Modern ultrasound imaging of pelvic floor dysfunction: clinical applications and capabilities

Introduction

Pelvic floor dysfunction (PFD) is one of the most significant problems in modern gynecology and urogynecology, as it affects quality of life, daily activity, body image perception, as well as sexual and reproductive health [1]. The clinical spectrum is broad and often includes pelvic organ prolapse (POP), urinary incontinence, fecal incontinence, defecatory disorders, and pelvic pain; many patients present with multiple concurrent symptoms [2].

The disease burden is substantial. Pelvic floor dysfunction is common in middle-aged and elderly women, but it is also relevant during the reproductive period, especially after pregnancy and vaginal delivery, when structural damage to the pelvic floor may occur. Obstetric trauma, levator ani muscle injury, connective tissue weakness, age, obesity, and prior pelvic surgery contribute to the development and progression of dysfunction [3]. Estimates suggest that the prevalence of symptomatic POP among women ranges from 2.9% to 11.4%, whereas when using the Pelvic Organ Prolapse Quantification (POP-Q) system, clinical signs of prolapse are identified in 31.8–97.7% of women [4].

Since symptoms often overlap, clinical examination alone may be insufficient for comprehensive characterization of the condition. A comprehensive diagnostic approach should include history taking, physical examination, Valsalva maneuver, pelvic organ prolapse assessment, and, increasingly, targeted imaging. Pelvic floor ultrasound has become a first-line method in urogynecology and related disciplines, offering dynamic, non-invasive, and cost-effective assessment of pelvic floor anatomy and function [5]. This review summarizes current evidence on the role of pelvic floor ultrasound in evaluating muscle integrity, prolapse diagnosis, functional parameters, and guiding conservative and surgical treatment [6].

Methodology

This article presents a narrative literature review of the clinical and technical role of pelvic floor ultrasound in women with pelvic floor dysfunction. The review focuses on translabial and transperineal sonography, transvaginal and integrated ultrasound approaches, as well as three-dimensional and four-dimensional imaging. Ethical committee approval was not required for this literature review.

Search strategy. The literature search was conducted in the electronic databases PubMed, Scopus, and Cochrane Library for the period from January 2000 to May 2025. The following keywords and their combinations were used: "pelvic floor dysfunction," "pelvic floor ultrasound," "transperineal ultrasound," "3D ultrasound," "4D ultrasound," "pelvic organ prolapse," "stress urinary incontinence," "levator ani avulsion," "obstetric anal sphincter injury," "biofeedback," "mesh complications." The search was limited to publications in English.

Inclusion criteria. The review included original studies, systematic reviews, meta-analyses, and clinical guidelines that evaluated the diagnostic or therapeutic role of pelvic floor ultrasound in adult women. Priority was given to randomized controlled trials (RCTs) and prospective cohort studies.

Exclusion criteria. Studies focusing exclusively on magnetic resonance imaging (MRI) or defecography without an ultrasound component, individual case reports (unless illustrating a rare complication), and studies in which ultrasound was used only for anatomical assessment without functional maneuvers were excluded.

Data analysis. From each study, the following were recorded: study type, sample size, ultrasound approach used (transperineal, transvaginal, endoanal, etc.), measured parameters (levator hiatus area, bladder neck mobility, levator ani avulsion, etc.), main results, and limitations. Due to the heterogeneity of protocols and outcomes, quantitative meta-analysis was not performed; data were synthesized narratively. Risk of bias assessment was not conducted due to the narrative design.

Results

Anatomical structures assessed by pelvic floor ultrasound. Pelvic floor ultrasound evaluates several anatomical areas relevant to diagnosis and treatment. In the anterior compartment, bladder descent, bladder neck mobility, urethral integrity, and urethral rotation during straining are examined. These findings are clinically important in stress urinary incontinence (SUI) and cystocele [3]. In the middle compartment, ultrasound can detect uterine or vaginal vault descent and loss of apical support. In the posterior compartment, transperineal ultrasound allows identification of rectocele, enterocele, sigmoidocele, and rectal intussusception [2]. Particular importance is given to imaging of the levator ani muscle and diagnosis of its avulsion [5].

Assessment of muscle integrity and levator hiatus dimensions. Pelvic floor ultrasound enables accurate assessment of pelvic floor muscle integrity and thickness, detection of traumatic injuries, and measurement of levator hiatus dimensions [7]. The levator ani muscle is the primary supporting structure of the pelvic organs, and its detachment (avulsion) is a common consequence of vaginal delivery, representing a major etiological factor in POP development [8].

