Pregnancy Risk Assessment Flashcards
What features are investigated in a maternity risk assessment during the booking appointment
Gestational diabetes risk
Pre-eclampsia
Foetal growth restriction
Venous thromboembolism
What are the risk factors for a high risk pregnancy
Any previous complicated pregnancies (biggest risk for another abnormal pregnancy)
Maternal factors
- Age <15yo or >35yo
- Pre-pregnancy weight under 45kg or obese
- Height under 5 ft (1.5m)
- Hypothyroid/Hyperthyroid
Gynaecological
- Incompetent cervix
- Uterine malformations
- Small pelvis
- Previous obs hx for recurrent miscarriages
Social
- Being single
- Smoker or alcohol
- Illicit drugs
- No access to early prenatal care
- Low socioeconomic status
What should be done for women with a high risk pregnancy
Refer for obstetrician led care
Continued surveillance - more frequent scans
Consider aspirin, high dose folic acid etc.
Who is given high dose folic acid
Previous child with NTD
Diabetes mellitus
Woman on an anti-epileptic
Obesity (>30 BMI)
HIV positive taking co-trimoxazole
Sickle cell disease
What are the methods of monitoring pregnancy
Cardiotocography
Growth scans
Foetal doppler
Foetal blood sampling
Describe the production of amniotic fluid as the pregnancy progresses
0-12 weeks: Passive transfer of fluid across the amniotic membranes from chorionic cavity
Before 20 weeks: Amniotic fluid isotonic like maternal plasma
19 weeks: Keratinisation of foetal skin AF circulation from foetus
Production: foetal urination, the respiratory tract system, oral secretion and transfer across the cord and placenta
Removal: foetal swallowing, intra-membranous, respiratory fluid
Define oligohydramnios
Decreased volume of amniotic fluid, <5th centile
Deepest pool <2cm
What are the risk factors for oligohydramnios
Reduced input fluid: placental insufficiency, pre-eclampsia
Reduced output fluid: structural pathology (AR PKD), medications (ACEi, NSAIDs)
Lost fluid: ROM, IUGR, post-term pregnancy carry, TTTS
Chromosomal abnormalities
Multiple pregnancy
Infections
What are the signs and symptoms of oligohydramnios
History of fluid leak PV, rupture of membranes – commonly asymptomatic
Abdominal exam – decreased fundal height, foetal parts easily palpable
Speculum – assess for membrane rupture if appropriate
What investigations should be done for oligohydramnios
USS – liquor volume, foetal anomalies
CTG– foetal wellbeing
What is the management for oligohydramnios
Term – delivery is appropriate, IOL if no CI
Pre-term – monitor serial USS for growth, liquor volume, dopplers, regular CTGs, delivery if further abnormalities arise (note: amnioinfusion has a very limited role or effect)
What are the complications of oligohydramnios
Labour – increased incidence of CTG abnormalities, meconium liquor, emergency CS
Neonate – pulmonary hyperplasia, limb deformities
Prognosis – increased perinatal mortality rates with early onset oligohydramnios
Define polyhydramnios
AFI >95th centile, 2-3L fluid
Deepest pool >8cm
What are the risk factors for polyhydramnios
Failure of foetal swallowing:
- Neurological - neurology, chromosomal abnormalities
- GIT - duodenal atresia, oesophageal atresia
Congenital infections
Foetal polyuria: maternal diabetes, TTTS
What are the signs and symptoms of polyhydramnios
Symptoms of underlying cause
Abdomen – increased fundal height, impalpable foetal parts, tense abdo
What investigations should be done for polyhydramnios
Liquor volume, foetal growth, umbilical artery dopplers, exclude foetal anomalies
Other – exclude maternal diabetes
What is the management for polyhydramnios
Antenatal monitoring of foetus, ensure diabetes control, paediatrician present at delivery
Amnioreduction (if gross polyhydramnios + discomfort)
COX inhibitors to decrease foetal urine output
What are the complications and prognosis of polyhydramnios
Pre-term labour (PTL), malpresentation, placental abruption, cord prolapse, PPH, increased risk CS
Prognosis – increased perinatal morbidity and mortality, related to PTL/congenital
What are the types of doppler scan
Umbilical artery
Cerebral circulation: middle cerebral artery
Venous circulation: ductus venosus
What is a sign of foetal compromise in the doppler
severe placental dysfunction: Absent end diastolic flow or reverse end diastolic flow (suggests high resistance circulation) in the UMBILICAL doppler
Compromise: low-resistance pattern in comparison to thoracic aorta or renal vessels (MCA)
Ratio of the pulsatility index (PI) (MCA vs UmbA)
Describe chorionic villi sampling and what is the miscarriage rate
USS-guided needle aspirate of placental tissue
performed 10-13/40 (i.e. week 12)
1% miscarriage rate
Describe amniocentesis and what is the miscarriage rate
USS guided needle, avoid entry of placenta, small aspirate of amniotic fluid
performed ≥15/40
1% miscarriage rate
What supportive management must be done for diagnostic procedures (amniocentesis and CVS)
anti- RHD given to RH-neg women (sensitising event)
What are the indications for diagnostic testing of the foetus
Demonstrated risk at antenatal screening
Suspected foetal anomaly on USS
FHX of inherited disorder
Known carrier status for inherited disorder
Previous pregnancy with chromosomal disorder
Increased maternal age
What are the complications of foetal diagnostic testing
Generic: bleeding, infection, damage to local structures, procedural failure
Abdominal pain
Miscarriage (both CVS and amniocentesis at 1%)
Chorioamnionitis
Limb abnormalities if CVS performed before 10/40
What are the two ways of CTG monitoring in labour
Intermittent auscultation
- At least 60s immediately after a contraction
- First stage: at least every 15 minutes
- Second stage: at least every 5 minutes
Continuous:
- for any antenatal or intrapartum risk factors
What are some of the indications for continuous CTG monitoring in labor
Maternal: previous c-section, cardiac problems , PET, prolonged pregnancy, PROM >24h, IOL, GDM, haemorrhage
Foetal: IUGR, prematurity, oligohydramnios, abnormal doppler, multiple pregnancy, meconium stained liquor, breech
Intrapartum: maternal HR >120, temp >38, suspected sespsis, vaginal bleeding, delay, oxytocin use
What is the structure for interpreting a CTG
DR C BRAVADO
DR - Define the risk
C - contractions
Bra - Baseline rate
V - Variability
A - Accelerations
D - Decelerations
O - Overall impression
How should one assess contractions on CTG
The number of contractions present in a 10 minute period
Assess for:
- Duration: how long do they last?
