Within the evaluation process for pelvic muscle health, a woman is often asked to "bear down" so that the examiner can assess muscle coordination. This maneuver is also utilized during assessment for prolapse or pelvic organ descent. Clinically, the patient's ability to perform a lengthening or bearing down is quite varied, depending upon many factors such as levator plate resting position, strength and coordination, childbearing status, and comfort with the maneuver. What are the implications of not being able to bear down? An interesting study published in 2007 concluded that women, when asked to perform a Valsalva maneuver (a forced expiration against a closed glottis), frequently co-contracted the levator ani muscles.
Participants included 50 nulliparous women between 36-38 weeks gestation and they were assessed with translabial 3D/4D ultrasound following emptying of the bladder. In almost half of the subjects, a pelvic floor muscle contraction was noted during the attempted Valsalva. Patients were provided with visual biofeedback to train the levator muscles to avoid a concurrent contraction, and despite the training, 11 of the 50 women were still unable to avoid a co-activation. (Keep in mind that for purposes of assessment, the prolapse would be best imaged or viewed if the levator muscles were not tightening.) For this reason, the study concludes that levator muscle co-activation is a significant confounder of pelvic organ descent. While a contraction of the pelvic floor muscles may be a positive, protective action when thoracic pressure is increased, a woman's degree of prolapse or pelvic organ descent may appear diminished during an examination. The authors of the study conclude that a clinician may have a false-negative finding for prolapse in the presence of strong, intact pubovisceral muscles.