Kidney bruise - causes, symptoms and therapy

Kidney bruise - causes, symptoms and therapy

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Bruised kidney treatments and signs

Compared to many other kidney diseases, which can sometimes be life-threatening, a kidney bruise (kidney contusion) means in most cases only minor lesions that can be easily remedied by suitable treatment measures. However, there are exceptions in which the bruise causes more severe damage to the kidney. For this reason, regardless of their suspected severity, kidney bruises should always be examined by a doctor. Our contribution to this topic gives you more details on the character, possible causes and treatment steps.


The paired kidneys (Ren or Nephros) are essential for our metabolism. Not only do they regulate the body's water balance by forming the urine (urine) necessary for natural drainage, they also use it to discharge harmful toxins from the body. In addition, residues of usable substances are absorbed in the kidneys, which guarantees the best possible nutrient use for the metabolism. And the kidneys are even involved in the formation of blood and blood pressure because, on the one hand, the excretion of fluid regulates the blood volume and thus controls the pressure within the blood vessels. On the other hand, the kidneys also form hormones such as erythropoietin, which is responsible for the formation of red blood cells.

In order for the kidney to be able to perform its various tasks, it has an extremely complex structure, which is characterized by various, functional tissue structures, the so-called parenchyma. In the area of ​​the kidney, this functional subunit of the organ is also called the nephron and essentially consists of the following two elements:

  • Renal corpuscles:
    The kidney corpuscles withdraw the primary urine from the blood via the kidney's own vascular system. It mainly consists of protein-containing blood plasma, which is still unfiltered when it enters the kidney body.
  • Kidney tubule:
    After its arrival in the kidney corpuscles, the primary urine is passed on to the kidney tubules, which filter important nutrients from the blood plasma and transfer them back into the bloodstream. A large amount of water is also removed from the primary urine, which means that the urine concentrates and becomes the actual final urine.

What is left here is an aqueous mixture of substances, which in addition to a water content of 95 percent consists primarily of the following substances:

  • Uric acid - end product of purine metabolism,
  • Urea - end product of protein metabolism,
  • Creatinine - end product of muscle metabolism and digestion of meat,
  • Salts and phosphates - mostly end products of acid metabolism,
  • Urochrome - end products in the breakdown of protein and the red blood pigment bilirubin; Urochromes are natural, nitrogen-containing dyes that give urine its typical yellow color.

Localized, the kidneys are well hidden on the back wall of the abdomen. From the front they are equally protected and fixed in position by the numerous abdominal organs and from behind by the spine, ribs and the strong muscular features of the back muscles. Thanks to this good padding, the kidneys are rarely affected by injuries unless they are affected by an external trauma. And this is exactly where the kidney bruise originated. It describes a lesion that results in short-term bruising of kidney parts, mostly due to an accident, and is accompanied by bruising. Medically, the kidney bruise is included in the so-called kidney trauma, which describes the totality of all kidney injuries or kidney lesions.

Overall, the kidney bruise accounts for just about two percent of all injuries in everyday life. However, if the abdominal and pelvic area is affected by external violence (e.g. due to a traffic accident), the likelihood of kidney involvement increases to around 35 percent. Depending on how severe the bruise was in the kidney area, a kidney bruise can be more or less dangerous. Here is a brief overview of the different degrees of severity:

  • Grade I renal bruise:
    A good two thirds of all kidney bruises are first degree bruises, which cause slight bruising but no serious injuries. This type of kidney bruise is not dangerous, since the bruise is limited to the connective tissue capsule that surrounds the kidney. The parenchyma, i.e. kidney corpuscles and kidney tubules, are displaced in a first degree kidney bruise, but not damaged and the bruise does not expand in the further course.
  • Grade II kidney bruise:
    A second degree renal bruise is accompanied by an additional injury to the parenchyma, even if it is still relatively small in the second degree. In detail, it is a parenchymal tear of less than one centimeter. The bruise is usually still harmless and can be easily remedied by appropriate treatment. The hematoma may extend beyond the connective tissue capsule in case of a grade II renal bruise.
  • Grade III kidney bruise:
    With a third degree renal bruise, the parenchymal tear is significantly larger at over one centimeter. In addition, bruises of this severity almost always have a deeper hematoma. However, conservative treatment methods are usually still sufficient in this case too.
  • Grade IV kidney bruise:
    Kidney bruises become really serious if they go beyond the first three degrees of severity. A fourth degree bruise already means serious injuries to the functional structures of the kidney, which can lead to disorders in urine formation. Operative measures to treat the bruise can hardly be avoided in such a scenario.
  • Grade V kidney bruise:
    A fifth degree kidney bruise occurs after an unlikely amount of violence from the outside and, in addition to kidney injuries, also results in injuries to the urinary tract. The urinary tract can even be torn off completely, resulting in a life-threatening condition. Only emergency surgery can prevent fatal kidney failure. Fortunately, such severe bruises are rare.

