Week 5 part 1 Flashcards
Rupture of membranes (ROM):
The amniotic sac has ruptured.
Spontaneous rupture of membranes (SROM):
The amniotic sac has ruptured spontaneously
Prolonged rupture of membranes (also PROM):
The amniotic sac ruptures more than 18 hours before delivery.
Prematurity
Prematurity is defined as birth before 37 weeks gestation. The more premature the baby, the worse the outcomes
The World Health Organisation classify prematurity as:
- Under 28 weeks: extreme preterm
- 28 – 32 weeks: very preterm
- 32 – 37 weeks: moderate to late preterm
Prophylaxis of Preterm Labour options
Vaginal Progesterone
Cervical Cerclage
Vaginal Progesterone
Progesterone can be given vaginally via gel or pessary as prophylaxis for preterm labour. Progesterone has a role in maintaining pregnancy and preventing labour by decreasing activity of the myometrium and preventing the cervix remodelling in preparation for delivery. This is offered to women with a cervical length less than 25mm on vaginal ultrasound between 16 and 24 weeks gestation.
Cervical Cerclage
Cervical cerclage involves putting a stitch in the cervix to add support and keep it closed. This involves a spinal or general anaesthetic. The stitch is removed when the woman goes into labour or reaches term.
Cervical cerclage is offered to women with a 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).
“Rescue” cervical cerclage may also be offered between 16 and 27 + 6 weeks when there is cervical dilatation without rupture of membranes, to prevent progression and premature delivery.
Diagnosis of Preterm Prelabour Rupture of Membranes
Speculum examination revealing pooling of amniotic fluid in the vagina. No tests are required.
Management of Preterm Prelabour Rupture of Membranes
Prophylactic antibiotics should be given to prevent the development of chorioamnionitis. The NICE guidelines (2019) recommend erythromycin 250mg four times daily for ten days, or until labour is established if within ten days.
Induction of labour may be offered from 34 weeks to initiate the onset of labour.
Preterm Labour with Intact Membranes
Preterm labour with intact membranes involves regular painful contraction and cervical dilatation, without rupture of the amniotic sac.
Diagnosis of Preterm Labour with Intact Membranes
Clinical assessment includes a speculum examination to assess for cervical dilatation. The NICE guidelines (2017) recommend:
• 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.
Fetal fibronectin
An alternative test to vaginal ultrasound. Fetal fibronectin is the “glue” between the chorion and the uterus, and is found in the vagina during labour. A result of less than 50 ng/ml is considered negative, and indicates that preterm labour is unlikely.
Tocolysis
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 can tocolysis be 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).
Antenatal Steroids
Giving the mother corticosteroids helps to develop the fetal lungs and reduce respiratory distress syndrome after delivery. They are used in women with suspected preterm labour of babies less than 36 weeks gestation.
An example regime would be two doses of intramuscular betamethasone, 24 hours apart.
Magnesium Sulfate
Giving the mother IV magnesium sulfate helps protect the fetal brain during premature delivery. It reduces the risk and severity of cerebral palsy. Magnesium sulphate is given within 24 hours of delivery of preterm babies of less than 34 weeks gestation. It is given as a bolus, followed by an infusion for up to 24 hours or until birth.
Magnesium toxicity symptoms
Mothers need close monitoring for magnesium toxicity at least four hourly. This involves close monitoring of observations, as well as tendon reflexes (usually patella reflex). Key signs of toxicity are:
• Reduced respiratory rate
• Reduced blood pressure
• Absent reflexes
The Bishop score
The Bishop score is a scoring system used to determine whether to induce labour.
Five things are assessed and given a score based on different criteria (minimum score is 0 and maximum is 13):
• Fetal station (scored 0 – 3)
• Cervical position (scored 0 – 2)
• Cervical dilatation (scored 0 – 3)
• Cervical effacement (scored 0 – 3)
• Cervical consistency (scored 0 – 2)
What bishop score predicts a successful induction of labor?
A score of 8 or more predicts a successful induction of labour. A score below this suggests cervical ripening may be required to prepare the cervix.
There are two means for monitoring during the induction of labour; what are they?
- Cardiotocography (CTG) to assess the fetal heart rate and uterine contractions before and during induction of labour
- Bishop score before and during induction of labour to monitor the progress
Uterine hyperstimulation
Uterine hyperstimulation is the main complication of induction of labour with vaginal prostaglandins. This is where the contraction of the uterus is prolonged and frequent, causing fetal distress and compromise.
