Normal Labour Flashcards
What is meant by the following terms: Labour, Lie, Presentation and Position, Station, Attitude?
Labour: The process by which the foetus and placenta are expelled from the uterus.
Lie: general position of where the baby is lying longitudinal/transverse/oblique
Presentation: the lowest part of the fetus: cephalic, breached
Position: Which way round the baby is facing OA or OP or OT (occipital anterior/posterior/transeverse)
Station: How high is the baby’s head in relation to the ischial spine.
Same level = 0
+ve = lower than ischial spine
-ve = higher than ischial spine
Attitude: the degree the head is flexed, full flexion = vertex
may also be brow (extended) or face (hyper extended)
When doing a vaginal examination during labour what are the 5 things you should comment on?
- Dilation of cervix
- Station
- Position of head (OA is best, OT/OP may need assisted delivery.
- Caput (baby head swelling due to reduced venous drainage due to pressure from cervix/pelvic inlet)
- Moulding (refers to the bones in the skull squeezing together to slightly reduce the size of the head, this is possible due to the fontanelles not being fused)
Note: OT position is incompatible with an non assisted labour
What are the 3 P’s factors which affect the course of labour?
Power aka uterine contractions (frequency, intensity, duration)
Passenger aka fetal position
Passage aka bony pelvis and soft tissue resistance different types of female pelvic shape (gynecoid is the most common)
What are the different planes and structures which need to be manoeuvred for passage of the fetus? (3 bony pelvis + soft tissue)
Pelvic Inlet:
Transverse diameter is ~13cm
Anterior posterior is ~ 11cm
Mid-Pelvis:
Ischial spines are palpable vaginally used to calculate fetus’s station
Outlet:
Anterior - posterior ~ 12.5cm
Transverse diameter ~ 11cm
Soft Tissue:
Cervix softens and distends
The soft tissues of the vagina and perineum need to be overcome in the 2nd stage. There perineum may tear or may be artificially cut (episiotomy) to aid delivery of the head.
When is a women classed to be in labour and how this can be diagnosed?
When she is experiencing:
- regular, painful uterine contractions 3 in 10 mins
- which increase in frequency
- dilation and effacement of cervix
Cervical effacement = thinning of the cervix
Contractions usually last 45-60 sec and occur every 3 mins.
Contractions can be assessed by:
- Palpation
- Pressure transducer on CTG (also known as a tonometer)
- Intrauterine pressure catheter
Cervical dilation and effacement is assessed with a VE
What are the different stages of labour?
Stage 1: Initiation: painful uterine contractions leading to full cervical dilation (10cm)
Stage 2: Starts at full cervical dilation to delivery of fetus
Stage 3: From delivery of fetus to delivery of placenta
Latent phase: period between onset of labour where uterine contractions become irregular and cervical dilatation slows, usually occurs when cervix is less than 10cm dilated
What is meant by the terms water’s breaking and show?
Water’s breaking refers to the membranous bag containing the fetus and the amniotic fluid being ruptured and the amniotic fluid rushing out.
Show refers to the mucus plug around your cervix coming away from the cervix and ‘showing’
What are the functions of the amniotic fluid and mucus plug?
Both protect against fetal infection
Amniotic fluid also helps protect against trauma and infection.
What should you be monitoring during labour?
FHR every 15 mins or continuously with CTG.
Contractions frequency and strength should be monitored.
Maternal Observations hourly.
VE 4 hourly.
Urine dip for ketones, 4 hourly/when they pass urine.
What are the potential causes for a poor progressing labour?
Power:
-Inaffective uterine contractions
Passenger:
-Malposition, Malpresentation or large baby
Passage:
-Small pelvis
How do you manage a poorly progressing labour?
Review aka abdo exam, hydration status, analgesia, FHR, VE
If water’s have not broke: Artificial rupture of membranes using an amniotic hook
Can give Syntocin infusion (oxytocin) needs CTG if this is being started. (needs senior review for this to be started if this is a multi para women). VE should be performed on a 2hourly basis.
Consider a lower segment caesarean if not progressing after 12hours on syntocin drip or if there is fetal distress.
How should you dose syntocin?
Start at 6mls/hr (4mU/min)
Increase in 30 min increments until there are regular contractions.
Max dose is 30mls/hr (20mU/min)
What time span classes as a poorly progressing labour in stage 1?
Latent phase
Nulliparous >20hrs
Multipara>14hrs
Lack of cervical dilation in active phase. Approximately you should expect 1cm/hr dilation when in active phase.
What time span classes as a poorly progressing labour in stage 2?
Nulliparous:
Prolonged if >2hrs
Multipara
Prolonged if> 1hr
Note if woman has local anaesthesia 1 hr extra is allowed before it is classed as prolonged.
Describe the normal path a fetus will take in stage 2?
- Engagement: passage of the widest diameter of the head through the pelvic inlet. Foetus’s head is usually in OT position at this point (transverse diameter is greater than OA here).
- Descent downward through the pelvis.
- Flexion of the fetal head (chin rests on chest) occurs passively due to the shape of the bony pelvis.
- Internal Rotation: the fetus’s head rotates so that it is no longer OT but OA. This is occurs passively due to the shape the pelvis and the pelvic floor musculature.
- Extension and delivery. The fetus is at the level of the introitus (the opening of the vaginal canal). The occiput is in contact with the pubic symphysis. A downward force is exerted on the foetus by the uterine contractions and an upward force is exerted by the pelvic floor muscles causing the fetal head to deliver by extension.
- External rotation (restitution). The fetal head rotates 90 degrees so that it is facing in its original position.
- Expulsion refers to the delivery of the rest of the body with anterior shoulder coming first.
