Injuries to the kidney

In civilian life injuries to the kidney result most often from either blows or falls on the loin or crushing injury to the abdomen, typically in a road traffic accident. Haematuria after trivial injury to the kidney should suggest the possibility of a pre-existing abnormality, e.g. calculus, hydronephrosis or tuberculosis.

The degree of injury varies considerably from a small subcapsular haematoma to a complete tear involving the whole thickness of the kidney (Fig. 64.14). The kidney may be partially or wholly avulsed from its vascular pedicle; one pole may be completely detached.

Closed renal injury is almost always extraperitoneal. The exception is seen occasionally in young children who have very little extraperitoneal fat. The peritoneum, which is closely applied to the kidney, can tear with the renal capsule allowing blood and urine to leak into the peritoneum.

Clinical features

Superficial soft tissue bruising may testify to the severity of the blow but is often absent. There is likely to be local pain and tenderness.

Haematuria

Haematuria is the cardinal sign of a damaged kidney, but it may not appear until some hours after the injury. Profuse bleeding may be accompanied by clot colic.

Severe delayed haematuria

Sudden profuse haematuria can occur between the third day and the third week after the accident in a patient who appears to be progressing favourably. It is due to a clot becoming dislodged.

Meteorism

Abdominal distension 24—48 hours after renal injury is probably due to retroperitoneal haematoma implicating splanchnic nerves.

Management and treatment

Conservative treatment of closed renal trauma is usually successful but appropriate measures must be instituted without delay. The possibility of injury to other organs must be considered at an early stage.

1. Blood should be cross matched and available for trans­fusion if there is evidence of hypovolaemic shock or continuing haemorrhage. Intravenous access should be established.

2. The patient must be confined to bed while there is macro­scopic haematuria and physical activity must be curtailed for at least 1 week after the urine clears.

3. Morphine should be given as an analgesic and sedative.

4. Hourly pulse and blood pressure charts must be kept.

5. Antibiotics should be given to prevent infection of the haematoma.

6. Each sample of urine passed should be checked for haematuria and the result charted.

7. An intravenous urogram (IVU) should be obtained urgently (a) to assess the damage to the kidney and (b) to show that the other kidney is normal.

Surgical exploration

Surgical exploration is necessary in less that 10 per cent of closed injuries and is indicated if either there are signs of progressive blood loss or there is an expanding mass in the loin. The aim is to stop bleeding while conserving as much renal tissue as possible; and a renal arteriogram performed preoperatively can be helpful in framing a strategy for doing this. There is also a chance that a skilled radiologist will be able to stop the haemorrhage by embolisation if a bleeding vessel can be identified.

The approach to the kidney should be transperitoneal to exclude the possibility of damage to other abdominal organs. The danger is that release of the tamponading effect of the perirenal haematoma will result in massive uncontrollable haemorrhage and this eventuality must be prepared for. When the kidney is irretrievably ruptured or avulsed from its pedicle, nephrectomy is the only course. Small tears can be sutured over a haemostatic sponge or a piece of detached muscle. Large single rents in the kidney are best dealt with by passing a tube nephrostomy through the defect and suturing the renal tissue around it. If the laceration is confined to one pole of the kidney, partial nephrectomy may be practicable.

When a solitary existing kidney is sufficiently damaged to need exploration, it must be repaired. Failing this, the wound is packed firmly with gauze to stop the bleeding in the hope that some renal function may be retained when the ruptured kidney heals.

Multiple injuries

The mortality of cases of ruptured kidney with damage to the liver spleen or hollow intra-abdominal organs is high.

Complications

1. Heavy haematuria may lead to clot obstruction of the bladder outflow and bladder washout through a catheter or a cystoscope may be necessary.

2. Para renal pseudohydronephrosis may occur in the course of a few weeks as a result of a combination of complete cortical tear and ureteric obstruction caused by scarring.

3. Hypertension resulting from renal fibrosis may occur 3 months or more after injury. It is often refractory to medical treatment and nephrectomy may be necessary.

4. Aneurysm of the renal artery (Fig. 64.15) is a rare but striking complication of severe renal trauma. There is pain in the loin and a nontender swelling may be felt if the aneurysm is large. Congestion of the parenchyma leads to intermittent haematuria. Aortography is diagnostic. Rupture of a renal artery aneurysm is liable to be fatal and excision or nephrectomy is urgently indicated.