Induction_of_Labour_Flashcards

Question 1

What is induction of labour?

Answer 1

Induction of labour describes a process where labour is started artificially. It happens in around 20% of pregnancies.

Question 2

What are the indications for induction of labour?

Answer 2

Prolonged pregnancy (1-2 weeks after the estimated date of delivery), prelabour premature rupture of the membranes, maternal medical problems, diabetic mother > 38 weeks, pre-eclampsia, obstetric cholestasis, intrauterine fetal death.

Question 3

What is the Bishop score?

Answer 3

The Bishop score is used to help assess whether induction of labour will be required. It includes components such as cervical position, consistency, effacement, dilation, and fetal station.

Question 4

What does a Bishop score of < 5 indicate?

Answer 4

A score of < 5 indicates that labour is unlikely to start without induction.

Question 5

What does a Bishop score of ≥ 8 indicate?

Answer 5

A score of ≥ 8 indicates that the cervix is ripe, or ‘favourable’ - there is a high chance of spontaneous labour, or response to interventions made to induce labour.

Question 6

What are the possible methods for induction of labour?

Answer 6

Methods include membrane sweep, vaginal prostaglandin E2 (PGE2), oral prostaglandin E1 (misoprostol), maternal oxytocin infusion, amniotomy (‘breaking of waters’), and cervical ripening balloon.

Question 7

What is a membrane sweep?

Answer 7

A membrane sweep involves the examining finger passing through the cervix to rotate against the wall of the uterus, separating the chorionic membrane from the decidua. It is regarded as an adjunct to induction of labour.

Question 8

When should membrane sweeping be offered?

Answer 8

Nulliparous women are typically offered this at the 40- and 41-week antenatal visit, whereas parous women are offered it at the 41-week visit. It should be offered prior to formal induction of labour.

Question 9

What is vaginal prostaglandin E2 also known as?

Answer 9

Vaginal prostaglandin E2 is also known as dinoprostone.

Question 10

What is oral prostaglandin E1 also known as?

Answer 10

Oral prostaglandin E1 is also known as misoprostol.

Question 11

What does the NICE guideline recommend if the Bishop score is ≤ 6?

Answer 11

NICE guidelines recommend vaginal prostaglandins or oral misoprostol, or mechanical methods such as a balloon catheter if the woman is at higher risk of hyperstimulation or has had a previous caesarean.

Question 12

What does the NICE guideline recommend if the Bishop score is > 6?

Answer 12

NICE guidelines recommend amniotomy and an intravenous oxytocin infusion.

Question 13

What is the main complication of induction of labour?

Answer 13

The main complication of induction of labour is uterine hyperstimulation, which refers to prolonged and frequent uterine contractions.

Question 14

What are the potential consequences of uterine hyperstimulation?

Answer 14

Intermittent interruption of blood flow to the intervillous space may result in fetal hypoxemia and acidemia, and in rare cases, uterine rupture.

Question 15

What is the management for uterine hyperstimulation?

Answer 15

Management includes removing the vaginal prostaglandins if possible and stopping the oxytocin infusion if one has been started, and considering tocolysis.

Question 16

summarise induction of labour

Answer 16

Induction of labour

Induction of labour describes a process where labour is started artificially. It happens in around 20% of pregnancies.

Indications
prolonged pregnancy, e.g. 1-2 weeks after the estimated date of delivery
prelabour premature rupture of the membranes, where labour does not start
maternal medical problems
diabetic mother > 38 weeks
pre-eclampsia
obstetric cholestasis
intrauterine fetal death

Bishop score

The Bishop score is used to help assess whether induction of labour will be required. It has the following components:

0 1 2 3
Cervical position Posterior Intermediate Anterior -
Cervical consistency Firm Intermediate Soft -
Cervical effacement 0-30% 40-50% 60-70% 80%
Cervical dilation <1 cm 1-2 cm 3-4 cm >5 cm
Fetal station -3 -2 -1, 0 +1,+2

Interpretation
a score of < 5 indicates that labour is unlikely to start without induction
a score of ≥ 8 indicates that the cervix is ripe, or ‘favourable’ - there is a high chance of spontaneous labour, or response to interventions made to induce labour

Management

Possible methods
membrane sweep
involves the examining finger passing through the cervix to rotate against the wall of the uterus, to separate the chorionic membrane from the decidua
can be done by a midwife at the antenatal clinic. Nulliparous women are typically offered this at the 40- and 41-week antenatal visit, whereas parous women are offered it at the 41-week visit
membrane sweeping is regarded as an adjunct to induction of labour rather than an actual method of induction
prior to formal induction of labour, women should be offered a vaginal examination for membrane sweeping
vaginal prostaglandin E2 (PGE2)
also known as dinoprostone
oral prostaglandin E1
also known as misoprostol
maternal oxytocin infusion
amniotomy (‘breaking of waters’)
cervical ripening balloon
passed through the endocervical canal and gently inflated to dilate the cervix

NICE guidelines
if the Bishop score is ≤ 6
vaginal prostaglandins or oral misoprostol
mechanical methods such as a balloon catheter can be considered if the woman is at higher risk of hyperstimulation or has had a previous caesarean
if the Bishop score is > 6
amniotomy and an intravenous oxytocin infusion

Complications

Uterine hyperstimulation
the main complication of induction of labour
refers to prolonged and frequent uterine contractions - sometimes called tachysystole
potential consequences
intermittent interruption of blood flow to the intervillous space over time may result in fetal hypoxemia and acidemia
uterine rupture (rare)
management
removing the vaginal prostaglandins if possible and stopping the oxytocin infusion if one has been started
consider tocolysis

Question 17

A 32-year-old woman G1P0 currently at 41 weeks of gestation presents to the labour and delivery unit with infrequent contractions. This is her first pregnancy, and she has had an uncomplicated antenatal period. She attended all of her appointments and scans, and she already received a membrane sweep.

