Thursday, July 13, 2006

renal trauma an overview

Renal trauma
Initial Evaluation
Blunt Trauma
Results warranting further radiological investigation :
Gross haematuria
Microscopic haematuria and shock
Imaging patients with gross haematuria alone can miss two thirds of renal injuries.
Penetrating Trauma
Image all suspected injuries There is no correlation between the degree of haematuria and the extent of the injury.
14% of major injuries have no haematuria
10% of minor injuries have no haematuria
Intravenous Urography
90% accurracy under best of conditions
Poor study in hypotensive patients
Poor grading study
Does not evaluate retroperitoneum
One shot study may be important in unstable patients to identify a contralateral functioning kidney
Computed Tomography
Gold standard
Delineates grade of injury
Shows infarcted segments of kidney
Images whole abdomen and retroperitoneum
Not appropriate for haemodynamically unstable patients
Delineates vascular injury
Where CT equivocal or unavailable
Classified according to the Organ Injury Scaling (OIS) Committee Scale
Microscopic or gross haematuria, Urological studies normal

Subcapsular, nonexapnding without parenchymal laceration.

Nonexapnding perirenal haematoma confined to renal retroperitoneum.

<1cm parenchymal depth of renal cortex without urinary extravasation.
>1cm depth of renal cortex, without collecting system rupture or urinary extravasation

Parenchymal laceration extending through the renal cortex, medulla and collecting system.

Main renal artery or vein injury with contained haemorrhage.

Completely shattered kidney.

Avulsion of renal hilum which devascularizes kidney.
Goals of management :
minimize morbidity & mortality
preserve renal function
Surgical vs Non-operative management:
Most grade I - IV injuries can be treated conservatively, thus avoiding unnecessary surgery. Surgery is indicated for :
Vascular (renal pedicle) injury
Shattered kidney
Expanding or pulsatile haematoma
Shocked polytrauma patient
Relative indications for surgery include :
A devitalized renal segment in the presence of other abdominal injuries
Persistent extravasation
Loculated collections
Incomplete grading (CT or angiography)
9% of kidney injuries will require surgical exploration, and of these there is on average an 11% nephrectomy rate. Most nephrectomies are for haemorrhage, and 61% of nephrectomies are for renovascular injury. Patients underggoing nephrectomy tend to be more severely injured.
Surgical Technique
Midline laparotomy
Gain proximal control
Ligate bleeding vessels
Repair collecting system
Close capsule or use omental graft
Retroperitoneal drainage
Proximal control of the renal artery and vein before mobilisation of the colon and opening of Gerota's fascia results in an increased rate of renal salvage and hence lower nephrectomy rate. On the left, the vessels can be exposed through the posterior peritoneum, by dividing it vertically between the inferior mesenteric vein and the fourth part of the duodenum. The renal vein and artery can then be identified an controlled with vessel loops. On the right side, it is often easier to control the renal vein and artery after mobilisation of the colon.
If bleeding occurs on mobilisation of the colon or opening of perinephric fascia, atraumatic vascular clamps may be placed on the renal artery and vein. Warm ischaemia is poorly tolerated, and acute tubular necrosis develops after 20 minutes, though this is usually transient.
Partial nephrectomy is often possible. Preserving the capsule of the kidney if possible, devitalised tissue is debrided and bleeders controlled with diathermy or suture. The collecting system is closed with a running absorbable suture. Alternatively, pledgeted matress sutures may be placed across the capsule. If possible the capsule is closed, or an omental flap closed over the defect.
Nephrectomy is inidicated in the shattered kidney or renal pedicle injury in an unstable patient. The pedicle vessels are ligated separately, to avoid later arteriovenous fistula formation. The ureter is tied and kidney removed.
Retroperitoneal drainage is necessary post partial or total nephrectomy. This should not be in contact with the renal collecting system. If the collecting system has been reparied, a nephrostomy tube and/or double-J stent should be placed. Injuries to other abdominal organs should be drained separately.