Mechanisms of Labor & Vocab
Posted by Laura on March 12, 2010
7 cardinal movements
Engagement – biparietal diameter of head passes the pelvic inlet.
Descent – process of presenting part through pelvis. (Forces descent depends upon: pressure exerted by AF, pressure exerted by contracting fundus on fetus, force of contraction of maternal diaphragm and ABD muscles in 2nd stage of labor, Extension and straightening of fetal body)
Flexion – chin of head brought into closer contact with fetal chest, allowing smallest diameter to present first to inlet.
Internal Rotation – fetal head guided by body pelvis and muscles to rotate occiput anteriorly to fit at outlet
Extension – emerging head by first the occiput, then face then chin.
Restitution and External Rotation – rotation of head (45°) after born to the position it occupied when it was engaged in the inlet. Then (external rotation) the head rotates further as the anterior shoulder engages.
Expulsion – After birth of shoulders, baby is born by flexing laterally in the direction of the symphysis pubis.
Synclitism – Pelvic inlet plane is parallel with sagital suture of infants head. Each ear of the infant passing through the inlet at the same time.
Asynclitism – Pelvic inlet plane is intersected by the plane of the sagital suture. You can think of this as one ear passing through the inlet before the other.
True Labor vs. False Labor –
Signs of false labor include:
- Contractions are irregular, unpredictable
- No progression is seen over time
- Contractions are felt as a generalized abdominal tightening
- Change in activity or position causes contractions to slow down or stop
- Usually no bloody show
- Membranes will not rupture
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