Tips and tricks for continence preservation following robot-assisted radical prostatectomy

Anatomy and mechanisms of male urinary continence

The prostate is located surrounding the proximal part of the male urethra and it is adjacent to several anatomical structures that are involved in maintaining UC and responsible for erectile function. As a result, the wider the resection to ensure the oncological outcome, the greater the risk of impairing UC due to inadvertent damage to surrounding tissues. Considering the close involvement of periprostatic structures in UC, in most patients, incontinence occurs early and is followed by gradual recovery over time.

Although the mechanisms of UC in males are not completely understood, alongside advances in volumes and techniques of radical prostatectomy, a large amount of related anatomical knowledge has been recently accumulated. Currently, male UC is considered as the combined actions of multiple anatomical structures surrounding the prostate gland ; together, these structures constitute the urethral sphincter complex and are summarized below:

• 1.

  The smooth muscle sphincter (lissosphincter) consists of two layers (inner longitudinal and outer circular) and is innervated by the autonomous nervous system. It forms a spongy structure below the urethral mucosa, and external contraction completely cuts off the urine flow.

• 2.

  The stratified sphincter (rhabdosphincter; the posterior part forms the median fibrous raphe [MFR] with no muscle layer) is responsible for the slow-twitch, passive control. It forms a cylindrical shape that originates from the prostate apex and attaches to the deep, transverse perineal muscles. In the transverse cross-section, the muscle in the stratified sphincter is distributed in an omega shape; posteriorly, there is no muscle, but instead, forming the MFR are dense fibrous tissues. The MFR forms a posterior support complex by connecting the central tendon posteriorly and Denonvilliers’ fascia superiorly.

• 3.

  The puboperinealis muscle is responsible for fast-twitch, active control. It forms the medial part of the levator ani muscle. In the coronary view of magnetic resonance imaging, the puboperinealis muscle appears as two teardrop shapes running bilaterally, lateral to the urethra. As it attaches to the perineal body posterior to the urethra, the puboperinealis muscle ultimately forms a structure that supports the urethra.

Based on this understanding of the urethral sphincter complex, widespread efforts have been made to mitigate UI by identifying and preserving this complex during surgery. Conceptually, these techniques can be summarized as the preservation of the internal/external sphincters and reconstruction of anterior/posterior support structures.