Pelvic floor dysfunction represents a significant clinical and social health burden, especially among women. Functional disorders such as pelvic organ prolapse (POP), urinary incontinence, and defecatory dysfunction collectively impact millions of women worldwide and substantially affect their quality of life. POP, in particular, is characterized by the descent of pelvic organs-namely, the bladder, uterus, vagina, or rectum-through the urogenital hiatus as a result of weakness or injury to the supportive musculofascial structures of the pelvic floor. The etiology of this condition is multifactorial, encompassing both intrinsic and extrinsic factors such as childbirth trauma, aging, hormonal changes, obesity, genetic predisposition, and previous pelvic surgeries. These conditions often co-exist, leading to overlapping symptoms such as incontinence, constipation, incomplete evacuation, pelvic heaviness, and dyspareunia.^[1]

The female pelvic floor consists of a complex interplay of muscular, fascial, and bony structures that maintain the static and dynamic equilibrium of pelvic viscera. The three compartments of the pelvic floor-the anterior (bladder and urethra), middle (uterus and vagina), and posterior (rectum and anal canal)-function in concert to maintain continence and pelvic organ support. Weakness in any of these compartments may result in functional disturbances that affect urination, defecation, or sexual function. The levator ani muscle group, comprising the puborectalis, pubococcygeus, and iliococcygeus, forms the dynamic foundation of the pelvic floor, while the endopelvic fascia provides essential static support through its condensations such as the uterosacral, cardinal, and pubocervical ligaments. Damage to either structure leads to pelvic floor insufficiency, resulting in the clinical manifestations of prolapse.^[2]

Conventional clinical examination often fails to detect the extent and compartmental distribution of pelvic organ prolapse. Studies have shown that clinical assessment may underestimate or misdiagnose prolapse in nearly 45-90% of patients, largely due to its inability to evaluate all compartments simultaneously. Moreover, clinical evaluation provides little information about fascial defects, muscle avulsions, or perineal descent. Traditionally, fluoroscopic techniques such as evacuation proctography and cystocolpography were considered the gold standard for assessing dynamic pelvic floor motion. However, these methods are invasive, involve ionizing radiation, are uncomfortable for patients, and visualize only one compartment at a time.^[3]

Magnetic Resonance Imaging (MRI) has emerged as the modality of choice for comprehensive pelvic floor evaluation owing to its multiplanar capability, excellent soft-tissue contrast, and noninvasive nature. Dynamic MRI, in particular, provides real-time visualization of pelvic floor motion during rest, straining, and defecation phases. The ability to image all three compartments simultaneously allows for accurate assessment of both anatomical and functional abnormalities. Additionally, MRI can depict the degree of muscular damage, fascial tearing, and perineal descent without the need for contrast administration or radiation exposure.^[4]

Pelvic organ prolapse frequently involves multiple compartments, and surgical outcomes are often compromised when all involved areas are not addressed. For example, recurrence after single-compartment surgery (e.g., colposuspension for cystocele or hysterectomy for uterine prolapse) has been reported in up to 30% of patients due to overlooked defects in other compartments. Dynamic MRI provides crucial preoperative information for comprehensive surgical planning, identifying levator ani defects, fascial discontinuities, and compartmental descent. Furthermore, it plays a valuable role in postoperative follow-up and in patients with recurrent prolapse following surgical repair.^[5]

The diagnostic parameters in dynamic MRI rely on standard anatomical reference lines such as the pubococcygeal line (PCL), the H-line, and the M-line. These measurements enable quantification of organ descent, hiatal widening, and pelvic floor relaxation. The PCL, drawn from the inferior symphysis pubis to the last coccygeal joint, serves as the principal reference. Distances of the bladder base, vaginal vault, and anorectal junction from this line are used to stage prolapse as mild, moderate, or severe. Similarly, the H-line measures the anteroposterior diameter of the levator hiatus, while the M-line measures the vertical descent of the pelvic floor relative to the PCL. Together, these metrics provide objective assessment of pelvic floor dysfunction, allowing for consistent reproducibility.^[6]

Aim

To evaluate the role of dynamic MRI in assessing pelvic floor muscles and fascial support in women with pelvic organ prolapse.

Objectives

1. To identify and localize compartmental involvement in women presenting with pelvic organ prolapse.
2. To detect and characterize muscular or fascial defects contributing to pelvic floor weakness using dynamic MRI.
3. To correlate MRI findings with clinical presentation for comprehensive assessment and surgical planning.

