OBS - Basics of Labour

Question 1

Onset of Labour

Stages of Labour
First Stage of Labour
Braxton-Hicks Contractions
Diagnosing Onset of Labour

Answer 1

1. ) Stages of Labour - labour and delivery normally occur between 37 and 42 weeks gestation.
   - first stage: onset of labour to 10cm cervical dilatation
   - second stage: 10cm until delivery of the baby
   - third stage: delivery of the placenta
2. ) First Stage of Labour - has 3 phases
   - involves cervical dilation and effacement (thinning)
   - ‘show’: mucus plug in the cervix, prevents bacteria from entering the uterus during pregnancy, falling out and creating space for the baby to pass through
   - latent phase: 0-3cm, 0.5cm/hr, irregular contraction
   - active phase: 3-7cm, 1cm/hr, regular contractions
   - transition phase: 7-10cm, 1cm/hr, strong contraction
3. ) Braxton-Hicks Contractions - occasional irregular contractions of the uterus felt during T2 and T3
   - not true contractions and do not indicate the onset of labour as they do not progress or become regular
   - sx: women can experience temporary and irregular tightening or mild cramping in the abdomen

4.) Diagnosing Onset of Labour
- latent first stage: painful contractions and changes
to the cervix, with effacement and dilation up to 4cm
- established first stage: regular, painful contractions with dilatation of the cervix from 4cm onwards
- other signs: show (mucus plug), ROM

Question 2

Failure to Progress

What is It?/Definitions
Partogram
Factors affecting Progress of Labour
Management of Failure to Progress

Answer 2

1. ) What is It? - labour doesn’t progress normally
   - this increases the risk to the fetus and the mother
   - more likely in primips compared to multips
   - delay in the first stage: <2cm dilation in 4 hours or slowing of progress in multiparous women
   - delay in the second stage: pushing for >2hrs in nulliparous women or 1 hour in multiparous women
   - delay in the third stage: >30mins with active management, >60mins w/ physiological management
2. ) Partogram - used in the 1st stage to monitor:
   - cervical dilatation (4hrly), fetal station
   - maternal HR, BP, temperature and urine output
   - fetal HR, frequency of contractions (per 10mins)
   - drugs/fluids given, fetal membrane status, presence of liquor (stained w/ blood or meconium?)
   - there are two lines on the partogram indicating failure to progress, labelled “alert” and “action”:
   - crossing alert line is an indication for amniotomy
   - crossing action line means care needs escalating
3. ) Factors affecting Progress of Labour
   - Power: strength of uterine contractions
   - Passenger: fetal size, attitude, lie, presentation
   - Passage: size/shape of the passageway (pelvis)
4. ) Management of Failure to Progress
   - amniotomy (ARM) for women w/ intact membranes
   - oxytocin infusion for strong uterine contractions, start low then titrate up at intervals of at least 30mins
   - instrumental delivery or C-section if required

Question 3

Third Stage of Labour

Active Management
Steps Involved

Answer 3

1. ) Active Management - assist in placental delivery
   - shortens the 3rd stage and reduces bleeding risk
   - can be associated with nausea and vomiting
   - routinely offered to all women to reduce PPH risk
   - initiated in prolonged 3rd stage (>60mins) or if there is haemorrhage
   - physiological management is where the placenta is delivered without medications or cord traction
2. ) Steps Involved - oxytocin + controlled cord traction
   - prophylactic IM oxytocin 10IU after vaginal deliveries or IV oxytocin 5IU for C-sections
   - cord is clamped and cut w/in 5mins (at least 1-3mins)
   - controlled cord traction is carefully applied during uterine contractions to help deliver the placenta, stopping if there is resistance
   - another hand presses the uterus upwards (in the opposite direction) to prevent uterine prolapse
   - after delivery, the uterus is massaged until it is contracted and firm
   - placenta is examined to ensure it is complete and no tissue remains in the uterus

Question 4

Pain Relief in Labour

Non-Opiates/Anaesthetics
IM Pethidine or Diamorphine
Patient Controlled Analgesia
Epidural

