Normal Labor Flashcards
At the onset of labor, the position of the fetus with respect to the birth canal is critical to the route of delivery and thus should be determined in early labor. Important relationships include_______________________________.
fetal lie,
presentation,
attitude,
and position.
“FPAP”
The relation of the fetal long axis to that of the mother is termed ________and is either longitudinal or transverse.
Fetal Lie
The relation of the fetal long axis to that of the mother is termed fetal lie and is either______________
longitudinal or transverse.
Occasionally, the fetal and the maternal axes may cross at a 45-degree angle, forming an _________ This lie is unstable and becomes longitudinal or transverse during labor.
oblique lie.
A _____________ is present in more than 99 percent of labors at term.
longitudinal lie
Predisposing factors for transverse fetal position include ________________(Chap. 23, p. 468).
multiparity,
placenta previa,
hydramnios, and
uterine anomalies
“HUMP”
The __________ is that portion of the fetal body that is either foremost within the birth canal or in closest proximity to it.
It typically can be felt through the cervix on vaginal examination.
Fetal Presentation
Accordingly, in___________, the presenting part is either the fetal head or breech, creating cephalic and breech presentations, respectively.
longitudinal lies
When the fetus lies with the long axis transversely, the______________ is the presenting part. Table 22-1 describes the incidences of the various fetal presentations.
shoulder
Cephalic Presentation
Such presentations are classified according to the relationship between the head and body of the fetus (Fig. 22-1). Ordinarily, the head is flexed sharply so that the chin is in contact with the thorax. The occipital fontanel is the presenting part, and this presentation is referred to as a______________
vertex or occiput presentation.
less commonly, the fetal neck may be sharply extended so that
the occiput and back come in contact,and theface is foremost
in the birth canal—__________ (Fig. 23-6, p. 466).
face presentation
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_________ (Fig. 23-8, p. 468).
brow presentation
These latter two presentations are usually__________.
As labor progresses, sinciput and brow presentations almost always convert into vertex or face presentations by neck flexion or extension, respectively. Failure to do so can lead to dystocia, as discussed in Chapter 23 (p. 455).
transient
The term fetus usually presents with the vertex, most logically
_______________.
because the uterus is piriform or pear shaped
Although the fetal head at term is slightly larger than the breech, the entire podalic pole of the fetus—that is, the _________________—is bulkier and more mobile than the cephalic pole.
breech and its flexed extremities
The____________ is composed of the fetal head only. Until approximately 32 weeks, the amnionic cavity is large compared with the fetal mass, and the fetus is not crowded by the uterine walls. Subsequently, however, the ratio of amnionic fluid volume decreases relative to the increasing fetal mass. As a result, the uterine walls are apposed more closely to the fetal parts.
cephalic pole
If ____________, the fetus often changes polarity to make use of the roomier fundus for its bulkier and more mobile podalic pole. As discussed in Chapter 28 (p. 559), the incidence of breech presentation decreases with gestational age. It approximates 25 percent at 28 weeks, 17 percent at 30 weeks, 11 percent at 32 weeks, and then decreases to approximately
3 percent at term.
presenting by the breech
The high incidence of breech presentation in
hydrocephalic fetuses is in accord with this theory, as the larger
fetal cephalic pole requires more room than its podalic pole.
Breech Presentation
When the fetus presents as a breech, the three general configurations are_____________and are described in Chapter 28 (p. 559).
NOTE :
Breech presentation may result from circumstances that prevent normal version from taking place. One example is a septum that protrudes into the uterine cavity (Chap. 3, p. 42). A peculiarity of fetal attitude, particularly extension of the vertebral column as seen in frank breeches, also may prevent the fetus from turning.
If the placenta is implanted in the lower uterine segment, it may distort normal intrauterine anatomy and result in a breech presentation.
frank, complete, and footling presentations
■ Fetal Attitude or Posture
In the later months of pregnancy, the fetus assumes a characteristic posture described as attitude or habitus as shown in Figure 22-1. As a rule, the fetus forms an ovoid mass that corresponds roughly to the shape of the uterine cavity. The fetus becomes folded or bent upon itself in such a manner that the back becomes markedly convex; the head is sharply flexed so that the chin is almost in contact with the chest; the thighs are flexed over the abdomen; and the legs are bent at the knees.
In all cephalic presentations, the arms are usually crossed over the thorax or become parallel to the sides.
The umbilical cord lies in the space between them and the lower extremities. This characteristic posture results from the mode of fetal growth and its accommodation to the uterine cavity.
Abnormal exceptions to this attitude occur as the ____________ from the vertex to the face presentation (see Fig. 22-1). This results in a progressive change in fetal attitude from a convex (flexed) to a concave (extended) contour of the vertebral column.
fetal head becomes progressively more extended
■ ___________________ refers to the relationship of an arbitrarily chosen portion of the fetal presenting part to the right or left side of the birth canal.
Accordingly, with each presentation there may be two positions—right or left.
Fetal Position Position
The________________________ are the determining points in vertex, face, and breech presentations, respectively (Figs. 22-2 to 22-6). Because the presenting part may be in either the left or right position, there are left and right occipital, left and right mental, and left and right sacral presentations. These are abbreviated as LO and RO, LM and RM, and LS and RS, respectively.
fetal occiput, chin (mentum), and sacrum