Why do patients leak urine even though they have a urinary catheter

The causes of urinary leakage from an indwelling urinary catheter are complex and difficult to manage. Clinically, a timely and comprehensive assessment of the patient's bladder function is essential. Urodynamic testing can be used to identify the cause and take appropriate measures. After the indwelling urinary catheter is placed, if the patient is at rest and the bladder is full, the catheter is not clamped, or the catheter is clamped, urine naturally seeps out of the urethra. This can be considered urinary leakage if the patient wets their pants or bed. Catheter leakage can be related to obstruction, folding or twisting of the catheter or drainage tube, an oversized catheter, excessive fluid injection into the balloon, prolonged clamping, overactive bladder, urinary tract infection, constipation, and other causes. Poor catheter drainage and bladder spasm are the two main causes of urinary leakage from a catheter.

Cause analysis: Catheter obstruction and poor drainage can occur due to improper patient positioning or improper drainage bag placement, leading to kinking, compression, or folding of the catheter. Other potential causes include acute bacterial infection, turbid urine, sedimentation of impurities, or blood clots. Long-term indwelling catheters without regular changes and flushing, and calcium deposits from insufficient fluid intake, leading to obstruction and poor drainage, resulting in urine leakage. Catheter clamping in patients undergoing bladder function training, particularly during diuretic therapy or high-volume fluid infusions, and failure to promptly assess the patient's bladder volume and open the catheter. When urine reaches a certain pressure in the bladder, urine flows out through the catheter, causing leakage.

Nursing measures: Patients with indwelling urinary catheters should frequently check whether the catheter is compressed or twisted. The drainage bag must be located 50 cm below the bladder. If there are no medical conditions, encourage patients to drink more water, >2500 ml per day, and flush the bladder physiologically. For patients with long-term indwelling urinary catheters, flush the bladder or replace the catheter immediately if sediment is found. If necessary, flush the bladder with 100-200 ml of sodium bicarbonate to prevent calcium salt deposition, or take sodium bicarbonate tablets orally to alkalinize the urine and reduce mucus secretion, so as to keep the urinary catheter drainage unobstructed and prevent the formation of urine scale.

Cause Analysis: This condition primarily refers to urinary incontinence caused by an overactive bladder. Overactive bladder is a syndrome characterized by urinary frequency, urgency, and urge incontinence due to unstable detrusor contractions caused by non-neurogenic factors and detrusor hyperreflexia caused by neurogenic factors. Urinary incontinence is accompanied by a sense of urgency and a rapid, linear urine stream. The most common causes of unstable bladder are detrusor fibrosis leading to decreased bladder compliance, detrusor damage, detrusor instability, and detrusor degeneration.Central nervous system diseases such as cerebrovascular accidents and spinal cord diseases are the main causes of detrusor hyperreflexia. The bladder trigone and bladder neck mucosa are sensitive to stimulation. Any foreign body or inflammatory stimulation can cause urinary urgency, dysuria, and perineal discomfort. During indwelling catheterization, the front end of the catheter and the balloon can both mechanically stimulate this area, causing bladder spasms. When bladder spasms occur, urine cannot be discharged through the drainage port of the catheter and can only be discharged between the catheter wall and the urethral mucosa, resulting in urine leakage. In such patients, the pressure in the bladder increases, and upper urinary tract reflux may even occur, which should be carefully excluded clinically.

Nursing measures: The contraction of the bladder detrusor muscle is controlled by cholinergic receptors. Tolterodine tartrate is a competitive M cholinergic receptor blocker that can effectively inhibit the involuntary rhythmic contractions of the bladder. However, when using anticholinergic drugs, attention should be paid to adverse drug reactions, such as dry mouth, nausea, and vomiting. The smaller the catheter model and the thinner the diameter, the less irritation to the urethral mucosa and bladder neck. While ensuring optimal catheterization without causing catheter dislocation, the amount of liquid or gas in the balloon or the use of a catheter with a smaller balloon volume can be used to avoid direct contact between the balloon and the bladder wall, which can lead to excessive bladder muscle contraction.

Numerous studies have shown that biofilm formation is associated with refractory urinary tract infections in patients with long-term indwelling urinary catheters. Replacing a new urinary catheter can remove established biofilms. Furthermore, antibiotics can be used to control infection, reduce bladder irritation, and control urinary incontinence. Furthermore, during bladder irrigation, the temperature of the irrigation fluid should be adjusted to near body temperature, especially during cold winter months, to reduce cold stimulation and effectively prevent bladder spasms.