Source of Data

The study was conducted in the Department of Radiodiagnosis at a tertiary care hospital. Fifty female patients presenting with symptoms suggestive of pelvic organ prolapse were included. Data were obtained from both inpatients and outpatients referred for pelvic MRI evaluation.

 Study Design

A prospective, observational study was conducted.

 Study Location

Department of Radiodiagnosis at a tertiary care hospital.

 Study Duration

The study was carried out over a period of two years, from December 2017 to November 2019.

 Sample Size

A total of 50 female patients with clinically suspected pelvic organ prolapse were enrolled.

 Inclusion Criteria

• All female patients presenting with symptoms of pelvic floor weakness or organ prolapse.
• Patients referred for MRI evaluation of pelvic floor dysfunction.

 Exclusion Criteria

• Patients with contraindications to MRI (e.g., metallic implants, pacemakers, cochlear implants, defibrillators, neurostimulators).
• Claustrophobic patients.
• Pregnant women.

 Procedure and Methodology

After obtaining ethical clearance and informed consent, MRI was performed using a Philips Achieva 1.5T system equipped with a phased-array pelvic coil. Patients were instructed to empty their bladder one hour before the scan to achieve moderate filling during the examination. The rectum and vagina were filled with approximately 60 mL of ultrasound gel as required for optimal delineation of pelvic structures. Patients were positioned supine, and sequences were acquired at rest and during the Valsalva maneuver.

MRI Protocol:

• Sequences: T2-weighted images in axial, coronal, and sagittal planes.
• Dynamic single-shot fast spin-echo (SSFSE) sequences during rest and strain.
• Slice thickness: 5 mm
• Matrix size: 384 × 224
• Field of view: 140-160 mm during strain to reduce scan duration.

 Imaging Parameters Evaluated:

• Integrity of levator ani components (puborectalis, pubococcygeus, iliococcygeus).
• Visualization of endopelvic fascial condensations.
• Descent of pelvic organs relative to the pubococcygeal line.
• Measurements of the H-line and M-line for assessing hiatal widening and perineal descent.
• Assessment of cystocele, rectocele, enterocele, uterine/vault prolapse, and perineal descent.
• Urethral morphology and funneling during strain.

Each MRI was analyzed for both static (anatomical) and dynamic (functional) abnormalities. Organ descent >3 cm below the pubococcygeal line was defined as pathological.

 Sample Processing and Data Collection

All images were reviewed independently by two radiologists with experience in pelvic MRI. The degree and type of prolapse, presence of fascial or muscular defects, and involvement of specific compartments were recorded. Data were entered into a structured proforma including demographic details, clinical symptoms, and MRI findings.

 Statistical Methods

Collected data were analyzed using SPSS version 25.0. Continuous variables such as age and BMI were expressed as mean ± standard deviation, while categorical data such as type of prolapse were presented as frequencies and percentages. Comparisons between MRI findings and clinical examination were performed using chi-square or t-tests where applicable. A p-value < 0.05 was considered statistically significant.

 Ethical Considerations

The study was approved by the Institutional Ethics Committee. Written informed consent was obtained from all participants prior to the MRI examination. Confidentiality of patient data was maintained throughout.

Table 1: Baseline profile by MRI-defined prolapse status (N = 50)

Table 1 compares demographic and clinical characteristics between women with MRI-confirmed pelvic organ prolapse (n = 36) and those without prolapse (n = 14). The mean age of the prolapse group (51.6 ± 8.1 years) was significantly higher than the non-prolapse group (43.8 ± 7.6 years), with a mean difference of +7.8 years (95% CI: 3.02-12.58; p = 0.0037). Similarly, BMI was higher in women with prolapse (27.8 ± 3.2 kg/m²) compared to those without (24.9 ± 2.9 kg/m²), yielding a significant mean difference of +2.9 kg/m² (95% CI: 1.06-4.74; p = 0.0048). Parity ≥2 was strongly associated with prolapse (77.8% vs 42.9%; OR = 4.38; p = 0.017), underscoring the role of childbirth-related stress in pelvic floor weakness. Postmenopausal status was also significantly more prevalent among prolapse patients (66.7% vs 28.6%; OR = 4.57; p = 0.014), suggesting hormonal atrophy as a contributing factor. Although chronic constipation and previous pelvic surgeries were more common in prolapse cases, these differences did not reach statistical significance (p > 0.05).