In a retrospective cohort study by Serrano et al. (2022) involving 848 women with pelvic floor dysfunction symptoms, complete levator ani avulsion was identified in 23% of patients, with women with complete avulsion having a 4.7-fold higher likelihood of POP compared to those with partial avulsion [9]. Moreover, women with severe POP had a 3.13-fold higher probability of bilateral complete avulsion.

The diagnostic accuracy of ultrasound for levator ani avulsion was thoroughly evaluated by van Gruting IMA et al. (2022) in a cross-sectional study of 135 women: four-dimensional perineal ultrasound demonstrated 100% specificity and 71% sensitivity, confirming its role as an effective screening test [10]. Quantitative assessment of levator hiatus dimensions is also crucial. Normative values established by Dietz HP et al. (2023): in nulliparous women, mean hiatal area is 11.84 cm² at rest; in asymptomatic parous women — 15.1 cm²; in women with POP — 25.8 cm² [11]. A hiatal area exceeding 25 cm² during Valsalva maneuver is defined as abnormal distension ("ballooning") and is strongly associated with prolapse symptoms [12].

Diagnosis of pelvic organ prolapse. Pelvic floor ultrasound plays an important role in diagnosing pelvic organ prolapse — a condition characterized by descent or protrusion of pelvic organs due to weakening of the supportive apparatus [13]. The International Continence Society POP-Q system is the standard clinical examination tool, but it has limitations in fully reflecting the dynamic and multicompartmental nature of POP [14]. Ultrasound overcomes these limitations by providing simultaneous visualization of all three pelvic compartments during dynamic maneuvers [15].

The clinical utility of pelvic floor ultrasound in POP diagnosis is further enhanced by its ability to influence surgical decision-making. Transperineal ultrasound can change surgical indications in patients with symptomatic POP, complementing and refining clinical data [14]. In recurrent prolapse after sacrocolpopexy, ultrasound is commonly used to assess mesh implant position and guide individualized surgical revision [16].

Functional assessment: urethral mobility and anal sphincter integrity. A key advantage of pelvic floor ultrasound is its capacity for functional assessment. It allows evaluation of urethral and bladder neck mobility, as well as diagnosis of anal sphincter injuries [17]. Pelvic floor muscle training using ultrasound biofeedback improves all urethral mobility parameters in women with varying degrees of muscle strength [18].

Regarding the posterior compartment, ultrasound plays a crucial role in assessing obstetric anal sphincter injuries (OASI). The prevalence of OASI is estimated at 2.9% (range 0.5–11%), reaching 6% in primiparous women [19]. Pelvic floor ultrasound, including assessment of the anal sphincter complex, should be performed after vaginal delivery in all women with OASI and in those at high risk of obstetric trauma [20]. Four characteristic sonographic signs have been described in OASI: discontinuity of the external and/or internal anal sphincter, thickening of the external sphincter at the repair site, thinning of the internal sphincter at the tear site, and associated thickening, which determine therapeutic management [19].

Role in guiding conservative and surgical treatment. Pelvic floor ultrasound is increasingly recognized as a first-line imaging modality in urogynecology, proctology, and pediatric urology, providing clinicians with valuable data for personalized treatment approaches [21]. In conservative management, rehabilitative ultrasound imaging (RUSI) serves as a visual biofeedback tool [22]. According to a review by Daniel DS et al. (2026), 57% of participants who could not correctly contract their pelvic floor muscles after verbal instructions achieved correct contraction using ultrasound biofeedback [22].

In a randomized controlled trial by Del Forno et al. (2021) involving 34 nulliparous women with deep infiltrating endometriosis, the use of 3D/4D transperineal ultrasound to monitor pelvic floor muscle manual therapy led to significant improvement in muscle relaxation, pain reduction, and increased treatment adherence [23].

In surgical management, ultrasound is indispensable for preoperative planning and postoperative assessment. Preoperative ultrasound parameters, such as urethral funneling, bladder wall thickness, and urethral length, can predict functional outcomes of midurethral sling procedures [24]. The ability of ultrasound to visualize synthetic mesh implants is another important advantage, making it invaluable for postoperative surveillance [5].

Pelvic floor ultrasound in endometriosis and chronic constipation. Raimondo D et al. (2022) in a prospective cohort study of 87 women with endometriosis demonstrated that patients with chronic constipation had significantly smaller levator hiatus area during Valsalva maneuver (12.6±3.2 cm² vs. 14.6±4.4 cm², p=0.041) and higher prevalence of levator ani coactivation (65.5 vs. 18.9%, p<0.001) compared to women without constipation [25]. In the subgroup of isolated ovarian endometriosis, these differences persisted, whereas in deep infiltrating endometriosis, no statistically significant differences were found, indicating different pathophysiological mechanisms of constipation in different disease phenotypes.

