obstetrics Flashcards
at what age does en embryo become a foetus?
10 weeks
what day does implantation occur
day 24
What are the 3 trimesters?
I- weeks 1-12
II- weeks 13-27
III- weeks 28-birth
what does the average term foetus weigh?
3.4kg
what structure in foetal circulation allows blood to bypass the liver?
ligamentum venosum
what structures in foetal circulation allows bypassing of the lungs?
foramen ovale
ductus arteriousus
how many days after conception can BhCG be detected in the blood?
8-9 days after conception/ 4wks after LMP, doubles every 48 hours to 10wks. Pregnancy test positive when >25. BhCG maintains progesterone from corpus luteum until placenta takes over
what are the roles of progesterone, oestrogen, oxytocin and prostaglandins during pegnancy
progesterone maintains uterine quiescence until labour
oestrogen stimulates growth of duct cells and prolactin production, closer to labour increase in myometrium and gap junctions, stimulate prostaglandin production. increases number of oxytocin receptors therefore increasing sensitivity
prostaglandins help ripen cervix
oxytocin stimulate contractions in labour, positive feedback leads to increased prostaglandins
what normal physiological changes occur in pregnancy?
RS- less tidal volume so less pC02 and resp alkalosis (compensated)
CVS- progesterone reduces vasc resistance therefore intial drop in BP, rises back to normal as RAS (aldosterone) increases fluid retention, dilutional anaemia
GI- progesterone relaxes smooth muscles so delayed emptying and reflux. more gallstones and more insulin resistance
Other, pro-clotting state so higher risk of VTE
reduced immunity
linea nigra
at what age would you ask about foetal movements
26 weeks
when is the dating scan?
8- 13+6
when is the anomaly scan?
18- 21 weeks
Which vessels does the doppler look at?
umbilical arteries and middle cerebral artery. End diastolic flow should always be positive
what is part of the combined test and when is it done?
done at 10-13+6 weeks. nuchal translucency and BhCG, PAPP-A blood test (high risk if BhCG high and PAPP-A low)
what is the quadruple test?
done at 14-20 weeks, measures BhCG, AFP, inhibin A and unconjugated estriol uE3
BhCG and inhibin-A raised, uE3 and AFP low in Downs
what level of risk would you offer CVS/ amniocentesis
1:150
What is CVS and what are the risks
Chorionic villous sampling, done at 11-14 weeks for high risk of Downs. needle passed through tummy to get sample of placenta. uncomfortable not painful and may get spotting for a few days. Risk of miscarriage (1%) or infection
What is amniocentesis and what are the risks?
done if high risk of Down’s (>1:150) and later 15-20 weeks. needle inserted through tummy to get sample of amniotic fluid. uncomfortable not painful and may get spotting for a few days. Risk of miscarriage (0.5%) or infection
what maternal ages make a pregnancy high risk
<18 (IUGR), >38 (IUGR, chromosomal abnormalities, stillbirth)
why does maternal obesity make a pregnancy high risk
increased risk of HTN, GDM, shoulder dystocia, VTE, NTD.
low maternal weight increases risk of IUGR
what factors in the current pregnancy make it high risk?
pre-eclampsia GDM fibroids (increase risk of PPH or unstable lie) multiple pregnancy assisted conception
which antiemetics can be used for hyperemesis
cyclizine, reassurance will settle by week 20
what can you use for reflux in pregnancy
ranitidine (H2 receptor blockers)
what would differentiate hyperemesis gravidum from normal nausea and vomitting?
5% pre-pregnancy weight loss
electrolyte imbalances
check for molar/ multiple pregnancy, increased risk of VTE
why might a foetus be large for dates?
