Parturition Flashcards
Describe the relationship between cervical effacement and cervical dilation
Effacement is thinning/flattening of the cervix (the thinner the membrane, the more % effaced it is, ideally you want a 100% effaced cervix)
As the cervix becomes softer (cervical ripening) and thinner, it becomes easier to dilate/open.
Prostaglandin synthesis increases in response to what?
Relative fall in progesterone when comparing it to levels of estrogen, either by progesterone dropping or an increase in estrogen
When does the first stage of labour end?
When the cervix is fully dilated at 10 cm
Reasons for failure to progress can be divided into separate categories. List the categories and give an example of each
Power - inadequate contractions
Passage - abnormally shaped pelvis
Passenger - large-sized fetus, number and position
What is labour progression plotted on?
Partogram
What is the diameter of the pelvic inlet? How might the diameter change during pregnancy?
11cm, during pregnancy there is softening of the ligaments surrounding the pelvic inlet to increase the diameter to facilitate passage of the baby
What is considered an ideal orientation for the fetus to be in delivery and why?
Longitudinal lie, cephalic presentation (part of the fetus adjacent to pelvic inlet) with the head flexed so that the vertex (between parietal eminences and anterior-posterior fontanelles) is the presenting part.
What questions could you ask in regards to contractions to determine whether an individual is in labour?
The intensity and frequency of contractions
What is special about the way uterine muscles contract in labour compared to normal muscle contractions?
Brachystasis; myometrial fibres only partially relax and cannot return to their original size - therefore there is a permanent shortening of the muscle fibres after each contraction. This gradually increases the pressure within the uterus (as it’s becoming smaller) to drive the fetus out through the birth canal.
What features of the cervix would you assess to determine whether the patient is in active labour?
The dilation, effacement (how thin and pliable) and how short it’s become
Describe the mechanism by which the force of contractions is increased during labour? Other than contractions, what else does this mechanism assist when giving birth?
List 4 things that can aid this process
Ferguson reflex. Stimulated by contractions which are detected by sensory receptors in the cervix and vagina. These sensors send afferent info to the hypothalamus to increase oxytocin release. The oxytocin acts directly on the uterus to increase the FOC and increases the prostaglandins circulating to further increase the frequency.
Contractions lead to more pressure, and thus the cycle is positive feedback until the pressure is released when the baby passes through. This helps the cervix dilate and ruptures the amnion (breaking the water).
This can be aided by…
- Opening the pelvis to 55 degrees
- A water environment reduces gravity.
- Anything to increase pressure on the cervix like standing upright
- Oxytocin is released with parasympathetic stimulation so it’s important to be in a calm relaxing environment
What happens to the mother’s uterus after the fetus has been expelled and what can be given if it’s not happening as quickly as it should?
The uterus continues to contract and shrink, directing the placenta towards the cervix. Contractions of the uterine muscle (given that they’re big and becoming smaller) are also squashing arteries in the endometrium, muscle fibres also retract and seal off the vessels. As a result, blood can’t drain into the maternal bloodstream, completing the separation. Shutting off blood supply to the placenta also prevents maternal hemorrhage
Can give synthetic oxytocin to increase/facilitate these contractions which helps reduce the risk of maternal hemorrhage (side note: the placenta can also be manually pulled out)
What is type 1, 2, 3 and 4 genital mutilation? Why would it be carried out?
Type 1: partial or total removal of the clitoris
Type 2: When the clitoris or labia minora is partially or totally removed with or without removal of labia majora
Type 3: infibulation; narrowing the vaginal opening by creating a ‘covering seal’ by cutting or repositioning the labia minora or majora
Type 4: all other harmful procedures to the female genitalia for non-medical purposes
Cultural reasons i.e right of passage, etc
At which weeks must the baby be delivered for the following?
a) spontaneous abortion
b) pre-term
c) term
a) before 24 weeks
b) before 37 weeks
c) 37-42 weeks
What happens in the first stage of labour and what are the two phases?
It’s the interval between the onset of labour and full cervical dilation and creation of the birth canal through expansion of the soft tissues (cervix, vagina and perineum), and the cervix must retract anteriorly.
Latent phase: onset of labour with slow cervical dilation to ~4cm, contractions tend to be becoming more regular and increasing in intensity. Progresses to the…
Active phase: faster rate of cervical change, 1-1.2 cm/hour and regular uterine contractions
What marks the end of the second and third stages of labour? How long does each of them typically take?
Second: delivery of the fetus, usually up to 1 hr but 2 allowed if it is the first pregnancy
Third: delivery of placenta + membranes, usually 5-15 min but can go up to an hour