Obstetrics Flashcards
how and when will a low-lying placenta usually present?
Painless bleeding at 26-28 weeks.
what is placenta previa?
Placenta previa is an obstetric complication that classically presents as painless vaginal bleeding in the third trimester secondary to an abnormal placentation near or covering the internal cervical os.
at how many weeks is it uncommon to feel fetal movements?
Before 20 weeks
*must ask about fetal movements from 26 weeks,, impossible to do anything before this time.
in pregnancy, when does the risk of VTE end?
Risk starts from the beginning of pregnancy until 6 weeks after delivery.
why are UTIs more common in pregnancy?
Due to the effects of progesterone
if a woman has had Large Loop Excision of the Transformation Zone what is she at risk of in pregnancy?
Preterm birth
what is the usual recommended pre-conceptual folate dose?
400mcg
*5mg if antiepileptics, Diabetes etc.
when are drugs the most teratogenic?
1st trimester (<12 weeks)
when is the early pregnancy scan performed?
12 weeks
11w +2 –> 14w +1
when is the fetal anomaly scan performed?
20 weeks
18w - 20w + 6
when is combined screening performed?
At the early pregnancy/dating scan: 12 weeks
11w +2 –> 14w +1
what does combined screening detect for?
Down’s syndrome
Edwards syndrome
Pataus syndrome
what 3 tests make up the combined screening?
Nuchal translucency scan
hCG
PAPPA
what happens to the hCG in Down’s syndrome?
It is increased
what happens to the PAPPA in Down’s syndrome?
It is decreased
when does the nuchal translucency scan lose accuracy?
14weeks + 1
what is offered to women with a high-risk result for Down’s after combined screening?
Chorionic villous sampling (CVS) from 11 weeks or
Amniocentesis from 15 weeks
when can the quaruple test be performed?
14+2 –> 20 weeks (2nd trimester)
what is the detection rate for Down’s using the combined screening?
85%
what is the detection rate for Down’s using the quadruple test?
80%
does the quaruple test detect Edwards and Patau’s syndrome?
No
what is the detection rate of the non-invasive pre-natal screening (NIPT)?
> 99%
*placental DNA extracted from maternal blood sample
what infectious diseases are tested for at the booking bloods?
HIV, Hep B, Syphilis
why can the rubella vaccine not be given in pregnancy?
Live vaccine
what is done to reduce the risk of HBV transmission to the newborn baby from Hep Be antibody +/Be antigen + mothers?
Newborn requires a dose of immunoglobulin at birth
is a pregnant woman tests positive for syphilis what is required to prevent transmission to the newborn?
Antibiotic treatment 4 weeks to prior to delivery.
*treatment too early incrases risk of miscarriage
Treatment to late - baby will require IV antibiotics
When is the rhesus group of the mother taken?
at booking bloods + at 28 weeks.
at what point are rhesus negative mothers offered anti-D immunoglobulins?
at 28-30 weeks
in what circumstances is the mother given anti-D immunoglobulins after delivery?
If the baby is rhesus positive
when are haemaglobinpathies tested for?
At booking bloods
is the mother is positive for a haemoglobinopathy trait- what is the next step?
Test the partner for the trait
is both the mother and father are positive for traits of haemoglobinpathies - what is offered?
Prenatal diagnosis via invasive testing
at what point is a blood spot performed on the newborn and what is test for?
5 days post delivery
Sickle cell, thalassaemia, hypothyroidism, phenylketonuria, MCADD, maple syrup urine disease
are haemoglobinopathies tested for in all mothers?
Universal screening in high prevalence areas
In low prevalence areas - identify higher risk ethnic groups
is chlamydia routinely screened for?
No - encourage under 25s to participate in opportunistic screening
in whom is hep C screened for as part of the antenatal screening process?
IVDU, obstetric cholestasis
Is group B strep part of the antenatal screening programme?
No (unless swab/urine tested)
how long does the latent phase of labour last?
<1 hour to a few days
what are the characteristics of the latent phase of labour?
painful contractions. Non-continuous period of time
what are the criteria for established labour?
Regular painful contractions (2-4 every 10 mins)
Progressive cervical dilatation from 4cm
in the 1st stage of labour how is he descent of the baby’s head assessed?
Vaginal examination: head position in relation to ischial spines of the pelvis
Abdominal palpation: how many 1/5 of the baby’s head is felt above the pelvis
what is defined as a term birth?
37weeks +
what are the 3 stages of labour?