Answer 4

1. ) Non-Opiates/Anaesthetics
   - general: good support, relaxed environment, changing positions, controlled breathing
   - water births may be helpful for some women
   - TENS machines may be useful in the early stages
   - simple: paracetamol +/- codeine, avoid NSAIDs
   - gas and air (Entonox): mix of 50% N2O and 50% O2, inhaled during contractions for short term pain relief, can cause light-headedness, nausea or sleepiness
2. ) IM Pethidine or Diamorphine - opioid medications
   - may help with anxiety and distress
   - may cause drowsiness or nausea in the mother
   - can cause respiratory depression in the neonate if given too close to birth which may make the first feed more difficult
3. ) Patient Controlled Analgesia - using IV remifentanil
   - press at the start of a contraction to give a bolus
   - needs careful monitoring and anaesthetic input
   - can cause respiratory depression: tx w/ naloxone
   - can cause bradycardia: treat with atropine
4. ) Epidural - offers good pain relief during labour
   - LA is infused through an inserted catheter into the epidural space (outside dura mater) in the lower back
   - levobupivacaine or bupivacaine, mixed w/ fentanyl
   - adverse effects: headache, hypotension, nerve damage, motor weakness in legs, prolonged second stage so increased probability of instrumental delivery
   - urgent anaesthetic review is needed if they develop significant weakness (unable to SLR) as the catheter may be within the SC rather than epidural space

Question 5

Cardiotocography (CTG)

Method/Operation
Indications for Continuous CTG Monitoring
DR C BRAVADO
Classification of a CTG
Management Options based on the CTG

Answer 5

1. ) Method/Operation
   - one transducer is placed above the fetal heart to measure the fetal HR using doppler ultrasound
   - 2nd transducer is placed near the fundus to monitor uterine contractions using tension in the uterine wall
2. ) Indications for Continuous CTG Monitoring
   - suspected infection: temp >38°C, sepsis or chorioamnionitis
   - ↑BP: pre-eclampsia, severe hypertension (>160/110),
   - new PV bleed in labour, maternal HR >120
   - delay in labour, oxytocin use, significant meconium
   - disproportionate maternal pain

3.) DR C BRAVADO - assess CTG in a structured way
- DR: Define Risk of the pregnancy (high or low) based on maternal medical illness and obstetric complications
- Contractions: should be 3/4 every 10 minutes
- BRa (Baseline Rate) and V (Variability)
- Accelerations: ↑ in baseline fetal HR >15bpm for >15s,
this is normal and a good sign that the fetus is healthy
- Decelerations: ↓ in baseline HR >15bpm for >15s
- Overall impression of the CTG (classification)

3. ) Classification of a CTG - 4 categories based on 3 features (baseline HR, variability and decelerations):
   - normal: no non-reassuring features
   - suspicious: a single non-reassuring feature
   - pathological: 2 non-reassuring or 1 abnormal feature
   - needs urgent intervention: acute bradycardia or prolonged deceleration of more than 3 minutes
4. ) Management Options based on the CTG
   - escalating to a senior midwife or obstetrician
   - further assessment to identify possible causes
   - conservative interventions such as repositioning the mother or giving IV fluids for hypotension
   - fetal scalp stimulation (accelerations in response)
   - late decelerations: fetal scalp blood sampling to test for fetal acidosis (if pH <7.2, deliver the baby)
   - delivery: instrumental or emergency C-section
   - prolonged fetal bradycardia: 3 mins = call for help, 6mins = move to theatre, 9mins = prepare for delivery and 12 mins = deliver the baby within 15 minutes

Question 6

Baseline Rate, Variability, Decelerations, Sinusoidal

Baseline Rate
Variability 
Early and Variable Decelerations 
Late and Prolonged Decelerations
Sinusoidal CTG

Answer 6

1. ) Baseline Rate - avg fetal HR within a 10min window
   - normal/reassuring fetal HR is 110-160
   - fetal tachycardia: 160-180 is non-reassuring, >180 is abnormal
   causes include: hypoxia, chorioamnionitis, hyperthyroidism, fetal or maternal anaemia
   - fetal bradycardia: 100-110 is non-reassuring, <100 is abnormal
   causes include: cord compression, cord prolapse, anaesthesia, seizures, rapid fetal descent
2. ) Variability - a variation of fetal HR from beat to beat
   - normal/reassuring variability is between 5-25
   - low variability: <5 for 30-50mins is non-reassuring and for over 50 minutes is described as abnormal, causes inc: sleeping, acidosis, tachycardia, prematurity
   - high variability: >25 for 15-25 mins is non-reassuring and for over 25 minutes is described as abnormal
3. ) Early and Variable Decelerations
   - early: gradual dips and recoveries that correspond with contractions due to compression of the fetal head, this is normal and not considered pathological
   - variable: decelerations unrelated to contractions, lasting <2mins, they are due to intermittent cord compression causing fetal hypoxia
4. ) Late and Prolonged Decelerations
   - late: delay between the contraction and deceleration, due to fetal hypoxia caused by excessive contractions, maternal hypotension or hypoxia, concerning feature
   - prolonged: last between 2-10 mins, often indicates compression of the umbilical cord –> fetal hypoxia, these are abnormal and very concerning
5. ) Sinusoidal CTG - indicates severe fetal compromise
   - pattern similar to a sine wave, with smooth regular waves up and down that have an amplitude of 5 – 15
   - associated with severe fetal anaemia, for example, caused by vasa praevia with fetal haemorrhage