Maternal DM
fibroids (may palpate as large for dates)
antenatal infection (TORCH) causes polyhydramnios
What infections are TORCH?
toxoplasmosis other (syphilis, VZV, parvovirus B19) rubella cytomegalovirus Herpes
Why might a foetus be small for gestational age?
previous SGA/ IUGR preeclampsia smoking Asian maternal illness (including anaemia, renal disease, HIV etc) Drug use (cocaine)
what complications can arise from cocaine use during pregnancy?
IUGR, neonatal withdrawal
describe the OGTT
anyone at risk of gestational diabetes has this between 24 and 28 weeks. Glucose measured first thing in the morning and repeated 2hrs after a glucose drink
what on an USS differentiate SGA and IUGR?
in SGA baby equally small
IUGR HC larger than AC as blood diverted to vital organs. may have oligohydramnios
what investigations would you want to do in a SGA foetus?
OGTT, Maternal Abs to TORCH, BP, urinalysis, USS and doppler, FBC, U&Es, LFT, CTG
when do you first feel foetal movements?
18-20 weeks, after 20 weeks get into pattern, reduced foetal movements indicator after 28 weeks
if mother unsure whether feeling reduced foetal movements, what advice should be given?
lie on left side for 2 hours and relax, if <10 movements felt call maternity unit
what age can you start doing CTG
28 weeks
what is the management for RFM?
<28 weeks auscultate HB
>28 weeks CTG
assess for risk factors for stillbirth (SGA, IUGR, placental insufficiency, congenital malformations, recurrent episodes of RFM)
if still concerned USS
what are the risks of prolonged pregnancy?
intrauterine infection
macrosomnia (prolonged labour, shoulder dystocia, birth injury-> cerebral palsy)
PPH
placental insuffiency
What is PROM?
Premature rupture of membranes, one hour or more before the onset of labour
What is PPROM?
preterm, premature rupture of membranes- before 37 weeks
if PPROM is suspected what would investigations be>
Sterile speculum-> pooling of fluid and pH neutral (not usual 4.5)
Actim partus (insulin-like GF binding protein 1)/ foetal fibronectin >500 suggests labour soon
admit (likely to deliver in 48hrs)
prophylactic erythromycin 250mg QDS 10 days or until in labour
2 doses 12mg(?) betamethasone if 24-33+6 12/24 hours apart
induce at 34weeks
what can be done for a woman with a history of PPROM
cervical cerclage
PV progesterone
what is the “T” sign on USS suggestive of?
monozygotic (monochorionic) twins
what is the “lamda” sign on USS suggestive of?
dizygotic (dichorionic) twins
which multiple pregnancies are at risk of twin to twin transfusion?
diamniotic/ monoamniotic monochorionic twins
most are dichorionic diamniotic (75%)
risks of multiple pregnancies?
foetal malformations PPROM (Cervical suture?) TTTS- (blood shunted-> one twin anaemic and IUGR-> death in 80%) low birth weight preeclampsia DM placenta previa placental abruption
when would you expect pregnancy induced hypertension to resolve by?
6 weeks post delivery
when would you give aspirin to a mother?
75mg a day from 12 weeks, if high risk of pre-eclampsia (FHx of Pre-eclampsia, previous pregnancy, multiple pregnancy, BMI>35, age>40, nulliparip/ last pregnancy>10 years ago)
If a mother has pre-existing hypertension, how would you manage her?
diet and lifestyle advice,
If on ACEi/ ARB can continue medication. ACEi/ ARB must be switched to labetalol. Obstetric led care from booking. aim for BP <150/100.
aspirin 75mg OD 12 weeks-> delivery
doppler at 28-30/ 32-34weeks
what gestation differentiates pre-exisiting hypertension and pregnancy induced hypertension?
20 weeks
what are the symptom of pre-elampsia?
severe headaches visual problems gastric/ RUQ pain vomiting SOB sudden swelling of hands/ face/ feet
what are the complications of pre-eclampsia?
HELLP syndrome- haemolysis, elevated liver enzymes, low platelets. eclampsia- one or more seizures pulmonary oedema retinal detachment PPH abruption IUGR