The criteria for uterine hyperstimulation varies slightly between guidelines (always check local policies and involve experienced seniors). The two criteria often given are:
- Individual uterine contractions lasting more than 2 minutes in duration
- More than five uterine contractions every 10 minutes
Uterine hyperstimulation can lead to:
- Fetal compromise, with hypoxia and acidosis
- Emergency caesarean section
- Uterine rupture
Management of Uterine hyperstimulation
- Removing the vaginal prostaglandins, or stopping the oxytocin infusion
- Tocolysis with terbutaline
Cardiotocography (CTG)
Used to measure the fetal heart rate and the contractions of the uterus. It is also known as electronic fetal monitoring. It is a useful way of monitoring the condition of the fetus and the activity of labour.
CTG can help guide decision making and delivery. However, it should not be used in isolation for decision making, and it is essential to take into account the overall clinical picture.
The indications for continuous CTG monitoring in labour include:
- 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
Accelerations in CTG monitoring
Accelerations are generally a good sign that the fetus is healthy, particularly when occurring alongside contractions of the uterus.
Decelerations in CTG monitoring
Decelerations are a more concerning finding. The fetal heart rate drops in response to hypoxia. The fetal heart rate is slowing to conserve oxygen for the vital organs. There are four types of decelerations to be aware of: • Early decelerations • Late decelerations • Variable decelerations • Prolonged decelerations
Early decelerations
Early decelerations are gradual dips and recoveries in heart rate that correspond with uterine contractions. 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.
Variable decelerations
Variable decelerations are abrupt decelerations that may be unrelated to uterine contractions.
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
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
The four categories for CTG are:
- 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
Fetal Bradycardia
There is a “rule of 3’s” for fetal bradycardia when they are prolonged:
• 3 minutes – call for help
• 6 minutes – move to theatre
• 9 minutes – prepare for delivery
• 12 minutes – deliver the baby (by 15 minutes)
A sinusoidal CTG
A sinusoidal CTG is a rare pattern to be aware of, as it can indicate severe fetal compromise. It gives a pattern similar to a sine wave, with smooth regular waves up and down that have an amplitude of 5 – 15 bpm. It is usually associated with severe fetal anaemia, for example, caused by vasa praevia with fetal haemorrhage.
Ergometrine
It stimulates smooth muscle contraction, both in the uterus and blood vessels. This makes it useful for delivery of the placenta and to reduce postpartum bleeding. It may be used during the third stage of labour (delivery of the placenta) and postpartum to prevent and treat postpartum haemorrhage. It is only used after delivery of the baby, not in the first or second stage.
Syntometrine
Syntometrine is a combination drug containing oxytocin (Syntocinon) and ergometrine. It can be used for prevention or treatment of postpartum haemorrhage.
Nifedipine
Nifedipine is a calcium channel blocker that acts to reduce smooth muscle contraction in blood vessels and the uterus. It has two main uses in pregnancy:
• Reduce blood pressure in hypertension and pre-eclampsia
• Tocolysis in premature labour, where it suppresses uterine activity and delays the onset of labour
Terbutaline
Terbutaline is a beta-2 agonist, similar to salbutamol. It stimulates beta-2 adrenergic receptors. It acts on the smooth muscle of the uterus to suppress uterine contractions. It is used for tocolysis in uterine hyperstimulation, notably when the uterine contractions become excessive during induction of labour.
Carboprost
Carboprost is a synthetic prostaglandin analogue, meaning it binds to prostaglandin receptors. It stimulates uterine contraction. It is given as a deep intramuscular injection in postpartum haemorrhage, where ergometrine and oxytocin have been inadequate. Notably, it needs to be avoided or used with particular caution in patients with asthma, as it can cause a potentially life-threatening exacerbation of the asthma.
What are the three phases of the 1st stage of labour?
- Latent phase – from 0 to 3cm dilation of the cervix. This progresses at around 0.5cm per hour. There are irregular contractions.
- Active phase – from 3cm to 7cm dilation of the cervix. This progresses at around 1cm per hour, and there are regular contractions.
- Transition phase – from 7cm to 10cm dilation of the cervix. This progresses at around 1cm per hour, and there are strong and regular contractions.
Partogram
Women are monitored for their progress in the first stage of labour using a partogram. It is worth becoming familiar with partograms and how they are recorded.
Uterine contractions
Uterine contractions are measure in contractions per 10 minutes. When the midwife says “she is contracting 2 in 10”, it means she is having 2 uterine contractions in a 10 minute period.
The main options for managing failure to progress are:
- Amniotomy, also known as artificial rupture of membranes (ARM) for women with intact membranes
- Oxytocin infusion
- Instrumental delivery
- Caesarean section
Pethidine and diamorphine
Pethidine and diamorphine are opioid medications, usually given by intramuscular injection. They may help with anxiety and distress. They may cause drowsiness or nausea in the mother, and can cause respiratory depression in the neonate if given too close to birth. The effect on the baby may make the first feed more difficult.
