Obstetrics Flashcards
Medical abortion
- which drugs are used
- how do the drugs work
- what happens if <10 weeks
- what happens for 10-24 weeks
Oral mifepristone (anti-progesterone) followed by a misoprostol pessary (prostaglandin) 48 hours later
Mifepristone ends the pregnancy by blocking the progesterone which causes the uterus lining to break down
Misoprostol causes the uterus to contract (cramping and bleeding) allowing for expulsion of products
<10 weeks: take mifepristone in clinic, then go home. Take misoprostol at home 48 hours later. Abortion completed at home.
10-24 weeks: take mifepristone in clinic, then go home. Second appt in clinic 48 hours later for misoprostol. Abortion completed in clinic with analgesia and observation. May require surgery to if all products havent been expelled. Anti-D needed if Rh-ve. If >22weeks, digoxin or KCl may be injected to stop foetal heartbeat.
Contraindications to medical abortion
?ectopic, CKD, liver disease, allergies to the drugs, long term steroid use, haemorrhagic disease, currently on anticogulation
Surgical abortion
- what happens
- <15 weeks
- 15-24 weeks
Cervical preparation with misoprostol and dilators to soften and dilate the cervix
<15 weeks: vacuum aspiration. Under LA if <14weeks and under GA if <15 weeks.
15-24 weeks: dilatation and evacuation under GA.
Complications of TOP
retained products, haemorrhage, infection, sepsis, psychological distress, DIC
Iatrogenic trauma: uterine perforation, cervical injury
Folic acid requirements pre-pregnancy and during pregnancy
400 micrograms taken daily from 12 weeks prior to conception until 12 weeks gestation, to prevent neural tube defects
5mg recommended for women on antiepileptics, or those with a family history or past obstetric history of neural tube defects
Where is b-hCG produced?
What is the role of b-hCG?
What is the trend of b-hCG levels at the beginning of pregnancy?
How do pregnancy tests work?
Produced by the embryo initially, and then by the placental trophoblast
Main role is to prevent disintegration of the corpus luteum
Levels double every 48 hours in the first few weeks and peak at 8-10 weeks
b-hCG in the woman’s urine travels up the test strip and binds to a pigmented antibody on the test strip -> creates a pigmented line on the test strip to confirm pregnancy
Naegele rule
Factors affecting the accuracy of naegele rule
Expected delivery date = LMP + 9 months + 7 days
Relies on the woman’s accuracy of recalling her last period
Relies on regular cycles
Doesnt consider presence of early or light bleeding
The use of OCP or breast feeding could affect ovulation timings
At what gestation should singletons and multiple pregnancies stop air travel?
Singleton up to 37 weeks
Uncomplicated multiple pregnancy up to 32 weeks
Obstetric conditions which cause an increased AFP
Obstetric conditions which cause a reduced AFP
Increased: neural tube defects, abdominal wall defect, multiple pregnancy
Reduced: down’s syndrome, trisomy 18 (edwards), maternal diabetes mellitus
Antenatal care timetable (brief detail)
- <10wks: Booking visit
- 10-13+6: dating scan
- 11-13+6: combined tests for Downs (21), Edwards (18), Pataus (13)
- 15-20: triple/ quadruple test for Down’s
- 16: review blood tests and screening results. OGTT is woman has had GDM in a previous pregnancy.
- 18-20+6: foetal anomaly scan
- 25: only for primip. BP, urine dip, symphysis-fundal height (SFH)
- 28: anti-D if Rh-ve, OGTT if high risk, second anaemia screen, routine BP/ urine dip/ SFH
- 31: primip. BP, urine dip, SFH
- 34: second anti-D, discuss labour/birth plan, BP, urine dip, SFH
- 36: check foetal presentation (offer ECV if breech), BP, urine dip, SFH
- 38: routine BP, urine dip, SFH
- 40: primip BP, urine dip, SFH, discuss prolonged pregnancy
- 41: induce labour or membrane sweep
What happens at the booking visit? and when is it?
