Renal Trauma

Serious falls, punches to the flank and motor cycle accidents can each lead to the possibility of renal trauma or trauma to the kidney. Usually only one kidney is damaged at a time; however, in severe injuries like motor vehicle accidents, both kidneys can sustain trauma.

What is renal trauma?

Renal trauma occurs when blunt force trauma strikes the abdomen or flank region of the body. The incidence of this type of trauma depends on the type of group being studied. In general, renal trauma is found in about 3 percent of admissions to the hospital due to trauma. As many as ten percent of patients who have sustained abdominal trauma end up having renal trauma. By far and away, most patients have sustained blunt trauma but a few have their trauma come from a penetrating injury. In fact, blunt trauma renal injuries are 9 times more common than penetrating trauma renal injuries. Both kidneys are equally prone to getting injured.

The kidneys are two bean-shaped organs located in the back of the abdomen in the flank area. They are surrounded with a capsule, which somewhat protects them from trauma. Their job is to filter the blood, ridding it of urea and other molecules which go on to make urine. The kidneys are attached to the renal artery, the renal vein and the ureter, which drains the urine from the kidneys to the bladder. Any one of these connections can be broken with renal trauma, causing severe problems.

The care of renal injuries has changed dramatically over time with more cases of renal trauma being treated by expectant management instead of operative management, even if the kidney has been shown to be seriously injured.

There are three types of renal injuries: 1) renal laceration; 2) renal contusion; and 3) a renal vascular injury. Doctors need to have a high index of suspicion when it comes to these three types of kidney injuries and they need to give the patient prompt evaluation and swift management.

In a renal laceration situation, there is a fracture through the renal cortex and medulla and there is localized bleeding and blood in the urine. It certainly can be repaired surgically; however, watching the lesion to see if it heals spontaneously can also work. Renal contusions result in blood in the urine but the injury usually heals or scars over in time. Renal vascular injuries are serious injuries that involve injuries to either the renal artery or renal vein. This can cause profuse bleeding and can disrupt the viability of the entire kidney.

What causes Renal Trauma?

Most cases of renal trauma come from sources like motor vehicle accidents, severe falls or penetrating injuries. In penetrating trauma to the kidney, the cause is often a gunshot wound or perhaps a knife wound from an altercation. Blunt trauma can happen because of rapid deceleration in a fall or car accident. There can be a direct blow to the flank area such as in a sports injury or pedestrian automobile accident.

Doctors can accidently traumatize the kidney during certain procedures. This includes endourologic procedures, extracorporeal shock wave lithotripsy, percutaneous procedures on the kidney and kidney biopsies. The doctor can also damage the kidney when performing a diagnostic peritoneal lavage. In rare conditions, the kidney can be damaged from a renal transplant rejection or during childbirth.

Of all of the organs of the urinary system, the kidney is the most commonly injured one. In a blunt trauma injury, there are sometimes no obvious external injuries; however, bruises may show up on the back area or in the abdominal area. Penetrating injuries are easier to determine but with things like a small caliber gunshot, there may be little external injury.

When it comes to closed injuries or blunt trauma injuries, about 80 percent are now treated conservatively. In penetrating injuries, surgery is used in almost all situations.

Blunt trauma can be from direct causes, such as damage through the skin of the lumbar area, lateral part of the trunk or the anterior part of the trunk. The blow can come from a knee kick, a fist, a sporting accident, crush injury to the abdomen or trauma secondary to a motor vehicle accident.

Blunt trauma can be indirect as well. These are factors that result in sudden displacement of the kidney so that it collides with the spine or ribs, or suffers a pedicle injury, a tear of the urethra or a bending of the kidney. Lifting a heavy object can cause an indirect injury.

Kidney trauma is also divided into the following:

  • Small renal contusion or rupture with an intact capsule, such as a subcapsular hematoma or a renal rupture with the capsule intact
  • Rupture of the fibrous capsule of the kidney
  • Rupture that results in an opening of the calyces into the space around the kidneys
  • Multiple renal ruptures with disruption of the calyces
  • Avulsion of the renal pole
  • Fragmentation of the kidney, usually from crushing the kidney. This is usually associated with an injury to surrounding organs of the kidney and a tear in the urethra
  • Tear into the renal vein or renal artery
  • A mixed injury to the pelvicalyceal system and severe injury to the parenchyma of the kidney.