Standardization and quality. Despite its advantages, pelvic floor ultrasound remains a technique-dependent method. Quality and interpretation of results may vary depending on transducer type, scanning plane, patient position, bladder filling, and adequacy of Valsalva maneuver performance [2]. Standardization is essential: uniform protocols improve reproducibility and allow comparison of results across patients and institutions [5]. The development of automated analysis and specialized software may further reduce variability [3].

Discussion

This review demonstrates that pelvic floor ultrasound is a highly informative, safe, and accessible diagnostic method for pelvic floor dysfunction. Its key value lies in the ability to simultaneously assess anatomy and function dynamically, which is not possible with static imaging methods [12].

Comparison with other imaging modalities. Unlike magnetic resonance imaging (MRI), ultrasound does not require ionizing radiation, can be performed at the bedside, and allows real-time assessment during repeated stress maneuvers (cough, Valsalva) [5]. Although MRI provides higher soft tissue resolution and better visualization of deep structures, ultrasound, due to its accessibility and ability for dynamic repetition, becomes the method of choice for primary assessment and treatment monitoring [10]. Frazão LB et al. (2021) in an integrative review of pelvic floor muscle assessment methods indicated that ultrasound was used in 9 of 54 studies (16.7%), with the most frequent parameter being levator hiatus area at rest [26].

Clinical effectiveness of ultrasound biofeedback. One of the most significant findings of this review is the confirmation of RUSI effectiveness as a biofeedback tool. Matsunaga A et al. (2022) demonstrated that in men with persistent urinary incontinence after radical prostatectomy, TPUS-guided pelvic floor muscle training significantly improved contraction frequency (from 7.5 to 10.0 contractions, p<0.001) and duration (from 2.6 to 9.0 seconds, p=0.017), and reduced urine leakage volume from 397.0 g to 248.6 g (p=0.024) [27]. Kuo YL et al. (2024) in an RCT of 53 postpartum women with pelvic pain showed that adding TAUS-guided biofeedback to stabilization exercises led to greater pain reduction (mean difference 2.6 points on NRS) and improved functional outcomes compared to exercises alone [28].

These data are consistent with earlier work by Dietz HP et al. (2001), who first demonstrated that 57% of women unable to perform correct pelvic floor muscle contraction after verbal instruction achieved this after just five minutes of TPUS-guided biofeedback [29].

Ultrasound and emerging treatment technologies. In recent years, studies have emerged investigating the combined use of ultrasound with new energy-based technologies. Seki AS et al. (2022) in an RCT compared CO₂ laser, microablative radiofrequency, and placebo in women with SUI: at one year, subjective cure rates were 72.6% for laser and 61.7% for radiofrequency versus 30% in the placebo group, with comparable results between active treatment groups [30]. Although these methods do not replace ultrasound, they expand the therapeutic arsenal, and ultrasound remains a key tool for patient selection and efficacy assessment.

Limitations

This review has several limitations. First, the narrative design and heterogeneity of included studies do not allow for quantitative meta-analysis or the formulation of standardized threshold values for all ultrasound parameters. Second, most studies have relatively small sample sizes and short follow-up periods. Third, validated norms for ultrasound parameters across different age groups and parity are lacking. Fourth, the comparative effectiveness of RUSI versus other biofeedback methods (electromyography, manometry) remains an open question — available data are preliminary in nature [22].

Conclusion

Pelvic floor ultrasound today is a critical tool for diagnosis and management of pelvic floor dysfunction. It provides accurate assessment of muscle integrity, levator hiatus dimensions, pelvic organ prolapse, urethral mobility, and anal sphincter injuries through a combination of static and dynamic scanning [8, 11]. Its non-invasiveness, wide accessibility, and cost-effectiveness make this method available for routine clinical use [5].

The principal value of the method lies not only in anatomical description but also in the integration of structure, function, symptoms, and treatment selection [2]. Its role as a visual biofeedback tool improves conservative treatment outcomes [22], and its ability to assist in preoperative planning and postoperative monitoring supports personalized surgical management [24].

As three-dimensional imaging, standardized protocols, and automated analysis continue to develop, pelvic floor ultrasound is likely to become even more significant in urogynecology, obstetrics, and rehabilitation. Future research should focus on:

1. Development of international standards for pelvic floor ultrasound performance and interpretation;

2. Conducting large multicenter RCTs comparing RUSI with other biofeedback methods;

3. Creation of normative databases of ultrasound parameters accounting for age, parity, and mode of delivery;

4. Investigation of long-term outcomes (beyond 5 years) in patients receiving ultrasound-guided treatment.

Given the growing evidence base, pelvic floor ultrasound should be integrated into standard diagnostic algorithms for pelvic floor dysfunction to optimize patient care and treatment outcomes [6, 21].