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OBGYN 4MB > The Stages Of Labour And Normal Delivery > Flashcards

The Stages Of Labour And Normal Delivery Flashcards

Mechanism, management and special circumstances

1
Q

Define Term

A

A baby born at 37 to 42 weeks gestation

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2
Q

What is the working definition of labour?

A

Painful uterine contractions accompanied by dilatation and effacement of the cervix

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3
Q

Define the first stage of labour

A

Initiation of labour to full cervical dilatation

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4
Q

Define the second stage of labour

A

Full cervical dilatation to delivery of the fetus

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5
Q

Define he third stage of labour

A

Delivery of the fetus to delivery of the placenta

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6
Q

List the 3 mechanical factors of labour

A
  1. Degree of force expelling the fetus (powers)
  2. Dimensions of the pelvis and the resistance of soft tissues (passage)
  3. Diameters of the fetal head (passenger)

“3 Ps”

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7
Q

What are the risk factors for poor uterine activity

A
  1. Nulliparity

2. Induced labour

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8
Q

What is the level of descent of the fetal head and how is it measured?

A
  • Level of descent called stations and measured by level in relation to ischial spines:
  • Station 0 = level of spines
  • Station +2 = 2cm below spines
  • Station -2 = 2cm above spines
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9
Q

How can the passage impact delivery?

A
  1. The bony pelvis:
    - Inlet transverse > AP
    - midcavity transverse = AP
    - outlet AP > transverse
  2. Soft tissues:
    - Cervical dilatation - depends on contractions, pressure of fetal head, ability of cervix to soften and allow distension
    - soft tissues of vagina and perineum
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10
Q

Define attitude

A

Degree of flexion of the fetal head on the neck

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11
Q

What is the ideal attitude for normal delivery?

A

Maximal flexion, vertex presentation, presenting diameter 9.5cm

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12
Q

How does extension of the fetal head affect the presentation?

A

Small extension leads to a larger diameter

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13
Q

List the types of presentation the fetus can have in labour

A
  1. Vertex
  2. Brow
  3. Face
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14
Q

Define position of the head in labour

A

Degree of rotation of the head in the neck

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15
Q

Describe how the head rotates during labour

A
  • Saggital suture transverse head fits in pelvic inlet best
  • Saggital suture vertical head fits in outlet best
  • Head must rotate 90 degrees during labour
  • Usually delivered with the occiput anterior
  • More difficult to deliver if position occiput posterior and needs assistance for delivery if position occiput transverse
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16
Q

What hormones are produced during labour and what is their function?

A
  1. Prostaglandin:
    - decrease cervical resistance
    - increase release of oxytocin from posterior pituitary
  2. Oxytocin:
    - aids stimulation of contractions
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17
Q

Define effacement

A

When the normally tubular cervix is drawn up into lower segment until flat

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18
Q

What are the phases of the first stage of labour?

A
  1. Latent phase - cervix dilates slowly for first 4cm

2. Active phase - follows latent phase

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19
Q

What is the cervical dilatation rate?

A

1cm/hr nulliparous

2cm/hr multiparous

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20
Q

What are the phases of the second stage of labour?

A
  1. Passive stage - full!l dilatation until head reaches pelvic floor and woman experiences desire to push
  2. Active stage - when mother is pushing
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21
Q

Describe the moment of delivery

A
  • Head reaches perineum and extends to come out of the pelvis
  • Perineum stretches and often tears
  • Head adopts transverse position to deliver the shoulders
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22
Q

What is the normal length and blood loss for third stage of labour?

A

Length roughly 15mins

Blood loss roughly 500ml

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23
Q

Describe the different degrees of perineal tears

A

First degree tear = minor damage to fourchette
Second degree tear and episiotomies = involve perineal muscle
Third degree tears = involve anal sphincter
Fourth degree tears = involve anal mucosa

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24
Q

What observations need to be done in labour?

