Normal Delivery - Shoham Flashcards
What is the mechanism of myometrium relaxation?
- Decreased intracellular calcium and calcium seequestration
- give Ca-channel blockers to delay preterm delivery - Dephosphorylation of myosin light chain
- Inactivation of myosin light chain kinase (by cyclic AMP-dependent phosphorylation)
How many contractions are required for adequate labor?
2-4.5 per 10 minutes
over 5 is hypercontractions
What are the stages of normal delivery?
• First stage:
latent phase – beginning of uterine contraction to actual dilatation of cx. ( 3-4 cm. ) ,
active phase – 4cm to FD (10cm) of uterine cx.
• Second stage: From FD to actual delivery of the baby
• Third stage : Delivery of the placenta
What is the difference in cervical effacement and descent between first pregnancy and multiparous women?
In first pregnancy, will efface without dilating first
Often engaged at onset of labor but may not descend until second stage
In multiparous, cervix will dilate before effaces before labor
Descent begins with engagement
In both cases when effaces, the inner os dilates first.
What is the biparietal diameter and what is its significance?
The narrowest part of the baby’s head
When it reaches the ischial spines this is station 0
Baby is ready for labor
Can feel where the BPD is based on the locations of the anterior and posterior fontanelle
Indicates engagement of the fetus (otherwise floating head)
Name determinants of the Bishop score
Factor 0:
Closed cervix
0-30% effaced
-3 station
Firm consistency of cervix
Posterior position
1:
1-2cm dilation
40-50% effaced
-2, -1 station
Medium consistency of cervix
Midposition of head
2:
3-4cm dilation
60-70% effacement
0 station
Soft consistency
Anterior position
3:
5+ dilation
>80% effacement
+1/2 station
Soft consistency, anterior position
Points for each area, from 0-13 points
If <4 points, will have a failed induction of labor
What are the cardinal movements?
- Engagement
- Descent
- Flexion
- resistance of presenting part to pelvis (head flexes and chin tucks) - Internal rotation
- from sideways to posterior - Extension
- External Rotation
- Head delivered
- Shoulders move to AP diameter (back to sideways) - Expulsion
- Anterior shoulder, posterior shoulder, body
What are the rates of cervical dilatation and descent?
How long should the second stage of labor last?
- Nullipara: less than 1.2 cm dilatation per hour or less than 1 cm descent per hour
- Multipara: less than 1.5 cm dilatation per hour or less than 2 cm descent per hour
- Arrest of dilatation: 2 hours with no cervical changes
- Arrest of descent: 1 hour without fetal descent
For nulliparous women: 2 hours (3 with analgesia), median 50 minutes
Multiparous: 1 hour (2 with analgesia), median 20 minutes
What are possible presentations at birth?
- Cephalic (96%)
- Flexion (occiput or vertex) - normal
- Extension (Face) - deliverable
- Partial flexion (sinciput)
- Partial extension (brow)
Brow and sinciput not deliverable but usually resolve by themselves - Breech
- Frank (hip in flexion and knee in extension)- butt first.
- Complete (hip and knee in flexion)
These two deliverable but most do c-section to be safe - Incomplete, footling (one or both feet or one or both knees first)- not deliverable because one part isn’t opening for the rest
- Shoulder
What is the position during birth and what are the three possible positions?
Position is relation of presenting part to the right or left side of the birth canal.
- Occiput-vertex
Right/left occiput posterior/transverse - Mentum (chin) - face
- Sacrum- breech
What are the four pelvic types and how do they respond to childbirth?
- Gynecoid
50% of women
Best for birth
Wide angle of pubic arch-Subpubic angle is 90-100’
Pelvic inlet evenly divided into posterior and anterior
Sacrom is wide with average concavity and inclination
Side walls straight with blunt ischial spines
Sacro-sciatic notch is wide - Android
20%
Less favorable
Inlet is triangular or heart shaped with anterior narrow apex
Side walls converge with projecting ischial spines
Sacro-sciatic notch is narrow
Subpubic angle is narrow - Anthropoid pelvis
25%
Riskiest type
A-P diameter longer than transverse diameter
Sacrum is long and narrow
Sacro-sciatic notch is wide
Subpubic angle is narrow - Platypelloid Pelvis
<5%
All A-P diameters short and transverse long
Sacro-sciatic notch is narrow
Subpubic angle wide
Very flat
What are caput succedaneum and molding?
Changes in shape of fetal head
Caput succedaneum is elongated
How long does the third stage of labor take?
What are the two types of placental separation?
5-30 minutes
Shultz separation:
More common, central, caused by shrinking of the uterus and a retroplacental hematoma, inversion of amniotic sac
Fetal part is first
Duncan separation:
Maternal surface presents first, umbilical last
Separation in periphery first, placenta slides down sideways
Bleeding out
