Incidental portomesenteric thrombosis after colorectal surgery resolved without treatment

Design

Single-centre retrospective cohort with routine day-6 CT

Population

799 consecutive patients after colorectal cancer surgery

Primary outcome

Incidence and course of asymptomatic portomesenteric venous thrombosis

Effect

4.1% incidence; 33 of 33 resolved within a year, including 12 of 12 not anticoagulated

At one centre every patient having colorectal cancer surgery has a CT scan on postoperative day 6. Over six years, 799 consecutive patients were scanned and 33 (4.1%) had asymptomatic portomesenteric venous thrombosis, mostly confined to peripheral intrahepatic branches. Twenty-one were anticoagulated and 12 were watched.

All 33 thrombi resolved radiologically within a year, including every patient managed without anticoagulation, and there were no cases of extension, portal hypertension or bowel ischaemia. In exploratory analysis, age 60 or under (OR 2.45, 95% CI 1.19 to 5.03) and a white cell count above 10 on day 5 (OR 2.39, 1.16 to 4.93) were associated with thrombosis.

Incidental thrombus on a postoperative scan often triggers anticoagulation, a thrombophilia screen or a delay to chemotherapy. This series suggests that for small, peripheral, non-occlusive thrombi a conservative approach is reasonable. The authors do not recommend routine postoperative CT, and the numbers are too small to be confident about thrombi in the main portal or superior mesenteric vein.

• Note the location and extent of any incidental portomesenteric thrombus before deciding on treatment.
• Consider surveillance rather than anticoagulation for small, non-occlusive peripheral intrahepatic thrombi.
• Avoid delaying adjuvant chemotherapy for an incidental peripheral thrombus alone.
• Treat thrombus in the main portal or superior mesenteric vein on its merits; this series says little about it.
• Do not add routine postoperative CT on the strength of this study.

Why it matters

An incidental finding should not set off treatment and delays that the clot itself does not warrant.

Don't overread it

A single-centre series with 12 untreated patients cannot show that withholding anticoagulation is safe for every incidental thrombus.

The statistics, in plain English

With 33 events, the risk-factor estimates have wide intervals and the authors call them exploratory. Zero complications in 12 untreated patients is reassuring but is too few to rule out an occasional bad outcome.

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