<10 weeks (usually 8-10)
- Provide general advice about food, alcohol, smoking, antenatal classes
- Check BP, urine dip, BMI (pre-eclampsia risk factors)
- Vitamins: folate 400mcg until 12wks, vit D 10mcg daily
Routine tests:
- FBC (anaemia)
- G+S (rhesus state, rhesus isoimmunisation)
- Electrophoresis (haemoglobinopathies)
- Infection screen (syphillis, hep B, HIV, rubella)
- Urinalysis (glycosuria, proteinuria, haematuria, bacteruria)
When is the dating scan and what happens?
10 - 13+6 weeks
Crown-rump measurement - allows you to date the pregnancy and provide an EDD
Can also check for ectopic pregnancy, multiple pregnancies and abnormal early development
When is the combined test and what happens?
What happens with abnormal results?
11 - 13+6 weeks
Combined test check for down’s (21), edwards (18) and pataus (13)
Nuchal translucency scan, serum b-hCG and serum pregnancy-associated plasma protein-A (PAPP-A)
Nuchal translucency is an US observation referring to the black space within the back of the foetal neck (Down’s has increased nuchal translucency)
If results suggest a high probability, a diagnostic amniocentesis is offered at 15-20 weeks
What happens at the triple/quadruple test and when is it?
15 - 20 weeks. Offered to women who havent had a combined test (eg. late bookers). Tests for Down’s.
Serum b-hCG, unconjugated oestriol, AFP (+/- inhibin A)
When is OGTT carried out antenatally?
16 weeks if woman has had GDM in a previous pregnancy
28 weeks if high-risk
When is anti-D given during pregnancy?
28 weeks and 34 weeks
Physiological changes to the uterus during pregnancy
Hypertrophy of myometrium
From 28 weeks, lower third of uterus becomes thinner and less vascular (allows for C-section)
Uterine artery branches into spiral arteries to supply the decidua (maternal section of placenta)
Normal trophoblast invasion
What happens when there is incomplete trophoblast invasion?
Trophoblast invasion widens arteries -> reduced resistance -> increased flow by 16 weeks
If there is incomplete trophoblast invasion:
- Increased resistance causes reduced flow -> reduced nutrients to foetus -> IUGR
- Increased resistance also causes increase BP in the system -> causes clots in the maternal placental bed which further reduced flow -> backlogs into systemic circulation -> maternal HTN/ pre-eclampsia
- During labour, the foetus receives less oxygen as a result of reduced flow -> foetal distress
Physiological changes to cardiorespiratory systems in pregnancy
CVS:
- Stroke vol and heart rate increases -> CO increases.
- Systolic BP should remain the same
- Diastolic BP reduced in tri 1 and 2, and returns to normal in tri 3
- Enlarged uterus may interfere with venous return -> ankle oedema, supine hypotension, varicose veins
Resp:
- Progesterone acts on resp centre -> increased tidal vol -> ventilation increases
- Ventilation increases by 40% but only 20% more O2 is needed -> hyperventilation leads to reduced pCO2 -> leads to a sense of dyspnoea (worsened by uterus displacing the diaphragm)
Physiological changes to the blood in pregnancy
Blood vol increases (mostly in 2nd half of pregnancy) - allows for gas/nutrient exchange and reduces impact of blood loss in labour
Autotransfusion: blood loss in labour is compensated for by autotransfusion of 300-500ml of blood from the contracting uterus into the venous system
RBCs increase by 20% but plasma vol increases by 50% -> haemodilution -> iron and folate needed to restore the relative low Hb
Increased coagulant activity (increased fibrinogen, and factors VII, VIII, X) and reduced fibrinolytic activity: prevents excessive bleeding in labour but creates a hypercoagulable state
Physiological changes to the urinary system in pregnancy
Blood flow to the kidneys increases
GFR increases
Elevated sex steroids -> increased salt and water retention
Urinary protein losses increases
Progesterone causes urine stasis in the ureters and renal pelvis -> more prone to infection
Dizygotic vs monozygotic twins
Types of monozygotic twins
Dizygotic: non-identical, two separate eggs fertilised at the same time
Monozygotic twins: identical, one egg which divides to form 2 embryos
Monochorionic monoamniotic: one placenta, one sac
