Your patient has had a long, slow labor, with pain predominantly in her back (the infamous "back labor"). She is now fully dilated and the head has progressed well into the pelvis, but it is not crowning, and you find that the patient's exam is notable for right occiput posterior (OP) position. The patient is exhausted. She has tried a number of physical maneuvers and labor positions with minimal progress. Manual rotation of the head was unsuccessful. The choice at this point is to move to a cesarean delivery or to try a Scanzoni rotation to turn the head with forceps with physicians aiding the rotation abdominally. A cesarean delivery is less desirable in this case as the head is wedged down deep in the pelvis.
The Scanzoni maneuver was invented by Friedrich Wilhelm Scanzoni, a German obstetrician, in 1849. His method for changing a posterior presentation into an anterior one required the use of forceps twice in the process of delivery.1
OP positions are the most common type of malposition, cited to comprise between 1% and 5%.2 They are often accompanied by some degree of deflexion, resulting in a larger presenting diameter. The presence of asynclitism and molding can make it difficult to correctly determine position, leading to an inaccurate diagnosis of occiput anterior (Figure 1). Risk factors for OP position include smaller pelvic outlet capacity, prior OP, nulliparity, maternal age >35, gestational age ≥41 weeks, birth weight >4000 g, artificial rupture of the membranes (AROM), and epidural anesthesia.3 OP position as a cause for persistent labor dystocia can be corrected using the Scanzoni method, allowing successful vaginal delivery.
All illustrations by Alex Baker, DNA Illustrations, Inc.