1) dilatation of 4-10cm
2) full dilatation to birth
3) birth of baby to expulsion of placenta
what are the 2 key things that happen in the 1st stage of labour?
Opening of the cervix (4-10cm)
Descent of the baby’s head
is the descent of the baby’s head is negative what does that mean?
That the baby is still high up = above the ischial spine
what is characteristic of active 2nd stage labour?
Expulsive contractions or active maternal effort with full dilatation of the cervix
what are the signs of the 2nd stage of labour (full dilatation at birth)?`
bulging of the perineum
anal diltation
Red congestion mark
why is the time the head birth noted?
So if shoulder dystocia occurs the time at which this happened can be determined.
what is shoulder dystocia?
Baby’s shoulders can catch on the bony pelvis of the mother leading to a medical emergency because the imbilical cord becomes compressed in the birth canal.
do most women have active management or physiolocal management of the 3rd stage of labour?
Active management is recommended
what drugs are used in active management of the 3rd stage of labour?
Uterotonic drugs - syntometrine
why and when is deferred clamping of the cord performed?
benefit to the baby - prevents anaemia.
atleast > 1minute
what are the side effects of syntometrine?
nausea and vomiting
what is controlled cord traction?
Where counter-pressure is applied just above the pubic bone to guard the uterus and gentle downwards traction is placed on the cord. Reduces bleeding risk.
why is active management recommended in the 3rd stage of labour?
Reduces the risk of post-partum haemorrhage and shortens the length of the 3rd stage
Quicker than physiological (10 mins compared iwth 30mins-1hour)
in physiological management of expulsion of the placenta when is the cord clamped?
No clamping of the cord until pulsation has ceased
what is the definition of induction of labour?
Artificial induction of a baby of gestational age
what is the difference between induction and augmentation of labour?
Induction - Artificial induction of a baby of gestational age
Augmentation - enhanvement of uterine contractility
what are the dangers of prolonged pregnancy?
Increased risk of stillbirth
what are the absolute contra-indications to induction of labour?
Acute fetal compromise
Unstable lie
Placenta previa
Pelvic obstruction
what are the relative contra-indications to induction of labour?
Previous C-section
Breech
Prematurity
High parity
what is unstable lie?
From 37 weeks onwards, unstable lie is the term given to a baby that continues to change its position inside the womb
what are the maternal indications for induction of labour?
Pre-eclampsia
Chronic renal disease
Diabetes
Malignancy
what are the fetal indications for induction of labour?
Prolonged pregnancy (>42 weeks)
Placental insufficiency + IUGR
Rhesus isoimmunisation
Chorioamnionitis
in a woman with pre-labour rupture of membrances how long do you wait before inducing labour?
Allow 24 hours to see if the woman goes into labour if not - induce
*risk of infection
what maneouvres can be performed to reposition a breeched baby?
External cephalic version (ECV)
what 4 things are assessed before induction of labour?
1) Favourability of the cervix - Bishop’s score
2) Obstetric examinatio - confirm life, cephalic presentation + engagement
3) MEWS score - maternal early warning score
4) CTG
what does the modified bishops score assess?
Favourability of the cervix
what 5 parameters are included in the modified bishops score?
Position of the cervix Dilatation of the cervix Length of the cervix Consistency of the cervix Station of the presentation part
in a non-pregnant woman how long is the cervix?
4-5cm
What is the 1st thing tried to induce labour?
Membrane sweeping - finger into cervical os and separate the membrane from the cervix manually
how does membrane sweeping work?
Causes a release of prostaglandins which induce labour
when is membrane sweeping performed in a nulliparous woman?
40-41 weeks
when is membrane sweeping performed in a parous woman?
41 weeks
what do vaginal prostaglandins do to the cervix and uterus induce labour?
Cervix - promote ripening
Uterus - smooth muscle contraction
What are the commonly used vaginal prostaglandins?
Dinoprostone gel (predidil) Misoprostol (PGE1)
what must be performed before an oxytocin infusion is given to induce labour?
Membranes must be ruptured:
either spontaneously or artifically
why is continuous CTG monitoring required if a oxytocin infusion is given?
As it can cause uterine tachysystole and fetal distress
what is the name of the oxytocin infusion given?
syntocinon
how does oxytocin induce labour?
