Physiology & Dx Of Labour Flashcards
Definition of labour
Is is the process by which the fetus is delivered after the 24th week of gastation
Labour is characterized by:
• onset of uterine countactions
• cervical effacement and dilatation
• rupture of memebranes with leakage of amniotic fluid
• descent of the presenting part through the birth canal
• birth of baby
• delivery of the placenta and membranes.
Each uterine contraction must be followed by a resting phase, why?
To maintain placental blood flow and adequate perfusion of the fetus
When does labor start?
When the factors that inhibit contractions and maintain a closed cervix diminish and are over taken by the actions of factors that do the opposite
Myometrial contraction occurs in response to:
Oxytocin & and prostaglandin, which increase intracellular Ca+
Which segment of the uterus becomes thicker contracted and which becomes thinner and more stretched?
The upper segment becomes thicker and actively contracted
Ferguson reflex:
It is 6 feedback
The pressure of presenting part of fetus against the cervis trigger oxytocin release from posterior pituitary
Leading to strong contraction and further increase the pressure against cervix»_space; ++oxytocine
Types of pelvis:
Gynaecoid pelvis (50%): (female pelvis) most suitable for child birth
Anthropoid pelvis (25%):
Oval, see in tall woman
Android pelvis (20%):
(male pelvis) Childbirth is difficult
Wider transverse diameter
Platypelloid (flat) pelvis (5%):
Kidney shaped
Rare
Wider transverse diameter
not conductive to vaginal delivery
Diameter of fetal skull:
Suboccipito-frontal: 10cm
Occipito-frontal: 11cm
submento-bregmatic: 9.5cm
suboccipito-bregmatic: 9.5cm
occipito-mental: 13cm
Fetal head enters the pelvis in a …., rotates in the ….. and delivers in ……
Transverse position
Midpelvis
AP position
Pelvic dimensions may increase during labor due:
Pelvic ligament laxity
Fetal Position that is most favorable for vaginal birth:
Fetus in a Flexed occipito-anterior with gynaecoid pelvis
Active phase of 1st stage is considered abnormal if:
If it occurs at less than 1cm in 2hrs
Active phase of 1st stage is variable in length (2-6hrs)
It is shorter in multiparous woman
There is no maternal urge to push, and fetal head is still relatively high in the pelvis
The passive phase of 2nd stage
There is a maternal urge to push because the fetal head is low, often visible
The active phase of 2nd stage
Which stage is its length affected by using the epidural anaesthetia
Second stage
The placenta is usually delivered within:
A few minutes (30min)
A third stage lasting more than … is defined as abnormal:
30 minutes
Unless the woman has opted for physiological management (60 minutes)
Both prolonged and precipitous labor increase maternal and fetal morbidity and mortality
T or F?
T
When the labor is regarded as prolonged:
When it lasts longer than 12 hours in nulliparous women and 8 hours in multiparous women.
Step of mechanism of labor
Engagement
Descent
Flexion of the head
Followed by internal rotation
Extension
Restitution
External rotation
Ended by delivery of shoulders and fetal body
Engagement in nulliparous women
It occurred in nulliparous women prior to labor, usually by 37wks
not for multiparous
How to diagnose engagement
By palpation of the number of fifths of fetal head abdominally
if more than two-fifths, the head is not yet engaged
The descent occurs in:
1st stage and passive phase of the 2nd stage of labor
as a result of uterine contractions.