A
  1. Temp and BP every 4hrs
  2. Pulse every hour in first stage and every 15mins in second stage
  3. Contraction frequency every 30mins

Do more frequently if abnormal

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25
Q

Comment on mobility and position, hydration and eating in labour

A
  • Freedom of movement encouraged, avoid supine position
  • Encourage to drink isotonic drinks or water
  • IV fluids may be necessary if prolonged
  • Eating is appropriate, contents can be aspirated if GA required
  • Eating discouraged if labour high risk
  • Ranitidine given to decrease stomach acidity
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26
Q

How do we manage pyrexia in labour?

A
  • Defined as temp >37.5
  • More common with epidural and prolonged labour
  • Cultures of vagina, urine and blood taken
  • Give paracetamol
  • IV antibiotics and CTG monitoring if fever ≥38
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27
Q

How do we manage urine output during labour?

A
  • Encourage to micturate frequently

- Catheterisation may be needed if epidural

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28
Q

What measures can be taken to reduce anxiety for the mother during labour?

A
  1. Ensure nice environment
  2. Birth attendent for continuous support
  3. Include the partner - important potential source of support but may also need support
  4. Give patient control - birth plan
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29
Q

What is a partogram used for?

A

Used to record progress in dilatation of the cervix and descent of the head
Assessed on VE and plotted against time
Alert and Action lines indicate slow progress

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30
Q

Define slow progress in stage one

A

Slow progress is diagnosed if <2cm dilatation in 4hrs

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31
Q

What problems with the powers can cause slow progress?

A
  1. Inefficient uterine contraction - most common cause; nulliparous and induced labour
    - Persistently slow tx is augmentation - first amniotomy and then oxytocin
  2. Hyperactive uterine contraction - associated with placental abruption, too much oxytocin or SE of induction
    - Tx depends on cause - tocolytic given IV or subcut if no sign of abruotion; C-section often indicated due to fetal distress
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32
Q

How is slow progress managed in a nulliparous labour?

A

FIRST STAGE

  1. Augmentation:
    - ARM
    - Oxytocin if ARM fails to further cervical dilatation in 2hrs
    - Use electronic fetal monitoring
    - Full dilatation not imminent within 12-16hrs = C-SECTION

PASSIVE SECOND STAGE

  • Start oxytocin infusion if poor descent
  • Pushing not encouraged until feel urge
  • Urge diminished with epidural

ACTIVE SECOND STAGE

  • Direct pushing if ineffective or epidural present
  • Stage longer than 1-2hrs spontaneous delivery less likely due to maternal exhaustion
  • INSTRUMENTAL DELIVERY
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33
Q

How is slow progress managed in a multiparous labour?

A

FIRST STAGE

  • Exclude malpresentation of fetus
  • Augment with oxytocin CAREFULLY - more prone to rupture

SECOND STAGE

  • Oxyticin should not be started for the first time
  • Caution with instrumental delivery
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34
Q

What issues with the fetus can contribute to slow progress?

A
  1. OP position - labour longer and more painful; use augmentation for slow progress; prolonged active second stage use instrumental delivery with rotation to OA position
  2. OT position - only significant if vaginal delivery not achieved after 1hr of pushing in 2nd stage; rotation with traction required for delivery (ventouse)
  3. Brow presentation - caesarean section required; anterior fontanelle, supraorbital ridges and nose palpable
  4. Face presentation - mouth, nose and eyes palpable; vaginal delivery in most cases if chin anterior to allow extension over oerineum; C-section if chin posterior
  5. Fetal abnormality - hydrocephalus, breech presentation, transverse or oblique lie
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35
Q

List the causes of damage to the fetus during labour

A
  1. Fetal hypoxia (distress)
  2. Infection/inflammation in labour
  3. Medium aspiration
  4. Trauma (usually due to obstetric intervention)
  5. Fetal blood loss
36
Q

Define fetal distress and hypoxia

A
  • Hypoxia that might result in fetal damage or death if not reversed of the fetus urgently delivered
  • pH <7.2 in fetal scalp blood sample indicates significant hypoxia
  • pH <7 neurological damage more common
37
Q

List the causes of acute hypoxia

A
  1. Placental abruption
  2. Hypertonic uterus states and use of oxytocin
  3. Prolapse of umbilical cord
  4. Maternal hypotension
38
Q

List the intrapartum risk factors for fetal dustress

A
  1. Long labour
  2. Meconium
  3. Use of epidurals and oxytocin
39
Q

List the antepartum risk factors for fetal distress

A
  1. Pre-eclampsia

2. IUGR

40
Q

How is fetal distress diagnosed?

