Impact of Ring Pessary on Pelvic Anatomy in Upright Position: Insights from Prospective Upright MRI Study

Highlight

• Ring pessary insertion elevates the bladder and cervix relative to pelvic inclination line in women with pelvic organ prolapse (POP).
• Upright MRI reveals immediate anatomical changes, with persistent uterine elevation one week post-insertion but diminished bladder lift.
• Changes in uterine angulation suggest a biomechanical role of pessaries in symptom relief of POP through uterine support.
• Quantitative imaging offers objective metrics to understand pessary function and optimize clinical management of prolapse.

Study Background

Pelvic organ prolapse (POP) is a common condition affecting women, characterized by descent of pelvic organs such as the bladder, uterus, or rectum through the vaginal canal resulting from defects in pelvic support structures. Symptoms often include pelvic pressure, urinary incontinence, and sexual dysfunction, significantly impacting quality of life. Conservative management frequently involves the use of vaginal pessaries — devices inserted into the vagina to support descending organs. Despite widespread clinical use, the precise anatomical effect of pessaries, particularly in physiological weight-bearing positions, remains insufficiently characterized. Understanding the biomechanical and positional changes induced by pessary use is critical to optimizing patient selection, improving symptom relief, and guiding clinical decisions such as timing for surgical intervention.

Study Design

This study was a prospective observational cohort conducted in an outpatient gynecology clinic. Fifteen women with diagnosed POP and successful prior use of a ring-shaped pessary were enrolled. The study utilized upright magnetic resonance imaging (MRI) — allowing visualization of pelvic anatomy in weight-bearing positions — to assess anatomical changes before pessary insertion, immediately after insertion, and one week later. Key pelvic landmarks including the lowest points of the bladder, cervix, and pessary were measured against the pelvic inclination correction system (PICS) line, a standardized reference in pelvic MRI imaging. Additionally, angular measurements of the uterus and pessary relative to the PICS line were examined in the midsagittal plane. This approach enabled three-dimensional dynamic assessment of pelvic organ displacement induced by pessaries under near-physiological conditions.

Key Findings

The study revealed several significant anatomical changes following pessary insertion. The bladder’s lowest point was initially positioned 0.1 cm below the PICS line but was elevated to 0.6 cm above immediately post-insertion (p = 0.015), indicating a modest but statistically significant lift. However, this effect diminished after one week, with the bladder remaining only 0.2 cm above PICS (p = 0.334 compared to baseline), suggesting some loss of initial elevation over time.

In contrast, the cervix demonstrated a more pronounced and sustained elevation. From baseline at the PICS line (0.0 cm), the cervix was lifted 2.5 cm above immediately after pessary insertion, a highly significant change (p < 0.001) that persisted at one week (p = 0.470 for difference between immediate and 1-week post-insertion). This indicates the pessary provides stable uterine support over time.

Angular analysis showed the uterus shifted from 97° relative to PICS at baseline to 115° after pessary insertion (p = 0.008), with this increased angulation maintained at 113° after one week (p = 0.198), further supporting a persistent change in uterine positioning secondary to pessary placement. The pessary’s own position relative to PICS shifted closer to the line over one week (from 0.7 cm below to 0.3 cm below, p = 0.020), but its angulation remained stable (56° to 54°, p = 0.820).

These findings collectively suggest that pessaries provide mechanical elevation and reorientation of the POP-affected organs, most notably the uterus, which may account for symptomatic improvements noted clinically.

Expert Commentary

This study leverages upright MRI, an advanced imaging modality that approximates physiological conditions better than traditional supine imaging, to provide compelling evidence of the biomechanical effects of ring pessaries in POP management. The differential retention of bladder lift versus sustained uterine elevation may explain variability in symptom relief, particularly discrepancies between urinary and pelvic pressure symptoms.

Limitations include the small sample size and single pessary type evaluated, which may restrict generalizability. Additionally, outcomes were limited to anatomical parameters; correlation with symptom scores or functional outcomes would enhance clinical relevance. Nonetheless, these data corroborate the mechanical rationale for pessary use, highlighting that uterine support seems crucial in prolapse symptom mitigation.

Future studies could explore larger cohorts, other pessary designs, and longer-term effects, alongside patient-reported outcomes to optimize tailored therapy. Integrating dynamic imaging with symptomatic evaluation represents a promising avenue for refining conservative management strategies.

Conclusion

Insertion of a ring pessary in women with POP induces significant anatomical repositioning of pelvic organs in the upright position, with a pronounced and sustained lift and angulation of the uterus and a transient elevation of the bladder. These mechanical changes provide a plausible mechanism for symptom alleviation, particularly through uterine support. Upright MRI offers a valuable tool for objectively assessing pessary effects and may guide personalized management and future device development in pelvic floor disorders.

Funding and ClinicalTrials.gov

The original study details regarding funding sources were not provided. No clinical trial registration number was cited.

References

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