99. labour Flashcards
Stages of labour?
Latent phase: irregular contractions, mucous plug, cervix beginning to efface up to 4cm
First stage: strong regular uterine contractions, cervical dilatation up to 10cm
Second stage: from full dilation to delivery of baby
Third stage: from birth of baby to expulsion of placenta
Define labour
regular painful contractions with cervical changes
mechnism of labour
Descent
Flexion
Internal rotation
Extension
Restitution
External rotation
Delivery of body
cardinal movements of labour
Descent
Flexion
Internal rotation
Extension
Restitution
External rotation
Delivery of body
Ideal foetal position
occiput anterior
left occiput anterior is ideal
entonox
gas and air
Gas and air contains a mixture of 50% nitrous oxide and 50% oxygen. This is used during contractions for short term pain relief.
IM diamorphine vs IM pethidine
Pethidine shorter
Diamorphine longer and more powerful
Braxton-Hicks Contractions
occasional irregular contractions of the uterus. They are usually felt during the second and third trimester.
Diagnosing labour
Show (mucus plug from the cervix) clear or bloody show
Rupture of membranes
Regular, painful contractions
Dilating cervix on examination
Active management of the third stage
intramuscular oxytocin
Rupture of membranes (ROM)
The amniotic sac has ruptured.
Spontaneous rupture of membranes (SROM)
The amniotic sac has ruptured spontaneously
Prelabour rupture of membranes (PROM)
The amniotic sac has ruptured before the onset of labour.
Preterm prelabour rupture of membranes (P‑PROM)
The amniotic sac has ruptured before the onset of labour and before 37 weeks gestation (preterm).
Prolonged rupture of membranes (also PROM)
The amniotic sac ruptures more than 18 hours before delivery.
cervical length less than 25mm on vaginal ultrasound between 16 and 24 weeks gestation
vaginal progesterone to maintain pregnancy
cervical length less than 25mm on vaginal ultrasound between 16 and 24 weeks gestation, who have had a previous premature birth or cervical trauma (e.g. colposcopy and cone biopsy)
Cervical cerclage
Complications of PPROM
fetal: prematurity, infection, pulmonary hypoplasia
maternal: chorioamnionitis
Investigation PPROM (premature, prelabour)
A sterile speculum examination should be performed (to look for pooling of amniotic fluid in the posterior vaginal vault)
but digital examination should be avoided due to the risk of infection.
Ultrasound may also be useful to show oligohydramnios.
Management PPROM prolonged
- admission
- regular observations to ensure chorioamnionitis is not developing
- oral erythromycin should be given for 10 days 250mg four times daily
- antenatal corticosteroids should be administered to reduce the risk of respiratory distress syndrome
- delivery should be considered at 34 weeks of gestation - there is a trade-off between increased risk of maternal chorioamnionitis with a decreased risk of respiratory distress syndrome as the pregnancy progresses
Preterm labour with intact membranes
regular painful contraction and cervical dilatation, without rupture of the amniotic sac.
Tests if diagnostic doubt about PPROM premature prelabour
Insulin-like growth factor-binding protein-1 (IGFBP-1)
Diagnosis of preterm labour with intact membranes
Less than 30 weeks gestation, clinical assessment alone is enough to offer management of preterm labour.
More than 30 weeks gestation, a transvaginal ultrasound can be used to assess the cervical length. When the cervical length on ultrasound is less than 15mm, management of preterm labour can be offered. A cervical length of more than 15mm indicates preterm labour is unlikely.
Tocolysis
involves using medications to stop uterine contractions. Nifedipine, a calcium channel blocker, is the medication of choice for tocolysis. Atosiban is an oxytocin receptor antagonist that can be used as an alternative when nifedipine is contraindicated.
When is tocolysis used
Tocolysis can be used between 24 and 33 + 6 weeks gestation in preterm labour to delay delivery and buy time for further fetal development, administration of maternal steroids or transfer to a more specialist unit (e.g. with a neonatal ICU). It is only used as a short term measure (i.e. less than 48 hours).
Bishop score
scoring system used to determine whether to induce labour
Score of 8 or more on bishop score
predicts a successful induction of labour. A score below this suggests cervical ripening may be required to prepare the cervix.
Options for induction of labour
- membrane sweep
- vaginal prostaglandin E2
- Cervical ripening balloon
- Artificial rupture of membranes
complication of induction of labour with vaginal prostaglandins?
Uterine hyperstimulation
Criteria for uterine hyperstimulation
Individual uterine contractions lasting more than 2 minutes in duration
More than five uterine contractions every 10 minutes
Management uterine hyperstimulation
Removing the vaginal prostaglandins, or stopping the oxytocin infusion
Tocolysis with terbutaline
Indications for continuous CTG monitoring
Sepsis
Maternal tachycardia (> 120)
Significant meconium
Pre-eclampsia (particularly blood pressure > 160 / 110)
Fresh antepartum haemorrhage
Delay in labour
Use of oxytocin
Disproportionate maternal pain
5 key features to look for in CTG
Contractions – the number of uterine contractions per 10 minutes
Baseline rate – the baseline fetal heart rate
Variability – how the fetal heart rate varies up and down around the baseline
Accelerations – periods where the fetal heart rate spikes
Decelerations – periods where the fetal heart rate drops
Reassuring baseline rate and variability
110-160
5-25
Non-reassuring base line rate and variability
100-109 or 160-180
<5 for 30-50 mins
> 25 for 15-25 mins
Abnormal baseline rate and variability
<100 or >180
Less than 5 for over 50 minutes or
More than 25 for over 25 minutes
what are accelerations a sign of?
Accelerations are generally a good sign that the fetus is healthy, particularly when occurring alongside contractions of the uterus
Early decelerations
gradual dips and recoveries in heart rate that correspond with uterine contractions. The lowest point of the declaration corresponds to the peak of the contraction. Early decelerations are normal and not considered pathological. They are caused by the uterus compressing the head the fetus, stimulating the vagus nerve of the fetus, slowing the heart rate.
Late decelerations
are gradual falls in heart rate that starts after the uterine contraction has already begun. There is a delay between the uterine contraction and the deceleration. The lowest point of the declaration occurs after the peak of the contraction. Late decelerations are caused by hypoxia in the fetus, and are a more concerning finding. They may be caused by excessive uterine contractions, maternal hypotension or maternal hypoxia.
urgent fetal blood sampling
Variable decelerations
abrupt decelerations that may be unrelated to uterine contractions. There is a fall of more than 15 bpm from the baseline. The lowest point of the declaration occurs within 30 seconds, and the deceleration lasts less than 2 minutes in total. Variable decelerations often indicate intermittent compression of the umbilical cord, causing fetal hypoxia. Brief accelerations before and after the deceleration are known as shoulders, and are a reassuring sign that the fetus is coping.
Prolonged decelerations
last between 2 and 10 minutes with a drop of more than 15 bpm from baseline. This often indicates compression of the umbilical cord, causing fetal hypoxia. These are abnormal and concerning.
4 types of decelerations
early
late
variable
prolonged
A CTG is normal with respect to decelerations when…
no decelerations, early decelerations or less than 90 minutes of variable decelerations with no concerning features.
Four categories of CTG?
Normal
Suspicious: a single non-reassuring feature
Pathological: two non-reassuring features or a single abnormal feature
Need for urgent intervention: acute bradycardia or prolonged deceleration of more than 3 minutes