Accidents as the main cause

In most cases, kidney bruises are caused by blunt violence. This defines itself as a large and broad force that is exerted on a region of the body at more or less high speed. Typical scenarios in which such violence affects the kidney are:

  • Traffic accidents (e.g. rear-end collision),
  • Sports accidents (e.g. in contact or martial arts),
  • Everyday accidents (e.g. falls from a great height),
  • Occupational accidents (e.g. due to collision with extremely heavy loads),
  • physical disputes (e.g. blows or kicks in the kidney).

In connection with car accidents, kidney bruises occur comparatively frequently, since the impact causes the persons involved in the accident to very strongly recoil into the car seats. In addition, massive violent effects on the abdomen (so-called blunt abdominal trauma) can have an unfavorable effect on the kidney area due to the force exerted. Assault, especially blows or kicks on the flank, is the second most common cause of renal bruise after a car accident.

Iatrogenic causes

In a few cases, kidney contusions can also be iatrogenic. In this regard, one speaks of an iatrogenic cause if the injury is caused by a medical or nursing measure. It does not primarily matter whether the injury was theoretically avoidable or inevitable. Only the fact that it was induced by medical personnel is important here. An example of an iatrogenic renal bruise is given in the therapy of kidney stones using shock wave treatment. Here, the externally induced shock waves at the level of the kidneys can lead to a mostly slight kidney bruise. However, this should resolve itself within a few days after the end of the shock wave therapy.


Cardinal symptoms of the bruised kidney are the bruise typical of the bruise (hematoma) and severe flank pain in the affected kidney area. The bruise can also be accompanied by typical injury complaints, some of which can also be seen or felt from the outside. Which includes:

  • Bleeding to the outside (with accompanying laceration),
  • Pressure pain in the area of ​​bruising,
  • Warming of the bruise,
  • Blue discoloration under the skin,
  • Redness,
  • Swelling.

The flank pain is mostly described by those affected as dull and boring, but can also be of a sharp quality. The pain is usually localized on one side, in relation to the bruised flank area, possibly with radiation to other parts of the back and abdomen. It is therefore often the case that sufferers with supposed abdominal or back pain come to the doctor or a doctor and only after a closer look at the accompanying circumstances is the suspected diagnosis of renal bruise considered.

The flank pain does not necessarily have to occur directly after the event, but can only show up in the course or with a time delay. Since the kidneys are well protected in the posterior abdominal cavity and also have a connective tissue capsule and a fat pad, it may take some time before tensions within the kidney capsule caused by the ruptured blood vessels become so great that they lead to pain.

For this reason, attention should be paid to the flank pain that starts after the accident. A typical scenario here is a minor rear-end collision, which initially apparently had no consequences for those involved in the accident and in which a severe flank pain only appears after a day or two to indicate a kidney trauma.

Another symptom that can be associated with higher severity of the kidney bruise is blood in the urine (hematuria). This symptom is very likely, particularly in cases of fourth and fifth degree kidney bruises, and is due to the kidneys' task of filtering the blood flowing through and excreting the urinary substances via the urine. In the case of a bruised kidney, which is associated with deeper injuries to the kidneys, there are varying degrees of smaller or larger bleeding into the kidney corpuscles or kidney tubules. If the ureters are also involved in the injury, the escaping blood can get directly into the draining ureters and thus discolor the urine even after the actual filtering.