Table 2: Dynamic MRI measurements & key features by prolapse status (N = 50)

Table 2 details MRI-based quantitative parameters and structural abnormalities differentiating prolapse from non-prolapse subjects. The mean H-line, representing the anteroposterior dimension of the levator hiatus, was significantly longer in the prolapse group (6.2 ± 0.7 cm) than controls (5.1 ± 0.6 cm), indicating hiatal widening (p < 0.001). Likewise, the M-line (vertical descent of the levator plate) was markedly increased (3.5 ± 0.8 cm vs 2.0 ± 0.5 cm; p < 0.001). The anorectal junction (ARJ) and bladder base descents below the pubococcygeal line were significantly greater in prolapse cases, with mean differences of +2.2 cm each (p < 0.001), confirming measurable pelvic floor relaxation. The anorectal angle also widened significantly during straining (132° ± 12° vs 119° ± 11°; p = 0.001), reflecting loss of muscular tone.

Among categorical findings, urethral funneling occurred in half the prolapse patients but only in one control (p = 0.005). Cystocele (61.1%) and rectocele (47.2%) were predominant MRI findings, while enterocele was less common (16.7%). Notably, perineal descent > 3 cm was seen in over half of the prolapse group (55.6%) compared to 7.1% of controls (p = 0.0018).

 Table 3: Compartmental involvement among women with MRI-proven prolapse (n=36)

Table 3 summarizes compartmental distribution among 36 women with MRI-diagnosed prolapse. The anterior compartment (bladder and urethra) was most frequently affected (72.2%; 95% CI: 56.0-84.2%), followed by the middle (uterovaginal/vault) compartment in 50.0% and the posterior (rectal) compartment in 41.7%. Approximately half of the patients (52.8%) demonstrated multicompartmental involvement, underscoring the importance of comprehensive imaging, as isolated single-compartment defects were observed in only 47.2%. These results highlight MRI’s ability to reveal occult multicompartmental prolapse that might be missed clinically, thereby refining surgical planning and minimizing recurrence risk.

Table 4: Agreement of MRI with clinical examination for detecting prolapse

Overall “any compartment” (N = 50): MRI+ 36, MRI- 14; Clinical+ 30, Clinical- 20; TP=28, FN=2, FP=8, TN=12

Sensitivity 93.3% (95% CI 78.7-98.2); Specificity 60.0% (95% CI 38.7-78.1);

Cohen’s κ = 0.56 (moderate agreement); McNemar test p=0.109 (NS)

Table 4 compares MRI findings with clinical assessment across all pelvic compartments. Overall, MRI demonstrated a sensitivity of 93.3% (95% CI: 78.7-98.2%) and specificity of 60.0% (95% CI: 38.7-78.1%), reflecting its high accuracy for detecting true prolapse cases. The Cohen’s κ value of 0.56 indicates moderate agreement between MRI and clinical findings, while a non-significant McNemar p = 0.109 suggests that discordance was not systematic. On a compartmental basis, sensitivity ranged between 85.7-91.7%, and specificity between 83.3-87.5%. The highest agreement was observed for anterior compartment prolapse (κ = 0.76), while slightly lower agreement was noted in the middle and posterior compartments.

Figure: ROC curve with AUC

Baseline profile (Table 1). Cohort shows significantly higher age and BMI among women with MRI-proven prolapse versus those without (Δage = +7.8 years; ΔBMI = +2.9 kg/m²), along with strong associations for multiparity (≥2) and postmenopausal status. This pattern mirrors epidemiologic evidence that advancing age, increasing parity, and menopausal transition elevate prolapse risk, while higher BMI confers additional mechanical load on the pelvic floor. Large reviews identify obesity as an independent risk factor for POP, with risk rising progressively across BMI categories. Classic risk-factor syntheses also emphasize age, parity, and menopausal status as consistent predictors across populations. Signal for constipation and prior pelvic surgery trends in the same direction but is underpowered (non-significant), which is common in single-center datasets and has been variably reported across studies. Arian A et al.(2022)^[7]

