Which of the following is a mechanical dilation method?

The Foley catheter is recognized as a mechanical dilation method primarily used for cervical ripening and the induction of labor. This device consists of a flexible tube that is inserted into the cervical canal. Once positioned, the balloon portion of the catheter is inflated with sterile fluid, which exerts pressure on the cervix. This mechanical pressure can help to stimulate the release of prostaglandins and promote cervical dilation.

In contrast, oxytocin infusion is a pharmacologic approach that works by stimulating uterine contractions but does not mechanically expand the cervix. Amniotomy, or artificial rupture of membranes, while sometimes facilitating labor progress, does not mechanically dilate the cervix either but can be used to augment labor after cervical dilation has begun. Laboratory testing has no relevance in the context of cervical dilation methods, as it does not affect the cervix physically or mechanically. Thus, the Foley catheter stands out as the method that directly involves mechanical dilation of the cervix.