Question 7

Prematurity

Definitions
Prophylaxis of Preterm Labour
Preterm Labour with Intact Membranes
Management of Labour w/ Intact Membranes

Answer 7

1. ) Definitions
   - prematurity/pre-term: birth < 37wks <28w is extreme, 28-32w is very preterm and 32-37w is mod-late
   - PROM: premature ROM (>1hr before labour) >37wks
   - PPROM: pre-term PROM at <37wk gestation
2. ) Prophylaxis of Preterm Labour
   - vaginal progesterone (gel/pessary): ↓ activity of the myometrium and prevents cervix remodelling, offered between 16-24wks w/ cervical length <25mm on TVUS
   - cervical cerclage: keeps the cervix closed via stitch, which can be removed at 37w or woman is in labour,
   - offered to those w/ a previous premature birth or cervical trauma between 16-24wks (length <25mm)
   - ‘rescue’ cervical cerclage may also be offered between 16-28w when there is cervical dilatation without ROM, to prevent progression and premature delivery
3. ) Preterm Labour with Intact Membranes - regular painful contraction and cervical dilatation, w/o ROM
   - <30w: clinical diagnosis w/ hx and speculum
   - >30w: TVUS shows cervical length <15mm
   - an alternative to TVUS is fetal fibronectin: <50ng/ml is negative, indicating that preterm labour is unlikely
4. ) Management of Labour w/ Intact Membranes
   - fetal monitoring w/ CTG or intermittent auscultation
   - tocolysis (stop uterine contractions) with nifedipine
   - antenatal corticosteroids at <35 weeks gestation
   - IV Mg sulphate <34wks for neonatal neuroprotection
   - delayed cord clamping or cord milking: can increase circulating blood volume and Hb in the baby at birth

Question 8

Premature Rupture of Membranes (inc P-PROM)

Pathophysiology
Clinical Features
Differential Diagnoses

Answer 8

1. ) Pathophysiology - early weakening and rupture of fetal membranes due to several reasons:
   - early activation of normal physiological processes: ↑↑ levels of apoptotic markers and MMPs in amniotic fluid
   - infection: inflammatory markers weaken membranes, 1/3 with P-PROM have positive amniotic fluid cultures
   - genetic predisposition
   - risk factors: previous PROM/pre-term, smoking, UTI, APH, invasive procedures, polyhydramnios, multiple pregnancy, cervical insufficiency
2. ) Clinical Features
   - ‘broken waters’: painless popping sensation, with a gush of watery fluid leaking from the vagina
   - non-specific sx: gradual leakage of watery fluid, damp underwear/pad, change in vaginal discharge
   - ‘washed clean’: lack of normal vaginal discharge
   - avoid vaginal examination in suspected PROM
3. ) Differential Diagnoses
   - urine: urinary incontinence, vesicovaginal fistula
   - normal vaginal secretions, loss of mucus plug, or just increased sweat/moisture around the perineum
   - increased cervical discharge (e.g. due to infection)

Question 9

Management of Premature Rupture of Membranes

Investigations
Management of (P)PROM
Complications

Answer 9

1. ) Investigations
   - clinical diagnosis from hx and examinations:
   - speculum showing pooling of fluid in the posterior vaginal fornix (woman should lie down for >30mins) OR if amniotic fluid is seen draining from the vagina
   - no amniotic fluid on speculum: consider performing an insulin-like growth factor-binding protein 1 test or placental alpha microglobulin-1 test of vaginal fluid
   - high vaginal swab: to find potential causes such as GBS or bacterial vaginosis (common causes)
2. ) Management of (P)PROM
   - monitor for chorioamnionitis, avoid having sex
   - intrapartum IV benzylpenicillin if GBS +ve
   - prophylactic erythromycin 250mg QDS for 10 days (or until labour) if PPROM < 36weeks
   - antenatal corticosteroids if < 35weeks gestation
   - IOL if >34wks and labour hasn’t started within 24hrs
   - expectant management until 34wks if 25-33wks
3. ) Complications - depends on gestational age
   - chorioamnionitis: infection/inflammation of the fetal membranes, ↑ risk the longer the baby is undelivered
   - oligohydramnios: esp if <24 weeks gestation
   - neonatal death: due to complications associated with prematurity, sepsis and pulmonary hypoplasia
   - placental abruption, umbilical cord prolapse