In spite of the fact that the kidneys are well protected in the back of the abdomen and are surrounded by a decent support system, they do easily get injured, especially when high speeds are involved, a crush injury happens, or the patient is unlucky enough to sustain a gunshot or knife injury to the area where the kidneys reside.

What are the Symptoms of Renal Trauma?

Trauma to the kidneys can be isolated or can be associated with injuries to nearby organs. There are five grades of kidney injury classified according to their severity. Grade I injury is a low grade injury such as bruising of the kidney. Grade V injury is the worst and represents a shattering, crushing injury of the kidney along with tearing off of the blood supply from the kidney.

The most common symptom of renal trauma is hematuria or blood in the urine. It can be gross hematuria in which it can be seen by the naked eye or microscopic hematuria, in which the blood cells can only be seen on microscopic evaluation of the urine. It can easily be noticed by means of a dipstick test of the urine which picks up blood cells in the sample.

There can also be symptoms related to failure of the kidney. There can be an accumulation of urea and other nitrogen substances within the bloodstream. Leading to symptoms such as tiredness, headache, loss of appetite, vomiting, and nausea. If the potassium level rises too much beyond normal, cardiac arrhythmias can occur, which can be life threatening or, at the very least, dangerous. The balance of fluid in the body can be off balance but it is rare to get high blood pressure.

The patient with renal trauma can experience flank pain, especially if there are blood clots located in the blood vessels of the kidney or inflammation of the kidney. The pain comes from stretching of the capsule from increased pressure in the kidney itself. If the kidney injury becomes the result of dehydration of the body, the patient can be thirsty and have physical evidence of dehydration on physical examination. There may be a palpable bladder from fluid overload in the bladder. If the kidney cannot excrete enough fluid, there is then a buildup of fluid and edema from too much fluid in the body.

There can also be excessive abdominal pain even though the kidneys are essentially in the back. Anytime a patient has sustained abdominal trauma, there needs to be the thought that some kind of renal trauma may have occurred.

Diagnosis of Renal Trauma

Renal trauma can be diagnosed several ways. One common way is to do an intravenous pyelogram or IVP. This involves the injection of radiocontrast dye into the bloodstream. It travels quickly to the kidneys where it is processed and goes to the ureters and finally into the bladder. The shape of the kidneys can be highlighted and if there is a complete disruption of the renal artery from the kidney, there will be no uptake of radiocontrast dye to the affected kidney.

CT scans or MRI scans of the abdomen can show the shape of the kidneys as well as any fractures or blood clots. They are good tests to outline the damage done to the kidney but do not tell you whether or not the kidney is functioning. Both the IVP and CT/MRI scans can be done together to see where the kidneys are located, their shape and their functionality. A scan of the kidneys will also show the presence of air in the peritoneum as with a viscus rupture and the shape and damage to the spleen and liver as well.

In some cases an ultrasound of the kidney can be done to see if there is damage to the organ. It is a good and quick screening tool, especially if it is completely normal but if there are abnormal findings, they may not outline completely what those abnormal findings are. In such cases, an IVP or CT scan of the abdomen may be the best tool to use as an adjunct to the ultrasound procedure.

Treatment of Renal Trauma

The treatment of renal trauma depends on how the patient is doing, the severity of the renal injury and on the presence of other injuries besides the renal injury. Conservative treatment is done in cases where the patient is stable from a cardiovascular component and if no other injuries are noted. The bleeding stops and the kidney heals itself. The urine turns clear and the kidney functions again to varying degrees. There is a possibility of late onset bleeding so the patient should be monitored even after being discharged from the hospital.

If the patient is unstable and seems to be losing a lot of blood, then surgery is indicated. The goal is to repair the damaged kidney but if the kidney is irretrievably damaged, it must be removed. Patients with damage to the spleen, bowel or liver, who require operation, may also have surgical intervention in the kidneys themselves. Some serious injuries can be treated with an angiographic embolization procedure, which cuts off the blood supply to the kidney.

