Obstetrics Flashcards
What are the 4 key things to ask ALL pregnant women when taking a history?
Foetal movements - change in pattern/frequency/strength
Rupture of membranes - quantity and timing, colour etc.
PV bleeding - quantify, painless/painful, provoked etc.
Abdominal pain - SOCRATES, intermittent/constant
Pregnancy is dated from…
…the last menstrual period (LMP).
How long is the median duration of pregnancy?
40 weeks (280 days).
How is expected delivery date (EDD) calculated?
Taking the date of the last menstrual period, adding 9 months and then adding 7 days.
NOTE: If the patient’s cycle is longer than 28 days, add the difference between their cycle length and 28 to compensate.
If the first scan is performed after ___ weeks, the pregnancy cannot be dated.
20.
NICE Guidance - pregnancy dates should only be set by ultrasound using which 2 measurements?
Crown-Rump measurement between 10 weeks to 13+6 weeks.
Head circumference from 14-20 weeks.
Define gravidity.
Total number of pregnancies regardless of how they ended.
Define parity.
Number of live births at any gestation or stillbirths after 24 weeks.
When taking past gynaecological history, irregular periods may be suggestive of which syndrome?
Polycystic ovarian syndrome.
Previous pelvic inflammatory disease increases the risk of…
…ectopic pregnancy.
Recurrent miscarriage may be associated with antiphospholipid syndrome, which increases the risk of…(name 3)
…further pregnancy loss, foetal growth restriction and pre-eclampsia.
Donor egg or sperm is associated with increased risk of what?
Pre-eclampsia.
Which are the major pre-existing diseases that impact pregnancy? (8)
Diabetes mellitus Hypertension Renal disease Epilepsy Venous thromboembolic disease HIV Connective tissue diseases Myasthenia gravis/myotonic dystrophy
In pregnant women, BMI < 20 is associated with…
…increased risk of foetal growth restriction and perinatal mortality.
In pregnant women, BMI > 30 is associated with…
…increased risk of gestational diabetes and hypertension.
Urinary examination:
All women should be offered routine screening for _____ by _____ early in pregnancy. This reduces the risk of pyelonephritis.
Asymptomatic bacteriuria
MSU culture
What is the mean symphysis-fundal height at 20 weeks?
How much does it increase per week?
What should it be at 36 weeks?
20 weeks - 20cm
Increases by 1cm per week
36 weeks - 36cm
Large symphysis-fundal height may suggest…(name 3)
Multiple pregnancy
Macrosomia
Polyhydramnios
Small symphysis-fundal height may suggest…(name 2)
Foetal growth restriction
Oligohydramnios
If a pole is present in the pelvis, what is the lie of the foetus?
Longitudinal.
When the leading pole is not over the pelvis, but to one side, what is the lie of the foetus?
Oblique.
What is it called when the foetus lies directly across the abdomen?
Transverse.
When is the head considered to be ‘engaged’?
When it is no longer moveable.
If the foetal heartbeat cannot be heard with a Pinard stethoscope, what should you use?
Hand-held Doppler.
What are the indications for vaginal examination in a pregnant women? (5)
Excessive or offensive discharge
Vaginal bleeding (if the absence of placenta praaevia is known)
To perform a cervical smear
To confirm potential rupture of the membrane
To confirm and assess the extent of female genital mutilation
What are the contraindications for digital examination of a pregnant women?
Known placenta praevia or vaginal bleeding when the placental site is unknown and the presenting part unengaged.
Pre-labour rupture of the membranes (increased risk of ascending infection).
During examination of a pregnant woman, how many beats of clonus are considered abnormal?
> 3 beats of clonus.
Why is oedema of the extremities not a good indicator of pre-eclampsia?
Because it is present in 80% of term pregnancies.
What are the 4 main risks of smoking during pregnancy?
Foetal growth restriction
Preterm labour
Placental abruption
Intrauterine foetal death
At the booking visit, if BMI is > 35 it is recommended that the woman be reviewed by an obstetric consultant or another healthcare professional that can provide advice on increased pregnancy risks.
What risks are associated with obesity in pregnancy (broken down into antenatal (8), intrapartum (5) and postnatal (4))?
Antenatal: Congenital malformations Neural tube defects Gestational diabetes mellitus Macrosomia Foetal growth restriction Hypertension and pre-eclampsia VTE Miscarriage/Stillbirth
Intrapartum: Difficulty with analgesia Difficulty with monitoring during labour Increased rate of instrumental delivery Increased caesarian section rate Macrosomia/shoulder dystocia
Postnatal: VTE Wound infection Depression Childhood becoming obese/developing diabetes
What are the WHO recommendations on breastfeeding? (3)
Initiate within 1 hour of birth
Exclusive breast feeding for 6 months
Continued breast feeding up to at least 2 years of age
What is urine screened for at each antenatal test and why? (3)
Protein - detect renal disease or pre-eclampsia
Persistent glycosuria - diabetes (pre-existing or gestational)
Nitrites - detect UTIs (if nitrites are present, send for MC&S to detect asymptomatic bacteriuria)
What happens to blood pressure in the first and second trimester?
Blood pressure falls in the first trimester (a small amount) and will rise to pre-pregnancy levels by the end of the second trimester.
