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
if a woman presents with proteinuria after 20 weeks what should you do?
send urine for MSU and microscopy
24hr urine or protein: creatinine (severe if >30mg/mmol)
FBC, U&E, kidney function, transaminases and bilirubin
what blood pressure would you start labetalol at?
150/100
how often should a woman with pre-eclampsia monitor BP and bloods?
BP at least 4 times a day
bloods- FBC, kidney function, U&Es, transaminases, bilirubin twice a week
what are the risks of gestational diabetes?
macrosomnia-> shoudler dystocia
polyhydramnios-> IUD/ stillbirth
frequent UTI
(risk of pre-exisiting diabetes include above but also miscarriage/ NTD)
what HbA1C should a diabetic woman aim for pre-regnancy?
<48mmol
If at risk of gestational diabetes what test would you do and when?
OGTT (75g glucose, 2hrs) at booking and at 24-28wks
risk factors for gestational diabetes-
asian
previous macrosomnic baby
BMI>30
FHx
how often would you monitor foetal growth and liquor volume in a woman with gestational diabetes?
every 4 weeks from 28 weeks
what are possible maternal causes of stillbirth?
pre-eclampsia
diabetes
sepsis
what are possible foetal causes of stillbirth?
chromosomal abnormalities
rhesus disease
IUGR (TTTS)
What are placental causes of stillbirth?
post-dates
abruption
praevia-> significant bleed
prolapse
what support is available after a miscarriage?
miscarriage association (helpline)
cruse bereavement centre
stillbirth-SANDS (stillbirth and neonatal death society)
If a DVT is suspected but a compression duplex ultrasound is negative what should you do?
continue LMWH and repeat scan on days 3 and 7
what are first line investigations in someone presenting with signs of a PE?
ECG
CXR
if symptoms of DVT then compression duplex USS (if DVT present no further investigations needed)
If a woman presents with signs of a PE but no signs of a DVT what additional investigations would you do?
ventilation/ perfusion (V/Q) or computerised tomography pulmonary angiogram (CTPA)
If VTE suspected what bloods would be done before starting LMWH?
FBC
coagulation screen
U&Es
LFT
Once LMWH started how long should it be continued for?
at least 6weeks PP and until 3months given
what is the risk of uterine rupture in VBAC?
0.5%
what are the contraindications to VBAC?
previous rupture
classic caesarean
caution if 2+ LSCS
what are the pros and cons of VBAC?
pros- shorter recovery, lower risk of haemorrhage/ infection etc
Cons- risk of rupture (3% if induced), may need emergency cesarean-> increased risk of placenta praevia/ accreta in future pregnancies,
what is the success rate of VBAC?
70-75% (85-90% if previous vaginal birth)
what are the 3 stages of labour?
1- onset to fully dilated
2- fully dilated to birth of foetus
3- delivery of placenta
what describes the onset of labour?
regular contractions
passage of mucoid plug
rupture of membranes
dilation and effacement of cervix (4+cm)
at what rate should cervical dilation occur?
at least 2cm every 4 hours
how many contractions should a woman have in 10 minutes?
4
what position should the baby be in at the start of labour?
occipito-anterior or occipito-transverse, neck flexed
how long should a good contraction last?
at least 60 seconds
what does engagement describe?
the fifths of the babys head (or presenting part) palpable- ie fully engaged when no fifths palpable
what does foetal station describe?
the relationship of the foetal head to the ischial spines on a VE. if +1 the head is 1cm below the ischial spines.
name 5 things recorded on a partogram
FHR MHR/ BP liquor cervical dilation descent of presenting part (station) contractions syntocinon units temp urine output
how is foetal heart rate monitored during pregnancy?
low risk- intermittent auscultation with pinard stethoscope
high risk- continuous monitoring with CTG, if not possible (e.g. in obese mothers) foetal scalp electrode
describe the mechanism of labour
occipito-transverse, head flexed-> occipito-anterior and neck extension to allow delivery of head-> restitution (turn so shoulders in AP position)-> delivery of anterior shoulder-> delivery of posterior shoulder
cons of entenox?
pain relief only at time of inhalation, nausea, light-headedness
cons of morphine?
Maternal: drowsiness, N+V (give anti-emetic, no birth pool)
Baby: short term drowsiness and resp depression.
cons of epidural:
2nd stage may take longer and may need instrumental. drop in BP-> light-headedness, temporary loss of bladder control, N+V, headaches. No long term back ache (often a concern)
what is Erb’s palsy?
paralysis of an arm seen after shoulder dystocia, caused by damage to C5-6.
what would you try in shoulder dystocia?
get help early!, McRobert’s position- flex hips (knees to chest), suprapubid pressure, internal rotation techniques, delivery of posterior arm, epiosiotomy, fracture clavicles
describe the medical management of the third stage of labour
oxytocin (syntocinon) 5 units IM when anterior shoulder delivered
clamping and cutting the cord
cord traction and suprapubic pressure to deliver placenta
(then check placenta and membranes, check for tears, palpate fundus to check contracted to umbilical level, record EBL)
describe the physiological management of the third stage of labour
no oxytocin (therefore less N+V)
no clamping and cutting the cord until pulsations stopped
placenta delivered by maternal effort.
higher risk of PPH
(then check placenta and membranes, check for tears, palpate fundus to check contracted to umbilical level, record EBL)
what are contraindications to induction of labour?
acute foetal compromise unstable lie pelvic obstruction placenta praevia (less so; breech, previous LSCS, premature, high parity)
what are indications for the induction of labour?