Surgical treatment of kidney damage should be done through a usual midline abdominal incision. This allows the surgeon to look at all of the viscera that might be damaged, including genitourinary structures. Major bleeding should be stopped immediately through surgical control and repair. Associated damage to the abdominal structures should be taken care of before the kidneys are looked at, including the bowels, liver, pancreas and spleen.

The surgeon looks at the retroperitoneal space to look at the renal vessels. If these are bleeding, they should be repaired. It reduces local bleeding and allows the kidneys to be looked at more carefully. If the major arteries and veins are bleeding, they need to be occluded for a period of time so that the bleeding can stop. After it is determined where the bleeding is coming from, the vessel is repaired and circulation can be restored to the kidney.

In certain cases, such as polar injuries of the kidney, the doctor would do a partial nephrectomy, leaving the healthy portion of the kidney behind. The healthy part is sutured together after the damaged part is cut off. Methylene blue is a dye injected into the kidney to check for leaks in the sutures. Sometimes there isn’t enough kidney material to hold together the kidney and omentum must be used to close over the defect.

Injuries to the midportion of the kidney are harder to repair than polar injuries. The nonviable tissue is removed surgically and sites of bleeding are repaired. The collecting system is sealed up tight and Gelfoam is used to clean up small bleeding areas. Omentum should be used to cover areas of the kidney that doesn’t have enough capsule to cover it.

Renal vascular injuries are more serious than direct kidney injuries. The bleeding is more extensive and injuries to the renal vessels often lead to a total nephrectomy. In some cases, venous injuries can be completely ligated because there are other veins that can pick up the slack.

Once the surgery is done, the urine clears itself of blood within 24 hours and patients need to be on bed rest until the urine is clear. Delayed bleeding is possible so that serial hematocrits need to be done to make sure the hemoglobin status is stable. Drains are usually placed at the time of surgery; they are removed by about 48-72 hours after surgery. A radionuclide scan is done at the time of discharge to see how much of the damaged kidney is actually working. This this test is often repeated at 3 months following the injury.

Complications of Renal Trauma

Complications of renal trauma depend on how severe the injury was in the first place and how the injury was managed. Early complications generally occur within a month of injury. These include what’s called a urinoma or collection of urine that doesn’t go anywhere, delayed bleeding problems, abscess formation, a urinary fistula and high blood pressure. The most common complication is prolonged urinary extravasation or leakage of urine into the abdomen.

A urinoma usually does not need to be treated because its volume is usually stable and it is not infected. If it is too large, however, it is treated by inserting an endoscope and draining the urinoma. Urinomas account for less than 1 percent of cases of renal trauma.

Delayed kidney bleeding usually happens two weeks or sooner after the injury. If he bleeding is heavy, the doctor may order transfusions or may do an angiography to find the source of the bleeding. Then selective embolization is generally done. Urinary fistulas can happen with an undrained collection of urine or if there is a big area of devitalized kidney tissue.

If the patient develops an abscess, it can be associated with an ileus, high grade fever and septicemia. They are often treated by means of percutaneous drainage. CT scans are used to identify the abscesses.

High blood pressure is another early complication that can usually be treated with medication. It is generally transient.

Long term complications include getting an arteriovenous fistula, chronic pyelonephritis, a renal calculus or hydronephrosis. Delayed high blood pressure is also possible. There can be scar tissue in the area of the renal pelvis and ureter so that no urine can pass. Stones can form and there can be pyelonephritis.

Arteriovenous fistulae are more common following a penetrating trauma to the kidney. Penetrating trauma can also reveal delayed bleeding. If there is an arteriovenous fistula, an angiogram can find it and can be used to create a thrombosis in the AV fistula.

High blood pressure that occurs late in the trauma picture is probably overdiagnosed. Its presence actually occurs only in about 0.2 percent of trauma cases. It is caused by sustained ischemia to the kidney tissue.

If you or a loved one has suffered renal trauma as a result of someone else's negligence, and would like to get your questions answered and discuss your legal options, contact me online or call us at 916-921-6400 or 800-404-5400 to set up a FREE consultation.

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