Components of Labor (4Ps)

passageway
passenger
power
psyche

what are the four components of labor?

the woman's pelvis

known as the passageway

the fetus

known as the passenger

uterine factors

known as the power

the woman's view

known as the psyche

passage

Refers to the route a fetus must travel from the uterus through the cervix and vagina to the external perineum.

true

true/false:
▪ Because the cervix and vagina are contained inside the pelvis, a fetus must pass through the bony pelvic ring.

1. diagonal conjugate (AP diameter of the inlet)
2. the transverse diameter of the inlet

What are the 2 pelvic measurements that are important to determine the adequacy of the pelvic size?

anteroposterior diameter

the narrowest diameter of the pelvic inlet

12.5 cm

anteroposterior diameter measures?

transverse diameter

the narrowest diameter of the pelvic outlet

11 cm

transverse diameter measures?

true

true/false: If a disproportion between the fetus and pelvis occurs, the pelvis is the structure at fault.

true

true/false:
➢When an infant cannot be born vaginally, emphasize that it is the pelvis that is too small, not that the head is too big

GYNECOID

female pelvis; round, shallow, and open

ANDROID

- male pelvis; heart or wedge shape

ANTHROPOID

- ape-like pelvis; upright egg or oval shape

PLATYPELLOID

- flat pelvis; egg or oval lying on its side

false pelvis

above the pelvic brim and has no obstetric importance

true pelvis

below the pelvic brim and related to the child -birth.

inlet
pelvic cavity
pelvic outlet

comprises the true pelvis

passenger

the fetus is regarded as the?

head

The body part of the fetus that has the widest diameter is the ______________- so this is the part least likely to be able to pass through the pelvic ring

cranium

the uppermost portion of the skull

eight

the cranium is comprised of how many bones?

1. FRONTAL (two fused bones)
2. TWO PARIETAL
3. OCCIPITAL

what are the four superior bones?

base

the other four bones of the skull lie at the__________ of the cranium

true

true/false: - the four bones at the base of the cranium are of little significance in childbirth because they are never presenting parts

sphenoid
ethmoid
two temporal bones

enumerate the other four bones of the skull lie at the base of the cranium

9.25 cm

what is the normal biparietal length of a newborns head?

suture lines

The bones of the skull meet at the?

suture lines

they allow the cranial bones to move and overlap, molding or diminishing the size of the skull so that it can pass through the birth canal more readily.

fontanelles

membrane-covered spaces found at the junction of the main suture lines

anterior fontanelle

lies at the junction of the coronal and sagittal sutures

bregma

also known as anterior fontanelle

DIAMOND

fusion of 2 frontal bones and 2 parietal bones making the anterior fontanelle __________-shaped

Posterior Fontanelle

lies at the junction of the lambdoidal and sagittal sutures

triangular

because the two parietal bones and the occipital bone are involved at this junction, the posterior fontanelle is ______________ shaped

true

true or false: the PF is smaller than the AF

fontanelle

this helps establish the position of the fetal head and whether it is in a favorable position for birth

vertex

the space between the two fontanelles is referred to as the ?

sinciput

the area over the frontal bone is referred to as the?

occiput

the area over the occipital bone is referred to as the?

molding

is the change in the shape of the fetal skull produced by the force of uterine contractions pressing the vertex of the head against the not-yet-dilated cervix causing the bones of the fetal skull to overlap and cause the head to become narrower and longer

a day or two

molding last for ?

attitude

describes the degree of flexion a fetus assumes during labor or the relation of the fetal parts to each other

Good attitude

is in complete flexion
--- the spinal column is bowed forward
---- the head is flexed forward so much that the chin touches the sternum
--- - the arms are flexed and folded on the chest
--- the thighs are flexed onto the abdomen
-- - and the calves are pressed against the posterior aspect of the thigh

Moderate flexion

if the chin is not touching the chest but is in an alert or "military position"

Partial extension

presents the "brow" of the head to the birth canal

Poor flexion

the back is arched, the neck is extended, and a fetus is in complete extension presenting the occipitomental diameter of the head

Engagement

refers to the settling of the presenting part of a fetus far enough into the pelvis to be at the level of the ischial spines, a midpoint of the pelvis.

vaginal examination
cervical examination

the degree of engagement is assessed by?

floating

presenting part that is not engaged is said to be ?

dipping

a presenting part that is descending but has not yet reached the ischial spines is called?

-4

floating corresponds to what number in the station?

0

engaged corresponds to what number in the station?

+4

at the outlet corresponds to what number in the station?

station

refers to the relationship of the presenting part of a fetus to the level of the ischial spines.

ischial spine

when the presenting part is at the level of the _______________, it is at 0 station

above the spines

if the presenting part is _________________, the distance is measured and described as minus stations, which range from -1 to -4 cm.

below the ischial spines

if the presenting part is ________________, the distance is stated as plus stations (+1 to +4 cm)

perineum

at a +3 or +4 station, the presenting part is at the ___________ and can be seen if the vulva is separated

crowning

when part of the baby is visible through the vaginal opening

fetal lie

- is the relationship between the long (cephalocaudal) axis of the fetal body and the long (cephalocaudal) axis of a woman's body

transverse

also known as horizontal

longitudinal

also known as vertical

true

true/false: approximately 99% of fetuses assume a longitudinal lie

cephalic

Most frequent type of presentation (95%)

cephalic presentation

The fetal head is the body part that will first contact the cervix

vertex, brow, face, and mentum

four types of cephalic presentation

vertex

The head is sharply flexed, making the parietal bones or the space between the fontanelles the presenting part. This is the most common presentation.

brow

Because the head is only moderately flexed, the ______ or sinciput becomes the presenting part

face

The fetus has extended the head to make the _________-the presenting part. From this position extreme edema and distortion of the face may occur. The presenting diameter is so wide that birth may be impossible.

mentum

The fetus has completely hyperextended the head to present the chin. The widest diameter (occipitomental) is presenting. As a rule, the fetus cannot enter the pelvis in this presentation

Breech Presentation

means that either the buttocks or the feet are the first body parts that will contact the cervix.

true

true/false: Breech presentations occur in approximately 3% of births and are affected by fetal attitude

complete
frank
footling

types of breech presentation

complete breech

hips and knees flexed

frank breech

hips flexed, knees extended

footling breech

one or both feet are present first at the cervix

types of fetal position

refers to the relationship of the presenting part to a specific quadrant of a woman's pelvis.

fetal landmark

denoted by the middle letter

first letter

defines whether the landmark is pointing to the mother's right (R) or Left (L).

last letter

defines whether the landmark points anteriorly (A), posteriorly, (P), or transversely (T)

descent
flexion
internal rotation
extension
external rotation
expulsion

mechanisms of labor (DeFIRE ERE)

POWERS OF LABOR

Supplied by the fundus, are implemented by the uterine contractions, a process that causes cervical dilatation and then expulsion of the fetus from the uterus

increment, acme, decrement

What are the 3 phases of a contraction?

increment

increase

acme

the highest point

decrement

decrease

interval

The distance between two contractions

effacement and dilation

what are the two cervical changes?

effacement

Shortening and thinning of the cervix

dilatation

enlargement of the cervical os

psyche

refers to the psychological state that a woman brings into labor