Prompt delivery may at times become necessary when the small occipital fontanel is directed toward one of the sacroiliac synchondroses. In these right OP (ROP) or left OP (LOP) positions, the fetal head is often imperfectly lexed. With OP positions, second-stage labor can be lengthened. In these cases, the head may spontaneously deliver OP, may be manually or instrumentally rotated to an OA position, or may be delivered OP by forceps or vacuum.
With manual rotation, an open hand is inserted into the vagina. The palm straddles the sagittal suture of the fetal head. The operator's ingers wrap around one side of the fetal face and thumb extends along the other side. If the occiput is ROP, rotation is clockwise to bring it to an ROA or OA position (Fig. 29-12).
/�(, _A.V\..IA...._ ./�...._/' B FIGURE 29-12 A. Manual rotation using the left hand, palm-up, to rotate from ROP. B. The head is flexed and destationed during clockwise rotation to reach an OA pOSition. (Reproduced with permission from Yeomans ER: Operative vaginal delivery. In Yeomans ER, Hofman BL, Gilstrap LC III, et al (eds): Cunningham and Gilstrap's Operative Obstetrics, 3rd ed. New York, McGraw-Hili Education, 201o7.)
FIGURE 29-14 Kielland forceps. The characteristic features are minimal pelvic curvature (A), sliding lock (8), and light weight.
With LOr position, rotation is counterclockwise. hree actions are performed simultaneously between contractions. The irst is fetal head flexion to provide a smaller diameter for rotation and subsequent descent. Second, slight destationing of the fetal head moves the head to a level in the maternal pelvis with sufficient room to complete the rotation. Importantly, destationing should not be confused with disengaging the fetal head, which is proscribed. Concurrently, some prefer to also place the other hand externally on the corresponding side of the maternal abdomen to pull the fetal back up toward the midline in synchrony with the internal rotation. Le Ray and colleagues (2007, 2013) reported a success rate of greater than 90 percent with manual rotation. Barth (2015) provides an excellent summary of this technique.
Manual rotations are most easily completed in multiparas. If manual rotation cannot be easily accomplished, application of forceps blades to the head in the posterior position and delivery from an or position may be the safest procedure. In many cases, the cause of a persistent or position and of the diiculty in accomplishing rotation is an anthropoid pelvis. his architecture opposes rotation and predisposes to posterior delivery (Fig. 2-17, p. 31).
With forceps delivery from an or position, downward and outward traction is applied until the base of the nose passes under the symphysis (Fig. 29-13). he handles are then slowly elevated until the occiput gradually emerges over the upper margin of the perineum. he forceps are directed downward again, and the nose, mouth, and chin successively emerge from the vulva.
or delivery causes greater distention of the vulva, and a large episiotomy may be needed. or deliveries have a higher incidence of severe perineal lacerations and extensive episiotomy compared with OA positions (de Leeuw, 2008; Pearl, 1993). Also, newborns delivered from or positions have a higher incidence ofErb and facial nerve palsies, 1 and 2 percent, respectively, than those delivered from OA positions. As expected, rotations to OA ultimately decrease perineal delivery trauma (Bradley, 2013).
Last, for forceps rotations from an or to OA position, the Kielland instruments are preferred because they have a less pronounced pelvic curve (Fig. 29-14). Cunningham and Gilstrapis
FIGURE 29-13 Outlet forceps delivery from an OP position. The head should be flexed ater the bregma passes under the symphysis.