The support system of urethra and bladder neck plays a crucial role in maintaining continence during sudden increase in intra-abodominal pressure. This system comprises all external structures that provide a layer on which the urethra and bladder neck are situated, including the LA, PB, endopelvic fascia, and the arcus tendineus fasciae pelvis [11,12,13]. The contraction of the LA interacts with the pelvic fascia to elevate the vaginal wall and prevent the downward movement of the urethra. As a result, the posterior urethral wall is pressed against the anterior urethral wall, aiding in sealing the urethral cavity and preventing urinary leakage [14].

Normal function of the urethral support system necessitates normal contraction and anatomical structure of the LA. This muscle can be divided into three regions: the posterior iliococcygeal portion, the anterior pubovisceral muscle (PVM) and puborectal muscle [12]. The bundles of PVM extend medially and interlace with the contralateral muscle bundle forming the anterior sling surrounding the anterior anal region [15]. In healthy women, magnetic resonance imaging (MRI) measurements show that the muscle fibers of the PVM are positioned at an angle of 41 ± 8.0 degrees relative to the horizontal line in the standing position [16]. The contraction of the PVM exerts two distinct mechanical forces: a closing force, characterized by a horizontal directional force that establishes a high-pressure zone within the vagina, resulting in the closure of the vaginal canal, urethral lumen, and genital hiatus (GH); and a lifting force, characterized by a vertical direction that prevents the downward displacement of pelvic organs [17]. During vaginal delivery, the tissues surrounding the vagina are significantly stretched by the baby’s head, causing severe deformation of the LA. Among the three regions of the LA, the PVM experiences the highest stress and is most susceptible to stress-related injuries [18, 19]. Although most injuries are subclinical and the vast majority of women regain function and appearance similar to their prenatal state [20], these women face an increased risk of developing pelvic floor dysfunction in the future due to the degeneration of pelvic muscles and ligaments [21, 22].

PB, a wedge-shaped fibromuscular structure located in the midline of the perineum between the posterior fourchette and anus, plays a key role in maintaining the integrity of the pelvic floor. It provides attachments to muscles and fascia, which work synergistically to maintain urinary continence and the orgasmic platform [23]. Injury to the PB has been reported in 10–30% of women during vaginal delivery, resulting in the separation of the free boundaries of the LA on both sides [24]. This injury is significantly associated with pelvic floor muscle dysfunction, often manifesting as POP or urinary incontinence [25].

In recent years, ultrasonography, as a dynamic examination modality, has become an important part of urogynecological assessments. For the pelvic reconstructive surgeon, ultrasonography provides additional information regarding the characteristic anatomical alterations associated with stress incontinence [26]. Certain indicators, such as URA, BND and RVA, are considered as anatomical indicators for the preoperative and postoperative evaluation of patients with SUI. In this study, the preoperative and postoperative ultrasonographic findings are demonstrated in Table 4. Compared with the preoperative data, URA, BND and RVA were significantly reduced. The improvement of these parameters suggests enhancement of the urethral support structures and reduction of urethral hypermobility. This may elucidate the efficacy of the surgical technique described in improving or resolving female SUI.

We hypothesize that three mechanisms contributed to the enhancement of urethral support structures and the amelioration of urethral hypermobility following the procedures: Firstly, the “stiffness” of the posterior wall of the vagina was augmented after the plication of the LA and reconstruction of the PB. Four-Dimensional ultrasonography conducted 3 months postoperatively revealed that the rectovaginal septum had significantly increased in thickness compared to the preoperative state, thereby reinforcing the supportive system of the urethra (Fig. 3A and B). Secondly, following the plication of the bilateral LA, an autologous muscular “sling” was formed around the bladder neck and the proximal and middle urethra. This muscular sling acts to prevent the downward displacement of the urethra and bladder neck under conditions of sudden intra-abdominal pressure elevation (Fig. 2B). Finally, the plication of the LA may have indirectly reinforced the suspensory ligaments, which can become relaxation as a result of vaginal delivery, aging, or menopause [27]. The pelvic muscles exert tension on these ligaments; consequently, muscle strength may diminish if the ligaments are loose, compromising the ability to maintain closure of the urethral, vaginal, and anal passages [27]. Through the combined action of these three mechanisms, urethral hyperactivity was inhibited, and the urethral closing capability was improved during episodes of increased intra-abdominal pressure, thereby averting the involuntary leakage of urine.

Ultrasonographic findings of a 53-yr-old woman: (A) preoperative view at level of levator hiatus on maximum Valsalva (1. levator hiatus: 30 cm2; 2. genital hiatus: 20 cm2; 3. rectovaginal septum: 4 mm); (B) postoperative view at level of levator hiatus on maximum Valsalva (1. levator hiatus: 20 cm2; 2. genital hiatus: 13 cm2; 3. rectovaginal septum: 10 mm); BL = bladder; RE = rectum; U = urethra; V = vagina

SUI has been linked to negative impacts on sexual function in females, primarily driven by concerns over coital incontinence, odor, psychological distress, loss of self-esteem, and embarrassment [28]. In recent years, there has been a growing body of research examining the effects of anti-incontinence surgeries on patients’ sexual wellbeing. Notably, most studies have observed improvements in sexual function following such procedures [29,30,31]. However, for those with concomitant vaginal laxity, sexual dysfunction may not be fully resolved without additional vaginal tightening measures [31]. Despite all patients in this study exhibiting combined vaginal laxity, postoperative improvements in sexual function were reported in 39 individuals who maintained regular sexual intercourse. We hypothesize that these improvements in sexual satisfaction can largely be attributed to the plication of LA and the reconstruction of PB, which work synergistically to narrow the vaginal canal and enhance its ‘holding power’ during sexual intercourse.

This study had several limitations. First, the majority of patients were premenopause, thus the treatment outcomes in postmenopausal and elderly women could not be determined. Second, no patients with detachment of LA from the tendinous arch or LA paralysis were encountered in our study. Further research is needed to to determine whether these patients would benefit from the surgical interventions we introduced. Third, all patients enrolled had primary SUI. The effectiveness of this surgical technique in recurrent SUI requires further study. In addition, our sample size was limited and the follow-up time was only 12 months. As pelvic muscles and ligaments deteriorate with age and menopause, the treatment outcome of this surgical method requires further evaluation in a larger population with longer follow-up.

In this research, we approximated and plicated the bilateral LA and reconstructed the PB via transvaginal approach to treat the female SUI. The objective and subjective cure rates at 12 mo follow-up were at 87% and 91.3%, respectively. Although the fresults are promising, the surgical technique we reported is not the standard procedure endorsed by current urinary incontinence guidelines. Due to the limited sample size and comparatively brief follow-up duration, the evidence supporting its widespread adoption as the favored intervention for female stress urinary incontinence is insufficient. Nevertheless, in routine clinical practice, a number of patients express reluctance towards undergoing MUS surgery due to perceived risks associated with potential complications. For these individuals, the surgical approach we have discussed presents a viable alternative treatment option. This is particularly pertinent for younger patients who place a high value on sexual well-being, as our proposed method not only mitigates symptoms of urinary incontinence and improves life quality but also holds the potential to augment sexual satisfaction.