Labor and Delivery Flashcards
“Engagement”
Positioning of the head in the lower pelvis
“Flexion”
Flexion of the head, placing the occiput in presenting position
“Descent”
Descent of the neonate through the pelvis
“Internal rotation”
Internal rotation of the vertex to maneuver past the lateral ischial spines, the major barrier that the neonate must cross
“Extension”
Extension of the head to pass beneath the maternal symphysis
“External rotation”
External rotation of the head after delivery to facilitate shoulder delivery
What is the clinical definition of labor?
- Two things must be present:
- Painful uterine contractions
- Cervical dilation
Painful uterine contractions without cervical dilation
These contractons are referred to as “Braxton-Hicks” contractions, and do not represent labor since cervical dilation is not present.
When a pregnant woman near term is experiencing contractions, when should she come to the hospital?
- If there is:
- Leakage of fluid
- Vaginal bleeding
- Painful contractions every 5 minutes for 1 hour
- Decrease in fetal movements
Exam components unique to obstetrics
- Fetal:
- Fetal heart tone exam
- Fetal presentation (orientation within uterus)
- Maternal:
- Sterile vaginal exam
- Cervical dilation (internal os)
- “Effacement” (distance between internal and external os)
- “Fetal station” (position of head relative to ischial spines)
- Sterile vaginal exam
Cervical dilation
Specifically opening of the internal os
Maximal or complete dilation is 10 cm
Effacement describes. . .
. . . the closure of the space between the internal and external cervical os
In a non-effaced cervix, this distances is about 4 cm
Measuring fetal station
Fetal station of zero is defined as having the infant’s head on par with the level of the ischial spines by palpation
+1 represents 1 cm past the ischial spines, +2 2 cm past, etc.
-1 represents 1 cm beneat the ischial spine, etc.
Stage 1 of labor
- Divided into latent and active phases
-
Latent phase:
- Cervical dilation <4 cm
- Can last for days, variable length and rate of dilation
-
Active phase:
- Cervical dilation >4 cm
- Consistent dilation of 1.2-1.5 cm/hour
-
Latent phase:
Stage 2 of labor
From complete dilation (10 cm) to delivery of the infant
Stage 3 of labor
From delivery of the infant to delivery of the placenta
Stage 4 of labor
The immediate post-partum period of approximately 2 hours post-delivery of the placenta
Why should women avoid eating during active labor?
GI motility is halted, and eating can lead to severe nausea and emesis
Pain at different stages in labor
- During stage 1, pain results from contrations of uterus and dilation of cervix ⇒ visceral pain at levels of T10 to L1
- During stage 2, pain results from the neonate’s passage through the vaginal canal ⇒ somatic pain at level of S2-S4
Treatment of choice for pain of labor
Epidural blockage
Why are opioids suboptimal for pain of labor?
Their sedating effects are not desirable
However, if epidural is either insufficient or contraindicated, they can still be used and are often second-line
The epidural trade-off
Epidural helps a lot with pain, but also makes labor last slightly longer
Stage 2 of labor lasts. . .
. . . 2-3 hours for a 1st-time delivery, or potentially as short as minutes for multiparous women
Delivery is imminent when. . .
. . . a half-dollar size circumference of the fetal vertex is visible in-between pushes







