It is better to use smaller forceps and take smaller amounts of tissue each time than to deliver fetal parts intact while traumatizing the cervix… At 16 to 17 weeks, fetal tissue is much more easily identifiable with the forceps and in some ways is easier to grasp and remove than in earlier gestations. The [skull] is about the size of a Ping-Pong ball and usually can be grasped readily with the Bierer. Collapsing it gives a definite sensation… At 18-19 menstrual weeks… fetal parts are significantly larger and more difficult to morcellate (tear into pieces)… [Abortion after the] 20-week gestation… can be a significantly more difficult procedure accompanied by unnerving hemorrhage. Forceps use must be sure and relatively rapid. There is frequently not much time for exploring the nuances of different tissue sensations. Grasping and collapsing the [skull is] often difficult. Stripping the [skull] of soft tissue is sometimes the first step in successful delivery of this part, followed by dislocation of parietal bones. In this case, care must be taken in removal because ossification is occurring and the edges are sharp… Regardless of the amount of dilatation, delivery of the [skull] and pelvis is sometimes difficult… The advantage obtained by having a softened cervix could become a disaster if a laceration develops at the level of the internal os as the result of too much force… The procedure changes significantly at 21 weeks because the fetal tissues become much more cohesive and difficult to dismember. This problem is accentuated by the fact that the fetal pelvis may be as much as 5 cm in width… [The skull] can be collapsed. Other structures, such as the pelvis, present more difficulty… A long curved Mayo scissors may be necessary to decapitate and dismember the fetus, since it may be impossible to apply forceps or to do so while avoiding the thinned-out cervix.
— Warren Hern, Late-Term Abortionist