Obstetrics Flashcards
Antenatal - Booking visit; when, what, why?
When; 8-12 weeks (ideally before 10 weeks)
What;
- Bedside Ix; BP, Urinalysis + culture (r/o asymptomatic bacteruria as can cause pyelonephritis and preterm labour), BMI
- Bloods; FBC (anaemia), Blood group, Rh status, Red cell alloantibodies (sickle cell for women at higher risk and thalassaemia for all), Hep B, syphilis, rubella, offer HIV test
- Given green book for documenting the progress during the pregnancy
(screening for Down’s - combined test - perfomed depending on gestational age from 11 weeks onwards)
Why; woman meets with a midwife to discuss all aspects of pregnancy (education, booking bloods, other physiological measures, risk assessment)
Antenatal - Folate supplementation; start, stop and doses in normal and high risk pregnancies?
Start - on conception or 1 month before conception in obesity or other high risk cases (risk of Neural Tube Defects)
Stop - 12 weeks
Dose:
*400mcg - normal pregnancy
*5mg - high risk pregnancy (obesity, smoking, FH)
Antenatal - Nuchal scan; when? 3 causes of increased nuchal translucency?
10 weeks
Causes:
- Down’s Syndrome
- Congenital Heart Disease
- Abdominal Wall Defects
Antenatal - Down’s findings in antenatal tests + definitive tests
10 weeks - increased nuchal translucency
11-13 weeks - Combined test:
- PAPP-A: ↓
- β-hCG: ↑
> 13 weeks - Quadruple test:
β-hCG: ↑
Inhibin-A: ↑
AFP: ↓
Oestriol (uE3): ↓
Definitive tests:
- Non-invasive prenatal testing (NIPT)
- CVS (< 15W)
- Amniocentesis (> 15W)
Antenatal - why might non-invasive prenatal testing (NIPT) be done?
- Rh status of foetus
- Down’s Syndrome screening; optional as parent may not want to know
Antenatal - routine care; begins when and what does it consist of?
Begins at 24 weeks
What:
- Symphysis-fundal height (SFH); to detect foetal intrauterine growth restriction
- BP; screen for pre-eclampsia
- Urinalysis; assess proteinuria as screen for pre-eclampsia
Antenatal - anti-D injections; why and when?
Why - in rhesus negative mother, if children are rhesus positive they express rhesus-D antigen. 1st pregnancy some foetal blood migrates into mother’s bloodstream and she begins to create antibodies to rhesus D antigen (sensitisation). Problem occurs in 2nd pregnancy onwards as rhesus-D antibodies can cross the placenta into the foetus attacking its red cells causing haemolysis -> haemolytic disease of the newborn
IM anti-D injections given to PREVENT sensitisation in rhesus-D negative women (no way to reverse sensitisation once it occurs); works by attaching to the rhesus-D antigens on the fetal red blood cells in the mothers circulation -> subsequently destroyed -> prevents the mother’s immune system recognising the antigen and creating it’s own antibodies to the antigen
When:
- 28 weeks gestation
- Birth if baby’s blood group found to be rhesus-positive
*Also within 72 hours of sensitisation event eg antepartum haemorrhage, amniocentesis, abdo trauma
What are the 3 stages of labour (overview)?
First Stage - from labour onset (true contractions) to 10cm cervical dilation
Second Stage - from 10cm cervical dilatation until delivery of the baby
Third Stage - from delivery of the baby until delivery of placenta
First stage of labour features
Onset of labour (true contractions) to full cervical dilatation (10cm)
- Cervical Dilation - cervix opens up from 0-10cm
- Cervical Effacement/Ripening - cervix gets thinner/shorter
- ‘Show’ - mucous plug in cervix (preventing bacteria entering uterus during pregnancy) falls out creating space for baby to pass through
- 3 Phases of First Stage -
1) Latent Phase - 0-3cm cervical dilation, progresses ~0.5cm/hour, irregular contractions
2) Active Phase - 3-7cm cervical dilation, ~1cm/hour, regular contractions
3) Transition Phase - 7-10cm cervical dilation, ~1cm/hour, strong + regular contractions
What are Braton-Hicks contractions?
Occasional irregular contractions of the uterus
Often felt during 2nd/3rd trimester
Can experience temporary/irregular tightening or milf abdo cramping
NOT TRUE CONTRACTIONS - don’t signify start of labour
* Don’t progress or become regular
How can Braxton-Hicks contractions be reduced?
Staying hydrated and relaxing
What are the signs of labour (4)?
1) Show - mucous plug from cervix
2) Rupture of membranes - waters breaking
3) Regular, painful contractions - true contractions
4) Dilating cervix on examination
How to distinguish between latent first stage and established first stage of labour?