- Intensity: How strong are they? (assessed in palpation)
How should one assess baseline rate
Baseline rate = The average heart rate of the foetus within a 10 minute window
Normal foetal heart rate is between 110-160bpm
<100bpm for 3 minutes → Foetal bradycardia → emergency → immediate delivery if cause not found
What are the causes of foetal tachycardia
Foetal hypoxia
Chorioamnionitis
Hyperthyroidism
Foetal or maternal anaemia
Foetal tachyarrhythmia
What are the causes of foetal bradycardia
Postdate gestation
Prolonged cord compression
Cord prolapse
Epidural and spinal anaesthesia
Maternal seizure
Rapid foetal descent
How should one assess variability
Variation of foetal heart rate from one beat to the next (Look at how much the peaks and troughs of the heart rate deviate from the baseline rate in bpm)
Normal variability (5-25bpm)
- <5bpm for 20-50mins is non-reassuring, >50 abnormal
- >20bpm for 15-25 minutes is non-reassuring, >25 abnormal
What are the causes of reduced variability
Foetal sleeping
Foetal acidosis
Foetal tachycardia
Drugs e.g. opiates/benzodiazepines/methyldopa/magnesium sulphate
Prematurity - variability is reduced at earlier gestation <28 weeks
Congenital heart abnormalities
How should one assess accelerations
Abrupt increase in the baseline foetal heart rate of greater than 15bpm for greater than 15 seconds
The presence of accelerations is reassuring
How should one assess decelerations
Abrupt decrease in the baseline foetal heart rate of greater than 15bpm for greater than 15 seconds
Occurs due to hypoxic stress (foetus reduces HR to preserve myocardial oxygenation and perfusion)
Are they
Early
Variable
Late
Prolonged
Describe early decelerations
start when contraction begins, stops when contraction stops
Increased foetal intracranial pressure →stimulation of the parasympathetic nervous system via the vagus nerve
Physgiological
Describe variable decelerations
Rapid fall in FHR with variable duration and relationships to contractions
Usually caused by umbilical cord compression
Variable decelerations without the shoulders or with Biphasic (W) shape are more worrying - suggests the foetus is becoming hypoxic
What is shouldering
Accelerations before and after a variable deceleration
Describe late decelerations
begins at the peak of the uterine contraction and recovers as it ends
Oxygen in retroplacental reservoir used up during contractions → hypoxaemia until full reoxygenation after relaxation
Seen in maternal hypotension, PET, uterine hyperstimulation
Very concerning → foetal blood sampling, expedite delivery
Describe prolonged decelerations
> 3 minutes (2-3 = non-reassuring)
→ FBS, emergency C-section
What is a sinusoidal pattern
Smooth, regular, wave-like pattern
Frequency of around 2-5 cycles a minute
No beat to beat variability
Indicates severe foetal hypoxia or anaemia and/or foetal/maternal haemorrhage
→ requires immediate caesarean section
What are the outcomes of overall impression from the CTG
Reassuring (BHR 110-160)
Non-reassuring (BHR 100-109 or 161-180)
Abnormal (BHR <100 or >180), sinusoidal pattern, decelerations for 30 minutes, bradycardia >3 minutes
Normal: all features reassuring
Suspicious: 1 non reassuring feature
Pathological: 2 non reassuring feature or 1 abnormal feature
What should be done if CTG is suspicious
Correct underlying causes
Obs
Inform obstetrician or senior midwife
Document plan for reviewing the clinical picture and CTG findings
What should be done if CTG is pathological
Obtain review by obstetrician AND senior midwife
Exclude acute events e.g. cord prolapse, suspected placental abruption, suspected uterine rupture
Correct underlying causes
Brief the mother and any companions
Digital foetal scalp stimulation
Consider foetal blood sampling, expediting birth
