Preterm birth Flashcards
Discuss fetal fibronectin
-What is it (3)
-When should it be tested for (5)
-Why should it be used (3)
-What tests use it and what are their sensitivity and specificity (2 tests)
-Cause of false positives (4)
- What is fetal fibronectin
-Extracellular matrix glycoprotein present at the decidual-chorionic interface
-Present in cervicovaginal secretions <16 weeks and after 37 weeks
-Disruption of the interface causes a release of FFN - When should it be tested for
-Use after 22/40
-Intact membranes
-Cervical dilation <3cm
-No gross vaginal bleeding
-No vaginal penetration in last 24 hrs - Why should it be used
-Helps predict likelihood of preterm delivery
-Can guide toco and steroid use
-Can guide transfer from smaller centres - Test types
-Qualitative: >50ng/mL = increased chance of delivery in 7 days. NPV 99.7%
-Quantitative: Gives exact number. Positive predictive value increases with increase in number
-Sensitivity - 65% specificity 93% PPV 43% NPV 97% - Cause of false positives
-semen, blood, digital cervical examination, lubricant
Discuss actim partus test for PTL
-What it detects
-How results are given
-Sensitivity and specificity
- What it detects
-Qualitative test
-Detects insulin-like growth factor binging protein one - How are results given
-Negative result shows unlikely to deliver in next 7-14 days - Sensitivity - 77%, specificity 81%
Discuss partosure to test for PTL
-What kind of test
-What it detects
-How results are given
-Sensitivity and specificity
- What kind of test
-Qualitative - What it detects
-Placental alpha microglobulin (PAMG-1) - How results are given
-Negative result shows reduced likelihood of delivery within 7 days - Sensitivity 83% specificity 95%
Discuss magnesium sulphate for neuroprotection
-Dose (1)
-Monitoring (6)
-Indications (2)
-Contra-indications (3)
-Timing (5)
- Dose
-4g bolus over 20-25mins then 1g per hr for 24 hrs or until baby is born whichever comes first. - Monitoring
-Do at least Q4H
-HR, BP, RR, Deep tendon reflexes, UO - Indications
-Any woman at risk of PTD under 30 weeks where birth is imminent - within 24hrs
-Do regardless of number of babies in utero, parity, mode of delivery, whether steroids have been given, the reason for delivery - Contra-indications
-Myasthenia gravis
-Women with myocardial compromise / conduction defects
-Caution with impaired renal function - Timing
-22+6 - 23+6 consider in discussion with NICU
-24-29+6 - offer if in established labour or planed delivery within 24 hrs.
-30-33+6 - consider if in established labour or if pre-term birth is planned within 24hr
-Don’t delay birth for MgSO4
-Ideally give more than 4 hrs prior to delivery
Discuss the evidence for magnesium sulphate as a neuroprotection
-Cochrane review included 5 RCTS 2009
-Looked at effect on neuroprotection in 6145 babies
-Included PTB up to 34 weeks. Only one trial <30
-Looked at neurodevelopmental outcomes (impairment, disability, mortality and maternal SAE)
-Reduced the risk of cerebral palsy RR 0.68 NNT 63 (NNT 29 if <28 weeks)
-Reduced risk of gross motor dysfunction RR 0.61
Discuss mechanism of action for MgSO4 to achieve neuroprotection (5)
-Antagonist for NMDA receptors - reduces seizure threshold
-Down regulates excitory stimuli through blocking NMDA receptors stopping influx of Ca and neuronal death
-Cerebral vasodilation through Ca antagonism increasing cerebral blood flow and minimising hypoxic ischemia
-Prevents neuronal injury by reduction of proinflammatory cytokines
-Anti apoptotic effect
Discuss neonatal outcomes of preterm delivery
-Percentage cause of neonatal death (1)
-Major causes of mortality (3)
-Influencing factors determining outcome (5)
- Percentage of neonatal deaths attributed to PTD
-50% - Major causes of mortality
-NEC, RDS, IVH - Influencing factors
-Gestation
-Gender - boys do worse
-Growth restriction
-Infected environment
-Steroid cover
What are the rates of mortality and severe morbidity for babies born at 22,23,24,25,26 weeks
- Babies born at 22 week
-7 die
-1 in 3 has severe disability - Babies born at 23 weeks
-6 die
-1 in 4 babies have severe disability - Babies born at 24 weeks
-4 babies die
