Labour And Delivery Flashcards
(41 cards)
Define parturition.
Transition from pregnant to non-pregnant state.
Define labour.
Physiologic process by which the fetus is expelled from the uterus to the outside world.
Define delivery.
The method of expulsion of the fetus, transforming the fetus to a neonate.
What does labour involve?
Sequential integrated changes in the uterine decidua (internal lining) and myometrium.
Changes in the cervix occur following these uterine contractions.
What are the 2 major end points of contractions in labour?
- Dilatation of the cervix.
2. Pushing the fetus through the birth canal.
What happens in the first stage of labour?
- The creation of the birth canal.
- Release of the structures which normally retain the fetus in utero.
- Enlargement and realignment of the cervix and vagina.
Define the first stage of labour physiologically.
Multiple changes resulting in creation of the birth canal and descent of the fetal head into it.
When does the first stage of labour start and finish?
Onset of labour to full dilation of the cervix (10cm dilated).
What are the 2 phases of the first stage of labour?
- Latent: onset of labour with slow cervical dilatation but softening.
- Active: faster rate of change and regular contractions.
When does the uterus first become palpable?
12 weeks.
Where has the fundus of the uterus reached at 20 weeks?
Umbilicus.
Where has the fundus of the uterus reached by 36 weeks?
Xiphisternum.
What is the lie of the fetus?
Describes the relationship of the long axis of the fetus to the long axis of the uterus.
Commonest longitudinal with head/buttocks posterior.
Fetus is normally flexed.
What is the presentation of the fetus?
Describes which part of the fetus is adjacent to the pelvic inlet.
If fetus lies longitudinally presentation will be head or breach.
Presenting part have different diameter and thus is clinically significant in management.
What is the diameter of presentation in a baby with cephalic presentation, well flexed and with vertex?
9.5cm
How big is the birth canal in diameter?
10cm.
What is the pelvic inlet bounded by?
- Posterior: sacral promontory.
- Lateral: ilio-pectineal line.
- Anterior: superior rubic rami and pubic symphysis.
What can allow the pelvic inlet to widen?
- Softening of the pelvic ligaments.
2. Opening legs.
What is needed to create a birth canal?
Cervix must dilate and be retracted anteriorly.
What causes cervical ripening?
Amniotic fluid contains prostaglandin and this allows forceful contractions of uterine smooth muscle.
What is cervical ripening?
Contractions cause thinning of the cervix (effacement) and dilation of the cervix.
The cervix changes: collagen decrease, GAGs increase, decreases aggregation of collagen fibres. Influx of inflammatory cells, and increased NO input from prostaglandins.
What prostaglandins trigger cervical softening?
E2 and F2alpha.
What happens to uterine smooth muscle?
Myometrium gets thicker (increased cell size and glycogen deposition). An intracellular apparatus contains actin and myosin, triggering a rise in intracellular calcium concentration, generating force. Rise in Ca conc produced from action potential.
Some smooth muscle cells are capable of spontaneous depolarisation and action potential generation (pacemakers).
What happens in contractions throughout pregnancy?
Early pregnancy contractions happen every 30 minutes and low amplitude.
Pregnancy continues, frequency falls with some increase in amplitude-> Braxton-Hicks contractions.