Maternal- severe pre-eclampsia, other pre-existing disease
Foetal- prolonged pregnancy, IUGR, PPROM, Rhesus disease, IUD
What factors affect the Bishop score? and what is a favourable score?
position cervix consistency effacement dilation station a score of 6 or less indicates unlikely to labour spontaneously and induction is indicated
what is the first step of induction?
PV PGE2 gel (1 dose followed by second after 6 hours if no labour)/ suppositories (stay for 24 hours)
may-> uterine hyperstimulation (5+ contractions in 10mins/ contraction lasting >2 minutes)-> FHR problems, uterine rupture, placental abruption
when is a membrane sweep done?
40-41 weeks, releases prostaglandins
what are the complications of induction?
failed induction
uterine rupture
uterine hyperstimulation
cord prolapse (ARM)
what are the risks of artificial rupture of membranes?
cord prolapse infection bleeding placental separation failure to induce contractions amniotic fluid embolism uterine hyperstimulation +/- rupture
what are the complications of oxytocin infusion in labour?
uterine hyperstimulation +/- rupture
abnormal FHR
fluid overload
titrate the dose to maternal contractions and FHR
name some reasons why a woman might fail to progress in labour?
passage- cephalopelvic disproportion, uterine abnormality, fibroids
passenger- macrosomnia, malposition, malpresentation
power- lack of contractions
when would you artificially rupture membranes?
failure to progress in second stage- no progress after 1 hour, will probably need instrumental birth.
how many breech babies can be resolved by ECV?
50%
done at 36 weeks, may be uncomfortable. remember rhesus anti-D immunoglobulin, may give tocolytics
what are contraindications of ECV?
antepartum haemorrhage ruptured membranes placenta praevia previous LSCS multiple pregnancy
what should you say to counsel someone on an episiotomy?
reason- breech, forceps, need for faster delivery (maternal heart disease, abnormal CTG)
local anaesthetic used/ epidural
small diagonal cut from back of vagina
dissolvable stitches used
after can use parcetamol (not ibuprofen if breastfeeding)/ ice packs
painful sex after but improves after first few months
look for red, swelling, persistent pain, discharge from cut
may need future episiotomy (as scar tissue doesnt stretch)
what are the degrees of perineal tears?
1st- perineal skin 2nd- perineal muscles 3a- <50% anal sphincter 3b- >50% anal sphincter 3c- internal anal sphincter 4th- anal epithelium
what are the long term complications of perineal tears?
1st/2nd complications rare. 3rd/4th 60-80% asymptomatic after 12 years: faecal incontinence, faecal urgency, pain, dyspareunia, flatulance incontinence
what are the indications for ventouse?
delay in second stage-> maternal exhaustion, foetal malposition, abnormal CTG
what factors must be present for a ventouse?
adequate analgesia
head 1/5 or 0/5 palpable (known F position)
regular contractions (and adequate M effort)
empty bladder
monitor with CTG?
how long would you use a ventouse for?
15 minutes,
what is the advantage of Simpson’s/ Keilland’s forceps over ventouse?
less maternal effort required, therefore can be used if mother unable to push/ unconscious
What complications should be explained to a mother considering a LSCS?
need for future (VBAC) haemorrhage N+V (epidural) infection (prophylactic Abx) damage to surrounding structures Foetal laceration VTE and longer hospital stays
how would placenta praevia classically present?
painless PV bleed in third trimester. uterus SNT.
Risk factors- increases M age, parity, previous LSCS, multiple pregnancy
how would you manage placenta praevia?
ABCDEF approach, if maternal or foaetal compromise-> LSCS
if not elective LSCS at 37 weeks
what is the recurrence risk pf placenta praevia?
4-8%
how would a placental abruption classically present?
painful PV bleed, abdo tender and uterus hard
Risk factors- pre-eclampsia, abdo trauma, cocaine or smoking, ECV
what are the causes of PPH?
Tone- most common
Trauma (lacerations/ uterine rupture)
Tissue (retained tissue/ clots)
Thrombin (coagulopathy)
what are the risk factors for PPH?
multiple pregnancy, multiparity, polyhydramnios, fibroids, prolonged labour, instrumental delivery, previous PPH, antepartum bleed
what is the definition of PPH?
> 500ml blood loss. primary < 24hrs, secondary 24hrs-6weeks
how would you manage PPH due to atony?
A-E approach, fluids/ transfusion? bimanual massage, IV syntocinon (+ergometrine)
balloon tamponade
surgery
what is the definition of puerperal infection?
temperature higher than 38 for >4 hours, less than 14 days after delivery
how common are the baby blues?
70%
how common is postnatal depression?
10%
how do baby blues and postnatal depression vary in onset?
baby blues sooner (day 4-5) whereas postnatal depression week 4-6
what percentage of eclamptic seizures occur postnatally?
40%
What is the recommended treatment for eclampsia?
4g MgSO4 over 5-15mins then infusion of 1g/hour for 24hours after seizure or delivery (whichever later)
which contraceptives are contr-indicated in breastfeeding?
COCP, (ring, patch)
When after delivery should contraception be started?
3 weeks if not breastfeeding, 6 weeks if breastfeeding?
when is the post-natal check?
6-8 weeks after delivery at the GP
