Grading pelvic prolapse and pelvic floor relaxation using dynamic magnetic resonance imaging.

OBJECTIVES With significant vaginal prolapse, it is often difficult to differentiate among cystocele, enterocele, and high rectocele by physical examination alone. Our group has previously demonstrated the utility of magnetic resonance imaging (MRI) for evaluating pelvic prolapse. We describe a simple objective grading system for quantifying pelvic floor relaxation and prolapse. METHODS One hundred sixty-four consecutive women presenting with pelvic pain (n = 39) or organ prolapse (n = 125) underwent dynamic MRI. The "H-line" (levator hiatus) measures the distance from the pubis to the posterior anal canal. The "M-line" (muscular pelvic floor relaxation) measures the descent of the levator plate from the pubococcygeal line. The "O" classification (organ prolapse) characterizes the degree of visceral prolapse beyond the H-line. RESULTS The image acquisition time was 2.5 minutes per study. Each study cost $540. In the pain group, the H-line averaged 5.2 +/- 1.1 cm versus 7.5 +/- 1.5 cm in the prolapse group (P <0.001). The M-line averaged 1.9 +/- 1.2 cm in the pain group versus 4.1 +/- 1.5 cm in the prolapse group (P <0.001). Incidental pelvic pathologic features were commonly noted, including uterine fibroids, ovarian cysts, hydroureter, urethral diverticula, and foreign body. CONCLUSIONS The HMO classification provides a straightforward and reproducible method for staging and quantifying pelvic floor relaxation and visceral prolapse. Dynamic MRI requires no patient preparation and is ideal for the objective evaluation and follow-up of patients with pelvic prolapse and pelvic floor relaxation. MRI obviates the need for cystourethrography, pelvic ultrasound, or intravenous urography and has become the study of choice at our institution for evaluating the female pelvis.