Three Dimensional Transperineal Ultrasonography of the Pelvic Floor

Abstract

: Ultrasound images have replaced conventional radiology as the modality of choice for imaging the female patients with voiding dysfunction and evaluation of pelvic floor function. Transvaginal, introital, and perineal ultrasound can all be performed with 3D and Doppler options. Recommended bladder filling to ensure reliability and reproducibility of obtained data is about 300 ml. Urethral funneling is more pronounced in an appropriately filled bladder. Prolapse is less apparent when pressing with a full bladder than with a partially filled bladder. 3D ultrasound sectional images are replacing MRI because of an equivalent resolution and the added advantage of ease of utility, dynamic display, and vascular display. Once the midsagittal view of the pelvic floor is obtained, the patient can be asked to strain, and a cine loop of the action can be recorded, allowing relative organ position changes to be assessed. The major muscle of the pelvic floor is the levator ani. The muscle complex spans the space between the obturator internus muscle laterally, the pubis symphysis anteriorly and the coccyx posteriorly. Levator ani muscles support the pelvic floor and counteract the pressure by contracting and creating a circular closing of the levator hiatus and an upward movement of the pelvic floor and perineum. The indices for evaluation of anterior compartment are H (distance between the bladder neck and a line through the lower edge of the pubic symphysis) and B (posterior urethrovesical angle). These indices are determined at rest, during the Valsalva maneuver, and during pelvic floor contraction. Normal range of H is 20.6 mm at rest and 14.0 mm during strain. Normal posterior urethrovesical angle is 96.8 at rest and 108.1during strain. The posterior compartment elements (internal sphincter, external sphincter, and longitudinal muscles) also can be evaluated with sonography. Four ultrasonographic signs of sphincter damage include thickening of the ES at the 12-oclock position, thinning of the IS in the area of rupture with thickening opposite the rupture site (the half-moon sign), IS/ES discontinuity and abnormality of the mucous folds.