Mechanisms of action of an intravesical balloon as a therapy for stress urinary incontinence

Aims:

Previous studies have indicated that the intravesical placement of an air-filled balloon alleviates much of the symptoms caused by stress urinary incontinence (SUI) in women. However, the exact working mechanisms behind this therapy are not yet fully understood. The current study aims to elucidate the potential physiological mechanisms underlying this minimally invasive intervention.

Methods:

We have evaluated video urodynamic data in women undergoing this therapy (n = 5), during which participants were asked to cough with increasing intensity. For each participant, we have videos before insertion of the balloon and one week following insertion. We identified a frame in a resting situation in which the maximum horizontal and vertical bladder dimensions were measured. We expressed the maximum vertical diameter as a ratio of the maximum horizontal diameter. We then used custom-written scripts to identify the bladder and balloon in each frame of the video urodynamic investigation and subtracted information regarding the location of the bladder neck and diameters of the balloon. We then used this information to plot the displacement of the bladder neck and size of the balloon during coughing.

Results:

The diameters of the balloon were significantly decreased during coughing (p $\le$ 0.05). We found a significant increase of the maximum vertical diameter expressed as a ratio of the maximum horizontal diameter before and after insertion of the intravesical balloon (p $\le$ 0.05). The maximum displacement of the caudal bladder limit increased significantly after placement of the intravesical balloon was (p $\le$ 0.05).

Conclusions:

Our results imply that the balloon compresses in response to increases in abdominal pressure, and the bladder obtains a significantly more vertically oriented shape after placement of the balloon. Moreover, it appears that placement of the balloon significantly increases the mobility of the bladder neck. The balloon is indicated to absorb some of the increases in intravesical pressure during episodes of high abdominal pressure. We propose that the balloon inwardly pushes the bladder wall upwards, causing the organ to acquire a more vertically oriented shape. Additionally, we postulate that this change in bladder shape will increase the mobility of the bladder neck, thereby increasing the kinking capability of the urethra.