Ch. 15 Labor and Birth Processes Flashcards
What are the five factors that affect the process of labor and birth (5 P’s)?
Passenger (fetus & placenta), Passageway (birth control), Powers (contractions), Position of mother, & Psychologic response
What are several interacting factors that effect the movement of the passenger during birth?
The size of the fetal head, fetal presentation, fetal lie, fetal attitude, and fetal position
What bones is the fetal skull composed of?
2 parietal bones, 2 temporal bones, the frontal bone, and the occipital bone
What membranous sutures are the bones of the fetal skull united by?
The sagittal, lambdoidal, coronal, and frontal
What are the membrane-filled spaces located where the sutures intersect called?
The fontanels
What does the palpation of fontanels and sutures during vaginal examination reveal?
Fetal presentation, position, and attitude
What makes the skull flexible to accommodate the infant birth?
Sutures and fontanels
What is slight overlapping of the bones of the fetal skull that occurs during childbirth called and what does it permit?
Molding. It permits the skull to adapt to the various pelvic diameters
What is the part of the fetus that enters the pelvic inlet first called?
Presentation
What are the 3 main types of presentation?
Cephalic (head first), Breech (buttocks first), and shoulder
What is the part of the fetal body first felt by the examining finger during a vaginal exam called?
Presenting part
Name the 3 main fetal presenting parts.
Occiput, sacrum, and scapula
What is the presenting part in a cephalic presentation?
The occiput
What is the presenting part in a breech presentation?
The sacrum
What is the presenting part in a shoulder presentation?
The scapula
What is the relationship of the long axis (spine) of the fetus to the long axis (spine) of the mother called?
The lie
What are the 2 primary lies?
Longitudinal (or vertical) and transverse (horizontal or oblique)
What is a longitudinal (or vertical) lie?
The long axis of the fetus is parallel with the long axis of the mother
What is a transverse (horizontal or oblique) lie?
The long axis of the fetus is at a right angle diagonal to the long axis of the mother
What type of lie is seen in either cephalic or breech presentations?
Longitudinal lies
Can a vaginal birth occur when the fetus stays in a transverse lie?
No
What is the relationship of the fetal body parts to one another called?
The attitude (posture)
What is the most common type of attitude?
General flexion
Describe general flexion attitude.
The fetus’s 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
What is a suboccipitobregmatic diameter?
Complete flexion of head on chest so that smallest diameter enters the pelvis
What is an occiptofrontal diameter?
Moderate extension (military attitude) so that large diameter enters
What is an occipitomental diameter?
Marked extension (deflection) so that the largest diameter, which is too large to permit head to enter pelvis, is presenting
What is the largest transverse diameter of the fetal skull and what is the diameter at term?
Biparietal diameter; 9.25 cm at term
What is the smallest anteroposterior diameter of the fetal skull to enter the maternal pelvis when the fetal head is in completed flexion and what is the diameter at term?
Suboccipitobregmatic diameter; 9.5 cm at term
What is the relationship of the fetal presenting part to the four quadrants of the maternal pelvis called?
The position
What does the first letter of the position abbreviation stand for?
The location of the presenting part in the right (R) or left (L) side of the mother’s pelvis
What does the middle letter of the position abbreviation stand for?
The specific presenting part of the fetus (O for occiput, S for sacrum, M for mentum [chin], & Sc for scapula [shoulder])
What does the third letter of the position abbreviation stand for?
The location of the presenting part in relation to the anterior (A), posterior (P), or transverse (T) portion of the maternal pelvis
What does ROA mean?
The occiput is the presenting part and is located in the right anterior quadrant of the maternal pelvis
What does LSP mean?
The sacrum is the presenting part and is located in the left posterior quadrant of the maternal pelvis
Term that indicates that the largest transverse diameter of the presenting part has passed through the maternal pelvic brim or inlet into the true pelvis reaching the level of the ischial spines.
Engagement (usually corresponds to station 0)
What is the relationship of the presenting part of the fetus to an imaginary line drawn between the maternal ischial spines called and what does it measure?
The station. This is a measure of the degree of fetal descent through the birth canal
What is the station when the lowermost portion of the presenting part is 1 cm above the spines?
Minus (-) 1
What is the station when its at the level of the spines?
0 (zero)
What is the station when the presenting part is 1 cm below the spines?
Plus (+) 1
When is birth imminent according to the station?
When the presenting part is at +4 to +5 cm
What are the 2 components of the maternal passageway or birth canal?
Bony pelvis and soft tissue
What is the false pelvis and does it play a role in childbearing?
The false pelvis is the part above the brim and plays no part in childbearing
What are the 3 planes in the true pelvis?
The inlet, or brim; The midpelvis, or cavity; & the outlet
What is the passageway, or birth canal, composed of?
Bony pelvis, lower uterine segment, cervix, pelvic floor muscles, vagina, introitus (external opening to the vagina)