 Dynamic MRI measurements & key features (Table 2). Marked increases in H-line and M-line in the prolapse group (= +1.1 cm and +1.5 cm, respectively) indicate hiatal widening and pelvic floor descent-exactly the constructs H and M capture. Reviews and technique papers concur that the PCL-referenced H- and M-lines are simple, reproducible metrics that expand with POP, with normal thresholds around H ≤5 cm and M ≤2 cm. Quantitative differences in organ descent (ARJ and bladder base = +2.2 cm each below PCL) dovetail with MR defecography literature using the “rule of 3s” (0-3 cm mild; 3-6 cm moderate; >6 cm severe) for grading descent relative to the PCL. The anorectal angle widening observe (particularly on strain) is physiologically plausible and aligns with reference values showing 100° at rest and 120° during evacuation in normal subjects, increasing further when pelvic support is compromised. Li X et al.(2025)^[8]

On categorical features, Data show substantially higher odds of urethral funneling, cystocele, rectocele, and perineal descent >3 cm among prolapse cases. Prior imaging studies confirm dynamic MRI’s ability to depict urethral hypermobility/funneling and anterior compartment defects, with good diagnostic performance in these domains. The predominance of anterior compartment abnormalities and robust H/M-line separation found are consistent with contemporary reviews and practice articles on dynamic pelvic floor MRI. Egorov V et al.(2022)^[9]

 Compartmental involvement (Table 3). In women with MRI-proven prolapse, report anterior involvement in 72%, middle in 50%, and posterior in 42%; over half show multicompartment disease. This matches multidisciplinary POP literature: multicompartment involvement is common and clinically important because repair of only one compartment risks recurrence if coexisting defects are missed. Cross-specialty reviews of multicompartment POP similarly note frequent co-occurrence-especially anterior with apical disease-and advocate comprehensive imaging to map the full defect burden before surgery. Dynamic MRI’s whole-pelvis perspective has been repeatedly highlighted as advantageous for delineating combined or occult defects that may be underestimated on clinical exam alone. Barba M et al.(2024)^[10]

 MRI vs clinical examination (Table 4). Overall sensitivity of 93% and specificity of 60% (κ=0.56; non-significant McNemar) indicate that MRI captures most true prolapse while flagging additional, clinically occult defects-especially anterior compartment changes-leading to moderate agreement and some “MRI-only” positives. Prior comparative studies find the best MRI-to-clinical agreement for cystoceles, with somewhat lower concordance for apical/posterior compartments, and minimal impact of using different reference lines (PCL vs MPL) for grading descent. Method papers also show that the exact PCL placement can influence measured magnitudes of descent and hiatal dimensions, which partly explains interstudy variability, but not the directionality observed (MRI consistently reveals more). Vijay K et al.(2023)^[11] & Tim S et al.(2021)^[12]

Dynamic MRI proved to be an excellent non-invasive diagnostic modality for evaluating pelvic floor muscles and fascial support in women with pelvic organ prolapse. The study demonstrated that MRI not only provides precise visualization of the levator ani complex and endopelvic fascia but also quantifies functional descent of pelvic organs across all compartments during strain. The findings confirmed that increasing age, higher BMI, multiparity, and menopausal status are key risk factors for prolapse. MRI parameters such as increased H-line, M-line, and organ descent below the pubococcygeal line correlated strongly with the degree of prolapse, while multicompartmental involvement was common. The technique showed high sensitivity and moderate agreement with clinical examination, often detecting additional, clinically occult defects. Hence, dynamic MRI serves as a comprehensive tool for diagnosis, staging, and preoperative planning, enabling individualized surgical management and reducing recurrence rates of pelvic organ prolapse.

1. The study was conducted on a relatively small sample size (n = 50), which may limit the generalizability of the findings to larger populations.
2. Being a single-center study, variations in patient demographics and scanner protocols across institutions were not represented.
3. Supine positioning during MRI may underestimate the degree of prolapse compared to upright gravity-assisted evaluation.
4. Dynamic MRI requires patient cooperation during the straining phase, which could lead to underestimation of organ descent in uncooperative subjects.
5. Lack of postoperative follow-up imaging prevented assessment of MRI’s role in predicting surgical outcomes or recurrence.
6. The absence of correlation with validated symptom severity or quality-of-life scores limited the functional interpretation of imaging findings.
7. MRI was compared only with clinical examination and not with fluoroscopic defecography, which remains a traditional dynamic gold standard.
8. Cost, limited availability, and longer scan times may restrict MRI use in routine prolapse assessment, particularly in resource-limited settings.

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