Chapters 9, 10, 11, & 12 Flashcards
asynclitism
oblique presentation of the fetal head at the superior strait of the pelvis; the pelvic planes and those of the fetal head are not parallel.
attitude
relationship of fetal parts to each other in the uterus (e.g., all parts flexed or all parts flexed except neck extended.)
biparietal diameter
Largest transverse diameter of the fetal head; measured between parietal bones.
approx. 9.25 cm at term
bloody show
vaginal discharge that originates in the cervix and consists of blood and mucous; increases as the cervix dilates during labor.
dilation
stretching of the external os from an opening a few millimeters in size to an opening large enough to allow the passage of the fetus
effacement
Thinning and shortening or obliteration of the cervix that occurs during late pregnancy or labor or both
engagement
in obstetrics, the entrance of the fetal presenting part into the superior pelvic strait and the beginning of the descent through the pelvic canal; usually the lowest part of the presenting part is at or below the level of ischial spines
Ferguson reflex
reflex contractions (urge to push) of the uterus after stimulation of the cervix when the presenting part of the fetus reaches the perineal floor. Caused by endogenous oxytocin
fontanels
broad areas, or soft spots, consisting of a strong band of connective tissue contiguous with cranial bones and located at the junctions of the bones.
lie
relationship existing between the long axis of the fetus and the long axis of the mother; in longitudinal lie, the fetus is lying lengthwise or vertically, whereas in a transverse lie, the fetus is lying crosswise or horizontally in the uterus.
lightening
sensation of decreased abdominal distention produced by uterine descent into the pelvic cavity as the fetal presenting part settles into the pelvis; usually occurs 2 weeks before the onset of labor in nulliparas
molding
overlapping of cranial bones or shaping of the fetal head to accommodate and conform to the bony and soft parts of the mother’s birth canal during labor
position
relationship of a reference point on the presenting part of the fetus, such as the occiput, sacrum, chin, or scapula, to its location in the front, back, of sides of the maternal pelvis
presentation
the part of the fetus that lies closest to the internal os of the cervix
station
relationship of the presenting fetal part to an imaginary line drawn between the ischial spines of the pelvis
suboccipitobregmatic diameter
smallest anterior-posterior diameter of the fetal head; follows a line drawn from the middle of the anterior fontanel to the undersurface of the occipital bone.
9.5 cm
valsalva maneuver
forced expiratory effort against a closed airway, such as holding one’s breath and tightening the abdominal muscles. (e.g., pushing during the second stage of labor)
vertex
crown, or top, of the head.
The 5 P’s
Passenger (fetus & placenta) Passageway (birth canal) Powers (contractions) Position of the mother Psychologic response.
The way the passenger moves through the birth canal is determined by
the size of the fetal head, fetal presentation, fetal lie, fetal attitude, and fetal position.
How many bones comprise the fetal skull
6 - 2 parietal, 2 temporal, frontal and occipital.
How many sutures and their names
4 - sagittal, lambdoidal, coronal, and frontal
The two most important fontanels
anterior and posterior
Anterior fontanel facts
diamond shaped, larger than the posterior, and lies at the junction of the sagittal, coronal, and frontal sutures.
closed by 18 months
Posterior fontanel facts
Triangular shaped, lies at the junction of the sutures of the two parietal bones.
closes 6 - 8 weeks after birth
Purpose of sutures and fontanels
to make the skull flexible to accommodate the infant brain, and to allow for flexibility for passage through the birth canal
Molding of the newborns head returns to normal…
within 3 days.
The 3 main presentations are…
Cephalic (head first) - 96%
Breech (buttocks or feet first) - 3%
Shoulder - 1%
Presenting part in each presentation is usually
cephalic - occiput
breech - sacrum
shoulder - scapula
Normal fetal attitude
Called general flexion
Back of the fetus is rounded so that the chin is flexed on the chest, the thighs are flexed on the abdomen, and the legs are flexed at the knees. The arms are crossed over the thorax and the umbilical cord lies between the arms and the legs.
The smallest and most critical anteroposterior diameters is the…
suboccipitobregmatic diameter
9.5 cm at term
Position documentation
3 letter abbreviation.
1st letter - location of the presenting part in the right (R) or left (L) side of the mother’s pelvis
2nd letter - the specific presenting part (O- occiput, S- sacrum, M- mentum and Sc- scapula.
3rd letter - location of presenting part in relation to the maternal pelvis (A- anterior, P- posterior, T- transverse)
SVE
Sterile vag exam
Four basic types of pelvises
Gynecoid (the classic female pelvis)
Android (resembling the male pelvis)
Anthropoid (resembling the pelvis of anthropoid ape)
Platyepaloid (flat pelvis)
Which pelvis type is the most common
Gynecoid, present in 50% of all women
True/False: Mixed types of pelvises are more common than pure
True
Primary Powers
Involuntary uterine contractions that signal the beginning of labor. They are responsible for effacement and dilation of cervix and descent of the fetus.
Secondary Powers
The voluntary bearing down efforts of the mother after the cervix has dilated. They augment the force of the involuntary contractions.