Cause Analysis: Urinary incontinence in this type of patient is caused by physiological degenerative changes, which are common in the elderly and those who are bedridden for a long time. Common causes include urethral sphincter relaxation, prostatic hyperplasia, changes in bladder structure and capacity, and constipation leading to increased bladder pressure.

-Elderly patients may experience urethral atrophy and urethral laxity due to decreased hormone levels. This can often lead to urine extravasation due to an undersized or thin catheter that doesn't fit neatly into the urethra. This type of leakage often results in a slow and short urine flow. Furthermore, elderly and bedridden patients, with reduced urethral tone and increased intra-abdominal pressure, may experience urine leakage through the urethra if the catheter is clamped. If the catheter is not clamped, urine may be discharged through the catheter or accompanied by urethral overflow. Prolonged catheter clamping can further increase the risk of leakage.

-Men over 60 often have varying degrees of prostatic hyperplasia (BPH), a major cause of mechanical obstructive urinary retention. This condition can make catheterization difficult, preventing the balloon from entering the bladder before it is fully inflated. The balloon can become lodged in the urethra, compressing the urethra and causing mucosal bleeding and necrosis. Necrotic material can obstruct the catheter, leading to urinary incontinence. Furthermore, varying degrees of BPH can damage the urethra during catheterization, leading to bleeding and blood clots that can easily block the catheter, causing urinary incontinence.

-Changes in bladder structure and capacity. Due to physiological aging, the bladder capacity of people over 50 years old is reduced by about 40% compared to those at 20 years old, and the amount of fluid injected into the balloon is also appropriately reduced.

-When constipated patients have difficulty defecating, it will lead to increased intra-abdominal pressure, which in turn will increase the intra-bladder pressure, causing the detrusor muscle to contract and causing urine to overflow along the urethra.

Nursing strategies:

-Choose an appropriate catheter: Sizes 18-24 are recommended for adults, and sizes 12-16 are recommended for adolescents. Elderly male patients, especially those with benign prostatic hyperplasia (BPH), may benefit from a smaller double-lumen balloon catheter due to the narrowing of the membranous urethra. Elderly, frail, and bedridden female patients, who have less elastic perineal muscles and a more relaxed urethral sphincter, should use a larger catheter to prevent leakage while ensuring patency and preventing blockage.

-Patients with relaxed urethral sphincter should strengthen pelvic floor muscle training actively or passively.

-Solve the problem of constipation.

In traditional urinary catheterization, the catheter is inserted approximately 20-22 cm in men and 4-6 cm in women, with an additional 1 cm inserted when urine begins to flow. However, measurements show that the lowest point of the balloon in a balloon catheter is 5 cm from the tip of the catheter. If a double-lumen balloon catheter is inserted at the same length as traditional catheterization, the balloon will be located directly within the membranous urethra. When the balloon is inflated, it will inevitably cause complications such as urethral overdistension, compression, and tearing.

Therefore, when using a double-lumen balloon catheter, the length of the inserted catheter should be the length of the urethra plus the length from the distal end of the balloon to the tip of the catheter (5 cm). That is, the length of a double-lumen balloon catheter inserted in female patients is about 10 cm, and the length of a double-lumen balloon catheter inserted in male patients is about 25 cm. Because the double-lumen balloon catheter has no scale markings, when using it, after the balloon is inflated, pull the catheter outward along the urethra until there is resistance, which is the optimal insertion length of the catheter.

Cause Analysis: During indwelling catheterization, the amount of fluid injected into the balloon is directly related to the incidence of urinary leakage. Too little fluid is injected, and the incidence of urinary leakage and catheter removal increases significantly. Excessive fluid injection creates excessive pressure on the urethral opening and bladder neck, which can cause bladder spasms, leading to a urge to urinate and occasional straining to urinate, which can cause urinary leakage. Injecting too much fluid too quickly can lead to compression and pain in the urethral sphincter. Furthermore, the greater the amount of fluid injected and the longer the fixation time, the worse the balloon's retraction, making catheter removal difficult.

Nursing Strategies: Once the appropriate catheter model is selected and objective factors related to urine leakage have been eliminated, the focus is on adjusting the balloon injection volume. In vitro experiments have confirmed that after injections of 10ml, 15ml, and 20ml into the balloon of a 16F double-lumen balloon catheter, elliptical bladder cavities with transverse diameters of 2.5cm, 2.8cm, and 3.0cm, respectively, are formed. As the injection volume increases, the bladder cavity becomes oblong, with a minimal increase in transverse diameter. When the injection volume is below 20ml, the greater the injection volume, the larger the transverse diameter, the fuller the balloon, the tighter the fit against the internal urethral opening, and the less likely it is to dislodge.