New or worsening abdominal pain after a bowel anastomosis is an anastomotic leak until proved otherwise, and the CST clinical station is testing whether you say so early and act on it. The Association of Coloproctology of Great Britain and Ireland, with the ASGBI, defines an anastomotic leak as a leak of luminal contents from a surgical join between two hollow viscera and puts its prevalence between 1% and 19% depending on the site. Your answer is CCrISP: immediate management by ABCDE, a full assessment that includes the operation note, and a decision that names the time limit for source control.

Key takeaways

  • An anastomotic leak is a leak of luminal contents from a surgical join between two hollow viscera, according to the ACPGBI and ASGBI 2016 guideline
  • Prevalence is 1% to 19%, highest for low pelvic anastomoses; tachycardia and pyrexia are the early signs the guideline's expert panel agreed on
  • A CRP above 150 mg/L on post-operative days 3 to 5 is the biochemical flag the ACPGBI guideline names
  • Contrast-enhanced CT with rectal and intravenous contrast is the investigation; do not send an unstable patient to CT without critical care support
  • Source control within 18 hours if there is no organ dysfunction, within 6 hours if there is, and within 3 hours in septic shock
  • NICE NG253 puts a NEWS2 of 7 or more at high risk of death from sepsis: antibiotics within 1 hour, a 250 ml bolus over 10 to 15 minutes, and a senior clinician

How does an anastomotic leak present on the ward?

An anastomotic leak presents as a patient who is not following the expected recovery: new abdominal pain, a rising heart rate, a fever, an ileus that persists, or a feeling from the nurses that the patient is simply not right. The ACPGBI Delphi panel agreed that tachycardia, pyrexia and a rising CRP are the signs that should prompt suspicion.

In practice the leak is often subtle in the first 24 hours and dramatic thereafter. A patient with a covering loop stoma may show quieter signs, because the leak is not carrying the faecal stream. The guideline also warns that the operating surgeon can find it hard to stay objective about a join they made, and recommends a second opinion from an equally experienced colleague.

What is the immediate management, A to E?

Immediate management of a suspected anastomotic leak is an ABCDE assessment with sepsis treated as you go, not after the diagnosis is confirmed.

Airway and breathing

Check the airway is patent and the patient is talking. Measure respiratory rate and saturations, examine the chest, and give oxygen to a target range. A raised respiratory rate is often the first NEWS2 point that moves in intra-abdominal sepsis.

Circulation

Pulse, blood pressure, capillary refill and urine output. Two wide-bore cannulae, blood cultures before antibiotics, and a blood gas for lactate. NICE NG253 recommends an initial 250 ml bolus of a balanced crystalloid over 10 to 15 minutes for a patient at high risk from sepsis, repeated as needed to 1,000 ml, with reassessment after each bolus and senior advice if the patient has not improved after 1,000 ml.

Disability and exposure

Level of consciousness and capillary glucose. Then expose the abdomen: the wound, the drains and what is in them, the stoma if there is one, and a full abdominal examination for peritonism. Look at the calves and the catheter while you are there.

What investigations confirm an anastomotic leak?

Contrast-enhanced CT of the abdomen and pelvis is the investigation for a suspected anastomotic leak, and the ACPGBI guideline states that accuracy for distal colonic leaks improves when rectal contrast is added to intravenous contrast.

Bloods are a full blood count, urea and electrolytes, CRP, clotting, a group and save and a lactate. The guideline's stated flag is a CRP above 150 mg/L on post-operative days 3 to 5, especially if albumin keeps falling, and it notes that a normal CRP has useful negative predictive value while the white cell count is less reliable.

However, imaging must not delay treatment. The guideline is explicit that when the patient is unwell and the leak is clinically evident, imaging is not essential, and that a haemodynamically unstable patient should not go to CT unless invasive monitoring is available and critical care staff accompany them. Intravenous contrast should be used with caution or avoided in dehydration, hypotension or acute kidney injury.

