Pelvic floor morphology in nulliparous women on magnetic resonance imaging
IUGA Academy. Krcmar M. Jun 30, 2018; 212946; 448
Michal Krcmar
Michal Krcmar

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Pelvic floor morphology in nulliparous women on magnetic resonance imaging

Krcmar, M1; Krofta, L1; Feyereisl, J1; Urbankova, I1; Grohregin, K1

1: Institute for the care of mother and child

Introduction: MRI is an excellent tool for describing the key structures of female pelvic floor.

Objective: This study aims to describe the physiological variability of the pelvis, levator ani muscle and obturator muscle in healthy nulliparous women.

Methods: Twenty-four healthy nulliparous women with normal pelvic organ support were recruited to undergo a 3T magnetic resonance imaging (MRI) of the pelvis and pelvic floor. MRI scans were performed in all three projections (slice thickness 2mm, inter-slice gap 0mm) and a dynamic midsagittal scan during the Valsalva maneuver plane. Axial and sagittal scans and dynamic sequence were evaluated by two independent researchers. In the axial scans, anatomy was evaluated in two parallel planes; (1) at the plane of the inferior pubic ligament that corresponds to the mid-urethra (pL1), and (2) at the plane defined by the bladder base (pL2). Following biometricparameters were measured: urogenital hiatus dimensions (anteroposterior dimension, width), the distance between the urethra and puborectal muscle insertion (urethral gap, UG), levator ani muscle thickness (pubovisceral muscle complex and iliococcygeal muscle, respectively), the internal obturator muscle thickness (only at pL2). Also, the distance between pL1 and pL2 was measured. Axial scans were also used to measure the pelvic bones biometry including the sacrococcygeal-inferior pubic point distance (SCIPP), the bi-spinal and bi-tuber diameter. In dynamic sequences measurements were done at the rest and at the maximal Valsalva maneuver. We measured the distance between the posterior aspect of the uterine cervix and the sacrococcygeal connection, the levator plate angle, and the sacrouterine angle, which was defined as an angle between the SCIPP line and connection between th sacrococcygeal connection and the posterior aspect of the uterine cervix. The difference between left- and rightsided measurements was compared with a paired T-test (SPSS®, ver. 19).

Results: The mean age and BMI were 27.5years ±3.3 (22, 34) and 22.6kg/m2±2.0 (18.8, 26.3), respectively. There were no differences in the left and right sided structures (i.e. levator ani, obturator muscle). All data showed normal distribution, thus they are reported as mean ± standard deviation, and range. At pL1: urethral gap 14.00mm ±2.5 (10; 19), pubovisceral muscle-complex thickness 8.1mm ±1.6 (4; 11). At pL2: iliococcygeal muscle thickness 4.6mm ±1.7 (1, 10), obturator muscle thickness 17.6mm ±3.9 (11, 26). The average distance between pL1 and pL2 was 21.5mm ±5.0 (12, 30). The bony pelvis dimensions: bispinal diameter 109.2mm ±8.9 (96, 128), bi-tuber distance 128.2mm ±10.4 (109, 149), SCIPP 115.9mm ±25.7 (97.0, 146.0), and the interpubic angle 86.3° ±8.9 (96, 128). Dynamic midsagittal sequences: the sacrococcygeal-uterine cervix distance at the rest 55.0mm ±15.2 (29, 92) and at the Valsalva 49.4mm ±10.6 (33, 75); the levator plate angle at relaxation 21.5° ±7.1 (11.3, 39) and at Valsalva 34.7° ±10.4 (14.2, 52.3); the sacro-uterine angle at relaxation 30.5° ±9.3 (14.3, 50.1) and at Valsalva 19.2° ±12.7 (-8.6, 41.2).

Conclusions: MRI is a suitable modality to analyse in vivo normal anatomy variations. In healthy nulliparous women the variability of MLA subdivisions is low.


Work supported by industry: no.

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