-1 in 7 babies have severe disability - Babies born at 25 weeks
-3 babies dies
-1 in 7 have severe disability - Babies born at 26 weeks
-2 in 10 babies die
-1 in 10 babies have severe disability
Discuss outcomes for babies born between 28-32 weeks
-Mortality is <10% and decreases with increasing gestation
-Chance of severe disability - <10%
-Completely normal outcome in 65%
-Chronic lung disease and IVH most common complications
Discuss complications experienced by premature newborns (12)
- Hypoglycemia
- Hypothermia
- Jaundice with increased risk of neurological effects from bilirubin
- Feeding difficult
- Hyaline membrane disease from surfactant deficiency - leads to ARDS
- Chronic lung disease due to pulmonary dysplasia increased risk of lifelong pulmonary dysfunction and abnormal neurodevelopment
- Intraventricular haemorrhage
- Periventricular leukomalacia - 60-90% results in CP
- Necrotising enterocolitis-bacterial invasion of gut wall following ischemia
- Persistent ductus arteriosis leading to congestive heart failure
- Retinopathy
- Intrapartum hypoxia
Discuss peri-viability
-Gestation range (1)
-What are the predictors of outcome in peri-viable babies (9)
- Gestation 23-24+6
- Predictors of outcome
-Gestational age. Make sure accurate. Every day counts
-Birthweight
-Doppler wave form - severe IUGR and abnormal dopplers - poor prognosis
-Fetal gender - boys do worse
-PPROM/Chorio - Short term risk of IUFD or death within 24 hrs
-Suspected or known fetal anomaly
-Multiple pregnancy - increased death rate
-Interventions received
-Site of delivery - Tertiary centre vs other
Discuss peri-viability
-Interventions and timing to modify outcomes (8)
Interventions and timing to modify outcome
1. Antenatal corticosteroids. Give from 22+5 + rescue at 7 days if not delivered and still at high risk of delivery
2. MgSO4 give if planning delivery after 23/40
3. Mode of birth
-Aim VB unless malpresentation and active management
-Need to balance risks and benefits as will be classical CS in 67% of cases
4. Delivery in a centre with NICU - transfer
5. Treat for GBS (Amoxicilin) + Gent (Gram -ve) in active labour
6. Monitoring depends on decision of management type
7. Delayed cord clamping 60s can reduce blood transfusion by 10%
8. Consider tocolysis to enable transfer and steroids if possible.
9. Consider rescue cerclage if Cx <10mm and no PPROM, APH, TPTL or infection
Discuss peri-viable delivery
-Options for management (6)
- Shared decision making with parents as not all will want the same thing. Give local data regarding outcomes
- Care should be individualised depending on clinical situation and family wishes
- Full active intervention including CS on fetal grounds and CTG
- Active intervention - MgSO4, steroids, transfer, Abx but no CS and intermittent ascultation.
- Comfort cares only - no fetal monitoring required can be transferred to tertiary site if desired
- As prognosis changes daily should have ongoing discussions with parents about what we are aiming for
Discuss preterm birth
-Definition (1)
-Incidence (4)
-Classification (3)
-Main causes (3)
- Definition
-Delivery 20-36+6 weeks - Incidence
-5-10% of all births born before 37/40
-1-3% <34/40
-0.5% <28/40
-Leading cause of neonatal mortality and morbidity (65% of all neonatal deaths)
-Australia and NZ 7-8% - Classification
-Extreme preterm birth <28/40
-Very preterm 28-32/40
-Moderate to late preterm 32-37/40 - Main causes
-Iatrogenic - PET/ Severe IUGR 20%
-PPROM 30%
-Spontaneous onset of labour 50%
Discuss risk factors for preterm birth (11)
- Previous PTB (15% after 1 PTB, 45% after 3 PTB)
- Infection - intrauterine and extrauterine
- Cervical: Previous surgery / mechanical dilation / trauma
- Congenital anomalies or chromosomal anomalies
- Uterine: congenital abnormalities, overdistension, trauma
- Placental causes: PET/Abruption / insufficiency
- Low pre-pregnancy weight
- Short pregnancy interval
- Extremes of age
- Substance use/abuse
- 66% of women with PTB don’t have risk factors
Discuss investigations for threatened preterm labour (4)
- Check fetal wellbeing - CTG + USS
- Check for infection - MSU / Swabs
- FFN
