Module 2A Flashcards
Dilation
the opening or enlargement of external cervical os
What are the 2 main functions of uterine contractions?
to dilate the cervix and to push fetus through birth canal
What happens hormonally and physically to initiate labor?
Estrogen levels increase / progestrone decreases which leads to increase in number of myometrium gap juncations (faciliatate contractions and stretching)
Number of oxytocin receptors increase. Fetal cortisol levels increase synthesizing prostaglandins, uterine contractions are initiated, cervical softening and myometrial sensitization = dilation.
Lightening
occurs when fetal presenting part begins to descend into true pelvis
False labor
condition occuring in later weeks of preg when irregular uterine contractions are felt but cervix is not affected
True labor
contractions occuring at regular intervals that increase in frequency, duration, and intensity. Brings about progressive cervical dilation and effacement
Factors that affect labor process
“five P’s”
- Passageway (birth canal)
- Passenger (fetus and placenta)
- Powers (contractions)
- Position (maternal)
- Psychological response
What are the 5 additional P’s?
- Philosophy
- Partners (support)
- Patience (natural timing)
- Patient preparation
- Pain managment
What is the false pelvis?
Greater - composed of upper flared parts of two iliac bones with their concavities and wings as base of sacrum
Linea terminalis
Imaginary line from scaral prominence at back to superior aspect of symphysis pubis at front
What is the true pelvis?
3 planes?
Bony passageway through which the fetus must travel. Made up of 3 planes. the inlet, mid-pelvis, the outlet
Pelvic inlet?
Entrance toward birth canal
Wider side ways than from front to back
What happens when fetus travels in the mid pelvis
Chest is compressed causing lung fluid and mucus to be expelled. Which removes the space occupying fluid so that air can enter lungs with newborns first breath
What measurements are assessed on the pelvic outlet for vaginal birth?
-Diagonal conjugate of inlet
-Transverse or ischial tuberosity diameter of outlet
-True or ob conjugate
What does diagnoal conjugate and true or ob conjugate need to measure for vaginal birth?
Diagnoal conjugate - at least 11.5cm
True conjugate - 10 cm
The pelvis is divided into what 4 shapes?
Gynecoid
Anthyopoid
Android
Platypelloid
Gynecoid pelvis
-Considered true female pelvis (40% of women)
-Vag birth most favorable
-Inlet is round, outlet roomy, optimal diameters in all 3 planes
*allows early and complete fetal internal rotation during labor
Anthropoid pelvis
-Common in men and non-white women. (25% of women)
-Pelvic inlet is oval and sacrum is long, producing a deep pelvis (wider front to back)
**more favorable compared to android or platypelloid
Android pelvis
-Considered male shaped and characterized by funnel shape (20% of women)
-Pelvic inlet heart shaped. Posterior segment is reduced in all pelvic planes. Descent of fetal head is slow and failure to rotate is common. Usually leads to C-section
Platypelliod (flate) pelvis
Least common (3%)
Pelvic cavity is shallow but widens at pelvic outlet, making it difficult for fetus to descend through mid pelvis.
Labor is poor, arrest at inlet common
What do the soft tissues of the passage way consist of
Cervix, pelvic floor muscles, vagina
Effacement
cervix effaces (thins) to allow presenting fetal part to descend into vagina
What 5 bones are not fused in fetus head?
2 frontal
2 parietal
Occipital
Fetal head
largest fetal structure (1/3 of body length)
What are sutures?
What are fontanelles?
Sutures - membranous spaces between cranial bones
Fontanelles - intersection of these sutures
Why are sutures important in newborns?
Allow cranial bones to overlap in order for head to adjust in shape when pressure is exerted by uterine contractions or maternal bony pelvis
Molding
Changing (elongated) shape of fetal skull at birth from overlapping of cranial bones
Caput saccedaneum
Caphalohematoma
Caput saccedaneum - fluid collected at scalp (can be described as edema). Disappears within 3-4 dats
Caphalohematoma- blood collected beneath scalp. reaborbed in 6-8 weeks
Sutures help the examiner
Detemine position of fetal head and degree of rotation
What is the soft spot called?
Anterior fontanelle
Diamond shape
Measures 1-4cm
Remains open for 12-18months to allow for growth of brain
Posterior fontanelle
Measures?
Located?
Closes?
1-2cm
back of fetal head
8-12 weeks after birth
What are the fetal skull diameters?
Occipitofrontal
Occipitomental
Suboccipitobregmatic
biparietal
BOLD is 2 most important
Fetal attitude
refers to posturing (flexion or extension) of joints and the relationship of fetal parts to one another
- most common is all joints flexed (back is rounded, chin to chest, thighs flexed on abdomen, legs flexed at knees)
What happens if fetal attitude is abnormal (no flexion or extension)?
nonflexed parts increase diameter increasing difficultly
Extension leads to larger fetal skull diameters which may make birth difficult
Fetal lie
Relationship of the long axis (spine) of fetus to the long axis (spine) of mother.
Three possible lies: Longitudinal (most common), transverse, oblique
What is longitudinal lie
Transverse lie
Oblique lie
Longitudinal - long axis is parallel with mothers
Transverse - long axis of fetus is perpendicular to mother
Oblique - fetal long axis is at an angle and no palpable fetal part is presenting. (usually transitioning between other lies)
*Transverse or oblique cannot be delivered vaginally
Fetal presentation
3 main?
refers to the body part of the fetus that enters the pelvic inlet first.
Cephalic (head first)
Breech (pelvis first)
Shoulder (scaplua first)
What are the 3 types of breech presentations
Frank- butt is first, legs extended
Full/complete - fetus sits crosslegged
Footling/incompete - one or both legs are presenting
*frank can result in vag birth all others - c-section
Breech presentation are associated with
Prematurity, placent previa, multiparity, uterine abnormalities (Fibroids), some congenital anomalies such as hydrocephaly.
Shoulder presentation or shoulder dystocia
occurs when fetal shoulders present first with head tucked inside
“turtle sign”