Labour Flashcards
Define labour.
Regular + painful uterine contractions that cause progressive dilation + effacement of the cervix.
Normal term labour is usually between 37-42w
EDD is 40w
What are Braxton Hicks contractions?
Throughout 3rd trimester, involuntary contractions of the uterine smooth muscle occur
Irregular
“practice contraction”
What are the borders of the pelvic inlet?
Posteriorly: Sacral promontory
Laterally: Iliopectineal line
Anteriorly: Pubic symphysis
What are the borders of the pelvic outlet?
Posterior: Tip of the coccyx
Lateral: Ischial tuberosity
Anterior: Pubic arch
What is foetal lie?
the relation of the long axis of the fetus in relation to the mother
Longitudinal
Oblique
Transverse
What is foetal presentation?
the part of the body of the foetus which leads
cephalic
frank breech: most common
complete breech
footling
Describe each breech type
Frank: legs flexed at hip + extended at knees
Complete: legs flexed at hips + knees (cross-legged)
Footling: one or both legs extended at the hip
What is foetal position?
the position of the presenting part in relation to a point on the maternal pelvis
L/R occipitoposterior
L/R occipitoanterior
L/R occipitotransverse
What is foetal engagement?
The passage of the largest part of the presenting part through the pelvic brim.
If fetal head is at the level of the ischial spines then it is engaged.
What is foetal station?
The relation of the presenting part to the ischial spine.
What are the stages of labour?
First stage: dilation to 10cm
Latent phase: 0-3cm dilation
Active phase: painful regular contractions leading to 10cm dilation
Second stage: 10cm to birth of foetus
Third stage: Placenta delivery
What happens in the latent stage of labour?
Uncoordinated contractions
Slow dilation up to 4cm
Early admission is not recommended at this stage
What is the rate of dilation and frequency of contractions in the first stage of labour?
1cm/ h nulliparous
2cm/ h multiparous
Contractions every 2-3 mins
How long does the latent stage of labour tend to last?
18h for 1st labour
12h for 2nd labour
With each subsequent labour, the time decreases
Describe the passive movements undertaken by the foetus in labour
Engagement
Descent
Flexion
Internal rotation
Crowning
Extension of the presenting part
Restitution
External rotation
Lateral flexion
What causes descent?
Increased abdominal muscle tone
Braxton hicks
Fundal dominance of uterine contractions during labour
Increased frequency + strength of contractions during labour
What is engagement?
Largest diameter of fetal head descends into maternal pelvis.
Fetal head is 3/5th palpable or less.
Primips: usually weeks before labour
Head usually occipital-transverse
What is flexion?
Fetal neck flexes (chin to chest) ensures the smallest diameter is presented at the pelvic outlet
Occurs due to head pushing against tissues of pelvic floor
What is internal rotation?
Foetus internally rotates from left or right OT position 90-degrees, to an occipital-anterior, oblique position, to lie under the subpubic arch.
Occurs during established labour + is commonly completed by start of the 2nd stage.
What is crowning?
= Widest diameter of fetal head successfully negotiates through the narrowest part of the maternal bony pelvis
Head no longer retreats between contractions.
What is extension of the presenting part?
Occiput slips beneath the suprapubic arch allowing the head to extend.
Fetal head facing maternal back with its occiput anterior.
What is restitution?
external movement of fetal head that corrects the torsion of neck sustained during internal rotation.
Direction of movement opposite to that of the internal rotation
What is external rotation?
the movement of the head due to the internal rotation of the shoulder as it comes into the antero–posterior diameter of the pelvic outlet.
The anterior shoulder escapes under the pubic arch, while the posterior shoulder sweeps over the perineum.
What is lateral flexion?
Upward traction assisting the delivery of the posterior shoulder.
What is caput succedaneum?
Diffuse swelling of the scalp, caused by pressure of the scalp against the dilating cervix.
Crosses suture lines (like a cap)
Spontaneously resolves
What is the strongest risk factor for cephalohaematoma?
Vacuum assisted delivery
(though also a/w forceps)
What is cephalohaematoma?
accumulation of subperiosteal blood
Typically in the parietal or occipital region
Caused by shearing forces on skull during birth
GRADUAL bleed- not immediate at birth
Does NOT cross suture lines
May take months to resolve
Jaundice may develop as complication
What is a subgaleal haematoma?
scalp bleeding in the potential space between the periosteum + galeal aponeurosis.
superficial to periosteum thus CAN cross suture lines
Life threatening
Develops ~ 12-72h after delivery
Give 2 risk factors for subgaleal haematoma
Vacuum assisted delivery
(Forceps delivery less so)
What is labour triggered by?
Decreased progesterone
Pacemakers in the uterus are suppressed by progesterone
When progesterone levels decrease, the pacemakers fire more, triggering Braxton-Hicks contractions.
What is cervical ripening?
Changes from fibromuscular to stretchy material to help baby be pushed out.
Why should oxytocin be given in moderation?
Too much oxytocin can cause strong contractions leading to hypoxia fro the fetus.
What 4 factors affect the progression of labour?
PASSENGER: big or small?
PASSAGE: shape + size of pelvis
POWER: sufficient regular contractions
POSITION: of foetal head- smallest is AP diameter is OA
