First and second year — the floor first, then every step
Reconstruct the TRAJECTORY first — entry, exit or projectile, and the organs in line between them — then look at every structure on that path, because the injury is wherever the track went, not where the blood is.
Orient first
Stab wounds injure what is directly under them; gunshot wounds injure along the path and by cavitation around it.
A trajectory that crosses the midline, the diaphragm or the mediastinum changes the risk profile for the whole study.
Skin markers on the entry and exit wounds make the trajectory legible on CT.
Acquire the study
Arterial and portal venous phase CT with skin markers on the wounds; thin slices and multiplanar reformats along the track.
Triple-contrast (IV, oral, rectal) CT is used in some centres for flank and back wounds — follow the local protocol.
The manoeuvre
Mark entry and exit (or the projectile) on the scout and axial images, then draw the track on reformats: gas, haemorrhage, bone and metal fragments along a line.
Diaphragm: any track within a few centimetres of either hemidiaphragm makes diaphragmatic injury likely until proven otherwise.
Each organ on the track: solid organ lacerations, bowel wall thickening or defects, extraluminal gas and contrast.
Vessels on the track: extravasation, pseudoaneurysm, occlusion, arteriovenous fistula on the arterial phase.
Mediastinum and heart when the track crosses the chest: pericardial blood, pneumomediastinum, oesophagus and airway.
Spine and spinal canal when the track is posterior.
What confirms it
An organ or vessel injury in continuity with the track.
What licenses you to exclude it
A CT cannot exclude a small bowel or diaphragmatic injury on a track that passes close to them; say so, and the decision on laparoscopy stays clinical.
The classic misread
Reading the organs one by one instead of along the track.
Mistaking air introduced by the wound itself for bowel perforation — the track is gas-filled.
Reporting the injury
Classification to use
Describe by trajectory and organ; each organ injury graded by its AAST scale where one applies (2018 revision for spleen, liver, kidney).
Measurements — and how to take them
Distance of the track from the diaphragm and from major vessels, in mm; fragment size.
What to report
Entry and exit (or projectile) location, the trajectory and which cavities it crosses, every organ and vessel on it, retained fragments, and structures the track passes close to without visible injury.
How to report it
CT: "Stab wound to the left upper quadrant with a track passing through the subcutaneous fat and the left rectus into the peritoneal cavity, ending at the splenic flexure. Focal wall thickening of the splenic flexure with adjacent free fluid and a tiny focus of extraluminal gas — bowel injury likely. The track passes within 1 cm of the left hemidiaphragm; diaphragmatic injury cannot be excluded."
What not to report
Do not state that the peritoneum is "not breached" when the track reaches the posterior rectus sheath — say it cannot be determined.