Labour and Delivery

Question 1

What is the definition of labour?

Answer 1

Painful, regular uterine contractions accompanied by the effacement and dilatation of the cervix

Question 2

How many stages is labour divided into?

What are these stages?

Answer 2

3 stages:

• First stage: initiation of regular, painful uterine contractions to full effacement and dilatation of the cervix
• Second stage: full effacement and dilatation of the cervix to delivery of the foetus
• Third stage: delivery of the foetus to delivery of the placenta

Question 3

What are the mechanical factors which determine the progress of labour?

Answer 3

The three P’s:

• Powers
• Passage
• Passenger

Question 4

What is meant by the ‘powers’?

Answer 4

The ‘powers’ refer to the uterine contractions

Question 5

What is meant by the ‘passage’?

Answer 5

The ‘passage’ refers to the bony pelvis and the soft tissues

Question 6

What is meant by the ‘passenger’?

Answer 6

The ‘passenger’ refers to the fetus and its attitude, position and the size of its head

Attitude:

• Degree of flexion/extension of the head
• Ideal = maximal flexion (vertex presentation)

Position:

• Degree of rotation of the head
• Ideal = OA

Size of the head:
- Sutures of skull allow compression of fetal head (‘moulding’)

Question 7

How is descent of the foetal head measured?

The level of descent is referred to as…

Answer 7

Descent is measured by comparison with the level of the ischial spines of the bony pelvis

The level of descent is referred to as the ‘station’

Question 8

1) What is meant by the term ‘lie’?

2) What are the different types?

Answer 8

1) ‘Lie’ is the relationship between the long axis of the mother and fetus
2) There are three different types: longitudinal, oblique and transverse

Question 9

1) What is meant by the term ‘presentation’?
2) What is the most common presentation?
3) Give some examples of other presentations

Answer 9

1) ‘Presentation’ refers to the fetal part that first enters the mother’s pelvis
2) Cephalic vertex (this is considered the safest)
3) Other presentations: cephalic brow/face, breech, shoulder

Question 10

Involuntary, irregular uterine contractions can sometimes be felt throughout the third trimester - what is the name of these contractions?

Answer 10

Braxton Hicks contractions

Question 11

How is perineal trauma classified?

Answer 11

• Classified as first, second, third or fourth degree tears
• First degree tear: damage to the fourchette
• Second degree tear (and episiotomies): involve perineal muscle
• Third degree tear: involve the anal sphincter also
• Fourth degree tears: involve the anal mucosa also

Question 12

Give some risk factors for abnormal lie, malpresentation and malposition

Answer 12

• Prematurity

- Multiple pregnancy

Question 13

Describe the identification, investigation and management of abnormal lie

Answer 13

Identification:
- Lie (longitudinal, transverse or oblique) can usually be detected on abdominal examination

Investigation:
- Confirmed by abdominal USS

Management:

• External cephalic version (ECV) between 36-38 weeks
• If unsuccessful, C-section

Question 14

Describe the identification, investigation and management of malpresentation

Answer 14

Identification:
- Presentation (cephalic or breech) can usually be detected on abdominal examination

Investigation:
- Confirmed by abdominal USS

Management:

• Breech: attempt ECV (36-38 weeks) if unsuccessful can try for vaginal breech delivery or C-section
• Other forms of malpresentation, e.g. cephalic brow/face, shoulder require C-section

Question 15

Describe the identification and management of malposition

Answer 15

Identification:
- Vaginal examination during labour

Management:

• Vast majority of malpositions spontaneously rotate to OA as labour progresses
• If the head does not spontaneously rotate, either instrumental delivery or C-section are required

Question 16

What is meant by prolonged rupture of membranes (PROM)?

Answer 16

Rupture of membranes lasting longer than 18-24 hours (i.e. between time of rupture and time of delivery)

Question 17

In a case of PROM, which investigations are required?

Answer 17

High vaginal swabs to detect infection (e.g. Group B strep which would indicate antibiotics during labour)

Question 18

Describe the management of PROM

Answer 18

• In the majority of cases, labour will start spontaneously

- If no sign of labour, induction is required

Question 19

What is the main complication of PROM?

Answer 19

Infection, e.g. chorioamnionitis

Question 20

What is the definition of preterm delivery?

Answer 20

Delivery occuring before 37 weeks gestation

Question 21

Give some risk factors for preterm delivery

Answer 21

• Previous preterm delivery
• Multiple pregnancy
• Pregnancy complications, e.g. pre-eclampsia, IUGR
• Infection, e.g. STIs, Group B strep, UTI

Question 22

What are the causes of slow progress in labour? (classified according to the mechanical factors)

Answer 22

Powers:
- Insufficient uterine activity (hypoactive uterus)

Passage:
- Cervical resistance (is cervix fully effaced/dilated?)

Passenger:

• Disorder of flexion (attitude)/malpresentation
• Malposition
• Fetal size too big (cephalopelvic disproportion) - this is rare

Question 23

i) What is the Bishop’s score?
ii) What are its components?
iii) How is the score interpreted?

Answer 23

i) The Bishop score is used to help assess whether induction of labour will be required

ii) Components:
- Cervical effacement
- Cervical dilatation
- Cervical position
- Cervical consistency
- Fetal station

iii) Interpretation:
- A score of < 5 indicates that labour is unlikely to start spontaneously (induction required)
- A score of > 9 indicates that labour is likely to start spontaneously

Question 24

1) Describe the process of induction of labour

2) Give some common indications for induction of labour

Answer 24

1)
- Membrane sweep
- Vaginal prostaglandins
- Artificial rupture of membranes
- Oxytocin

2)

• Prolonged pregnancy
• Prolonged labour
• Pregnancy complications, e.g. IUGR, pre-eclampsia, gestational diabetes

Question 25

What are the four features of a CTG trace?

Answer 25

Four features of foetal heart rate:

• Baseline rate
• Baseline variability
• Decelerations
• Accelerations

Question 26

CTG

1) What is the normal baseline heart rate?
2) Give a cause of fetal bradycardia
3) Give some causes of fetal tachycardia

Answer 26

1) 110-160 bpm
2) Maternal beta blocker use
3) Infection, hypoxia

Question 27

CTG

1) What is the normal baseline variability?
2) Give a cause of loss of baseline variability

Answer 27

1) 5-25 bpm

2) Hypoxia

Question 28

CTG

1) What is meant by ‘early decelerations’?
2) Early decelerations may indicate…

Answer 28

1) Deceleration of the heart rate which commences with the onset of a contraction and returns to normal on completion of the contraction
2) Head compression (harmless feature)

Question 29

CTG

1) What is meant by ‘late decelerations’?
2) Late decelerations may indicate…

Answer 29

1) Deceleration of the heart rate which lags behind the onset of a contraction and does not return to normal until after 30 seconds following completion of the contraction
2) Foetal distress

Question 30

CTG

1) What is meant by ‘variable decelerations’
2) Variable decelerations may indicate…

Answer 30

1) Deceleration of the heart rate which is independent of contractions
2) Cord compression