What tests are ordered at the booking appointment in pregnancy? (6)
FBC MSU Blood group and antibody screen Haemoglobinopathy screen Infection screen Dating scan and first trimester screening
How is anaemia defined in pregnancy (inc. postpartum)?
First trimester < 110 g/L
Second and third trimesters < 105 g/L
Postpartum < 100 g/L
When should pregnant women with known haemoglobinopathies be offered ferritin supplementation?
When ferritin is < 30mcg/L
What do we give to pregnant women who are rhesus D-negative at the time of potentially sensitising events such as amniocentesis or following trauma?
Anti-D immunoglobulin (ideally within < 72 hours).
When is anti-D prophylaxis indicated in pregnancies < 12 weeks? (4)
Ectopic pregnancies
Molar pregnancies
Therapeutic TOP
Uterine bleeding that is repeated, heavy or associated with abdominal pain
What is the minimum dose of anti-D immunoglobulin given?
250 IU
At what stage in pregnancy are women who are RhD-negative offered prophylactic anti-D immunoglobulin?
28 weeks (given as single large dose at 28 weeks or two doses at 28 and 34 weeks).
NOTE: RhD-negative mothers also receive anti-D postpartum after confirmation that their baby is RhD-positive on cord blood testing.
Screening for thalassaemia is offered to all pregnant women at the booking visit using FBC results and/or which questionnaire?
Family Origin Questionnaire (FOQ)
Which conditions are screened for in the first trimester infection screen?
Syphilis - can cause miscarriage/stillbirth
Hepatitis B - 90% born to women with HBV get it
HIV
Hepatitis C - only if mother is high-risk (IVDU, HIV etc.)
Rubella - this has largely been stopped due to the MMR vaccine in the UK
If a baby is born to a woman with active hepatitis B, what should we do?
The infant should receive the HBV vaccine
One dose of hepatitis B immunoglobulin should be given within 12 hours
Additional doses of vaccine should be given at 1 and 6 months
When should women who decline initial screening for HIV be offered screening again?
28 weeks.
What is the first trimester ultrasound important for? (4)
Dating
Identification of multiple pregnancies
Screening for trisomies
Examination of the foetus for gross anomalies (e.g. anencephaly, cystic hygroma)
When is the first trimester dating/screening ultrasound best performed? What will the crown-rump length be expected to be in this time?
11+3 to 13+6 weeks - CRL is expected to be 45-84mm in this time.
Before 14 weeks, the crown-rump length is used to date the pregnancy. What is used from 14-20 weeks?
Head circumference.
Nuchal translucency is measured in the first trimester ultrasound to assess for the risk of Down syndrome (amongst other conditions). What is the median NT if crown-rump length is:
45mm
84mm
Median NT if CRL is 45mm = 1.2mm
Median NT if CRL is 84mm = 1.9mm
What findings of beta-hCG and pregnancy-associated plasma protein A (PAPP-A) suggest trisomy 21?
High beta-hCG
Low PAPP-A
NICE recommends that women at high risk of pre-eclampsia should be given 75mg aspirin from 12 weeks to delivery. Who is considered high risk? (6)
Hypertensive disease during previous pregnancy
Chronic kidney disease
Autoimmune disease such as SLE and antiphospholipid syndrome
Diabetes mellitus
Chronic hypertension
Women with any high risk factors for pre-eclampsia should be given 75mg aspirin from 12 weeks to delivery, as should women with 2 or more moderate risk factors. What are the moderate risk factors? (6)
Primiparity Advanced maternal age (> 40 years) Pregnancy interval of more than 10 years BMI > 35 at booking visit Family history of pre-eclampsia Multifoetal pregnancy
Who is considered at risk of preterm birth? (4)
Previous preterm birth
Previous late miscarriage
Multifoetal pregnancies
Cervical surgery (e.g. cone biopsy) - these women should be offered serial cervical length screening (w/ or w/o monitoring foetal fibronectin)
NICE recommend that SFH measurements should be performed at every antenatal appointment from what stage (to assess for foetal growth restriction)?
24 weeks.
NICE recommends all pregnant and breastfeeding women take what dose of vitamin D supplements daily?
10 micrograms.
When is the anomaly scan carried out? What conditions may be identified? (4)
20-22 weeks.
Conditions: Spina bifida Major congenital anomalies Diaphragmatic hernia Renal agenesis
What are the criteria for diagnosis of GDM?
Fasting plasma glucose > 5.6 mmol/L
2-hour plasma glucose > 7.8 mmol/L
What are the risk factors for GDM?
Previous GDM
Previous macrosomia
Raised BMI
First-degree relative with diabetes mellitus
Asian, black Caribbean or Middle-Eastern origin
If risk factors for GDM are present, women should be offered what test at 24-28 weeks?
2-hour 75g oral glucose tolerance test (OGTT)
NOTE: Women with previous GDM should have an OGTT at 16-18 weeks and report at 24-28 weeks.
Continuous wave doppler ultrasound is used in the _______ (_ _ _) to provide continuous tracings of the foetal HR (these patterns change when the foetus is _____).
Cardiotocograph (CTG)
Hypoxic
At what stage in pregnancy should you be able to: Visualise the gestational sac Visualise the yolk sac Observe and measure the embryo See the beating of the foetal heart
Visualise the gestational sac = 4-5 weeks
Visualise the yolk sac = 5 weeks
Observe and measure the embryo = 5-6 weeks
See the beating of the foetal heart = 6 weeks
What is blighted ovum?
