Labour and Delivery Flashcards
When do labour and delivery normally occur?
between 37-42 weeks gestation
What are the three stages of labour?
first stage = from onset of labour (true contractions) until 10 cm cervical dilatation
second stage = from 10cm cervical dilatation until delivery of the baby
third stage = from delivery of the baby until delivery of the placenta
What are the three phases of the first stage of labour?
latent phase = from 0 to 3cm dilation of the cervix, progresses at around 0.5cm per hour, irregular contractions
active phase = from 3cm to 7cm dilation of the cervix, progresses at around 1cm per hour, regular contractions
transition phase = from 7cm to 10cm dilation of the cervix, progresses at around 1cm per hour, strong and regular contractions
What are the signs of labour?
show (mucus plug from the cervix)
rupture of membranes
regular, painful contractions
dilating cervix on examination
How is prematurity classified?
<28 weeks = extreme preterm
28-32 weeks = very preterm
32-37 weeks = moderate to late preterm
What are the prophylactic options for preterm labour and who gets them?
vaginal progesterone = cervical length <25mm on vaginal US between 16 and 24 weeks
cervical cerclage (stitch in cervix under anaesthetic) = cervical length <25mm on vaginal US between 16-24 weeks, previous premature birth, cervical trauma
How is rupture of the membrane diagnosed?
speculum examination revealing pooling of amniotic fluid in the vagina
insulin-like growth factor-binding protein-1 or placental alpha-microglobin-1 (PAMG-1) can be performed to confirm
What is the management of preterm prelabour rupture of membranes?
prophylactic antibiotics to prevent chorioamnionitis = erythromycin for 10 days
induction of labour offered from 34 weeks
How is preterm labour with intact membranes diagnosed?
<30 weeks = clinical assessment
> 30 weeks = transvaginal US to assess the cervical length - cervical length <15 indicates preterm labour
foetal fibronectin is an alternative to US - <50ng/ml = preterm labour unlikely
What are the options for improving the outcomes in preterm labour?
foetal monitoring
tocolysis (use of medications to stop uterine contractions)
maternal corticosteroids offered before 35 weeks to reduce neonatal morbidity and mortality
IV magnesium sulphate before 34 weeks to protect the foetus’s brain
delayed cord clamping or cord milking to increase circulating blood volume and haemoglobin
What are the medications that are used in tocolysis?
1st line = nifedipine (CCB)
2nd line = atosiban (oxytocin receptor antagonist)
When is tocolysis used?
24-33+6 in preterm labour to delay delivery and buy time for further foetal development, administration of maternal steroids or transfer to a more specialist unit
only used for 48hrs max
When may induction of labour be offered?
41-42 weeks gestation
prelabour rupture of membranes
foetal growth restriction
pre-eclampsia
obstetric cholestasis
existing diabetes
intrauterine foetal death
What are the options for induction of labour?
membrane sweep
vaginal prostaglandin E2 (1st line)
cervical ripening ballon (2nd line)
artificial rupture of membranes with an oxytocin infusion (2nd line)
intrauterine foetal death = oral mifepristone plus misoprostol
What is the main complication of the induction of labour
uterine hyperstimulation
What are the criteria for uterine hyperstimulation?
individual uterine contractions lasting more than 2 minutes in duration
more than five uterine contractions every 10 minutes
What can uterine hyperstimulation lead to?
foetal compromise with hypoxia and acidosis
emergency C section
uterine rupture
What is the management of uterine hyperstimulation?
removing the vaginal prostaglandins or stopping the oxytocin infusion
tocolysis with terbutaline
What is cardiotocography (CTG) used to measure?
foetal heart rate
contractions of the uterus
What are the indications for continuous CTG monitoring during labour?
sepsis
maternal tachycardia (>120)
significant meoconium
pre-eclampsia
fresh antepartum haemorrhage
delay in labour
use of oxytocin
disproportionate maternal pain
What are the five key features to look for on a CTG?
contractions = number of uterine contractions per 10 minutes
baseline rate = baseline foetal heart rate
variability = how the foetal heart rate varies up and down around the baseline
accelerations = periods where the foetal heart rate spikes
decelerations = periods where the foetal heart rate drops
What are the reassuring, non-reassuring and abnormal baseline rates on a CTG?
reassuring = 110-160
non-reassuring = 100-109 or 161-180
abnormal = <100 or >180
What are is the reassuring, non-reassuring and abnormal variability on a CTG?
reassuring = 5-25
non-reassuring = <5 for 30-50 minutes or >25 for 15-25 minutes
abnormal = <5 for >50 minutes or >25 for <25 minutes
Why do decelerations occur?
foetal heart rate drops in response to hypoxia
What are early decelerations?
gradual dips and recoveries in foetal heart rate that correspond with uterine contractions - lowest point of the deceleration corresponds to the peak of the contraction
What causes early decelerations?
