Mechanisms of labor

Question 1

Mechanisms of labor

Answer 1

1. Descent
2. Flexion
3. Internal rotation
4. Extention
5. Restitution (external rotation)
6. Expulsion

Question 2

( Stage 1 )

Answer 2

1. Presenting part reaches the pelvic inlet at the onset of labour
2. Fetal station ( degree of descent in proportion to the maternal ischial spines )
   - Fetus at pelvic inlet (-5)
   - At ischial spine (0)
   - Pelvic outlet (+4)
   - Crowning at vagina (+5)
3. Flexion - fetal chin presses against chest to meet resistance against the pelvic floor
4. Internal rotation - fetal shoulders internally rotate 45 degrees, widest part of shoulders inline with widest part of pelvic inlet
5. Extension - fetal head passes under the symphysis pubis (+4), and emerges from the the vagina
6. Restitution ( external rotation) - head externally rotates as shoulders pass through pelvic outlet under the symphysis pubis.
7. Expulsion - anterior shoulder slips under symphysis pubis, followed by posterior shoulder, rest of the body.

Question 3

• fetal station

Answer 3

2. Fetal station ( degree of descent in proportion to the maternal ischial spines )
   - Fetus at pelvic inlet (-5)
   - At ischial spine (0)
   - Pelvic outlet (+4)
   - Crowning at vagina (+5)

Question 4

stage 3 - flexion

Answer 4

3. Flexion - fetal chin presses against chest to meet resistance against the pelvic floor

Question 5

stage 4 - internal rotation

Answer 5

4. Internal rotation - fetal shoulders internally rotate 45 degrees, widest part of shoulders inline with widest part of pelvic inlet

Question 6

stage 5 - extention

Answer 6

5. Extension - fetal head passes under the symphysis pubis (+4), and emerges from the the vagina

Question 7

stage 6 - restitution

Answer 7

6. Restitution ( external rotation) - head externally rotates as shoulders pass through pelvic outlet under the symphysis pubis.

Question 8

descent 7 - Expulsion

Answer 8

7. Expulsion - anterior shoulder slips under symphysis pubis, followed by posterior shoulder, rest of the body.

Question 9

Fetal station

Answer 9

( degree of descent in proportion to the maternal ischial spines )

Question 10

• 5

Answer 10

Fetus at the pelvic inlet

Question 11

0

Answer 11

Fetus at the ischial spine

Question 12

+ 4

Answer 12

Fetus at the pelvic outlet

Question 13

+5

Answer 13

Crowning at the vagina