In shoulder presentations, the acromion (scapula) is the portion of the fetus arbitrarily chosen for orientation with the maternal pelvis. One example of the terminology sometimes employed for this purpose is illustrated in Figure 22-7. The acromion or back of the fetus may be directed either posteriorly or anteriorly and superiorly or inferiorly. Because it is impossible to diferentiate exactly the several varieties of shoulder presentation by clinical examination and because such speciic diferentiation serves no practical purpose, it is customary
FIGURE 22-3 Longitudinal lie. Vertex presentation. A. Right occiput posterior (RaP). B. Right occiput transverse (Ran.
to refer to all transverse lies simply as shoulder presentations. Another term used is transverse lie, with back up or back down, which is clinically important when deciding incision type for cesarean delivery (Chap. 23, p. 453) .
Several methods can be used to diagnose fetal presentation and position. Abdominal examination can be conducted systematically employing the four maneuvers described by Leopold in 1894 and shown in Figure 22-8. he mother lies supine and comfortably positioned with her abdomen bared. hese maneuvers may be diicult if not impossible to perform and interpret if the patient is obese, if amnionic luid volume is excessive, or if the placenta is anteriorly implanted.
he irst maneuver assesses the uterine fundus. It permits identification of fetal lie and determination of which fetal pole-that is, cephalic or podalic-occupies the fundus. he breech gives the sensation of a large, nodular mass, whereas the head feels hard and round and is more mobile.
he second maneuver is accomplished as the palms are placed on either side of the maternal abdomen, and gentle but deep pressure is exerted. On one side, a hard, resistant structure is felt-the back. On the other, numerous small, irregular, mobile parts are felt-the fetal extremities. By noting whether anterior (ROA). orientation can be determined.
FIGURE 22-4 Longitudinal lie. Vertex presentation. Right occiput the back is directed anteriorly, transversely, or posteriorly, fetal
FIGURE 22-5 Longitudinal lie. Face presentation. Left and right mentum anterior and right mentum posterior positions.
FIGURE 22-6 Longitudinal lie. Breech presentation. Left sacrum FIGURE 22-7 Transverse lie. Right acromiodorsoposterior (RADP). The posterior (LSP). shoulder of the fetus is to the mother's right, and the back is posterior.
and colleagues (1993), experienced clinicians have accurately identified fetal malpresentation using Leopold maneuvers with a high sensitivity-88 percent, speciicity-94 percent, positive-predictive value-74 percent, and negative-predictivevalue-97 percent. With experience, it is possible to estimate the size of the fetus with these maneuvers (Field, 1995). However, and especially with an obese woman, estimates by palpation and actual birth weights often correlate poorly (Fox, 2009; Goetzinger, 2014; Noumi, 2005).
Before labor, the diagnosis of fetal presentation and position by vaginal examination is often inconclusive because the presenting part must be palpated through a closed cervix and lower uterine segment. With the onset of labor and after cervical dila tion, vertex presentations and their positions are recognized by palpation of the various fetal sutures and fontanels. Face and breech presentations are identiied by palpation of facial features or the fetal sacrum and perineum, respectively. During this vaginal examination, it is advis able to pursue a deinite routine, comprising four movements. First, the examiner inserts two fingers into the vagina and the presenting part is found. Diferentiation of vertex, FIGURE 22-8 Leopold maneuvers (A-D) performed in fetus with a longitudinal lie in the left face, and breech is then accomocciput anterior position (LOA).