OSCE Flashcards
- Mechanism of labour
Also known as cardinal movements
Refers to changes in position of bb during its passage throu birth canal
2.Descent
Process where fetal head moves down birth canal, usually entering head first (cephalic)
Enters at largest diameter of pelvic inlet which is transverse diameter measuring at 13.5cm wide
Occurs due to contractioms which are a driving dfactor and apply pressure to fetus
Fetal bone moulding occurs where fetal skull bomes overlap allowing the fetal head to b a smaller diameter to fit.
3.Engagement
Passage of widest diameter of presenting part to a level below the plane of pelvic inlet
In cephalic births the widest diameter is the biparietal diameter at 9.5cm.
Occurs to ensure FH is properly positioned inin the mat pelvis.
It confirms that the widest diameter of the fetal head has entered the pelvic inlet, allowing further descent and fetus can move down with every contraction.
Know how many 5ths palpable and difference of a multiparous and primigravida
4.Flexion**
Bbs chin tucks down onto its chest
Occurs due to fetal axis pressure, shape of uterus, and uterine contractilns.
Smaller presenting diameters are a result of flexion. suboccipotobregma (occipital protuberance to the bregma) at 9.5 cm presents after flexion which is the optimal passage through the pelvis.
5.Internal Rotation
As head descends, occiput of fetus rotates towards symphysis pubis, allowing tbe widest part of fetus to negotiate the pelvis at ots widest dimension.
Causes slight twist in neck of fetus as head is no longer in direct alignment w shoulders
Onternal
6.Crowning
When widest part of bbs head is visible at vaginal opening w/o regression between contractions.
Confirms bbs head has descended sufficienttly throu birth canal.
Occiput then escapes under pubic arch and head is crowned.
Crowning usually occurs after internal rotation, meaning bbs head in best position for delivery.
Encourage mother to pant and have comtrolled breathing to avoid tears.
7.Extension **
After crowning FH can extend, pivoting on suboccipital region around the pubic bone.
This releases the sinciput, face and chin, whoch sweep the perineum and are born by extension.
Caused by downard force on fetus from contractions, and upward forces from muscles of pelvic flor.