Smooth muscle contraction of the uterus
what should be used in a very low bishops score - prostaglandins or oxytocin?
prostaglandins - work on the cervix and the uterus
oxytocin - work only on the uterus
what are the complications of induction of labour?
fetal distress precipitate delivery (can be too fast) uterine hypotonia + possible rupture amniotic fluid embolism systemic effects instrumental/operative delivery
when is the booking appointment ?
at 10 weeks
what is a normal nuchal translucency?
<3.5mm
what has a higher risk of miscarriage - CVS or amniocentesis?
CVS (chorionic villous sampling)
CVS = 1%
Amniocentesis = 0.8%
in CVS from where is the sample taken?
from the placenta
what is the risk of transmission of HIV via breastfeeding?
3%
what is the risk of transmission of HCV via breastfeeding?
none
The nutrition recommendations given in pregnancy are to prevent against which infections?
Listeriosis
Salmonellosis
Why are pregnant women advised to avoid excess oily fish?
Avoid mercury poisoning
Why are pregnant women advised to avoid liver and liver products m?
Avoid high levels of vitamin A
Why are women advised to avoid soft cheeses in pregnancy?
Listeriosis
When do you expect morning sickness to subside?
16-18 weeks (2nd trimester)
What is responsible for constipation during pregnancy?
Progesterone slows colonic motility and there is increased uterine pressure on the rectum
What is the definition of hyperemesis gravidarum?
Severe vomiting associated with weight loss >5% of pre pregnancy weight, dehydration, electrolyte imbalance and need for admission to hospital
Is bleeding in placental abruption painful or painless?
Painful
*unlike placenta previa = painless
Is placenta previa possible if there is a normal 20 week scan without a low lying placenta?
No
When is an oral glucose tolerance test warranted antenatally at 26 weeks?
Age >35
Ethnicity
BMI >30
Previous unexplained stillbirth
If a woman has a BMI >30 what is she at increased risk of?
GDM
Pre-eclampsia
Macrosomia
Intrauterine growth restriction (placental insufficiency)
What are the risk factors for antepartum haemorrhage?
Hypertension
Previous antepartum haemorrhage
Abdominal trauma
Cocaine/amphetamine use
What is the preferred head presentation at birth?
Occipito-anterior
what is cocaine a risk factor for in pregnancy?
antepartum haemorrhage
in relation to postpartum haemorrhage what do the 4 T’s stand for?
Tone – atonic uterus
Trauma – genital tract trauma
Tissue – retained products of conception
Thrombin – abnormal clotting
what is primary PPH?
> 500ml loss within 24 hours of delivery.
what is secondary PPH?
> 500ml from the genital tract between 24 hours and 6 weeks post-partum.
why is oxytocin used in PPH?
Induce uterine contraction and treat uterine atony
*also use ergometrine, misoprostol
what is HELLP syndrome?
haemolysis, elevated liver enzymes, low platelets
*complication of pre-eclampsia/eclampsia
what is the T sign?
Monochorionic twins - refers to the lack of chorion between the layers of the inter twin membrane
what is the lambda sign?
Dichorionic twins - triangular appearance of the chorion between the layers of the inter twin membrane
are the majority of twins dizygous or monozygous?
Dizygous 80% - derived from 2 separate embryos
Monozygous 20% - derived from division of a single zygote
which antibiotic is used in the management of PPROM?
Erythromycin 250mg QDS for 10 days
what are tocolytics?
Medications given to suppress preterm labour
before 24 weeks what is bleeding referred to?
Threatened miscarriage
after 24 weeks: antepartum haemorrhage
which steroid is used to promote lung maturity antenatally?
Betamethasone (24mg IM in 2 doses over 12 hours apart)
what is defined as a preterm delivery?
24 weeks - 36 weeks + 6 days
what is hydramnios?
Condition where excess amniotic fluid develops during pregnancy
what are the major causes of death in the pre-term infant?
Infection
RDS
Necrotising enterocolitis
Periventricular haemorrhage
at how many weeks would you inhibit uterine activity pharmacologically so cortosteroids can be given tot he mother if pre-term labour has occurred?
<34 weeks
how do B-adrenergic agonists work in preterm labour?
Inhibit myometrial cell contraction
what is indomethacin?
Prostaglandin synthase inhibitor (NSAID) used in preterm labour
in which leg is DVT more likely to occur in pregnancy?
Left leg
incorrect management of which stage is a risk factor for uterine inversion?
incorrect management of the 3rd stage.
what is the risk of uterine rupture in spontaneous labour after c-section? (VBAC)
0.3%
what is the risk of uterine rupture in induction of labour after c-section? (VBAC)
3%