The gestational sac is present but it is empty because the foetus has not developed.
What 4 measurements can be used in an equation to give an accurate estimate of foetal weight?
Abdominal circumference
Head circumference
Femur length
Biparietal diameter
Cessation of growth is suggestive of what condition?
Placental failure
What is meant by the term chorionicity?
The number of placentas.
When is the best time to perform an ultrasound to assess chorionicity?
9-10 weeks
What is placenta praevia?
When a placenta is inserted into the lower segment of the uterus and can cause life-threatening haemorrhage in pregnancy.
What percentage of women have a low-lying placenta at 20 weeks?
15-20%.
NOTE: 10% of this group will eventually develop placenta praevia.
What generally causes increased amniotic fluid volume?
Congenital abnormalities that impair the ability of the foetus to swallow (e.g. oesophageal atresia).
What generally causes decreased amniotic fluid volume?
Congenital abnormalities that cause a failure of urine production (e.g. renal agenesis).
Which 2 ultrasound measurement approaches give an indication of amniotic fluid volume?
Maximum vertical pool
Amniotic fluid index
Why is amniotic fluid volume reduced in FGR?
Because of redistribution of the foetal blood away from the kidneys to vital structures such as the brain and heart (this leads to reduced renal perfusion and GFR).
How is cervical length best measured?
Transvaginal probe
Under which 2 circumstances does NICE recommend serial measurements of cervical length from 16 weeks?
NOTE: Short cervical length suggests high-risk of early delivery.
History of spontaneous preterm birth
History of mid-trimester loss
When do NICE recommend all women are offered US scans? And why?
10-14 weeks - gestational age, multiple pregnancy, nuchal translucency
18-21 weeks - screen for structural abnormalities
What features of foetal heart rate are reported on CTG? (4)
Baseline rate
Baseline variability
Accelerations
Decelerations
What is considered normal foetal HR?
110-150 bpm
What are the causes of foetal tachycardia? (4)
Maternal or foetal infection
Acute foetal hypoxia
Foetal anaemia
Drug (e.g. ritodrine)
What is meant by short-term variability?
In normal physiological conditions, the interval between successive foetal heart beats varies.
What is meant by baseline variability?
Fluctuations in foetal heart beat occurring 2-6 times per minute.
When is baseline variability considered abnormal?
When it is < 10 bpm.
What factors affect baseline variability? (4)
Foetal sleep states and activity
Hypoxia
Foetal infection
Drugs (e.g. opioids)
Define foetal HR accelerations.
Increases in baseline foetal HR of at least 15 bpm lasting for at least 15 seconds. The presence of 2 or more accelerations on a 20-30 minute antepartum foetal CTG defines a ‘reactive trace’ and indicates a non-hypoxic foetus.
Define foetal HR decelerations. Give 2 causes.
Transient reductions in foetal HR of at least 15 bpm lasting more than 15 seconds.
Causes:
Foetal hypoxia
Umbilical cord compression
What is considered a normal CTG (give 3 findings).
Baseline HR of 110-150 bpm
Baseline variability exceeding 10 bpm
More than 1 acceleration in a 20-30 minute tracing
What are the 5 acute foetal variables which a biophysical profile (BPP) takes into account?
NOTE: A BPP gives a score of up to 10 (2 for normal on each variable, 0 for suboptimal).
Foetal breathing movements (FBMs) Foetal gross body movement Foetal tone CTG Amniotic fluid volume
What score is considered normal on a biophysical profile?
8-10.
How do waveforms (from Doppler USS) from the umbilical artery indicate placental health?
They provide information on placental resistance to blood flow.
What is meant be reversed end-diastolic flow (with regards to umbilical artery doppler USS)?
During diastole, blood is flowing away from the placenta back to the foetus - it is associated with foetal hypoxia and intrauterine death.
Which 2 Doppler USS indices are useful as they calculate variability of blood velocity in a vessel?
Pulsatility index
Resistance index
What is cerebral redistribution?
When falling oxygen levels in the foetus lead to redistribution of blood flow to the essential organs.
Absent diastolic flow in the foetal aorta is suggestive or what?
Foetal acidaemia.
What is the most sensitive index of foetal academia (and the impending heart failure)?
Increasing pulsatility in the central veins supplying the heart (ductus arteriosus and IVC).
Reduced velocity in the ductus venosus A-wave is suggestive of what?
Increasing end-diastolic pressure.
A retrograde ductus venosus A-wave is suggestive of what?
Overt cardiac compromise (this may require early delivery).
The velocity of blood flow in the middle cerebral artery is an indicator of what?
Foetal anaemia - when the foetus is anaemia, peak systolic velocity increases
Doppler USS of which blood vessel can be used to predict pregnancies that are at risk of adverse outcomes such as pre-eclampsia?
Uterine artery
High resistance patterns in the uterine artery are associated with what? (3)
Pre-eclampsia
GFR
Placental abruption
What is cerebroplacental ratio?
The ratio of the pulsatility indices of the middle cerebral artery and the umbilical artery.
NOTE: Foetuses with abnormal ratio that are appropriately grown for gestational age or have late-onset SGA (> 34 weeks) have a higher incidence of abnormal intrapartum CTG requiring emergency Caesarian section, lower cord pH and an increased rate of admission to NICU.
