• correct (inward movement of the catheter);
• no contraction (no movement);
• straining (outward movement).
No studies have been found evaluating the responsiveness of visual observation.
Devreese developed an inspection scale for the PFM and abdominal muscles to be used in crook lying, sitting and standing position. Contractions were inspected during both voluntary contraction and reflex contraction during coughing. They classified the contraction of the PFM as either ‘coordinated’ (inward movement of 1 cm of the perineum and a visible contraction of the deep abdominal muscle) or ‘not coordinated’ (downward movement of the pelvic floor and/or an outward movement of the abdominal wall. The results of inter-tester reliability showed kappa coefficients between 0.94 and 0.97.
Shull stated that by visual observation one is generally observing superficial perineal muscles. From this observation researchers assume that the levator ani is responding similarly. It may, however, not be the case. Observing the inward movement of a correct PFM contraction is the starting point for measurement of PFM function, and has the advantage of being a simple, noninvasive method. However, the inward lift may be created by contraction of superficial muscle layers only, and have no influence on urethral closure mechanism. Conversely, there may be palpable PFM contraction with no visible outside movement. A correct lift can be difficult to observe from the outside, particularly in obese women. Also it is questionable whether it is possible to grade cm of inward movement from the outside of the body. In the future ultrasound may take over the role of visual observation, and would also serve as a biofeedback and teaching tool Whether the muscle action observed by visual observation or ultrasound is sufficiently strong to increase urethral closure pressure can only be measured by urodynamic assessment in the urethra and bladder. Interestingly Bump found that, although contracting correctly, only 50% of a population of continent and incontinent women were able to voluntarily contract the PFM with enough force to increase urethral pressure.
Devreese used observation scores of coordinated contractions during PFM contraction and coughing, and compared continent and incontinent women with blinded investigators. The results showed that continent women exhibited significantly better coordination between the pelvic floor and lower abdominal muscles during coughing in all three positions (crook lying sitting and standing).
Visual observation can be used in clinical practice to give a first impression about ability to contract. Further estimation about the amount of the inward movement is not recommended. Visual observation should not be used for scientific purposes because MRI and ultrasound are more responsive, reliable and valid methods to assess movement during contraction, straining and physical exertion.