Monochorionic diamniotic: one placenta, two sacs
Dichorionic diamniotic: two placentas, two sacs
Predisposing factors for twins
Previous twins, family history, incresaed maternal age, multigravida, induced ovulation/IVF, afro-caribbean
Obstetric complications of twins
Foetal complications of twins
Labour complications of twins
Obstetric: polyhydramnios, pregnancy induced HTN, pre-eclampsia, eclampsia, anaemia, antepartum haemorrhage
Foetal: perinatal mortality, miscarriage, vanishing twin syndrome, prematurity, low birth weight, malformation
Twin to twin transfusion: only seen in monochorionic twins. Placenta diverts blood from one foetus to the other foetus. One gets too much blood (CVS overload and develops polyhydramnios) and the other receives insufficient blood (develops oligohydramnios and IUGR)
Labour: post-partum haemorrhage due to over-distended uterus and large placental area, malpresentation, cord prolapse/entanglement
Antenatal care for twins
When to deliver twins
Additional appointments for monochorionic twins
Additional appointments for dichorionic twins
Mode of delivery for twins
Indications for C-section
Additional appointments
Additional iron and folate
Prophylactic aspirin from 12 weeks if nulliparous
2 obstetricians present at delivery
Deliver monochorionic twins by 36 weeks and dichorionic twins by 37 weeks
No cut off point for delivery of dizygotic twins
Additional appts for monochorionic twins:
- US every 2 weeks for 16 weeks until delivery (monitor for twin to twin transfusion and check growth)
- IOL by 36 weeks (give steroids before delivery to encourage lung maturation in the twins)
Additional appts for dichorionic twins:
- US at 24,28, 32, 36 wks (check growth, abnormalities and umbilical artery doppler)
- IOL by 37 weeks (mode of delivery depends on presentation and lie of foetus 1)
Mode of delivery:
- Vaginal birth if foetus 1 is head first, otherwise C-section
- Not advised to have vaginal birth for twins if you have previously had a C-section
Indications for C-section:
Foetus 1 is breech or transverse, low lying placenta, monochorionic twins, previous history of difficult delivery
Obesity complications in pregnancy
Foetal monitoring is more difficult (SFH inaccuracies) GDM Pre-eclampsia and eclampsia Miscarriage and stillbirth Macrosomia Impaired foetal development Prematurity
Antenatal management for obesity depending on different BMIs
BMI 30-34: folate 5mg preconception until 12wks gestation, vit D, assess VTE risk, OGTT at 28 weeks, advise weight loss
BMI 35-39: all of the above plus, consultant-led care, assess pre-eclampsia risk, consider prophylactic aspirin, serial growth scans, frequent BP checks
BMI 40+: all of the above plus, antenatal anaesthetic review, manual handling and tissue viability risk assessment
Pre-existing diabetes mellitus during pregnancy
- preconception advice
- additional antenatal care
- intrapartum care
- postpartum care
Preconception: aim for fasting glucose 5-7, start on 5mg folate until 12wks gestation
Additional antenatal care: aim for fasting glucose <5.3, review DM medication, retinal assessment/ treat any retinopathy, measure HbA1c, switch oral hypoglycaemics to insulin (exc. metformin), attend diabetic antenatal appts every 1-2 weeks, prophylactic aspirin from 12wks until delivery
Intrapartum care: if uncomplicated DM, IOL/C-section at 37-38+6. consider insulin sliding scale during labour
Post-partum:
- Insulin treated DM: reduce insulin immediately after birth back to pre-pregnancy regime, due to increased risk of hypoglycaemia in post-natal period
- Eat a snack before breastfeeding
- If breastfeeding, continue metformin but avoid all other hypoglycaemics
Complications of DM during pregnancy
Miscarriage, IUGR, foetal obesity, foetal growth acceleration, polyhydramnios, birth defects
Epilepsy in pregnancy
- contraception advice
- preconception counselling
- Additional antenatal care
Contraception: avoid unplanned pregnancies, copper IUDs are contraception of choice, women on enzyme-inducing AEDs (carbamazepine, phenytoin) should be counselled about the risk of failure with some hormonal contraceptions
Preconception counselling: 5mg folate daily preconception until 12wks gestation.