The midwife performs an assessment which shows a soft, intermediate cervix with 50% effacement and 2 cm dilated. The foetal station is -3. This accounts for a Bishop score of 5.

What is the most appropriate next step for this patient?

Amniotomy
Cervical ripening balloon
Oxytocin infusion
Terbutaline infusion
Vaginal prostaglandins

Answer 17

Vaginal prostaglandins

Vaginal PGE2 or oral misoprostol is the preferred method of induction of labour if the Bishop score is ≤ 6
Important for meLess important
The correct answer is vaginal prostaglandins. This patient is presenting at 41 weeks with some infrequent contractions and a Bishop score of 5, on a background of a normal first pregnancy. The Bishop score is used to help assess whether induction of labour will be required, and if it is 6 or less, the NICE guidelines suggest that labour should be induced using vaginal or oral prostaglandins. A membrane sweep can be used before to induce labour, but in this case, it has been trialled with no success, making vaginal prostaglandins the correct answer.

Amniotomy is incorrect. Also known as artificial rupture of membranes, this is a procedure where the midwife or obstetrician intentionally breaks the amniotic sac to stimulate labour contractions. It is not used as a first-line due to the increased risk of infection associated with it. It is usually considered if vaginal or oral prostaglandins and oxytocin infusion are ineffective.

Cervical ripening balloon is incorrect. This is used to mechanically dilate the cervix by inserting a deflated balloon into the cervical canal and inflating it to create pressure and dilation. It is not used as a first-line due to the increased risk of infection associated with it. It is usually considered if vaginal or oral prostaglandins and oxytocin infusion are ineffective or not tolerated.

Oxytocin infusion is incorrect. This is a hormone used to induce or augment labour contractions, but NICE guidelines suggest that it should be used in cases when the Bishop score is greater than 6, making it an incorrect option. Oxytocin infusion alone is not supported by NICE, it should always be offered in conjunction with amniotomy.

Terbutaline infusion is incorrect. This medication is a β‚‚ adrenergic receptor agonist which is used to decrease uterine contractility following uterine hyperstimulation. It is not used to induce labour, making this an incorrect option.

Question 18

A 27-year-old primiparous female is at 39 weeks gestation. A midwife examines the patient and determines her Bishop score to be 4. What does this mean?

The cervix is 4cm dilated
Labour is unlikely to start spontaneously
The baby will require specialist support
The baby is at a +4cm station
The cervix is ripe

Answer 18

Labour is unlikely to start spontaneously

The Bishop scoring system is used to assess the need for induction. It takes into account cervical characteristics (position, consistency, effacement and dilatation) and foetal station. A Bishop score less than 5 generally means induction will likely be necessary. A score above 9 indicates labour will likely occur spontaneously.

Question 19

A 23-year-old woman is being reviewed on the labour ward.

She is 39 weeks gestation. She felt her waters breaking 2 hours ago.

She is G1P0, has no had no complications throughout her pregnancy and has no significant past medical history.

On examination, her Bishop’s score is calculated as 10. A vaginal exam confirms that her amniotic sac has ruptured. There is no evidence of contractions yet. Foetal heart rate is reassuring at 140/min.

What is the most appropriate next step in her immediate management?

Insertion of a Cook balloon
Membrane sweep
Oxytocin infusion
Reassure and monitor
Vaginal prostaglandins

Answer 19

A Bishop’s score of ≥ 8 indicates that the cervix is ripe, or ‘favourable’ - there is a high chance of spontaneous labour, or response to interventions made to induce labour

This woman is presenting without signs of labour commencing yet, but her amniotic sac has ruptured. Her Bishop’s score can be used to determine whether or not labour is likely to start spontaneously, with a score of 8 or above suggesting that the cervix is ripe and spontaneous labour is likely. Therefore, in this case, there is no reason to begin interventions to accelerate labour. The most appropriate option is to reassure and monitor since labour is very likely to begin soon.

Insertion of a Cook balloon is incorrect. This is a way to mechanically induce labour and ripen the cervix, by inserting a balloon above the cervix and inflating with saline. The pressure of the balloon helps make the cervix more favourable. However, a Bishop’s score of 10 would suggest this is not required.

A membrane sweep is incorrect. This can be done to loosen the amniotic sac from the uterine wall, encouraging membrane rupture. However, in this case, the amniotic sac has already ruptured, and therefore a membrane sweep is not possible.

A oxytocin infusion is incorrect. Oxytocin is used to encourage or strengthen contractions. It is not advised for first-line use in the induction of labour. Equally, there has not been enough time given to see if contractions may start on their own, and so any form of induction is inappropriate.

Vaginal prostaglandins are incorrect. This is the most appropriate method used to induce labour. However, there is a high probability of labour happening spontaneously and therefore induction is not needed at this stage.