The bleeding into the primary urine is often not so visually detectable due to the filter function in the kidney tubules, since the red blood cells are usually brought back into the bloodstream. Even minor bleeding is sometimes not so well visible in the urine.

In such cases, one also speaks of microhematuria, which due to the small amount of blood can usually only be detected by means of laboratory tests. The situation is different when there is bleeding into the urinary tract. There is no further filtering of the urine, which is why the blood contained in the urine or the red color of the urine associated with it is usually visible to the naked eye. Medically, this form of hematuria is also called macro hematuria.

The amount of blood found in the urine does not always provide information about the extent of the damage, but it does serve the treating doctor as a criterion for the course of the healing process.

Attention: If there is heavy internal bleeding or the person suffers a shock, severe kidney bruise quickly becomes a life-threatening situation as a result of an accident. This also suggests that other organs have been damaged by the accident and rapid intervention by medical personnel is imperative. A kidney trauma combined with a shock then also shows the following symptoms:

  • Disturbances in consciousness (restlessness, confusion, sleepiness),
  • pale skin,
  • Drop in blood pressure (hypotension),
  • Cold sweat,
  • fast, flat pulse (tachycardia).


To diagnose a bruise in the kidney area, the doctor often suffices a gaze diagnosis. Swelling and bruising speak a clear language here. In addition, the underlying accident course can easily be reconstructed on the basis of the patient survey and used as a guide to the extent of the bruise by means of a physical examination of the tenderness. In order to actually assess the severity of the kidney bruise, additional information is required.

For example, if the patient complains of painful urination and blood in the urine, there is reason to suspect that serious internal injuries have occurred. A urine sample is revealed here. In addition, if you suspect severe kidney bruises, doctors will use imaging techniques such as ultrasound, CT or MRI to get an idea of ​​the location and extent of kidney injuries.


With the exception of really severe cases, which are fortunately rare for kidney bruises, most bruises in the kidney area are treated conservatively. In addition, some private measures, herbs, and home remedies can help speed up the healing process.

Conservative treatment

Conservative treatment of lighter kidney bruises includes protection and cooling. Those affected should definitely reduce their daily workload and ensure adequate rest. In particular, movements that put a lot of strain on the flank and hip region, such as stooping, heavy lifting or intensive running units, should be avoided. Sufferers must lie as much as possible so that the body can concentrate on healing the bruised kidney. However, in view of the additional risk of back problems due to the long lying down, sometimes a little light movement, for example in the form of a slow walk, should be incorporated into everyday life.

If at all possible, an incapacity for work of at least one week should be considered, which the treating physician will issue in any case, especially in the case of work that is very busy and heavy.

As far as those affected tolerate, cooling elements such as cool packs or cool envelopes can be placed on the flank. Cooling reduces the bleeding into the tissue and the resulting swelling by contraction of the blood vessels. However, cooling only makes sense as long as it is good for the patient. Furthermore, cooling measures for conservative care of the bruise are to be used for a maximum of ten minutes at a time, since otherwise local frostbite, discomfort and in this special case also urinary tract infections and kidney inflammation may also occur.

Home remedies

The patient himself can largely help shape the healing of the kidney bruise even with conservative care by continuing to carry out the protective and cooling measures at home. The spread of the bruise-induced hematoma can also be reduced with envelopes that have previously been soaked in vinegar. Quark envelopes are also successfully used as home remedies for the treatment of large hematomas.

In the initial healing phase, on the other hand, the intensive action of local heat on the bruise should be avoided. The warmth can increase the pain, which is already severe. It is therefore not advisable to put on hot water bottles, take a hot shower or even take a full bath while the kidney is healed.

Of course, there is nothing to be said against a shower for conventional body care, since this improves the patient's situation with a view to good wellbeing. However, the temperature of the morning shower should not be chosen too high and the duration of the shower process should be reduced to a minimum. But those affected still know best what is good for them.

Since a kidney trauma can always lead to further kidney diseases, kidney function should also be maintained and boosted by appropriate private measures. Here the intake of a lot of liquid is the means of choice. If you like the taste, you can also use special bladder and kidney tea, because the herbs contained in it promote kidney and bladder activity.


