A day-2 CRP under 100 identified colon resections at low risk of leak

Design

Two-cohort multicentre diagnostic accuracy study

Population

614 patients after elective colon cancer resection with primary anastomosis

Primary outcome

Anastomotic leak, Clavien-Dindo grade 3 or more

Effect

Day-2 CRP <100 mg/L: NPV 98.8% (test) and 99.0% (validation)

This diagnostic accuracy study used two Danish multicentre cohorts — 401 patients to test and 213 to validate — after elective colon cancer resection with primary anastomosis. A leak was counted when it needed intervention (Clavien-Dindo grade 3 or more). It asked whether the familiar day-3 threshold of CRP below 100 mg/L could be brought forward to day 2.

Leaks occurred in 4.0% and 4.7%. About half to 60% of patients had a day-2 CRP below 100 mg/L, and among them leaks occurred in only 1.3% and 1.0% — negative predictive values of 98.8% and 99.0%. Above that threshold the leak rate was about 8%. In those patients, a day-3 CRP lower than day 2 added further reassurance (NPV 98.9% after minimally invasive and 97.9% after open surgery). Used in sequence, nearly 90% of patients could have been discharged by day 2 or 3 with a leak risk near 1%.

This applies to colon resections — not rectal anastomoses — and to an elective ERAS population. A low CRP should support discharge, not replace clinical judgement: a patient with pain, fever, tachycardia or ileus still needs assessment whatever the number.

• Check CRP on day 2 after elective colon resection if early discharge is planned.
• A day-2 CRP below 100 mg/L, in a patient who is clinically well, supports discharge.
• If day-2 CRP is 100 or more, repeat on day 3; a falling value adds reassurance.
• Rising CRP, or clinical signs of leak at any level, should prompt CT and senior review.
• Do not apply these thresholds to rectal or emergency resections without local validation.

Why it matters

The usual day-3 CRP check lags behind ERAS pathways that now discharge on day 2.

Don't overread it

Validated only in elective colon resections with primary anastomosis, not rectal or emergency surgery.

The statistics, in plain English

A negative predictive value of 99% means that of 100 patients with a low day-2 CRP, about one went on to have a leak. That is reassuring but not zero, which is why the safety-net advice at discharge still matters. Two cohorts giving almost the same result makes the threshold more trustworthy than a single-centre finding.

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