Mechanism of Labour Flashcards
What are the 3 P’s of labour?
Power
Passenger
Passage
What is Power?
Power of uterine contractions
What is passenger?
Foetal head diameter
Several factors determine how easily the fetal head fits through the pelvis:
the attitude (degree of flexion)
the position (degree of rotation)
the size of the head.
What is Passage?
Pelvic Dimensions
The bony pelvis has three principle planes with varying diameters. The fetal head rotates to negotiate the pelvis as it descends. Cervical dilatation is a prerequisite for delivery. In the second stage the soft tissues of the vagina and perineum stretch or tear to allow passage of the head.
What are the key parts of labour?
Painful contractions
Cervical Dilation and effacement
Passage of baby
Placental expulsion
What is Stage 1 of labour?
Cervical dilation and effacement
Latent up to 4cm
Active above 4 cm
Established = regular contractions
What is Stage 2 of labour?
Passive = no pushing Active = no pushing
What is Stage 3 of labour?
Placental birth
Physiological
Active = uterotonics + cord traction (Suggested)
What is the order of movement of the baby through the birth?
Engagement
Descent
Flexion
Internal Rotation
Extension and delivery of head
Restitution and rotation
Delivery of shoulder and body
What are the boundaries of the 3 important pelvic diameters?
Inlet- pelvic inlet is marked by the pelvic brim, a bony ring made up of the sacral prominence posteriorly, the arcuate line of the ilium laterally, and the pectineal line of the pubis and pubic symphysis anteriorly.
Midplane- plane that extends from the end of the sacrum to the inferior border of the pubic symphysis; it is bounded posteriorly by the end of the sacrum, laterally by the ischial spines, and anteriorly by the inferior border of the pubic symphysis.
Outlet:
anteriorly: the pubic arch
laterally: the ischial tuberosities
posterolaterally: the inferior margin of the sacrotuberous ligament
posteriorly: the anterior border of the middle of the coccyx
What constitutes delay in the first and second stages of labour?
After established labour
Normal = >2 cm per 4 hours in first labour
Delay is less
Second stage
Nullip 2+ hrs is delay
Multip 3+ hrs delay
What are the causes of delayed labour?
Cause big baby, small woman, uterus poor contraction
What is the treatment of delayed labour?
Treatment of delay
ARM- space for baby and some prostaglandin release
Oxytocin (syntocinon) - inadequate contractions
Instrumental birth
How do we fix malposition?
Instrumental delivery -
Forceps
Ventouse- sialastic cup, kiwi omni cup, metal cup
What is a partogram?
A partogram or partograph is a composite graphical record of key data (maternal and fetal) during labour entered against time on a single sheet of paper.
What are the types of malposition in labour?
Breech presentation (+ presenting part)
Rotation of head:
