The Last Hour of Labour

Department of Women’s Health

PROMPT Course 2017/18

Considerat ions and Complicat ions

Contents

• Why the last hour?

• What normally happens?

• Progress

• CTG changes

• Cord bloods

Why the last hour?

Why the last hour?

• Peak level of activity

• Demands on staff for preparation, support, monitoring and

procedures

• Emotional peak

• Physical energy may be low

• Potential for more rapid deterioration in clinical picture

• Potential for sudden onset of complications

• Whilst providing a positive birth experience

Preparation for BirthWhat Are The Elements Involved?

Preparation - Environment

• Lighting, noise

• Space

• Hazards

• Temperature/warmth

• Position

• Calm & supportive

Preparation - Equipment

• Normal Equipment – open pack: forceps, scissors, clamps,

packs

• Cot - warmer on, blankets towels

• Resuscitaire – (inside or outside) on, warm, tested (Gas flow

PIP, PEEP, suction, intubation, drugs)

• Emergency equipment – stocked (vacuum, forceps, cord

bloods, PPH box)

• Drugs prescribed & ready – oxytocic (syntometrine vs

syntocinon)

• Cord blood syringes if indicated

Assessment

• Maternal observations

1st stage – temp 4hrly, BP 2hrly, pulse 1/2hrly

2nd stage – temp 4hrly, BP 1hrly, pulse 1/2hrly

• Fetal heart rate assessment (CTG vs IA). If IA:

1st stage - 15-30mins, from end of contraction 30-60secs

2nd stage - every 5 mins or each contn)

• Abdo palpation – engaged, position

• VE to confirm full dilatation, station, position, caput, moulding,

l iquor

Preparation – Team

• When pushing Inform ANUM or Obs registrar

• Obstetric Registrar Present if:

Abnormal presentation, multiples

Risk of shoulder dystocia

Risk of PPH

• Paeds registrar (The above plus)

Meconium, abnormal CTG, known anomaly

Prematurity, sepsis

• 2nd midwife assist when birth imminent

Preparation - Communication

• Documentation – baby bradma, notes & ID

document full dilation and pushing times

observations

confirm blood group, recent results

document who was informed

• Counsel woman, reassure, discuss likely events

• Engage partner & family - support

Progress

VE is the cornerstone of assessing progress in labour but:

• Needs to be taken in the context of the whole woman’s wellbeing

• Can be invasive, painful, distressing, may raise issues of sexual

int imacy or assault.

• Lack of information or an unsympathetic att i tude can cause trauma

or complaint

• Needs to be justif ied to the woman and her family, the f indings

carefully explained and the implications discussed.

• “Examinations carried out with sensit ivity, in privacy by one midwife

with whom the woman has a good relat ionship wil l be experienced

as very different from brusque examinations from different

professionals whom the woman hardly knows.”

RCM, UK, Assessing Progress in Labour 2012

Progress in the 2nd Stage

• Passive & Active Definitions

• Normal second stage has a broad range

• 95 th% is 4hrs in primp

• Chance of vaginal birth 85% at 1hr but 9% by 5hrs

• Higher risk of atony (PPH), perineal trauma, infection, (local

experience - higher risk of technically complicated births)

• Neonatal risks debated – possible increase in morbidity,

sepsis, low Apgars

• Variation in local & international protocols

3 Centres Labour & Birth Guideline, 2012

PH CPG for delay in 2nd Stage• Combined passive and active second stage over 3 hours in a nul l iparous

woman.

• Combined passive and active second stage over 2 hours in a muli t iparous

woman.

• Encourage pushing with natural expulsive urge, posit ion changes.

• VE recommended:

To initially confirm full dilation

To confirm descent after passive descent of 1hr (exclude obstruction and to consider

augmentation if no descent).

• After 1hr active pushing inform ANUM & Obs Reg, commence CTG

Peninsula Health CPG, 2017

• Better to identi fy & manage abnormal contractions early in the 2 nd stage

rather than after 2hrs of pushing.

CTG ChangesW hat is normal?

Who Should Be Monitored

• RANZCOG Guidelines

Antenatal risk factors – see CPG

Intrapartum (eg induction)

Risk that may develop during labour:

Abnormal ausculation (changing FH even if within normal range)

Augmentation

Epidural

Bleeding, meconium, absent liquor post amniotomy

Pyrexia = 380c or more

Prolonged 1st or 2nd stage

Tachysystole (5:10)

Hypertonus (Contn >2mins or resting phase <60secs)

Optimising the CTG

• Active pushing impairs uterine blood f low and cerebral oxygenation

(within 10mins cf 30mins if passive)

• Prolonged breath holding may worsen this

• A compromised fetus may decompensate with pushing

• Hypertonus or tachysystole can turn to hyperstimulation

• Waiting unti l the urge to push starts (passive 2 nd stage) does not

increase the total t ime of the 2 nd stage.

• Passive descent:

shortens the active phase.

Reduces CTG abnormalities

Reduces the impact on acid-base status

J Perinatal Ed 2006

Reviewing CTG – False reassurance

• Pushing increases maternal heart rate

• May be similar to fetal HR

• Changes in position may detect maternal pulse

• In second stage:

Monitor maternal HR (30mins)- caution if similar

Consider pulse oximeter

Consider scalp electrode if any abnormalities

Beware an ‘improving’ CTG with accelerations

• What CTG changes are more common in the second stage?