Review AEDs: Stop valproate. Carbamazepine and lamotrigine are considered safe. Use lowest effective dose. Dont stop AEDs suddenly.
Additional antenatal care: 5mg folate until 12wks gestation, regular assessment of risk factors for seizures, serial growth scans due to risk of SGA baby
Epilepsy in pregnancy
- intrapartum care
- post-partum care
Intrapartum: risk of seizures in labour is low, adequate analgesia and appropriate care minimises risk factors of seizures, AEDs should be continued.
If seizure occurs, it should be terminated ASAP with benzodiazepine to reduce risk of hypoxia to mum and foetus
Long acting benzodiazepine (clobazam) should be continued if there is high risk of seizure
Post-partum: babies should have IM vit K 1mg to prevent haemorrhagic disease of the newborn, minimise seizure risk factors (sleep deprivation, pain, stress, etc), if AEDs were increased in pregnancy then review within 10 days of delivery to avoid toxicity. Safe to breastfeed.
Pre-existing hypertension during pregnancy
- first line antihypertensive
- additional antenatal care
- High risk of pre-eclampsia
- Labetalol is first line antihypertensive in pregnancy (then methyldopa, nifedipine)
- Start prophylactic aspirin at 12wks until delivery
- Check signs of pre-eclampsia at each visit (BP, urine dip)
Hep B in pregnancy
- screening
- risk of transmission
- management for baby
- risk of breastfeeding
Screened for at booking
90% chance of transmitting it to baby
Baby should receive a complete course of vaccination and hep B immunoglobulin immediately after birth to reduce transmission by 90%
Breastfeeding is safe
HIV in pregnancy
- screening
- how to reduce vertical transmission
- what to avoid if spontaneous labour occurs
Screened for at booking
Reduce vertical transmission by:
- Maternal antiretroviral therapy during pregnancy
- C section if there is a detectable viral load
- IV antiretroviral therapy 4 hours before C-section
- Neonatal antiretroviral therapy for 6 weeks
- Avoid breastfeeding
If spontaneous labour occurs, avoid ARM or foetal blood sampling
Pre-existing cardiac disease in pregnancy
- what drugs to consider stopping
- additional antenatal care
Stop ACE inhibitors and diuretics, all other medications are safe
Regular growth scans form 28 weeks due to risk of IUGR from reduced cardiac output
Anaemia in pregnancy
- screening
- causes
- management
- complications if untreated
Screened at booking and at 28 weeks
Causes: poor intake of folate/ B12/ iron (doesnt match increased demand), poor absorption (vomiting, increased pH of gastric acid, lack of vit C), increased utilisation (twins, veggie mother, grand multiparity, pregnancies close together)
Management: supplements
Complications:
- Iron deficiency: prematurity, low birth weight, blood transfusions, post-partum depression, anaemic baby, developmental delays in child
- Folate deficiency: neural tube defects, low birth weight
- Vit B12 deficiency: neural tube defects, preterm labour
Gestational diabetes
- antenatal care
- management of GDM
- postpartum care
Antenatal:
- usually diagnosed at 16 weeks or 28 weeks (fasting glucose >5.6 or OGTT >7.8)
- appointments every 1-2 weeks at diabetic antenatal clinic
- 32 weeks: US growth scan and amniotic fluid vol
- 36 weeks: US growth scan and amniotic fluid vol. Discuss birth plan, changes to medication during/after birth, care of baby postpartum, breast feeding, contraception
uncomplicated GDM should give birth no later than 40+6 weeks
If fasting glucose <7.0 at time of diagnosis, then trial diet and exercise changes, if glucose targets not met in 1-2 weeks, start metformin, if still not met then add insulin
If fasting glucose >7.0 at time of diagnosis, start straight away on insulin
If plasma glucose 6-6.9 and evidence of complications (eg. macrosomia, hydramnios) start straight away on insulin
Post partum:
- Weight loss, diet, exercise
