stress response and speed recovery.

  • Pre-op: optimisation (anaemia, nutrition, exercise), carbohydrate loading where used, minimal fasting, patient education, VTE plan
  • Intra-op: minimally invasive surgery where appropriate, multimodal opioid-sparing analgesia, normothermia, euvolaemic/goal-directed fluids, PONV prophylaxis, avoid routine drains/NG where possible (surgical), glycaemic control
  • Post-op: early mobilisation, early enteral nutrition, early removal of lines/catheters, proactive analgesia and PONV control, near-zero fluid balance, audit and pathway adherence
Previous FRCA-style theme: Compare epidural analgesia vs intrathecal opioid for colorectal surgery.

A common viva comparison: efficacy, side effects, logistics, and suitability.

  • Epidural: titratable, excellent dynamic analgesia (esp open), can reduce systemic opioids; downsides include hypotension, urinary retention, failure rate, motor block, need for monitoring and trained staff
  • Intrathecal opioid: simpler, rapid, reliable analgesia for ~12–24 h; less hypotension than epidural LA but risk of pruritus, nausea, urinary retention, and delayed respiratory depression (monitoring required)
  • Decision factors: open vs laparoscopic, expected pain, anticoagulation timing, haemodynamic reserve, availability of acute pain service, conversion risk

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