Which hypothesis states that there is an association between reduced foetal growth and increased susceptibility to several adult disease (e.g. coronary heart disease, stroke and diabetes).
Barker hypothesis
How do we define ‘small for gestational age’ (SGA)?
< 10th centile for foetal size.
What is the distinction between SGA and FGR?
Many SGA foetuses have reached their full growth potential, but SGA foetuses that have failed to reach their growth potential are termed FGR.
(BUT not all FGR foetuses will be SGA - some will have a birthweight that is within normal limits but still have not reached their growth potential).
Foetal hyperinsulinaemia occurs in association with maternal diabetes and results in foetal macrosomia and excessive fat depletion. It can lead to complications such as…(name 3).
Stillbirth
Shoulder dystocia
Neonatal hypoglycaemia
Name 3 infections that have been implicated in FGR.
CMV
Toxoplasmosis
Syphilis
Give 3 causes of placental insufficiency.
Poor maternal uterine artery blood flow
Thicket placental trophoblast barrier
Abnormal foetus villous development
What are the 4 shunts that ensure oxygenated blood from the placenta is delivered to the foetal brain?
Umbilical circulation
Ductus venosus
Foramen oval
Ductus arteriosus
Which circulation carries blood to and from the placenta for gas and nutrient exchange?
Umbilical circulation
The umbilical arteries arise from…
…the caudal end of the dorsal foetal aorta.
In a normal foetus, how many foetal arteries and veins are there in the umbilical circulation?
2 foetal arteries
1 foetal vein
The ductus venosus allows most oxygenated foetal blood to bypass the liver, and then joins the IVC before entering the right atrium. What stops the well-oxygenated blood in the ductus venosus and the desaturated blood in the IVC mixing?
The streaming of the ductus venosus blood, and a membranous valve in the right atrium called the crista dividens.
How does the ductus venosus stream pass into the left atrium?
Through the foramen ovale (from the right atrium).
Deoxygenated blood from the foetal head and lower body flows through the right side of the heart into the pulmonary artery - it then bypasses the lungs via what?
The ductus arteriosus. This means that deoxygenated blood from the right ventricle will pass down the aorta and enter the umbilical arterial circulation to be returned to the placenta for oxygenation.
Which 2 local vasodilators keep the ductus arteriosus patent before birth?
Prostaglandin E2
Prostacyclin
What can cause premature closure of the ductus arteriosus?
COX inhibitors.
At birth, what causes closure of the foramen ovale?
Cessation of umbilical blood flow causes cessation of flow into the ductus venosus. This causes a fall in pressure in the right atrium which closes the foramen ovale.
What causes the significant increase in pulmonary circulation at birth?
Ventilation of the lungs opens the pulmonary circulation, causing a rapid fall in pulmonary vascular resistance which dramatically increases pulmonary circulation.
What causes persistent foetal circulation?
The pulmonary vascular resistance fails to fall despite adequate breathing, resulting in left-to-right shunting of blood from the aorta through the ductus arteriosus into the lungs. The baby will be cyanosed and may suffer form life-threatening hypoxia.
There is a rapid increase in which type of brain matter in the last trimester?
Grey matter.
The lungs first appear as an outgrowth from which structure at about 3-4 weeks post-conception?
The primitive foregut.
Describe the development of the respiratory system.
- The lungs first appear as an outgrowth from the primitive foregut at about 3-4 weeks post-conception.
- By 4-7 weeks ,epithelial tube branches and vascular connections are forming.
- By 20 weeks, the conductive airway tree and parallel vascular tree is well developed.
- By 26 weeks, type I and II epithelial cells are beginning to differentiate.
- By 30 weeks, surfactant production has started.
- Up to delivery, dilatation of the airspaces, alveolar formation and maturation of surfactant continues.
What is the main phospholipid in pulmonary surfactant?
Phosphatidylcholine (lecithin).
What 3 factors can enhance the production of phosphatidylcholine?
Cortisol
Growth restriction
Prolonged rupture of the membranes
In which condition is surfactant production delayed?
Maternal diabetes mellitus.
What are the acute complications of respiratory distress syndrome? (3)
Hypoxia/asphyxia
Intraventricular haemorrhage
Necrotising enterocolitis
How can we reduce the incidence and severity of respiratory distress syndrome?
Antenatal steroids - these cross the placenta and stimulate premature release of stored foetal pulmonary surfactant in foetal alveoli.
Prolonged absence or impairment of foetal breathing movements (FBMs) results in reduced mean lung expansion and can lead to what condition?
Pulmonary hypoplasia.
What are the causes of pulmonary hypoplasia? (4)
Prolonged absence or impairment of foetal breathing movements
Oligohydramnios
Decreased intrathroacic space (e.g. diaphragmatic hernia)
Chest wall deformities
What does the foregut endoderm give rise to? (5)
Oesophagus Stomach Proximal half of the duodenum Liver Pancreas
What does the midgut endoderm give rise to? (7)
Distal half of duodenum Jejunum Ileum Caecum Appendix Ascending colon Transverse colon
What does the handgun endoderm give rise to? (3)
Descending colon
Sigmoid colon
Rectum
Failure of the midgut to re-enter the abdominal cavity results in what condition?
Omphalocele (exomphalos).
