Treatments & Therapies

Residual urine determination – treatment, effect & risks

Residual urine determination

The residual urine determination is an examination method of urology. The aim of this examination is to diagnose a bladder emptying disorder and, if necessary, to determine the cause.

What is the residual urine determination?

Residual urine determination is performed in the field of urology to diagnose a possible bladder emptying disorder. Residual urine is the persistence of urine in the bladder after an arbitrary leakage of urine.

The formation of residual urine is often an indication of a disorder of bladder function and occurs as a concomitant symptomatology. The fact that the bladder can only be emptied incompletely is often not noticed by the patient. This manifests itself only in the course of recurring bloating and frequent urge to urinate. Frequently, residual urine formation occurs when the state of tension of the bladder is not given.

Even if the symptoms do not cause any symptoms at first, it is necessary to determine the cause and then treat it adequately. Without treatment, the risk of urinary tract infection increases enormously and can lead to irreversible damage. To determine the residual urine, an examination is performed using sonography or a bladder catheter. Pathology is the retention of residual urine of 100 ml in an adult and about 10 percent of bladder capacity in children.

The residual urine forms a potential breeding ground for pathogens and bacteria. Therefore, the risk of recurrent urinary tract infections and the formation of bladder stones is increased. This manifests itself by a painful emptying of the bladder, fever and possibly also chills. The residual urine can accumulate back into the kidneys and leads to irreversible damage, up to acute kidney failure. Often it comes to a very painful overstretching of the bladder. The urine can no longer be drained, it comes to a so-called complete urine lock.

Function, impact & goals

There are many causes for the formation of residual urine. These can be, for example, pathological changes in the urethra or penis. Diseases in the area can be phimosis (narrowing of the foreskin), urethral stricture, injuries to the urethra or urethral carcinoma.Neurological diseases such as stroke, multiple sclerosis (MS), paraplegia or a herniated disc can also be responsible for residual urine formation. Occasionally, a traumatic pelvic floor fracture or side effects of antidepressants and antihistamines can also be triggers. Especially in the male sex, prostate enlargement (benign prostatic hyperplasia) or prostate cancer can be the cause of the formation of residual urine. The enlarged prostate or the proliferation of a carcinoma can lead to a narrowing of the urethra and thus influence or even block the outflow of urine.

Especially in the female sex, a uterine lowering can lead to residual urine formation. Due to the lowered uterus, the urethra can be compressed and thus the outflow of urine can be disturbed or blocked. In the first stage of residual urine formation, the affected person first observes a frequent urge to urinate with the release of small amounts of urine, which is not painful. The bladder cannot be completely emptied and residual urine remains within the bladder. In order to determine whether this is a pathological urinary behavior, a residual urine determination must be performed.

This determination can be performed sonographically (with an ultrasound probe) or through a bladder catheter. In sonographic residual urine determination, a distinction is made between transabdominal sonography (above the abdominal wall) and transvaginal sonography (through the vaginal entrance). In practice, transabdominal sonography is used more often.

In this case, the patient must go to the toilet and empty his bladder before the sonography. If possible, this should be done without pressing. Subsequently, the patient lies down in reserve on the examination table and exposes the lower abdomen. With a lubricant and the ultrasound probe, the remaining urine within the bladder can now be calculated through the abdominal wall and assessed by imaging.

Alternatively, the ultrasound probe can also be inserted with lubricant over the vagina. When determined by a bladder catheter, the transurethral bladder catheter and the suprapubic bladder catheter are distinguished. The transurethral catheter is placed through the urethra into the bladder. Here, a so-called disposable catheter is used. In the suprapubic catheter, the catheter is inserted through the abdominal wall into the bladder.

Also with this procedure, the patient must first empty his bladder without pressing. Subsequently, a disposable catheter is inserted into the bladder via the urethra and the residual urine is collected in a collection bag and thus the amount is determined. The residual urine determination is described as positive if a residual urine of more than 100 ml remains in adults and more than 10% of bladder capacity in children.

Risks, side effects & dangers

If residual urine remains in the bladder, bacteria and viruses form in it, which settle in the inner wall of the bladder. As a result, the bladder is not flushed regularly and it comes to recurring bladder infections. If the bladder emptying disorder is not remedied, the bacteria and viruses can migrate up to the kidneys and cause inflammation of the renal pelvis. This leads to severe pain and possibly also to irreversible damage to the kidneys.

In addition, urinary retention can occur. The kidney outflow is dysfunctional because the bladder does not have enough capacity to collect more urine. If there is a backlog within the kidneys, this can lead to tissue damage. Furthermore, the urinary bladder can be overstretched or the bladder muscle can become reflexively hypotonic. In order to prevent irreversible damage to the bladder and kidneys, residual urine should be determined and the causes treated appropriately.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.