Blunt renal trauma: grades and thresholds

Operative visualisation

UrOops3D · UroRef · © Nity G

Operative steps

1. The kidney in situ The kidney is read in layers from outside in: capsule and cortex, medulla, collecting system, then the hilar pedicle where artery, vein and segmental branches sit. The AAST grade climbs with depth, driven by two axes: how deep the laceration runs, and whether the collecting system or the pedicle is involved. The habit this step teaches is to name the injury in those anatomical terms before any decision is made, because the grade is an anatomical statement while the decisions come later from physiology. A grade quoted without the finding behind it cannot be handed over safely at shift change.
2. Grade I-II: contusion / subcapsular haematoma These injuries are confined to the cortex and capsule: contusion, or a subcapsular or perinephric haematoma without any laceration, with the collection held by the fascia around it. Management is non-operative by default: rest until the urine clears, serial examination of abdomen and flank, and serial haemoglobin at the intervals the local protocol sets. Observation is a treatment with its own observation chart, not a decision to do nothing. The specific failure of this grade is the subcapsular collection that quietly expands and strangles the kidney, which is why the patient who is observed must actually be observed.
   where it bites: a subcapsular haematoma can grow and strangle the kidney: observe, but actually observe.
3. Grade III: deep cortical laceration A grade III injury is a laceration that runs deep into the cortex without entering the collecting system and without segmental-vessel injury, and the perinephric haematoma stays contained around it. The stable patient remains on the non-operative pathway, with the same discipline of serial examination and haemoglobin as the lower grades. The CT is read as a whole study rather than at its most reassuring slice, because a laceration that looks purely cortical on one cut may reach a calyx on the next, and that finding moves the patient to grade IV and changes the follow-up. A deep laceration with a contained haematoma is also the injury that can declare itself again days later, which the discharge plan should anticipate.
   where it bites: the laceration that looks cortical on one slice may reach a calyx on the next: read the whole study, not the worst single image.
4. Grade IV: collecting system / segmental vessel Grade IV covers two injuries: a laceration into the collecting system, seen as contrast extravasation on the delayed phase, or a segmental-vessel injury with a contained haematoma or an active blush. The stable patient with a blush goes to angiography for selective embolisation, which treats the bleeding while preserving the parenchyma that surgery in this setting would take. The stable patient with extravasation is observed with planned early re-imaging, and a persistent or symptomatic leak is decompressed with a stent or nephrostomy and followed until imaging shows resolution. The failure to design against is the leak that is never re-imaged: new fever or ileus after extravasation is an untreated leak until proven otherwise.
   where it bites: extravasation plus fever or ileus is a missed leak until proven otherwise.
5. Grade V: shattered kidney / hilar avulsion Grade V is parenchyma shattered into devitalised, non-perfused fragments, or an avulsed hilum, and the signature on CT is a kidney that does not enhance. This is the grade that kills and the grade that explores: the management question is the resuscitation, not the kidney, and the patient who fails to respond belongs in theatre rather than the angiography suite. If exploration happens, proximal control of the pedicle at its origin is obtained before the haematoma is opened, because entering Gerota's fascia over an uncontrolled perinephric haematoma converts a contained bleed into exsanguination. In the shocked patient that exploration usually ends in nephrectomy, and the team should say so plainly before it starts.
   where it bites: exploration of a grade V in shock usually ends in nephrectomy; proximal control is obtained before the haematoma is opened.
6. Management: embolise or explore The decision fork is physiological, not anatomical. The stable patient with a contrast blush goes to angiography and selective embolisation, because that stops the bleeding and preserves parenchyma in one act, with serial haemoglobin and examination as the endpoints afterwards. The failing resuscitation goes to a midline laparotomy with proximal vascular control of the pedicle before the haematoma is touched, accepting that renal exploration in shock usually means nephrectomy, and that this is the correct trade. Between the poles sit the stable patients with a leak or devitalised fragments, who are followed on their leak and re-imaged to resolution rather than operated on. Whatever the fork, the grade, the findings and the timings are documented, because the patient who deteriorates overnight is managed by the record, not the memory.

Complications and immediate saves

Trigger each of these live in the Animation tab, then read the save: the first move, the escalation trigger, and the line that goes in the op note.

FRCS viva questions

The examiner stems this scene prepares you for. Try to answer out loud first, then reveal, and learn the discriminator, the detail that turns a pass into a strong pass.

Evidence and guidance