What is the most common fistula seen in foetal development?
Tracheo-oesophageal fistula. It may be seen alongside other congenital abnormalities (VACTERL association).
What is meant by an ‘atresia’ in the development of the alimentary canal?
When a segment of the alimentary canal has a lumen that is not patent.
Why will bowel atresias cause polyhydramnios in foetuses?
Because the foetus swallows amniotic fluid, so an obstruction that prevents passage of the fluid through the GI tract will cause polyhydramnios.
When does peristalsis begin in the intestines?
2nd trimester.
In the 3rd trimester, what happens to water content, glycogen stores and fat stores?
Water content decreases
Glycogen and fat stores increase (5x)
The liver and biliary tree of a foetus appear late in the 3rd week as what?
The hepatic diverticulum (an outgrowth from the ventral wall of the distal foregut).
NOTE: The larger portion of the diverticulum becomes to hepatocytes and hepatic ducts, and the smaller portion becomes the gallbladder.
At what stage does the foetal liver perform haematopoiesis?
From 6 weeks onward. This peaks at 12-16 weeks and stops at 36 weeks.
Why do neonates get transient unconjugated hyperbilirubinaemia (physiological jaundice)?
Because during foetal life, the placenta does the job of the liver, so the foetal liver has deficiencies of the enzymes required to conjugate bilirubin. After birth, loss of the placenta leads to transient unconjugated hyperbilirubinaemia.
What are the 2 primitive forms of the kidneys?
NOTE: The final form is known as the metanephric kidney.
Pronephros
Mesonephros
Explain the formation of the kidneys and urinary tract in foetuses.
- Pronephros originates at about 3 weeks in a ridge that forms on either side of the midline in the embryo (nephrogenic ridge)
- In this region, epithelial cells will arrange themselves in a series of tubules and join laterally with the pronephric duct
- Each pronephric duct will grow towards the tail of the embryo during which it will induce intermediate mesoderm in the thoracolumbar area to become mesonephric tubules
- The prenephros will then degrade whilst the mesonephric (Wolffian) duct extends towards the most caudal end of the embryo, ultimately attaching to the cloaca
- During the 5th week, the ureteric bud develops as an outpouching from the Wolffian duct
- This bud grows into the intermediate mesoderm and branches to form the collecting duct system (ureter, pelvis, calyces and collecting ducts) of the kidney. It also induces the formation of the renal secretory system (glomeruli, convoluted tubules, loops of Henle)
- Then, the lower portions of the nephric duct will migrate caudally and connect with the bladder, thereby forming the ureters
- As the foetus develops, the torso elongates and the kidneys rotate and migrate upwards within the abdomen causing the length of the ureters to increase
Failure of normal migration of the kidneys can lead to which condition?
Pelvic kidneys
Bilateral renal agenesis causes Potter’s syndrome, which is associated with what? (6)
Widely-spaced eyes Small jaw Low-set ears Secondary oligohydramnios Renal failure (and death) Pulmonary hypoplasia (secondary to oligohydramnios)
What does the epidermis develop from?
The surface ectoderm.
What do the dermis and hypodermic develop from?
Mesenchymal cells in the mesoderm.
Explain the development of the skin in utero.
- By 4 weeks gestation, a single-cell layer of ectoderm surrounds the embryo
- At 6 weeks, the ectodermal layer differentiates into an outer periderm and an inner basal layer
- The periderm will slough off as vernix
- The basal layer produces the epidermis and the glands/nails/hair follicles - Eventually the epidermis becomes stratified and by 16-20 weeks, all layers of the epidermis are developed
When do hair follicles develop in utero?
12-16 weeks. By 24 weeks they are producing lanugo hair.
What is the source of blood cells before 8 weeks in utero?
The blood islands of the yolk sac.
What is the source of blood cells between 8 and 20 weeks in utero?
The liver.
What is the source of blood cells after 20 weeks in utero?
The bone marrow.
At what stage are circulating mature T cells present?
From 16 weeks.
At what stage are B cells present in the circulation?
By 12 weeks.
Detection of IgM or IgA in the newborn without IgG is suggestive of what?
Foetal infection.
At what stage in utero is there a switch from HbF to HbA?
From 28-34 weeks.
When do foetal movements begin?
7-8 weeks.
What are the 4 foetal behavioural states?
1F - quiescence (like non-REM sleep in a neonate)
2F - frequent and periodic gross body movements with eye movements (like REM sleep)
3F - no gross body movements but eye movements (like quiet wakefulness)
4F - vigorous continual activity with eye movements (like active wakefulness)
At what stage does the amnion surface adhere to the chorion surface?
NOTE: They never fuse.
12 weeks.
Choriodecidual function is thought to be important in the initiation of labour by the production of what> (2)
Prostaglandin E2
Prostaglandin F2a
Amniotic fluid is initially secreted by the amnion, but by the 10th week it is mainly what?
Transudate of foetal serum via the skin and umbilical cord.
At what stage does the foetal skin become impermeable to water?
NOTE: This means that transudate of foetal serum via the skin can no longer contribute to amniotic fluid. The net increase in amniotic fluid thereafter is due to contributions through the kidneys and lung fluids.
16 weeks.