A

Made from funding if significant fetal acidosis or ominous FHR abnormalities

41
Q

List the methods of monitoring fetal wellbeing in labour

A
  1. Liquor colour
  2. FHR auscultation - every 15mins during first stage and every 5mins during second stage
  3. CTG
  4. Fetal ECG monitoring
  5. Fetal blood sampling (FBS)
42
Q

What are the indications of fetal distress on CTG?

A
  1. Tachycardias
  2. Sustained bradycardia
  3. Prolonged reduced variability
  4. Late decelerations - persist after contraction is completed
43
Q

List the indications for CTG

A
  1. Prelabour risk factors:
    - Pre-eclampsia
    - IUGR
    - Previous caesarean section
    - Induction
  2. In labour risk factors:
    - Presence of meconium
    - Use of oxytocin
    - Presence of temp >38
    - During the administration of epidural analgesia
  3. Intermittent auscultation abnormalities
44
Q

Describe the levels of investigation fetal distress

A

Level 1 = intermittent auscultation of fetal heart; if abnormal proceed to level 2
Level 2 = CTG; sustained bradycardia >5mins deliver; abnormal on other criteria correct, if correction fails move to level 3
Level 3 = FBS ; if abnormal proceed to level 4
Level 4 = Delivery by quickest route

45
Q

What is the management of fetal distress?

A
  1. In utero resuscitation:
    - Place mother in left lateral position
    - Administer O2 and IV fluid
    - Stop any oxytocin infusion
    - Stop contraction using beta 2 agonists
    - VE to exclude cord prolapse or very rapid progress
  2. Confirmation of distress and delivery:
    - FBS
    - Expedite delivery if pH <7.2
    - Scalp sampling impossible or FHR shows sustained bradycardia DELIVER
46
Q

List the other causes if fetal damage and their treatments

A
  1. Infection - screening for organism and treatment of high risk groups (IAP)
  2. Meconium aspiration - amnioinfusion of saline into the uterus
  3. Fetal trauma - iatrogenic usually
  4. Fetal blood loss
47
Q

What are the options for pain relief in labour?

A
  1. Non-medical:
    - antenatal classes prep
    - birth attendent
    - immersion in water at body temperature
  2. Inhalational agents:
    - Entonox (NO + O2); SE lightheadedness, nausea, hyperventilation
  3. Systemic opiates; small analgesic effect; SE sedation, confusion, feeling of loss of control, resp depression in the Newborn
  4. Epidural analgesia; indwelling epidural catheter between L3 and L4 or L4 and L5
48
Q

List the advantages and disadvantages of epidural analgesia

A

ADVANTAGES

  1. Only method that makes pain free
  2. Advised on medical grounds if labour is long, to decrease BP in HTN and to abolish premature urge to push

DISADVANTAGES

  1. Occasionally ineffective or incomplete
  2. IV access required
  3. Transient hypotension common after loading dose
  4. Mobility decreased
  5. Reduced bladder sensation
  6. Maternal fever more common
  7. Instrumental delivery more common
  8. May need directed pushing
49
Q

List the contraindications to epidural analgesia

A
  1. Severe sepsis
  2. Coagulopathy or anticoagulant therapy
  3. Active neurological disease
  4. Some spinal abnormalities
  5. Hypovolemia
50
Q

List the major complications of epidural anakgesia

A
  1. Spinal tap (inadvertent puncture of duration causing CSF leakage and severe headache)
  2. Inadvertent intravenous injection (convulsions and cardiac arrest)
  3. Inadvertent injection of local anaesthesia into CSF (total spinal analgesia, respiratory paralysis)
51
Q

List the different types of anaesthesia for obstetric procedures

A
  1. Spinal anaesthesia - C-section or midcavity instrumental delivery
  2. Higher dose epidural analgesia - combination with spinal best for c-section
  3. Pudendal nerve block - low cavity instrumental vaginal deliveries
52
Q

What needs to be done at the initiation and diagnosis of labour?

