Intrapartum Science Flashcards

1
Q

What is labour known as?

A

Parturition

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2
Q

How many stages of labour are there?

A

3

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3
Q

What are 2 considerations for the retrospective detection of labour?

A
  1. Cervical dilatation
  2. Cervical effacement
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4
Q

What are the 3 stages of labour?

A

Stage 1: Latent + active phase
Stage 2: propulsive + expulsive phase
Stage 3: Delivery of the placenta

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5
Q

What happens during stage 1 of labour?

A

Effacement and dilatation of the cervix up to full dilatation - 10 cm. Divided into:
- Latent phase (dilatation up to 4cm)
- Active phase (dilatation from 4cm onwards)

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6
Q

What happens during stage 2 of labour?

A

Stage 2 is from full cervical dilatation to delivery of the foetus. Is divided into:
1. Propulsive phase
2. Expulsive phase

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7
Q

What is considered a delay in the expulsive phase?

A

Delay is defined if the expulsive phase lasts >2hrs in nulliparous and >1 hour in multiparous women

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8
Q

What happens in the 3rd phase of labour?

A

Delivery of the placenta?

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9
Q

What is the curve of carus?

A

The angulation of the birth canal.

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10
Q

What is the mechanism of labour?

A
  • Engagement
  • Descent of fetal head to below the ishcial spines and flexion
  • Fetal head rotation to the occipito-anterior position, shoulders enter pelvis
  • Extension and delivery of fetal head
  • Restitution
  • Delivery of shoulders and rest of body
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11
Q

What happens during engagement?

A
  1. The transvers/oblique diameter of the fetal head enters the pelvic brim
  2. Asynclitism occurs prior to engagement
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12
Q

What are disorders of labour?

A
  1. Labour dystocia
  2. Breech presentation
  3. Shoulder dystocia
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13
Q

What are the 3 described patterns of labour dystocia?

A
  1. Prolonged latent phase
  2. Primary dysfunctional labour
  3. Secondary arrest
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14
Q

Key facts about prolonged latent phase

A
  • Incidence: 3.5% in nulliparous women
  • Relates to delayed cervical ripening
  • Augmentation with oxytocin is not beneficial
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15
Q

Key facts about primary dysfunctional labour

A
  • Is cervical dilatation slower than 1cm/hr during the active phase of stage 1 of labour
  • Incidence = 26% in nulliparous women and 8% in multiparous women
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16
Q

Key facts about secondary arrest

A
  • Incidence 6% in nulliparous women and 2% in multiparous women
  • Usually linked with fetal malposition
17
Q

Incidence of breech presentation

A

28 weeks = 30%
Term = 3%

18
Q

Pregnancy related causes of breech presentation

A
  • Increased parity
  • Multiple pregnancy
  • Prematurity
19
Q

Fetal structural abnormality related causes of breech presentation

A
  • Hydrocephalus
  • myelomeningocoele
20
Q

Fetal growth abnormality related causes of breech presentation

A
  • FGR
  • Oligohydramnios
  • Polyhydramnios
21
Q

Placental abnormality related causes of breech presentation

A
  • Placenta praevia
  • Short umbilical cord
22
Q

Uterine abnormality related to breech presentation

A
  • Bicornuate uterus
23
Q

Pelvic abnormality related to breech presentation

A

Contracted pelvis

24
Q

Types of breech

A
  1. Extended (or frank breech) = 60-70%
  2. Flexed (or complete breech)
  3. Footling
25
Q

Fetal risks of vaginal breech delivery

A
  1. Intracranial haemorrhage
  2. Brachial plexus injury
  3. Limb fractures
  4. Spinal cord injury
26
Q

Reasons for predominance of cephalic presentation

A
  1. Piriform shape of uterus
  2. Calcification of fetal skull (increased skull density).
27
Q

What is shoulder dystocia?

A

Occurs when there is failure of the shoulders to deliver with gentle downwards traction on the fetal head.

28
Q

Incidence of shoulder dystocia

A

0.6%

29
Q

Which shoulder is commonly involved in shoulder dystocia?

A

Anterior shoulder

30
Q

What are the signs of shoulder dystocia?

A

External rotation failure
Turtle necking

31
Q

In shoulder dystocia how can fetal distress be caused?

A

Due to a reduction in oxygen supply caused by:
1. Uterine contraction
2. Fetal chest compression

32
Q

What are fetal complications caused by shoulder dystocia?

A

Asphyxia
Brachial plexus injury
Fracture of clavicle (in 15%) and humerus (in 1%)

33
Q

Brachial plexus injury

A

Occurs in 10% of shoulder dystocia
Premanent neurological damage occurs in 10% of brachial plexus injury
Caesarean section does not eliminate the risk of brachial plexus injury

34
Q

What are the risk factors of shoulder dystocia?

A

Fetal macrosomia
Maternal diabetes
Maternal obesity
Previous shoulder dystocia
Prolonged labour
Instrumental delivery

35
Q

Percentage of shoulder dystocia in fetuses <4kg

A

48%

36
Q

What percentage of shoulder dystocia is predicted by conventional risk factors?

A

15%

37
Q

How many C sections need to be performed to prevent 1 permanent neurological injury from shoulder dystocia?

A

2300

38
Q

What is the recurrence rate of shoulder dystocia?

A

15%

39
Q

What is the rate of fetal pH dropping in shoulder dystocia?

A

0.04/min