Give the expected amniotic fluid volume at: 10 weeks 20 weeks 30 weeks 38 weeks
and after term, at:
40 weeks
42 weeks
10 weeks = 30ml 20 weeks = 300ml 30 weeks = 600ml 38 weeks = 1000ml 40 weeks = 800ml 42 weeks = 350ml
What are the functions of the amniotic fluid? (4)
Protection from mechanical injury
Permit movement of the foetus while preventing limb contracture
Prevent adhesions between foetus and amnion
Permit foetal lung development in which there is two-way movement of fluid into the foetal bronchioles
What are the causes of oligohydramnios? (3)
Renal agenesis
PKD (cystic kidneys)
FGR
What are the causes of polyhydramnios? (3)
Congenital neuromuscular disorders
Anencephaly
Oesophageal/duodenal atresia (prevents swallowing of amniotic fluid)
What is cell-free foetal DNA (cffDNA) used for? (3)
Determination of foetal blood group in cases of RhD alloimmunisation.
Determination of foetal sex in X-linked disorders.
Diagnose skeletal dysplasia (e.g. achondroplasia).
Which cells are collected in chorionic villus sampling?
Foetal trophoblast cells in the mesenchyme of the villi. These divide rapidly in the first trimester.
Before what stage in pregnancy should chorionic villus not be performed?
Before 10 weeks.
Amniocentesis is an investigation whereby 15-20mL of amniotic fluid is sampled and tested. Which important cells are contained in amniotic fluid?
Amniocytes and fibroblasts - these are shed from foetal membranes, skin and foetal genitourinary tract.
What is the advantage of chorionic villus sampling over amniocentesis?
CVS can be performed earlier in pregnancy (amniocentesis should not be performed until 15 weeks).
NOTE: CVS also provides a larger sample of DNA.
Which investigation is used when a sample of foetal blood is needed?
Cordocentesis.
What are the 2 most common conditions that cordocentesis is used to test for?
Suspected severe foetal anaemia
Thrombocytopenia
At what stage in pregnancy is it okay to perform cordocentesis?
From 20 weeks.
What is the screening test of choice for Down syndrome in the 2nd trimester?
Quadruple test - hCG, AFP, unconjugated oestriol and inhibit A.
Which mutation is associated with autosomal dominant severe skeletal dysplasia (achondroplasia, thanatophoric dysplasia)?
Mutation in FGFR3.
Backache during pregnancy causes exaggerated lumbar lordosis. What is it caused by?
Shifting centre of gravity as the uterus grows, additional weight gain and hormone-induced laxity of the spinal ligaments.
What is symphysis pubis dysfunction?
A very painful condition occurring in the 3rd trimester, where the symphysis pubis becomes loose causing the 2 halves of the pelvis to rub against each other when walking or moving (improves after delivery).
What is carpal tunnel syndrome?
Where the median nerve is compressed as it passes through the carpel tunnel - this often occurs in pregnancy due to increased soft tissue swelling.
What causes constipation in pregnancy?
A combination of hormonal and mechanical factors that slow gut motility.
Hyperemesis gravidarum:
Definition
Complications (5)
Definition: Severe, intractable form of nausea and vomiting seen in pregnancy (symptoms are usually most pronounced in the first trimester).
Complications: Electrolyte imbalances Malnutrition Vitamin deficiencies Adverse pregnancy outcome (increased risk of preterm birth and LBW) Mallory-Weiss tears
Hyperemesis gravidarum management.
Antiemetics:
Antihistamines (e.g. cyclising) and phenothiazines (e.g. promethazine) are first line.
Metoclompramide/Ondansetron are second line.
Rehydration and correction of electrolyte imbalances:
Normal saline with additional potassium chloride in each bag.
Check U&Es daily.
Thaimine supplementation.
How should severity of hyperemesis gravidarum be assessed?
Pregnancy-Unique Quantification of Emesis (PUQE) score.
What are the potential side-effects of phenothiazines and metoclompramide?
Extra-pyramidal side-effects and oculogyric crises.
What causes gastro-oesophageal reflux in pregnant women?
Weight effect of the pregnant uterus and hormonally induced relaxation of the oesophageal sphincter.
Why are haemorrhoids more common during pregnancy?
Effects of circulating progesterone on the vasculature, pressure on the superior rectal veins by the gravid uterus and increasing circulating volume.
Obstetric cholestasis (aka intrahepatic cholestasis of pregnancy):
Presentation
Associations (3)
Treatment
Presentation: Pruritus and deranged LFTs without an alternative cause, usually in the 2nd half of pregnancy.
Associations:
Increased risk of spontaneous preterm birth, iatrogenic preterm birth and foetal death.
Treatment:
Ursodeoxycholic acid - treats pruritus and hepatic function.
What causes varicose veins in pregnancy? What complication can occur in a large varicose vein?
The relaxant effect of progesterone on vascular smooth muscle. Thrombophlebitis may occur in a large varicose vein.
What causes oedema in pregnancy?
Generalised soft-tissue swelling and increase capillary permeability, allowing intravascular fluid yo leak into the extravascular compartment.
What is it important to rule out in a patient with generalised oedema in pregnancy?
Pre-eclampsia.
What is meant by the term chloasma?
A common skin condition among pregnant women. It usually presents as dark, brownish patches of skin, mostly on the forehead, nose, upper lip, and cheeks.
What is chloasma?