- >50ng/mL = diagnose PTL - TVUSS for Cx length - offer as first line
>15mm unlikely PTL
<15mm diagnose PTL
Discuss tocolytics for TPTL
-When to use (2)
-Contraindications (4)
-Types (4)
- When to use
-To delay birth and allow administration of steroids
-To delay birth and allow for in-utero transfer - Contra-indications
-APH
-Cx >4cm dilated
-Intra-uterine infection
-PPROM - Types
Firstline: Nifedipine (CCB)
-Reduces number of women giving birth within 7 days if <34/40
-Reduced RDS, NEC, IVH, Jaundice
Second line: IV Atosiban B-mimetic
Avoid: IV salbutamol - betamimetic
-Many side effects and same efficacy as IV Atosiban
Avoid: Indomethacin: NSAIDS
-Significant impact to multiple fetal organ systems
Discuss antibiotic use in preterm labour
-Recommendations from ORACLE II (2)
-GBS prophylaxis recommendation (1)
-Treatment of BV (2)
- Recommendations from ORACLE II
-Worse neonatal outcomes for O2 requirement and NEC in intervention arm (Erythromycin/Augmentin/Both)
-Do not give routine antibiotics in PTL - GBS prophylaxis
-NZ guidelines consider PTL as RF for GBS so give penicillin - BV
-Treatment of BV in pregnancy is not associated with decreased risk of PPROM or PTL
-Treat those with other risk factors for PTB
Discuss mode of delivery in preterm labour
-General points (1)
-Vaginal delivery (2)
-CS (4)
-Instrumental (3)
-Recommendations for FBS and FSE use (2)
- General points
-MOD should be guided by gestation, presentation, fetal condition, maternal wellbeing - Vaginal delivery
-If cephalic
-Can consider if breech but be prepared for head entrapment - CS
-If VB contraindicated
-For fetal wellbeing if distress
-For rapid delivery if maternal health compromised
-Incision depends on gestation and placental location - Instrumental
-Ventouse contra-indicated <34/40
-Forceps relatively contra-indicated <34/40. Only do if certain of fetal head position.
-Rotational forceps delivery contraindicated - FSE and FBS use
-Avoid <34/40 for FBS
-Avoid FSE in <34/40 unless very difficult to monitor and benefits outweigh risks
Discuss PPROM
-Incidence (2)
-Risk factors (6)
- Incidence
-2-3% of pregnancies
-In 40% of all Preterm births - Risk factors
-Previous PPROM (OR 8.7)
-Shorter inter pregnancy interval
-Urogenital infection
-Placental abruption
-Over distension - polyhydramnios, multiple pregnancy
-Smoking or drug use
Discuss investigations for PPROM (6)
- Assess fetal well being - CTG
- USS for presentation, fluid volumes. It’s role in Dx of PPROM is unclear
- Assess for infection
-Clinical assessment
-Swabs, MSU, Bloods
-CRP sens 69% spec 77% for histological chorio - Do sterile speculum and assessment for pooling liquor. If no liquor sen for Amnisure or actim
- Amnisure
-measures placental alpha micro globulin-1
-Sens 94-98%, Spec 87-100%
-High false positive rate
-Not impacted by small amount of semen or blood - Actim PROM
-Measures insulin like growth factor binding protein 1.
-Spec 98% Sens 93%
-Not impacted by small amount of semen, urine, infection or blood
Discuss PPROM
-Outcomes (3)
-Fetal risks at <34/40 (1)
-Fetal risks at >34/40 (1)
-Risks of lung hypoplasia if PPROM at 21/40 vs 29/40 (2)
- Outcomes
-Most likely outcome is labour
-80% born within 7 days
-25% deliver within 48hrs - Fetal risks at <34/40
-Risks are due to prematurity - RDS, NEC, IVH, PVL, CP - Fetal risks at >34/40
-Risks are due to infection - Risk of lung hypoplasia
-21/40 90% risk
-29/40 10% risk
Discuss management of PPROM (10)
- Admit to ward
- Q4H Obs - monitor for signs and sx of infection
- TDS CTG
- Twice weekly bloods
- Steroids if <34+6 (Not associated with increase risk of sepsis)
- Tocolysis contraindicated
-Worse apgars, more ventilation, increased chorioamnionitis - Antibiotics
- erythromycin 250-500mg PO Q6H 10/7 or until established labour. Prolongs pregnancy, reduces surfactant requirement
-Consider 48hrs IV ampicillin until GBS status known
-Avoid augmentin as increase in NEC (RR 4) - MgSO4
-If <30 weeks and delivery expected or planned - Amnioinfusion
-Not recommended routinely as poor data
-Associated with decreased: hypoplasia; neonatal sepsis; neonatal death; reduced puerperal sepsis - Meet with neonatologist