Extraluminal contrast or gas at the anastomosis, or a perianastomotic collection containing gas, 5–10 days after surgery — separated from the expected post-operative free gas and fluid by its location, growth and contrast.
Orient first
- Post-operative free gas is expected for days; increasing gas or gas localised at the anastomosis is not.
- Oral or rectal water-soluble contrast increases sensitivity (upper GI via the mouth, colorectal via the rectum).
- Oesophagectomy, gastrectomy, low anterior resection and bariatric surgery each have typical leak sites.
Acquire the study
- CT with intravenous contrast and positive enteric contrast introduced so that it reaches the anastomosis before scanning; fluoroscopic contrast study as an alternative.
The manoeuvre
- Anastomosis on axial and coronal reformats: extraluminal positive contrast (leak) — measure the collection in cm.
- Perianastomotic gas bubbles and fluid collection with an enhancing wall.
- Free gas pattern compared with the previous study: increasing or localised.
- Staple line position; drains and their tips relative to collections.
What confirms it
- Extraluminal enteric contrast from the anastomosis, or a gas-containing collection at it with clinical sepsis.
What licenses you to exclude it
- Contrast passing through an intact anastomosis on a study where it reached the anastomosis lowers the likelihood; it does not exclude a small sealed leak.
The classic misread
- Scanning before the enteric contrast reached the anastomosis.
- Calling expected post-operative free gas a leak without comparing volume and location.