A common skin condition among pregnant women. It usually presents as dark, brownish patches of skin, mostly on the forehead, nose, upper lip, and cheeks.
Fibroids (Leiomyomata):
What are they?
Where are they found?
What are they?
Compact masses of smooth muscle which may enlarge during pregnancy, causing problems during later pregnancy or delivery.
Where are they found?
In the cavity of the uterus (submucous)
Within the uterine muscle (intramural)
On the outside surface of the uterus (subserous)
NOTE: A subserous pedunculate fibroid case tort, causing acute abdominal pain and tenderness.
Red degeneration:
Definition
Differential diagnoses (5)
One of the most common fibroid complications in pregnancy. As fibroids grow they can become ischaemic, manifesting as acute pain, tenderness over the fibroid and vomiting. If severe, it can precipitate uterine contractions causing preterm labour or miscarriage.
Differential diagnoses: Acute appendicitis Pyelonephritis/UTI Ovarian cyst accident Placental abruption Torted subserous pedunculate fibroid
What proportion of women have a retroverted uterus?
15%
What complication of a retroverted uterus tends to present at 12-14 weeks?
Urinary retention.
The shape of the uterus is embryologically determined by fusion of the _____ _____.
Mullerian ducts.
Abnormalities in fusion of the Mullerian ducts can lead to which uterine anomalies?
Arcuate uterus Supseptate uterus Septate uterus Bicornate uterus Uterus didelphys
What are the 2 subtypes of uterus didelphys?
Bicollis (2 vaginas)
Unicollis (1 vagina)
What are the most common pathological ovarian cysts? (2)
Serous cyst
Benign teratoma
What are the 3 major problems that can occur with ovarian cysts?
Torsion
Haemorrhage
Rupture
NOTE: These cause acute abdominal pain and may result in miscarriage or preterm labour.
UTI (in pregnancy): Definition Associations (2) Predisposing factors (4) First-line antibiotics Most common organism
Definition: > 10^5 colony forming units/mL in urine culture.
Associations:
LBW
Preterm delivery
Predisposing factors: History of recurrent cystitis Renal tract abnormalities Diabetes mellitus Bladder emptying problems (e.g. with multiple sclerosis)
First-line antibiotics:
Amoxicillin or oral cephalosporins.
Most common organism:
E. coli.
What is the most common cause of direct maternal death in the UK?
Venous thromboembolism.
What changes to the thrombotic and fibrinolytic systems are seen in pregnancy?
Increase in factors 8, 9, 10 and fibrinogen
Decrease in protein C and antithrombin-III
How much is VTE risk increased in pregnancy?
6-10 fold.
What are the risk factors of thromboembolic disease in pregnancy (excluding pre-existing risk factors such as obesity etc.)? (7)
Multiple gestation Pre-eclampsia Grand multiparty Caesarian section Damage to pelvic veins Sepsis Prolonged bed rest
What is acquired thrombophilia in pregnancy most commonly associated with?
Anti-phospholipid syndrome (APS).
Define anti-phospholipid syndrome (APS).
The combination of lupus anticoagulant with or without anti-cardiolipin antibodies, with a history of recurrent miscarriage and/or thrombosis.
What its the first investigation used in suspected DVT in a pregnant woman?
Compression duplex ultrasound.
Why is warfarin contraindicated in pregnancy (except in women with mechanical heart valves)?
Because it closes the placenta and can cause limb and facial defects and foetal intracerebral haemorrhage.
What is the anticoagulant of choice in pregnancy?
Low molecular weight heparin (LMWH).
Under what circumstances should IVC filters be considered in the permpartum period?
For patients with iliac vein VTE or with proven DVT and those who have recurrent PE despite anticoagulation.
What are the treatment options for massive PE in pregnant women? (4)
IV unfractionated heparin
Thrombolytic therapy
Thoracotomy
Surgical embolectomy
What is the maintenance treatment of VTE in pregnancy?
Treatment with subcutaneous LMWH for the remainder of the pregnancy and for at least 6 weeks postnatally, and until at least 3 months of treatment in total.
What anticoagulant can be given during labour if necessary?
IV unfractionated heparin.
How long before planned delivery should LMWH be stopped?
24 hours.
Which markers of acute alcohol abuse are not reliable during pregnancy? (2)
MCV
GGT
Smoking in pregnancy reduces placental perfusion, and is associated with what? (3)
NOTE: Cessation by 15 weeks gestation reduces the risk as much as quitting before pregnancy.
Increased perinatal mortality
Smaller babies
Higher risk of placental abruption
OIligohydramnios:
Definition
Causes (7)
Consequences of severe early-onset oligohydramnios (2)
Definition: Amniotic fluid index (AFI) < 5th centile for gestation (AFI is an ultrasound estimation of amniotic fluid volume).
Causes: Renal agenesis (incompatible with life) Multicystic kidneys urinary tract abnormalities/obstruction FGR and placental insufficiency Maternal drugs (e.g. NSAIDs) Post-dates pregnancy PPROM
Consequences of severe early-onset oligohydramnios:
Pulmonary hypoplasia
Limb deformities
Polyhydramnios:
Definition
Maternal causes (4)
Foetal causes (6)
Definition: AFI > 95th centile for gestation.
