By noting whether the back is directed anteriorly, transversely, or posteriorly, the orientation of the fetus can be determinedģ. On the other, numerous small, irregular, mobile parts are felt-the fetal extremities. On one side, a hard, resistant structure is felt-the back. Performed after determination of fetal lie, the second maneuver is accomplisheĭ as the palms are placed on either side of the maternal abdomen, and gentle but deep pressure is exerted. The breech gives the sensation of a large, nodular mass, whereas the head feels hard and round and is more mobile and ballottableĢ. The first maneuver permits identification of which fetal pole-that is, cephalic or podalic-occupies the uterine fundus. These maneuvers may be difficult if not impossible to perform and interpret if the patient is obese, if there is excessive amnionic fluid, or if the placenta is anteriorly implanted.ġ. The mother lies supine and comfortably positioned with her abdomen bared. Occasionally plain radiographs, computed tomography, or magnetic resonance imaging may be used.Ībdominal examination can be conducted systematically employing the four maneuvers described by Leopold in 1894 and shown in Figure 17-8. These include abdominal palpation, vaginal examination, auscultation, and, in certain doubtful cases, sonography. Several methods can be used to diagnose fetal presentation and position. The high incidence of breech presentation in hydrocephalic fetuses is in accord with this theory, because in this circumstance, the fetal cephalic pole is larger than its podalic pole.ĭiagnosis of Fetal Presentation and Position It is approximately 25 percent at 28 weeks, 17 percent at 30 weeks, 11 percent at 32 weeks, and then decreases to approximately 3 percent at term. 24-1), the incidence of breech presentation decreases with gestational age. If presenting by the breech, the fetus often changes polarity to make use of the roomier fundus for its bulkier and more mobile podalic pole. As a result, the uterine walls are apposed more closely to the fetal parts. Subsequently, however, the ratio of amnionic fluid volume decreases relative to the increasing fetal mass. Until approximately 32 weeks, the amnionic cavity is large compared with the fetal mass, and there is no crowding of the fetus by the uterine walls. The cephalic pole is composed of the fetal head only. Although the fetal head at term is slightly larger than the breech, the entire podalic pole of the fetus-that is, the breech and its flexed extremities-is bulkier and more mobile than the cephalic pole. The term fetus usually presents with the vertex, most logically because the uterus is piriform or pear shaped. As labor progresses, sinciput and brow presentations almost always convert into vertex or face presentations by neck flexion or extension, respectively. These latter two presentations are usually transient. The fetal head may assume a position between these extremes, partially flexed in some cases, with the anterior (large) fontanel, or bregma, presenting- sinciput presentation- or partially extended in other cases, to have a brow presentation (see Fig. Much less commonly, the fetal neck may be sharply extended so that the occiput and back come in contact, and the face is foremost in the birth canal- face presentation (see Fig. The occipital fontanel is the presenting part, and this presentation is referred to as a vertex or occiput presentation. Ordinarily, the head is flexed sharply so that the chin is in contact with the thorax. Such presentations are classified according to the relationship between the head and body of the fetus (Fig.
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