CR-POSSUM Calculator | GastroChennai

CR-POSSUM Parameters

Section A — Physiological Score (PS)

1. Age

2. Cardiac Signs

3. Respiratory Signs

4. Systolic Blood Pressure (mmHg)

5. Pulse Rate (bpm)

6. Glasgow Coma Scale

7. Haemoglobin (g/dL)

8. White Cell Count (×10⁹/L)

9. Urea (mmol/L)

10. Sodium (mEq/L)

11. Potassium (mEq/L)

12. ECG

Section B — Colorectal Operative Score (OS)

1. Operative Type

2. Number of Procedures

3. Peritoneal Contamination

4. Malignancy

5. Mode of Presentation

CR-POSSUM Formula

L = −9.167 + (0.338 × Physiological Score) + (0.298 × Colorectal Operative Score) Predicted 30-day mortality = 100 × e^L / (1 + e^L)

PS range: 12–88 (12 variables scored 1/2/4/8). OS range: 5–40 (5 variables scored 1/2/4/8). Minimum L = −9.167 + (0.338×12) + (0.298×5) = −3.619 → ~2.6% mortality. Maximum theoretical mortality approaches 100%.

Interpretation

Predicted Mortality	Risk Level	Recommendation
< 5%	Low	Standard perioperative care
5–10%	Moderate	HDU-level post-operative care; senior anaesthetist
10–20%	High	ICU booking; consultant-led surgery; consider CPEX testing
> 20%	Very High	Detailed informed consent; palliative alternatives should be discussed

Physiological Score Parameters

Parameter	Score 1	Score 2	Score 4	Score 8
Age (yr)	≤ 60	61–70	71–80	> 80
Cardiac	No failure	Medication/hypertension	Oedema/warfarin	Raised JVP / CXR cardiomegaly
Respiratory	Normal	Mild dyspnoea	Moderate dyspnoea	Severe/O₂ dependent
Systolic BP	110–130	131–170 or 100–109	≥171 or 90–99	< 90
Pulse (bpm)	50–80	81–100 or 40–49	101–120	>120 or <40
GCS	15	12–14	9–11	< 9
Hb (g/dL)	Normal range	Mildly abnormal	Moderately abnormal	<10 or >18
WBC (×10⁹/L)	4–10	10.1–20 or 3.1–3.9	>20 or 1–3	< 1
Urea (mmol/L)	< 7.5	7.5–10	10.1–15	> 15
Sodium (mEq/L)	> 136	131–135	126–130	≤ 125
Potassium (mEq/L)	3.5–5.0	3.2–3.4 or 5.1–5.3	2.9–3.1 or 5.4–5.9	<2.9 or ≥6.0
ECG	Normal SR	AF (60–90)	Any abnormality	—

Colorectal Operative Score Parameters

Parameter	Score 1	Score 2	Score 4	Score 8
Operative type	Minor	Moderate (right hemi, sigmoid)	Major (APR, AR, total colectomy)	Major+ (exenteration)
No. of procedures	1	2	> 2	—
Peritoneal contamination	None	Serosal soiling	Local pus	Free faeces/pus/blood
Malignancy	None	Primary only	Node metastases	Distant metastases
Presentation	Elective	—	Emergency (>2h)	Emergency (<2h)

Clinical Application

CR-POSSUM was derived from 6,883 colorectal operations in 15 UK centres (Tekkis 2004) — it corrects the over-prediction of mortality by standard P-POSSUM in colorectal resections
Use for all major colorectal resections including anterior resection, abdominoperineal resection (APR), Hartmann's procedure, subtotal/total colectomy
Does not stratify by laparoscopic vs open approach — predicts mortality only, not morbidity or length of stay
SNAP (Second National Audit Programme) uses POSSUM as the standard risk-adjustment tool in UK colorectal audit
For consent and counselling purposes, use in conjunction with clinical judgement — a predicted mortality of 15% warrants detailed informed consent and discussion of palliative alternatives

References

Tekkis PP, et al. Evaluation of POSSUM and P-POSSUM scoring systems in patients undergoing colorectal surgery. Br J Surg. 2004;91(9):1183–1192.
Copeland GP, et al. POSSUM: a scoring system for surgical audit. Br J Surg. 1991;78(3):355–360.

CR-POSSUM