Common CTG changes in the second stage

• Absent accelerations

• Rise in baseline

• Reduced variabil i ty

• Variable decelerations

• Higher r isk of complicated variable decelerations

• Higher risk of late decelerations

• Which of these are ‘normal’

Normal CTG changes in the second stage

• Absent accelerations

• Rise in baseline

• Reduced variabil i ty

• Variable decelerations very common 85-90%

represent a physiological response

• Higher r isk of complicated variable decelerations

• Higher risk of late decelerations 8-10%

• There are no changes that are unique to the 2 nd stage

• Falsely attr ibuting abnormalit ies to 2 nd stage carries risk

M c D o n n e l l , B J M M R 2 0 1 5

Interpretation

• Context is everything

• Uncomplicated variable decelerations unlikely to be

associated with compromise

• Severe baseline changes, complicated variable or late

decelerations require action

• Action may be:

Proceed to normal birth if imminent

Intrauterine resuscitation (stop pushing, reduce contractions,

position, fluids)

Assisted birth (episiotomy, instrumental, caesarean)

Fetal Scalp Sampling in 2nd stage

• CTG abnormalities have a high false +ve rate

• In most cases an abnormal CTG in 2 nd stage would indicate

assisted birth

BUT

If vaginal birth is not easily achievable, consider a scalp sample

• Rarely indicated, consultant discussion

• Allow time for further descent

• Generally only if an ‘intermediate’ level of abnormality

• But no evidence of improved neonatal outcome (Eas t , Cochrane 2010)

CTG Discussion

• Women not having an active say in their decisions results in:

x6 risk of dissatisfaction in primips

x15 risk of dissatisfaction in multips

More likely to have unvoiced concerns about baby’s wellbeing

So:

• Careful explanation of indications, findings and plan for all

CTGs

• Reassurance not all CTG changes are serious

• Careful discussion if plans change

Cord BloodsW hy and interpretat ion

Benefits of Cord Blood Gas Analysis

• Record of the fetal acid – base status at birth

• Feedback to clinical staff – re appropriate decision making

• Information to paeds re risk of neonatal complications

• Education – case discussions

• Improves outcomes (reduces neonates born with Art pH<7.0)

• Medico-legal

White, ANZJOG 2010

Why a full blood gas

• pH results indicate fetal acidosis

• Best predictor of poor outcomes (along with lactate)

• Information from pCO2 and Base excess can indicate acute or

chronic picture and respiratory vs metabolic acidosis

• Birth Asphyxia:

Intrapartum hypoxia sufficient to cause neurological damage

Defined by: Art pH <7.00

Apgars at 5mins <4

Moderate or severe encephalopathy

Multi-organ dysfuction

Fetal Acid Production

• pH indicated concentration of hydrogen ions

• Stable pH is vital to maintaining body systems

• Dissolved carbon dioxide:

CO2 +H2O = HCO3- + H+ (hydrogen ion = acid)

Other Acids:

Lactic acid (product of anaerobic metabolism)

Keto-acids (breakdown of carbs and fatty acids)

Uric acid (breakdon of amino acids)

FETAL ACID

PRODUCTION

Glucose

Citric Acid

Cycle

Lactate - + H+Pyruvate

Glycolytic

Pathway

CO2 + H

20

(2 ATP)

(36 ATP)

CO2 + H20 H2CO3 H+ + HCO3-Respiratory

Aerobic

Anaerobic

Types of Acidosis

• Respiratory acidosis

CO2 + H20 H+ + HCO3-

• Metabolic acidosis

Glucose Lactate + H+

• Combined respiratory and metabolic acidosis

Causes of Metabolic Acidosis• Fetal:

Chronic metabolic derangement

Chronic utero-placental hypo-perfusion

anaerobic metabolism

• Maternal:

Sepsis

Reduction in acid excretion:

renal failure

alcoholic, diabetic or starvation keto-acidosis

Increased bicarbonate loss:

renal tubular acidosis

hyperparathyroidism

Diarrhoeal states

Causes of Metabolic Acidosis• Fetal:

Chronic metabolic derangement

Chronic utero-placental hypo-perfusion

anaerobic metabolism

• Maternal:

Sepsis

Reduction in acid excretion:

renal failure

alcoholic, diabetic or starvation keto-acidosis

Increased bicarbonate loss:

renal tubular acidosis

hyperparathyroidism

Diarrhoeal states

Normal Values

Artery Vein

pH 7.10 – 7.38 7.20 – 7.44

pCO2 39.1 – 73.5 14.1 – 43.3

pO2 4.1 - 31.7 30.4 – 57.2

HCO3- 19.7 – 28.5 18.4 – 26.8

Base Excess -9 – 1.8 -7.7 – 1.9

Practical Interpretation of pH<7.1

• Respiratory Acidosis

↑ pCO2 (>70 mmHg)

Base excess normal (-10 to 1)

• Metabolic

pCO2 normal (40-75 mmHg)

Low base excess (< -10)

Lactate (>6.1)

• Mixed

↑ pCO2

Low base excess

Indications

• Operative delivery (emergency CS or instrumental)

• Abnormal CTG

• Complex birth (breech, shoulder dystocia, twins)

• Low Apgars <7

• Any neonatal resuscitation

• Inform Paeds registrar if:

pH <7.1

Lactate >6.1

Summary

The Last Hour of Labour

• A key time period in labour with a combination of significantly

increased workload, greater risk and high expectations

• Vital to maintain situational awareness

• Assess risk factors & review them

• Monitor: The environment

The woman and her family

Observations and assessment (physical or CTG)

• Anticipate & prepare

• Consider a whole team approach