What is the definitive management of an anastomotic leak?

Definitive management of an anastomotic leak is source control, timed by the severity of sepsis. The ACPGBI guideline sets three limits: within 18 hours of diagnosis when there is no organ dysfunction, within 6 hours when organ dysfunction is present, and immediately and always within 3 hours in septic shock.

The guideline cites evidence that delaying source control beyond 12 hours after hypotension develops, compared with under 3 hours, raises mortality from 25% to 60%. That single statistic is worth saying at the interview because it explains why the registrar is called now and not after the CT.

Matching the operation to the grade

  • No sepsis: conservative treatment with intravenous antibiotics, intestinal rest and close observation on the ward
  • Contained leak or abscess: radiological drainage where possible, with a proximal defunctioning stoma if the leak needs surgical washout
  • Sepsis with ileus or single-quadrant peritonitis: laparoscopy or laparotomy, washout, drainage and a proximal defunctioning stoma or resection of the anastomosis
  • Severe sepsis or septic shock with generalised peritonitis: resuscitate, then laparotomy, washout, take down the anastomosis and form a stoma

Radiological drainage should not be attempted when imaging shows complete anastomotic discontinuity, and the guideline states that attempts to repair a leak should never be made in severe sepsis or septic shock. Deterioration during conservative treatment counts as failed treatment and lowers the threshold for theatre.

When do I escalate an anastomotic leak, and to whom?

Escalate a suspected anastomotic leak to the surgical registrar at the moment you suspect it, and to the consultant who performed the operation as soon as the registrar agrees. The ACPGBI guideline recommends that every patient with a leak and severe sepsis or septic shock is reviewed by critical care.

NICE NG253 gives the ward triggers. A NEWS2 of 7 or more, or a NEWS2 below 7 with a single parameter scoring 3 and a medical review confirming high risk, means a clinician with acute care competencies assesses the patient urgently, broad-spectrum intravenous antibiotics go in within 1 hour of the score, and the senior clinical decision maker is called. A NEWS2 of 5 or 6 needs a review of the patient and the lactate within 1 hour, and is treated as high risk if the lactate is over 2 mmol/L or there is acute kidney injury.

Say who you would call by role, and what you would say: the patient, the operation and day, the observations, the lactate, and what you have already done. Then say what would make you call again.

What is the interviewer listening for in an anastomotic leak scenario?

  • The words anastomotic leak said early, with the ACPGBI definition, rather than a list of every cause of post-operative pain
  • Sepsis treated in parallel with the diagnosis: cultures, antibiotics within the hour, a measured bolus and a reassessment
  • The source-control clock stated in hours, and the operating consultant named as the person who decides
  • Recognition that CT is for the stable patient and that an unstable one goes to theatre or critical care, not the scanner
  • A plan that names the CRP, the review time, the drain output and the fluid balance

What are the common mistakes with an anastomotic leak?

The commonest mistake in an anastomotic leak scenario is treating the tachycardia as pain or anxiety and waiting for the morning round. The second is ordering a CT and describing it as the plan, when the plan is resuscitation, antibiotics and a registrar at the bedside.

  • Sending an unstable patient to CT without critical care support
  • Giving intravenous contrast to a hypotensive patient with an acute kidney injury
  • Reassuring a patient with a defunctioning stoma because the signs are quieter
  • Continuing NSAIDs unquestioned: the guideline cites a 24% increase in the likelihood of leak with NSAID use
  • Forgetting to hand over the leak as a named concern at the end of the shift

How this comes up at the CST interview

The CST management and clinical station sets an anastomotic leak as a day-3 to day-5 patient after an anterior resection with pain, a heart rate over 100 and a rising CRP, and asks what you do. Answer in CCrISP order, name the guideline and the time limits, and escalate to a named person. The coresurgeryinterview question bank has 299 questions with AI-marked spoken practice, and its scored version of this scenario is at /Question-Bank/Sample-Questions.