Latent first stage is when there are both:
1) Painful contractions
2) Changes to the cervix, with effacement and dilation up to 4cm
Established first stage of labour is when there are both:
1) Regular, painful contractions
2) Dilatation of the cervix from 4cm onwards
Definitions - ROM, SROM, PROM (x2), P-PROM
Rupture of Membranes (ROM); amniotic sac has ruptured
Spontaneous Rupture of Membranes (SROM); amniotic sac has ruptured
Prelabour Rupture of Membranes (PROM) - amniotic sac has ruptured before the onset of labour
Prolonged rupture of membranes (also PROM) - The amniotic sac ruptures more than 18 hours before delivery
Preterm prelabour rupture of membranes (P‑PROM) - The amniotic sac has ruptured before the onset of labour and before 37 weeks gestation (preterm)
Prematurity - definition, viability, resuscitation considerations
Definition - birth before 37 weeks gestation (more premature = worse outcomes)
Non-viable if below 23 weeks gestation
Resuscitation -
* Born 23-24 weeks, not considered if not showing signs of life
(If born at 23 weeks - 10% chance of survival)
* ≥ 24 increased chance of survival so full resus offered
Classification of prematurity
Extreme preterm - <28 weeks
Very preterm - 28-32 weeks
Moderate to late preterm - 32-37 weeks
Prophylaxis of Preterm Labour - methods
Vaginal Progesterone - via gel or pessary
* Progesterone has role in maintaining pregnancy/preventing labour
* It decreases myometrial activity and prevents cervical remodelling in preparation of delivery
* Offered to women if cervical length <25mm on vaginal US between 16-24 weeks gestation
Cervical Cerclage - stitch in cervix supporting it and keeping it closed and removed when in labour/reaches term
* Spinal or GA needed
* Offered to women with cervical length <25mm on vaginal US between 16-24 weeks gestation + have had previous premature birth/cervical trauma (colposcopy and cone biopsy)
What is rescue cervical cerclage?
Offered to women between 16 and 27+6 weeks gestation if cervical dilation WITHOUT ROM - prevents progression and premature delivery
P-PROM - definition, diagnosis and management
Definition - amniotic sac ruptures, releasing amniotic fluid, before the onset of labour and in a preterm pregnancy (under 37 weeks gestation)
Diagnosis -
* Speculum exam; reveals pooling of amniotic fluid in vagina (no further tests required)
If diagnosis in doubt then:
* Insulin-like growth factor binding protein 1 (IGFBP-1); high conc in amniotic fluid, test vaginal fluid
* Placental alpha-microglobin-1 (PAMG-1); similar alternative to IGFBP-1
Management -
* Prophylactic Abx; to prevent chorioamnionitis - erythromycin 250mg QDS for 10 days or until labour established if within 10 days
*Induction of labour may be offered from 34 weeks
Preterm Labour w/ intact membranes - features + diagnosis
Features - regular, painful contraction + cervical dilatation WITHOUT ROM
Diagnosis - Speculum exam;
* <30 weeks - clinical assessment alone
* >30 weeks - transaginal US to measure cervical length; if <15mm management can be offered (labour unlikely if >15 mm)
* Fetal fibronectin - alternative test to vaginal ultrasound, -ve if <50ng/mL so preterm labour unlikely
(Fetal fibronectin is the “glue” between the chorion and the uterus, and is found in the vagina during labour)
Preterm Labour w/ intact membranes - management
- Fetal Monitoring - CTG or intermittent auscultation
- Tocolysis w/ nifedipine
- Maternal corticosteroids - offered <35 weeks to reduce neonatal morbidity and mortality
- IV MgSO4 - offeref <34 weeks gestation for fetal neuroprotection
- Delayed cord clamping/cord milking - increase circulating blood volume and Hb in baby at birth
Tocolysis - definition, medications, indications
Definition - use of medications to stop uterine contractions
Meds -
* Nifedipine (CCB) - 1st line
* Atosiban - oxytocin receptor antagonist to be used if nifedipine contraindicated
Indications -
* 24 - 33+6 weeks in preterm labour to delay delivery and buy time for fetal development, maternal steroids or transfer to specialist unit (eg NICU)
* Short term measure (<48 hours)
Antental steroids - use and indications
Helps to develop the fetal lungs and reduce respiratory distress syndrome after delivery
Used in women with suspected preterm labour of babies <36 weeks gestation
* Eg two doses of intramuscular betamethasone, 24 hours apart
IV MgSO4 - use, indications, considerations
Use - helps protect the fetal brain during premature delivery. It reduces the risk and severity of cerebral palsy
Indications - given within 24 hours of delivery of preterm babies of <34 weeks gestation
* It is given as a bolus, followed by an infusion for up to 24 hours or until birth
Considerations - Mg toxicity; close monitoring at least 4 hourly. Monitor obs as well as tendon reflexes (patellar mostly)
