OB: Unit 4

Question 1

Factors Affecting Labor: 5 P’s

Answer 1

1) passenger (fetus) 2) passageway 3) powers

4) position of the mother 5) psychologic (Crowder says physiologic in PP)

Question 2

passenger

Answer 2

the way the fetus moves through the birth canal is determined by the following factors: size of fetal head; fetal presentation; fetal lie; fetal attitude; fetal position
*b/c the placenta must also pass through the birth canal, it can also be considered a passenger

Question 3

anterior fontanel (size/shape/location); when does it close?

Answer 3

diamond shape - approx 3 cm x 2 cm - lies at junction of sagittal, coronal, and frontal sutures - closes by 18 months after birth

Question 4

posterior fontanel (size/shape/location); when does it close?

Answer 4

triangular shape - approx 1 cm x 2 cm - lies at junction of sutures of the two parietal bones and the occipital bone - closes 6 to 8 weeks after birth

Question 5

molding

Answer 5

slight overlapping of skull bones during labor - can be extensive, but most heads of newborns assume normal shape within 3 days after birth

Question 6

presentation

Answer 6

refers to part of fetus that enters the pelvic inlet first and leads through the birth canal during labor

Question 7

3 main presentations

Answer 7

1) cephalic 2) breech 3) shoulder

Question 8

cephalic presentation

Answer 8

head first; occurs in 96% of births

Question 9

breech presentation

Answer 9

buttocks, feet, or both first; occurs in 3% of births

Question 10

shoulder presentation

Answer 10

seen in 1% of births

Question 11

presenting part

Answer 11

the part of the fetus that lies closest to the internal os of the cervix - the part of the fetal body first felt by the examining finger during a vaginal examination

Question 12

vertex

Answer 12

when the presenting part is the occiput

Question 13

factors that determine the presenting part

Answer 13

fetal lie, attitude, and extension or flexion of the fetal head

Question 14

fetal lie

Answer 14

the relation of the long axis (spine) of the fetus to the long axis (spine) of the mother

Question 15

two primary lies

Answer 15

1) longitudinal (vertical): the long axis of the fetus is parallel with the long axis of the mother - present in more than 99% of term labors; either cephalic or breech presentation
2) transverse (horizontal or oblique): long axis of fetus is at right angle diagonal to long axis of mother

Question 16

fetal attitude

Answer 16

the relation of the fetal body parts to one another - fetus assumes a characteristic posture (attitude) in utero partly b/c of the mode of fetal growth and partly b/c of the way the fetus conforms to the shape of uterine cavity

Question 17

deviations from normal attitude may cause

Answer 17

difficulties in childbirth

Question 18

fetal position

Answer 18

the relationship of a reference point on the presenting part (occiput, sacrum, mentum {chin}, or sinciput {deflexed vertex}) to the 4 quadrants of the mother’s pelvis - denoted by a three-part abbreviation

Question 19

fetal position: three-part abbreviation

Answer 19

1) first letter denotes LOCATION of presenting part in right (R) or left (L) side of mother’s pelvis
2) second letter denotes the SPECIFIC presenting part of fetus (O = occiput; S = sacrum; M = mentum; Sc = scapula [shoulder])
3) final letter denotes LOCATION of presenting part in relation to portion of the maternal pelvis: anterior (A), posterior (P), or transverse (T)
EX: ROA = the occiput is the presenting part and is located in the right anterior quadrant of the maternal pelvis
EX: LSP = the sacrum is the presenting part and is located in the left posterior quadrant of the maternal pelvis

Question 20

station

Answer 20

the relationship of the presenting fetal part to an imaginary line drawn between the maternal ischial spines and is a measure of the degree of descent of the presenting part of the fetus through the birth canal

Question 21

station of presenting part

Answer 21

measured in centimeters above or below the ischial spines
EX: 1 cm above the ischial spines is noted as being minus (-) 1
EX: AT the level of the ischial spines, the station is said to be 0 (zero)
EX: 1 cm below ischial spines is noted as being plus (+) 1

Question 22

engagement

Answer 22

term used to indicate that the largest transverse diameter of the presenting part has passed through the maternal pelvic brim or into the true pelvis and usually corresponds to station 0 - can be determined by abdominal or vaginal examination

Question 23

passageway (birth canal)

Answer 23

composed of the mother’s rigid bony pelvis and the soft tissues of the cervix, pelvic floor, vagina, and introitus (external opening to the vagina)

Question 24

four basic types of pelvis

Answer 24

gynecoid; android; anthropoid; platypelloid

Question 25

gynecoid pelvis

Answer 25

the most common - the major gynecoid pelvic features present in 50% of all women

Question 26

anthropoid

Answer 26

oval shaped, with a wider anteroposterior diameter

Question 27

platypelloid

Answer 27

the flat pelvis

Question 28

soft tissues of the passageway

Answer 28

include stretchy lower uterine segment, the cervix, the pelvic floor muscles, vagina, and introitus

Question 29

powers (involuntary and voluntary)

Answer 29

combine to expel the fetus and placenta from the uterus

Question 30

primary powers

Answer 30

involuntary uterine contractions - signal beginning of labor - described with terms like frequency, duration, and intensity

Question 31

primary powers are responsible for

Answer 31

the effacement and dilation of the cervix and descent of the fetus

Question 32

effacement of the cervix

Answer 32

the shortening and thinning of the cervix during the first stage of labor - degree of effaceme\nt
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expressed in percentages from 0% to 100%

Question 33

dilation of the cervix

Answer 33

the enlargement or widening of the cervical opening and the cervical canal that occurs once