Session 10: Labour and Delivery Flashcards
What is labour?
When pregnancy end with the expulsion of the products of conception (fetus + placenta).
This is specifically after 24 weeks of gestation.
If pregnancy ends before 24 weeks, what is it called?
Spontaneous abortion (miscarriage)
What is labour called that happens before the 37th week of gestation?
Pre-term labour
Expulsion of the fetus requires a few processes. Which?
Creation of birth canal
Release of the structures that normally retain the fetus in utero.
Enlargement and realignment of the cervix and vagina.
Expulsion of the fetus.
Expulsion of the placenta and changes to minimise the blood loss of the mother.
What happens in the first stage of labour?
Creation of birth canal
Release of the structures that normally retain the fetus in utero
Enlargement and realignment of the cervix and vagina.
What does the lie of the fetus mean?
The relationship of the long axis of the fetus to the long axis of the uterus.
What is the commonest lie?
Longitudinal with the head or buttocks posterior.
What is the presentation of the fetus?
Which part of the fetus that is adjacent to the pelvic inlet.
In case of a longitudinal lie, what may be the presentation of the fetus?
Head (cephalic) or breech (podalic)
State lie and presentation in each picture.
What is the most common presentation and lie?
What is the diameter of the presentation in this case?
Longitudinal and cephalic so that the vertex presents.
9.5 cm
What is the pelvic inlet boundaries?
Pos - sacral promontory
Anteriorly - superior pubic rami and the upper margin of the pubic symphysis
Laterally - ilio-pectinal line
What is the true diameter of the pelvic inlet?
11 cm
Give mechanisms that occur some expansion of the pelvic inlet.
Softening of pelvic ligaments
What is the fetus normally retained in the uterus by?
Relative inactivity of the myometrium
The cervix
What does the cervix need to do in order to create a birth canal?
Dilate and retract anteriorly.
What is cervical dilation due to?
Structural changes known as cervical ripening.
Forceful contractions of uterine smooth muscle.
The contractions first thin the cervix and then dilate it.
Explain cervical ripening.
Marked reduction in collagen and marked increase in GAGs.
Collagen bundles loosen.
Influx of inflammatory cells and increase in NO output.
What is the cervical ripening triggered by?
Prostaglandins like E2 and F2alpha
Explain what happens to the myometrium during pregnancy.
It gets thicker (10x in hypertrophy) and also due to glycogen depositions.