- Fasting plasma glucose test at 6-13 weeks postpartum
- Annual HbA1c for GDM women who don’t have DM postpartum
Pre-eclampsia definition and risk factors
= Pregnancy induced HTN after 20 weeks + proteinuria
Risk factors identified at booking: Age >40, nulliparity, pregnancy interval >10yrs, FHx, previous pre-eclampsia, BMI >30, pre-existing vascular disease (eg. HTN), pre-existing renal disease, multiple pregnancy
Pre-eclampsia presentation
Severe headache Sudden swelling of face, hands, feet Visual problems (blurring, flashing) Severe pain below the ribs Vomiting
Investigations for pre-eclampsia
Urinalysis: proteinuria (+++)
MSU and 24hr collection to exclude UTI if only +1 protein
Frequent BP measurements for high risk women
A single diastolic reading of 110 or 2 consecutive reading of 90 at least 4 hours apart and/or significant proteinuria requires surveillance
Two consecutive systolic readings >160 at least 4 hours apart requires management
Bloods:
- FBC (low platelets and Hb = ?HELLP)
- U+Es (May be raised)
- LFTs (high ALT and AST, low albumin) (high GGT and bilirubin= ?HELLP)
Management and prophylaxis of pre-eclampsia
Prophylactic low dose aspirin from week 12 until delivery if high risk
Management:
- Delivery by 38 weeks is the only cure
- Treat HTN with labetalol (or nifedipine or methyldopa)
- Regular monitoring of BP, urinalysis, FBC, U+E, LFT, US growth scans and CTG due to risk of abruption or progression into eclampsia
- Magnesium sulphate reduces risk of seizures (eclampsia)
Complications of pre-eclampsia
IUGR due to uteroplacental insufficiency HELLP syndrome (haemolysis, elevated LFTs, low platelets) - manage the same as pre-eclampsia Pulmonary oedema due to low albumin and vasc endothelial dysfunction DIC Cerebral haemorrhage Placental abruption Eclampsia Prematurity Multi-organ failure Cardiac failure
Obstetric cholestasis
- what is it
- cause
- foetal complications
- diagnosis
- management
Jaundice and itching (no rash) due to increased bile
Disappears after delivery
Thought to be due to high oestrogen levels
Foetal complications: prematurity, still birth, passing meconium before birth
Diagnosis: itch + jaundice + abnormal LFTs and bile acid tests
Blood tests and USS can be done to exclude other conditions
Management:
- Delivery at 37 weeks (IOL or C-section)
- Creams and antihistamines to relieve itching
- Ursodeoxycholic acid to reduce bile levels and improve LFTs
- May require daily vit K due to clotting problems
- Vit K for the baby after delivery to prevent haemorrhagic disease of the newborn
UTis in pregnancy
Progesterone + enlarged uterus -> kinked dilated ureters => stasis and reflux -> risk of UTI and pyelonephritis
E coli
Ix: dipstick, MSU for MC+S
Mx of UTI or asymptomatic bacteruria: 7 days nitrofurantoin
If trimethoprim given in tri 1 then give 5mg folate too, avoid trimethoprim if folate deficient
mx of acute pyleonephritis: cefalexin 10-14 days
Investigations for VTE in pregnancy
Treat a ?VTE with LMWH until diagnosis is excluded
Do baseline FBC, coag screen, U+E and LFTs before starting LMWH
?DVT -> compression duplex USS
?PE -> CXR and ECG. If signs of DVT too then also do compression duplex USS, if no signs of DVT then do V/Q scan or CTPA (discuss which one with patient and radiologist)
Management of VTE in pregnancy
Antenatal care for a woman who has had a VTE in a previous pregnancy
Prophylaxis for high risk women
Subcut LMWH for remainder of pregnancy and for at least 6 weeks postnatally and until at least 3 months of treatment has been given in total
Prophylactic LMWH required during pregnancy if woman has had VTE in previous pregnancy
Women with 3 or more risk factors requires prophylactic LMWH from 28 weeks until 6 weeks postnatal
Women with 4 or more risk factors requires prophylactic LMWH immediately, until 6 weeks postnatal
Avoid DOACs and warfarin in pregnancy
Hyperemesis gravidarum
- when?