Maternal causes: Diabetes Placental Chorioangioma AV fistula
Foetal causes:
Multiple gestation
Idiopathic
Oesophageal atresia/tracheo-oesophageal fistula
Duodenal atresia
Neuromuscular fetal condition which prevents swallowing
Anencephaly
What are the 3 types of breech? Which is most common?
Extended (Frank) - most common
Flexed (Complete)
Footling
What are the 3 treatment options for breech?
External cephalic version
Vaginal breech delivery
Elective caesarian section
What is the best method of delivery a term breech singleton?
Planned caesarian section
Reasoning: Vaginal delivery is associated with 3% increased risk of death or serious morbidity to the baby. Also, although risk of maternal complications is lower in successful vaginal delivery than planned C-section, 40% of attempted vaginal deliveries result in emergency C-section, which has a higher incidence of maternal complications.
What are the features of high risk in a planned vaginal delivery in a breech presentation? (5)
Hyperextended neck on USS High estimated foetal weight Low estimated foetal weight Footling presentation Evidence of antenatal foetal compromise
External cephalic version can be performed at or after what stage in pregnancy?
37 weeks.
NOTE: A tocolytic (e.g. nifedipine) should given to prevent contractions.
What are the contraindications for external cephalic version? (8)
Foetal abnormality (e.g. hydrocephalus) Placenta praevia Oligo/polyhydramnios History of antepartum haemorrhage Previous C-section or myomectomy scar on the uterus Multiple gestation Pre-eclampsia or hypertension Plan to deliver by C-section anyway
In vaginal delivery of a breech presentation, which manoeuvre can be used to deliver the legs if they are extended?
NOTE: If the legs are flexed, they will deliver spontaneously.
Pinard’s manoeuvre - use a finger to flex the leg at the knee and extend the hip, first anteriorly and then posteriorly.
Although unnecessary to perform routinely, which manoeuvre can be used to deliver the shoulders of a breech baby in a vaginal delivery?
Loveset’s manoeuvre.
How is the head of a breech baby delivered in a vaginal delivery?
Using the Mauriceau-Smellie-Veit manoeuvre - the baby lies on the obstetrician’s arm with downward traction on the head via a finger in the mouth and one on each axilla. Delivery occurs with first downward and then upward movement.
Other than breech presentations, what foetal malpresentation exist? (2)
Transverse lie
Oblique lie
NOTE: Normal lie is known as longitudinal.
What risks are associated with transverse and oblique lie?
Cord prolapse following spontaneous rupture of the membranes
Prolapse of the hand, shoulder or foot once in labour
Post-term pregnancy:
Definition
What proportion of pregnancies are affected?
Definition: Pregnancy that has extended to or beyond 42 weeks gestation.
What proportion of pregnancies are affected?
10%.
In cases of post-term pregnancy, under which circumstances should immediate induction of labour take place? (5)
Reduced amniotic fluid on ultrasound Foetal growth is reduced Reduced foetal movements CTG abnormalities Mother is hypertensive or has another significant co-morbidity
What is the difference between threatened miscarriage and antepartum haemorrhage?
Vaginal bleeding at < 24 weeks is threatened miscarriage.
Vaginal bleeding at 24+ weeks is antepartum haemorrhage.
What are the causes of antepartum haemorrhage? (8)
Placental:
Placental abruption
Placenta praevia
Vasa praevia
Local causes: Cervicitis Cervical ectropion Cervical carcinoma Vaginal trauma Vaginal infection
The most clinically important Rhesus antigens are C, D and E. They are coded on two adjacent genes on which chromosome?
Chromosome 1.
Which Rhesus antibodies cause haemolytic disease of the foetal and newborn (HDFN)?
Anti-D (most commonly)
Anti-C (rarely)
Occurrence of HDFN from rhesus auto immunisation requires 3 things to happen - what are they?
- A rhesus negative mother must conceive a baby who has inherited the rhesus-positive phenotype from the father.
- Foetal cells must gain access to the maternal circulation in sufficient volume to provoke a maternal antibody response.
- Maternal antibodies must cross the placenta and cause immune destruction of red cells in the foetus.
Why does rhesus disease not affect the first pregnancy?
Because the primary immune response is usually weak and consists mostly of IgM which does not cross the placenta. In the subsequent pregnancies, B cells produce a much larger response with IgG antibodies which do cross the placenta.
What are the potential sensitising events for rhesus disease? (5)
Miscarriage Termination Antepartum haemorrhage Invasive prenatal testing (CVS, amniocentesis, cordocentesis) Delivery
Which test is used to identify the proportion of foetal cells in the maternal blood, allowing calculations of the seize of foeti-maternal transfusion and the amount of extra anti-D required in cases of potential rhesus isoimmunisation?
The Kleihauer test.
What are the signs of foetal anaemia (e.g. caused by HDFN)? (6)
Polyhydramnios Enlarged foetal heart Ascites and pericardial effusions Hyperdynamic foetal circulation Reduced foetal movement Abnormal CTG with reduced variability and eventually a sinusoidal trace
Which scans can we use to assess foetal anaemia?
Middle cerebral artery Doppler scans (peak velocity measurement).
What are the routes of administration for foetal blood transfusions in cases of foetal anaemia? (4)
Into umbilical vein at point of cord insertion
Into intrahepatic vein
Into peritoneal cavity
Into foetal heart
Multiple pregnancy accounts for what proportion of live births?
3%