Normal cervix size
2-3 cm long, 1 cm thick
effacement & dilation
1st pregnancy vs subsequent
effacement usually is progressed in 1st pregnancy before dilation occurs. In subsequent pregnancies they can occur at the same time.
Other phenomena in the days preceding labor
- loss of 0.5 to 1.5 kg in weight, caused by water loss resulting from electrolyte shifts produced by changes in estrogen & progesterone levels.
- a surge of energy
- lightening
- return of urinary frequency
- backache
- stronger braxton hicks contractions
- increased vaginal mucous or bloody show
- possible rupture of membranes.
how many stages of labor?
4
first stage of labor
onset of regular uterine contractions to full dilation of cervix. In a first pregnancy this can take 20 hours or longer, in multipara it can occur in less than an hour.
Divided further into 3 phases: latent, active and transition.
second stage of labor
lasts from the time the cervix is fully dilated to the birth of the fetus.
Average of 20 minutes in multiparous women and 50 minutes in nulliparas.
Asians longer second stage, Hispanic and African-American women shorter when compared to Caucasian women.
Divided into 3 phases.
first phase
2nd stage of labor
begins approximately the time of complete dilation of the uterus, when the contractions are weak, and the mother has no urge to push, is resting, or is exerting only small bearing-down efforts with contractions.
second phase
2nd stage of labor
period when contractions resume, the woman is making strong bearing-down efforts, and the fetal station is advancing.
third phase
2nd stage of labor
a period lasting from crowning until the birth
third stage of labor
last from the birth of the fetus until the placenta is delivered.
May be as short as 3-5 minutes, and up to 30 minutes is considered within normal limits.
When does the placenta typically separate
during the 3rd or 4th strong uterine contraction after the infant has been born. It is then delivered on the next contraction.
fourth stage of labor
lasts approximately 2 hours after the delivery of the placenta. The period of recovery when homeostasis is reestablished.
VERY IMPORTANT to observe for BLEEDING in this phase
7 cardinal movements
engagement descent flexion internal rotation extension external rotation (restitution) expulsion
Descent
the progress of the presenting part through the pelvis.
Descent depends on what 4 forces
- pressure exerted by the amniotic fluid
- direct pressure exerted by the contracting fundus on the fetus
- force of the contraction of the maternal diaphragm and abdominal muscles in the 2nd stage of labor
- extension and straightening of the fetal body.
When does the fetus’s head usually flex?
As soon as the head meets resistance from the cervix, pelvic wall, or pelvic floor, it normally flexes, bringing the chin closer to the fetal chest
restitution
the external rotation of the head after it is born
FHR
average at term is 140 beats/min
range 110 - 160 beats/min.
Earlier in gestation the FHR is higher than normal with an average of 160 beats/min at 20 weeks.
Factors affecting fetal circulation
- maternal position
- uterine contractions
- blood pressure
- umbilical cord blood flow.
What certain changes stimulate the chemoreceptors in the aorta and carotid bodies to prepare the fetus for initiating respiration after birth?
- fetal lung fluid is cleared from the air passages during labor and vaginal birth
- fetal oxygen pressure (PO2) decreases
- Arterial carbon dioxide pressure (PCO2) increases
- Arterial pH decreases
- Bicarbonate level decreases
- Fetal respiratory movements decrease during labor.
Maternal physiologic changes during labor
- Cardiac output increases 10-15% in the first stage, 30-50% in the second stage.
- HR increases slightly in the 1st and 2nd stages
- SBP increases during uterine contractions in 1st stage; SBP & DBP increase during contractions in second
stage.
-WBC count increases - Resp rate increases
-Temp may be slightly elevated - proteinuria may occur
- gastric motility and absorption of solid food is decreased; N/V may occur during transition to second-stage labor.
- blood glucose level decreases.
Maternal endocrine changes during labor
labor may be triggered by decreasing levels of progesterone and increasing levels of estrogen, prostaglandins, and oxytocin.
Normal volume of amniotic fluid
500 - 1200 mL
tests for presence of amniotic fluid
Nitrazine paper - will turn blue if positive
Amni-sure
Fern test
latent phase
first stage of labor
4 - 6 hours long
0-3 cm dilated
irregular contractions
active phase
first stage of labor
2-3 hours
4-7 cm
more regular, strong contractions
transition phase
first stage of labor
20-40 minutes
8-10 cm
strong to very strong contractions q 2-3 mins
analgesia
absence of pain without loss of consciousness
anesthesia
partial or complete absence of sensation with or without loss of consciousness
counterpressure
pressure applied to the sacral area of the back during uterine contractions
effleurage
gentle stroking used in massage, usually on the abdomen
epidural block
type of regional anesthesia produced by injection of local anesthetic alone or in combination with a narcotic analgestic into the epidural (peridural) space
epidural blood patch
a patch formed by a few mililiters of the mother’s blood occluding a tear in the dura mater around the spinal cord that occurs during induction of spinal or epidural block; its purpose is to relieve headache associated with leakage of spinal fluid
gate-control theory of pain
pain theory used to explain the neurophysiologic mechanism underlying the perception of pain; the capacity of nerve pathways to transmit pain is reduced or completely blocked by using distraction techniques.