- what causes it?
- risk factors
- protective factor
- triad
- investigations
- management
- complications
Usually between weeks 8 and 12 but may be up to week 20
Due to raised b-hCG
Risk factors: twins, trophoblastic disease, hyperthyroidism, nulliparity, obesity
Smoking is a protective factor
Triad: 5% pre-pregnancy weight loss, dehydration, electrolyte imbalance
Investigations: pregnancy-unique quantification of emesis (PUQE score)
Management:
- First line: promethazine (antihistamine) or cyclizine
- Second line: ondansetron or metoclopramide
- Admission for IV hydration in severe cases
- Thiamine to prevent Wernicke’s encephalopathy
Complications: Wernickes encephalopathy Mallory-Weiss tear Central pontine myelinolysis Acute tubular necrosis Foetal complications: SGA, pre-term delivery
Ways to assess foetal growth
Abdominal palpation of fundal height Symphysis fundal height measurement USS measurement Head circumference measurement Abdominal circumference measurement Femur length
What is the definition of a small for gestational age baby?
What are the causes of symmetrical IUGR and asymmetrical IUGR?
<10th population centile for gestational age
May be due to incorrect measurements of size or incorrect dates (woman is earlier through pregnancy than what has been estimated)
Symmetrical IUGR: abdominal circumference and head circumference equally small
-Race, maternal size, sex of foetus, alcohol/smoking/drugs, poor placenta, twins, malnutrition, ToRCH
Asymmetrical IUGR: abdominal circumference slows its growth relative to the head
-HTN, pre-eclampsia, smoking/drugs, chromosomal or congenital abnormalities
Maternal and foetal monitoring for SGA babies during pregnancy
Maternal monitoring: BP, urine dip, monitor maternal disease
Foetal monitoring: serial growth measurements every 2-4 weeks, foetal movement, foetal doppler, amniotic volume measurement, biophysical profile
Doppler wave forms
- normal end diastolic flow
- abnormal end diastolic flow
- reverse end diastolic flow
- complication
Normal end-diastolic flow: flow to placenta is present during diastole
Abnormal end-diastolic flow: flow to placenta is compromised during diastole
Reversed end-diastolic flow: pressure in placenta causes blood to flow in opposite direction away from foetus during diastole
Abnormal and reversed end diastolic flow (AREDF) causes significant malnutrition to foetus and compromises life
Timing and mode of delivery for small foetuses, depending on foetal doppler
Normal umbilical artery doppler: delay delivery until at least 37 weeks
AREDF with normal additional assessment: deliver if gestation >34 weeks
AREDF with abnormal additional assessment (abnormal CTG, BP, doppler) : deliver even if gestation <34 weeks
Mode of delivery depends on gestation, presentation, foetal condition and maternal factors
Complications of IUGR foetus
Perinatal death, need for resuscitation, hypothermia, hypoglycaemia, respiratory distress syndrome, necrotising enterocolitis, neurodevelopmental disability, cerebral palsy, adult disease
Definition of large for gestational age baby, and factors causing LGA babies
Which factors can give a false impression of an LGA baby?
> 90th popilation centile for gestational age
Factors:
- Maternal: DM, obesity, increased maternal age, multiparity, large stature
- Foetal: constitutionally large (ie. large mum), male, postmaturity, genetic disorders
Polyhydramnios, a pelvic mass and uterine fibroids can give a false impression of a LGA baby
Complications of LGA babies
Maternal: prolonged labour, caesarean, PPH, genital tract trauma
Foetal: birth injury, perinatal asphyxia, shoulder dystocia, erbs palsy, hypoglycaemia, childhood obesity, metabolic syndrome
What is breech presentation
Different types of breech presentation
Foetal buttocks occupies the lower uterine segment, rather than the head
Frank breech: buttocks presenting with the legs extended
Complete breech: legs flexed so the feet present behind the buttocks
Footling breech: one or both feet presents below the buttocks