A
  1. Contact maternity if contractions regular, painful, lasting at least 30secs and occurring every 3-4mins
  2. Brief hx pregnancy and past obstetric hx
  3. Temp, pulse, BP, Urinalysis
  4. Check presentation
  5. VE - cervical effacement and dilatation; confirm dx labour
  6. Assess descent
  7. Assess liquor colour
  8. FHR every 15mins
  9. CTG if high risk
  10. Read birth plan
53
Q

How is the mother managed in the first stage of labour?

A
  1. Position
  2. Fluid
  3. Observations
  4. Analgesia
54
Q

How is the fetus managed in the first stage of labour?

A
  1. Intermittent auscultation
  2. CTG if high risk
  3. Resuscitation +/- FBS if HR abnormal
  4. LSCS is fetal distress
55
Q

How is progress managed in the first stage of labour?

A
  1. VE (4hrly)
  2. Augmentation with ARM +/- oxytocin if nulliparous and progress
  3. LSCS if full dilatation not imminent by 12hrs
56
Q

What observations are performed on the mother and how frequently are they done in the first stage of labour?

A
  1. Contraction frequency - every 30mins
  2. Pulse - every hr
  3. BP, temp, VE - every 4hrs
57
Q

What observations are performed on the fetus and how frequently are they done in the first stage of labour?

A
  1. FHR - every 15mins
58
Q

When should pushing be initiated during the second stage of labour?

A
  • Non-directed pushing when mother has urge if no epidural

- Directed pushing and wait at least 1hr before starting if epidural

59
Q

When is an episiotomy performed?

A
  1. Fetal distress
  2. Head not passing over perineum despite maternal effort
  3. Large tear likely
60
Q

How are the shoulders delivered?

A

Anterior shoulder:
- Maternal pushing and gentle downward traction on the head
Posterior shoulder:
- Traction directed upwards

61
Q

When is the umbilical cord clamped after a normal delivery?

A

Not for at least 1min post delivery unless urgent resuscitation required

62
Q

How is the mother managed in the second stage of labour?

A
  1. Position
  2. Fluid
  3. Observations
  4. Analgesia
63
Q

How is the fetus managed in the second stage of labour?

A
  1. Intermittent auscultation
    OR
  2. CTG
64
Q

How is progression managed in the second stage of labour?

A
  1. Oxytocin if nulliparous and station high
  2. Start pushing when mother has desire or visible head
  3. Instrumental delivery if not delivered after 1hr of pushing and prerequisites met
65
Q

What observations are performed on the mother in the second stage of labour and how often are they done?

A
  1. Pulse - every 15mins
66
Q

What observations are performed on the fetus in the second stage of labour and how often are they performed?

A
  1. FHR - every contraction
67
Q

How is the third stage of labour managed?

A
  1. Oxytocin administered IM - combination with ergometrine often used but can cause maternal vomiting
  2. ‘Active management’ - reduces incidence of PPH
68
Q

How can we tell placental separation has occurred and what do we do then?

A
  • Lengthening of cord and passage of blood
  • Apply continuous gentle traction to deliver placenta
  • Check placenta for missing cotyledons and vagina and perineum for tears
  • Record blood loss
  • Continue maternal obs for at least 2hrs
69
Q

What indicates retained placenta and how is it managed?

