Cystometry is a diagnostic procedure in the field of urology. Here, the urinary bladder is filled with saline and contrast medium and the pressure inside the bladder is measured. These measurements are performed at rest and under stress. Furthermore, the measurements are performed with different filling values. Through the results, therapeutic measures can be adequately tailored to the diagnosis.
What is cystometry?
Cystometry is a diagnostic procedure in the field of urology. In this procedure, the urinary bladder is filled with saline and contrast medium and the pressure inside the bladder is measured. Cystometry is a procedure to establish or exclude a diagnosis of disorders of emptying and filling of the urinary bladder. The procedure is used to measure and evaluate the bladder pressure in relation to the volume and perception of the patient. The measurement results ran information about the muscle function of the pelvic floor muscles and sphincter and the neurological function of the nerves. The measurement refers not only to the urinary bladder, but also to the function of the urinary tract. As a physiological response to a full urinary bladder, stimulus impulses are sent to the brain via the nerve pathways to initiate emptying of the bladder. These stimuli can be processed voluntarily by humans, which means that it is possible to hold urine for a certain period of time. If the bladder continues to fill and is not emptied, despite the continuous stimulus, reflex emptying of the bladder may occur. However, if the bladder is emptied voluntarily, feedback impulses are sent, initiating contraction of the bladder and opening of the sphincter. If this physiological process is disturbed, urinary incontinence or urinary retention can occur. In order to analyze and assess the cause of this, the procedure of cystometry is used. Cystometry is often performed in combination with other examination methods of uroflowmetry.
Function, effect, and goals
Cystometry is used for various problems affecting the urinary bladder. Frequently, this diagnostic procedure is used in cases of urinary incontinence, bladder emptying disorder, unclear symptoms such as frequent urge to urinate with little or no urine output, reflux of urine from the bladder to the kidney, unclear urinary retention, and in children who are resistant to therapy for bedwetting. Bladder voiding disorders caused by neurological diseases or after spinal cord damage are also assessed with the help of cystometry. During cystometry, urinary bladder pressure is measured during filling. Data on bladder dynamics, volume capacity, distensibility and stability are recorded. Before cystometry can be performed, cystitis must be ruled out, as it is contraindicated for such an examination. During cystometry, a transurethral catheter is then placed through the urethra into the urinary bladder. Through this thin catheter, the urinary bladder is filled with saline. Furthermore, a transanal measurement catheter is inserted through the rectum. Through this measuring catheter, the pressure behavior is continuously recorded during the filling and emptying of the bladder. The pressure is measured at rest and under stress, such as when coughing. The values are recorded as a so-called pressure curve and can provide information as to whether there is a possible disorder in the area of the bladder muscles or the activity of the sphincter. By assessing cystometry, forms of incontinence can be ruled out and a diagnosis made. A distinction is made between stress incontinence, urge incontinence, high-pressure bladder, overactive bladder with a possible neurological cause and mixed urinary incontinence. Based on these measurement results and the exclusion of various disorders, an adequate diagnosis-oriented therapy can be performed. If the measurement results are not sufficiently conclusive, especially in the case of disorders with a neurological background, it is recommended to integrate further examinations in the form of an ice water test or a Carbachol test into the cystometry evaluation. To exclude benign prostatic enlargement, a pelvic floor EMG is often also performed. When cystometry is performed, a contrast medium is usually used to fill the bladder.This additionally enables a micturition cyturethrogram or also videourodynamics. The speed of filling is individual and is divided into 3 levels. A slow filling rate is considered to be about 10m/min, a medium filling rate is 10-100ml/min and a fast filling rate is considered to be over 100ml/min. In cystometry, it is recommended to start with a slow filling rate and then increase it. Generally, a body warm fluid is used for general cystometry, only if a neurological cause of the symptoms is suspected, a cold fluid is used to provoke autonomic detrusor contractions. These contractions are physiologically inhibited by the supraspinal centers. If there is no detrusor contraction, this is an indication of a neurologic disorder. The general bladder capacity in women is a filling volume of 250-550ml. In men, a physiologic filling volume of 350-750ml is established.
Risks, side effects and hazards
In principle, cystometry is a very safe and complication-free procedure to detect a possible disorder of the urinary bladder. Occasionally, however, urinary tract infection may occur after the procedure. Patients who suffer symptoms of urinary bladder voiding dysfunction due to a neurological cause may subsequently experience what is known as an autonomic reflex. This is manifested by severe headache, increased blood pressure, low pulse and profuse sweating. Cystometry should not be performed in patients with an acute urinary tract infection. Medications that affect urine flow and the urinary bladder must be discontinued before cystometry is performed. The attending specialist should discuss this with the patient before performing the procedure and weigh the risks individually based on the patient’s medical history and disease process.