uterus compressing the foetal head - stimulates the vagus nerve - slows the heart rate
(not pathological)
What are late decelerations?
gradual falls in foetal heart rate that starts after the uterine contraction has begun - lowest point of deceleration occurs after the peak of the contraction
What causes late decelerations?
hypoxia in the foetus
can be due to:
excessive uterine contractions
maternal hypotension
maternal hypoxia
What are variable decelerations?
abrupt decelerations that may be unrelated to uterine contractions
fall of more than 15bpm from the baseline
lowest point occurs within 30 seconds and the decelerations lasts les than 2 minutes in total
What causes variable decelerations?
intermittent compression of the umbilical cord, causing foetal hypoxia
What is a reassuring sign in variable decelerations?
brief acceleration before and after the deceleration - known as shoulders - show that the foetus is coping
What are prolonged decelerations?
drop of more than 15bpm from baseline lasting between 2-10 minutes
What causes prolonged decelerations?
compression of the umbilical cord causing foetal hypoxia
What is the rule of 3 for prolonged foetal bradycardia?
3 minutes = call for help
6 minutes = move to theatre
9 minutes = prepare for delivery
12 minutes = deliver the baby by 15 minutes
What is a good structure for CTG interpretation?
DR C BRaVADO
Define Risk (risk based on the individual patient and pregnancy before assessing the CTG)
Contractions (duration, intensity, number in 10 minutes)
Baseline Rate (average foetal heart rate over 10 minutes)
Variability
Accelerations
Decelerations
Overall impression
What is one big square on a CTG chart equal to?
one minute
What is foetal tachycardia?
baseline heart rate >160bpm
What are the causes of foetal tachycardia?
foetal hypoxia
chorioamnionitis
hyperthyroidism
foetal or maternal anaemia
foetal tachyarrhythmia
What is foetal bradycardia?
baseline HR <110bpm
When is it common to have a baseline foetal heart rate of 100-120bpm?
postdate gestation
occiput posterior or transverse presentations
What is severe prolonged foetal bradycardia?
<80bpm for more than 3 minutes
What are the causes of prolonged severe foetal bradycardia?
prolonged cord compression
cord prolapse
epidural and spinal anaesthesia
maternal seizures
rapid foetal descent
What can cause reduced variability?
foetal sleeping (most common cause, shouldn’t last longer than 40 minutes)
foetal acidosis
foetal tachycardia
drugs - opiates, benzodiazepines, methyldopa, magnesium sulphate
prematurity
congenital heart abnormalities
What are the characteristics of a sinusoidal pattern on CTG?
smooth, regular, wave-like pattern
frequency of around 2-5 cycles a minute
stable baseline rate around 120-160bpm
no beat to beat variabilty
What does a sinusoidal pattern on CTG indicate?
severe foetal hypoxia
severe foetal anaemia
foetal or maternal haemorrhage
What are infusions of oxytocin used for?
induce labour
progress labour
improve the frequency and strength of uterine contractions
prevent or treat postpartum haemorrhage
What is the MOA of ergometrine?
stimulates smooth muscle contraction in the uterus and blood vessels
What is ergometrine used for?
during the third stage to deliver the placenta
postpartum to prevent and treat postpartum haemorrhage
(only used AFTER the delivery of the baby)
What are the side effects of ergometrine?
hypertension
diarrhoea
vomiting
angina
What are the contraindications to ergometrine?
eclampsia
hypertension (only used with significant caution)
What is syntometrine?
combination drug containing oxytocin (Syntocinon) and ergometrine
What can syntometrine be used for?
prevention or treatment of postpartum haemorrhage
What is a key prostaglandin to be aware of?
dinoprostone (prostaglandin E2)
What are the forms of dinoprostone?
vaginal pessaries (Propess)
vaginal tablets (Prostin tablets)
vaginal gel (Prostin gel)
What the MOA of nifedipine?
reduces smooth muscle contraction in blood vessels and the uterus
What are the main uses of nifedipine in pregnancy?
reduce blood pressure in hypertension and pre-eclampsia
tocolysis in premature labour - suppresses uterine activity and delays the onset of labour
What is the MOA of terbutaline?
beta-2-agonist - acts on the smooth muscle of the uterus to suppress uterine contractions
What is terbutaline used for?
tocolysis in uterine hyperstimulation - notably when the uterine contractions become excessive during induction of labour
What is the MOA of carboprost?
synthetic prostaglandin analogue - stimulates uterine contraction
What is carboprost used for?
deep IM injection in PPH where ergometrine and oxytocin have been inadequate
What is the contraindication to carboprost?
asthma
What is the MOA of tranexamic acid?
anti-fibrinolytic
binds to plasminogen and prevents it converting to plasmin
plasmin is an enzyme that works to dissolve the fibrin within blood clots
fibrin is a protein that helps hold blood clots together
prevents breakdown of blood clots