A
  1. Third stage longer than 30mins
  2. Partial separation - blood loss and hypovolaemia
  3. Absence of bleeding - Allow 1hr for natural separation
  • Manage with manual removal
70
Q

Describe how perineal tears are managed

A
  • 1st and 2nd degree tears - sutured under local anaesthetic
  • 3rd and 4th degree tears:
  • Repaired under epidural or spinal
  • Antibiotics and laxatives given plus analgesia
  • Risk factors = forceps delivery, large babies, nulliparity, use of midline episiotomy
71
Q

List the criteria for a home birth

A
  1. Woman’s request
  2. Low risk
  3. 37-41wks
  4. Cephalic presentation
  5. Clear liquor
  6. Normal FHR
  7. All maternal obs normal
72
Q

Define induction of labour and explain when it is performed

A

IOL is labour that is started artificially.
It is performed in situations where allowing the pregnancy to continue would expose the fetus and/or mother to risk greater than that of induction

73
Q

List the methods of induction

A
  1. Medical:
    i) Prostaglandins
    ii) Oxytocin (after ARM)
  2. Surgical:
    i) Amniotomy
74
Q

What determines whether induction will be successful?

A

Success depends on favourability of the cervix.
Related to consistency, degree of effacement or early dilatation, how low in the pelvis the head is and the cervical position.
Bishop’s score is predictor - the lower the score the less favourable the cervix.

75
Q

Discuss induction with prostaglandins

A
  • Prostaglandin E2 as gel or SR preparation
  • Inserted into posterior vaginal fornix
  • Best method in nullips and most multips
  • Starts labour or improves cervix to allow amniotomy
76
Q

Describe induction with amniotomy +/- oxytocin

A
  • Membranes ruptured with amnihook

- Oxytocin infusion started within 2hrs if labour has not ensued

77
Q

What is natural induction?

A
  • Cervical sweeping

- Finger passed through cervix and ‘stripping’ between membranes and lower segment of uterus

78
Q

List the indications for induction

A
  1. Fetal indications:
    - Prolonged pregnancy
    - Suspected IUGR or compromise
    - Antepartum haemorrhage
    - Poor obstetric history
    - Prelabour term rupture of membranes
  2. Materno-fetal indications:
    - Pre-eclampsia
    - Maternal disease (e.g. DM)
  3. Maternal indications:
    - Social reasons
    - In utero death
  4. Routine induction
79
Q

List the common indications for induction

A
  1. Prolonged pregnancy
  2. Suspected growth restriction
  3. Prelabour term rupture of membranes
  4. Pre-eclampsia
  5. Medical disease - DM, HTN
80
Q

List the absolute contraindications to IOL

A
  1. Acute fetal compromise
  2. Abnormal lie
  3. Placenta praevia
  4. Pelvic obstruction
  5. After more than one C-section
81
Q

List the relative contraindication to IOL

A
  1. One previous C-section

2. Prematurity

82
Q

What are the complications of IOL?

A
  1. Failure to start or slow labour
  2. Hyperstimulation of uterus
  3. Increased risk of PPH
  4. Increased risk of intrapartum and postpartum infection
  5. Prematurity
  6. Increased instrumental delivery and C-section
83
Q

List the contraindications to a vaginal birth after a previous C-section

A
  1. Absolute indications for a C-section
  2. Verticle uterine scar
  3. Previous uterine rupture
  4. Multiple previous C-sections
84
Q

What are the increased risks if the mother has had a previous C-section?

A
  1. Placenta praevia
  2. Placenta accrete
  3. Difficult surgery
  4. Perinatal death
85
Q

How is labour managed after a previous c-section?

A
  1. Hospital delivery and CTG
  2. AVOID INDUCTION
  3. Cautious with augmentation
  4. Epidurals are safe
  5. Increased risk of scare rupture:
    * Fetal distress
    * Pain
    * Cessation of contractions
    * Vaginal bleeding
    * Maternal collapse
86
Q

What are the risks of prelabour term rupture of membranes?

A
  1. Cord prolapse

2. Neonatal infection

87
Q

How is prelabour term rupture of membranes managed?

A
  1. Confirm dx
  2. Check lie and presentation
  3. Avoid VE - only perform in sterile manner if risk of cord prolapse
  4. Intermittent auscultation or CTG
  5. Await spontaneous onset - 24hrs, obs every 4hrs
  6. Induction
  7. Presence of meconium or evidence of infection - IMMEDIATE induction
  8. After 18-24hrs - prescribe Abx and induction

OBGYN 4MB (25 decks)

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