Teas are always a good choice for urinary tract and kidney complaints, because they flush the urinary tract on the one hand, and on the other they are able to deliver healing agents directly on the spot. There are numerous kidney herbs that can contribute to rapid recovery. Bearberry, in particular, has always been used for complaints in the kidney area and can both support wound healing and reduce existing pain. Also to support the healing of a kidney bruise, especially with traumatic causes in connection with severe pain and hematoma, two homeopathic preparations promise relief:

  • Arnica:
    Applied externally as an envelope soaked in arnica tincture or internally in the form of taking three to five arnica globules several times a day.
  • Dreamel:
    Combined preparation of 14 homeopathic substances, including Arnica montana, Achillea millefolium, Symphytum officinale and Aconitum napellus, which supports the healing of blunt injuries. Can be used externally and internally depending on the form of application.

The list of tea herbs that particularly strengthen the kidney can be continued. For example, again and again

  • Aronia,
  • Ackerhell herb,
  • Marshmallow,
  • Blueberry,
  • Ginger,
  • Lovage
  • and Wasserdost

recommended. The medicinal plants, like bearberry, arnica and traumeel, have disinfectant properties, which additionally protects against injury-related inflammation. You can also incorporate herbs into the treatment when using envelopes to calm the bruise. The following herbs are particularly useful here:

  • Angelika,
  • Comfrey,
  • Spruce,
  • Johannis herbs,
  • Fighter,
  • Rosemary,
  • Stone clover,
  • Juniper.

Medical therapy

If the damage or pain that causes a kidney bruise is more pronounced, drug and surgical methods are also used. The treating doctor provides the indication for this depending on the degree of damage and the expected complications.

When it comes to medication, pain medications such as ibuprofen, diclofenac and novalgin can be administered in the acute phase of a kidney bruise, which, as mentioned, is usually accompanied by severe flank pain. If the affected person also suffers from cramp-like conditions in the abdominal cavity, Buscopan is a proven means to remedy the situation.

The external hematoma can be stopped with a blood-thinning and coagulation-promoting ointment. Known preparations include Voltaren, Mobilat, Doloben and Hepathromb. The ointments support the removal of metabolic breakdown products and clotted blood in the area of ​​the bruise and thus contribute to a faster decrease in the hematoma or swelling.

As a complication from a kidney bruise, there is always an impending kidney infection or even sepsis. Therefore, depending on the extent of the kidney trauma, adapted antibiotic therapies are included in the treatment regimen.

Surgical therapy

In the case of mild kidney bruises, surgical therapy is completely dispensed with in favor of a conservative approach to healing. However, kidney trauma on a larger scale may lead to such tension in the connective tissue capsule that it opens in the sense of organ preservation under operative conditions and the escaping blood must be drained off via drainage systems.

If the drainage pathways are at risk due to the consequences of the damage and, for example, there is a risk of rupture of the kidney pelvis, it may well be necessary to secure them through the surgical insertion of splints.

Surgical intervention is also indicated if the urinary tract or another abdominal organ has been injured. Depending on the type of injury, sewing may be necessary. Treating doctors decide on a case-by-case basis whether such an operation is necessary. (ma)

Author and source information

This text corresponds to the requirements of the medical literature, medical guidelines and current studies and has been checked by medical doctors.


  • Noel A. Armenakas: Nierentrauma, MSD Manual, (accessed 07.08.2019), MSD
  • Sascha Flohé, Bertil Bouillon, Dawid Pieper et al .: S3 - Guideline Polytrauma / Severely Injured Treatment, German Society for Trauma Surgery, (accessed August 7, 2019), AWMF
  • Michael Field, Carol Pollock, David Harris: Understanding Organ Systems - Kidney: Integrative Foundations and Cases, Urban & Fischer Verlag, Elsevier GmbH, 1st edition, 2017
  • Thomas Gasser: Basic knowledge of urology, Springer Verlag, 6th edition, 2015

ICD-Codes for this illness: S37.01ICD-Codes are internationally valid encodings for medical diagnoses. You can find e.g. in doctor's letters or on disability certificates.

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