Induction of labour

Question 1

Definition and Features

Induction of labor

Answer 1

artificially initiating uterine activity when the risks of continuing pregnancy overcome those of labor.

Features

• Perinatal mortality rate doubles after 42 weeks and triples after 43 weeks

• Maternal discomfort is also to be considered as some mothers will prefer induction

• Artificial rupture of membranes (AROM) after >40 weeks reduces the necessity for induction

Question 2

Induction of labor

Indications

Answer 2

Prolonged pregnancy (>42 weeks or 294 days)

Pre-eclampsia,

HELLP,

eclampsia

Placental insufficiency

Diabetes mellitus

Chronic renal disease

Placental abruption

Rh immunization

Maternal request at termIntrauterine death

Question 3

Induction of labor

Contraindications

Answer 3

1. History of uterine rupture; previouscesarean section
2. Placenta previa
3. Vasa previa
4. Transverse fetal lie
5. Cord prolapse
6. Nonreassuring fetal heart rate

Question 4

Cervical assessment

Answer 4

1. Cervical assessment and likelihood for successful induction using Bishop score.
2. Score above 6 is favorable for induction while less than 5 indicates the need for cervical ripening.

Question 5

Cervical assessment points

Answer 5

Question 6

Methods of induction of labor

Answer 6

1. Method is determined according to whether the membranes are intact and the bishop score.
2. Surgical AROM:

a. Forewater rupture

i. Done under aseptic conditions.

ii. Cervix should be soft, effaced and at least 2cm dilated

iii. Presenting part should be head (vertex) and engagediv.

Mother is supine and → finger introduced to cervix → fetal membranes are separated from lower segment (process called “stripping the membranes”) →membranes are ruptured with forceps (Kocher or Gelder amniotomy forceps).

v. FHR should be monitored 30 minutes before procedure.

Hindwater rupture (rarely used)

i. Sigmoid shape cannula (Drewe-Smythe catheter) penetrates the membranes through the cervix behind presenting part.

Balloon catheter – used for cervical ripening where balloon distends the cervix over a period of 12 hours and then removed to allow amniotomy.

Question 7

Pharmacological AROM and labor induction

Answer 7

a. Usually follows the surgical method of labor induction or used when surgical methods are unsuitable.

b. Aim is to reach 3-4 uterine contraction each lasting >40 second in every 10 minutes.

c. Syntocinon infusion – medical induction (more efficient when combined with surgical induction).

d. Prostaglandins

i. Used to ripen the cervix

ii. Orally – 0.5mg increased to 2mg per hour until contractions achieved

iii. Vaginally – gel or pessary. 1-2mg every 6 hours (4mg as the total maximum daily) until contraction achieved.

e. Complications:

i. Hyperstimulation – too many uterine contractions hinder blood flow and can result in fetal asphyxia

ii. Cord prolapse – examined by CTG monitoring for 30 minutes before and after forewater rupture looking for deceleration signs.

iii. Infection – maternal fever or stained amniotic fluid may appear.