Antenatal Care Flashcards
What is gravidity?
- how many times a woman has been pregnant
- includes miscarriage, ectopic, termination, live birth, stillbirth, molar pregnancies
Example: Mrs X currently 12/40, two miscarriages at 8/49 and 20/40, one son born at 38/40 → G4P1+2
What is parity?
- how many babies a woman has delivered at 24+ weeks gestation, alive or dead
- pregnancies delivering at <24/40 are denoted by a suffix eg P3+2
- Example 1: Ms Y not pregnant, has twins born at 34/40 → G1P2 or G1P1 (twins)*
- Example 2: Miss Z currently 28/40, one prev ectopic, two terminations both at 6/40, one stillbirth due to abruption at 25/40 → G5P1+3*
What do the terms primigravid, nulliparous and multiparous refer to?
- primigravid → first ever pregnancy ie. G1P0
- nulliparous → has had no delivery of a baby >24/40
- multiparous → has had one or more deliveries of babies >24/40
What is the most accurate way to calculate a woman’s gestation?
- all women should now be offered a first timester USS at 11-13/40
- crown rump length (CRL) most accurate way to date a pregnancy
- dating by USS is less accurate beyond this gestation, particularly >20/40
- after this, head circumference and biparietal diameter are used instead of CRL
NB: Nagele’s rule (for 28 day cycle) = LMP - 3months + 1 year+7days
NICE issued guidelines on routine care for the healthy pregnant woman in March 2008. They recommend:
- 10 antenatal visits in the first pregnancy if uncomplicated
- 7 antenatal visits in subsequent pregnancies if uncomplicated
- women do not need to be seen by a consultant if the pregnancy is uncomplicated
When is the booking visit and what is its purpose?
- 8-12 weeks (ideally <10)
- general info → diet, alcohol, smoking, folic acid, vit D, antenatal classes
- obs → BP, urine dip, check BMI
- FBC, blood group, rhesus status, red cell alloantibodies, haemoglobinopathies
- hepatitis B, syphilis, rubella
- HIV test offered to all women
- urine culture to detect asymptomatic bacteriuria
When is the dating scan?
- 11-13 weeks
- confirm dates + exclude multiple pregnancy
When is the combined screening test for Down’s syndrome?
- 11-13 weeks
When is the anomaly scan?
- 18-20+6 weeks
- looks for 11 conditions
- info about anomaly scan given prior at 16 weeks, when blood results also given and iron supplementation considered
When is anti-D prophylaxis given to rhesus negative women?
- 1st dose: 28 weeks
- 2nd dose: 34 weeks
the evidence base suggests that there is little difference in the efficacy of single-dose (at 28 weeks) and double-dose regimes (at 28 & 34 weeks). For this reason the RCOG in 2011 advised that either regime could be used ‘depending on local factors’
At 36 weeks, on top of routine care what else should be checked?
- check presentation - offer external cephalic version if indicated
- information on breast feeding, vitamin K, baby-blues
What is the relationship between maternal age and Down’s syndrome?
- is a major risk factor for Down’s syndrome
- risk is 2-3% for women over 45 years
- but there are many more pregnancies in younger women
- the risk for an individual is less, but there are more affected babies in younger women
- age alone is ineffective as a screening method
What is the combined test for Down’s?
- done @ 11-13+6 weeks
- recommended for those booking in 1st trimester
- combines ultrasound (nuchal translucency) and 2 serum markers:
- hCG
- PAPP-A
- advantages → early result, detection rate (85%), false +ve rate (2.2%)
- if women book later in pregnancy either the triple or quadruple test should be offered
- this tests for Down’s (21), Edward’s (18) + Patau’s (13)
The results of combined test and age of mother are all used by software to calculate high or low risk of having a baby with one of the conditions. Can choose to be screened for just Down’s or all 3; it does NOT tell you if you have it, just the risk. If screening test says you’re low-risk, should be told within 2wks. If high-risk, told within 3 working days.
What is the quadruple test and when is it done?
- 14-20 weeks
- 15% of women present after first trimester
- NT unreliable at this stage
- offered serum testing but has lower detection rate (80%) and a higher false positive rate (3.5%) than combined test
- it cheks alpha-fetalprotein (AFP), hCG, unconjugated oestriol and inhibin-A
- combined w/ maternal age to provide individualised risk
What does a positive/high-chance combined test result mean?
- risk of 1 in 150 or greater regarded as “positive”
- 1 in 9 turn out to have affected fetus after positive combined screening test
- that means 8 false positives for every 1 true positive
- screen positive women offered CVS or amniocentesis
- CVS performed early (11-14wks) but miscarriage rate 1-2%
- amniocentesis possible from 15wks so later result but miscarriage rate lower at 0.5-1%
What happens during chorionic villus sampling (CVS)?
- involves removing + testing sample of cells from placenta
- carried out under guidance of USS
- transabdominal CVS (predominantly) → through tummy, cleaned + local anaesthetic injected into skin; needle inserted through skin into womb + guided to placenta using USS; syringe attached to needle to take small sample of cells
- transcervical CVS → sample of cells collected via cervix; thin tube attached to syringe or small forceps inserted through vagina + cervix and guided towards placenta using USS
- usually takes 10 mins, monitored afterwards for up to an hour, arrange for someone to drive pt home
What advice should be given after CVS (as well as amniocentesis), to the woman?
- described as being uncomfortable (rather than painful), may have slightly sore tummy after
- normal to have cramps after, similar to period pain + light PV bleeding (spotting) for a day or two
- can take painkillers such as paracetamol (but NOT iboprufen or aspirin), may wish to avoid strenuous activity for rest of day
- contact midwife or hospital if any of the following develop:
- persistent/severe pain, high temp, chills, shivering, heavy PV bleeding, contractions
This advice is the same as for recovery for amniocentesis too
What are the associated risks of having CVS?
-
MISCARRIAGE → 1-2% ie. 1-2 women out of a 100 will have a miscarriage after having CVS
- difficult to determine which miscarriages would have happened anyway + which are result of CVS procedure
- most miscarriages that happen after CVS occur within 3 days of procedure
- INADEQUATE SAMPLE → in around 1% of procedures; may need to be carried out again, or wait to have amniocentesis
- INFECTION → rare; occurs in less than 1/1000
- RHESUS SENSITISATION → if mothers blood type is Rhesus negative but baby’s is RhD positive, it is possible for sensitisation to occur
Amniocentesis is similar to CVS but is carried out between the 15th and 20th week.
What happens in amniocentesis?
- take small sample of amniotic fluid so cells can be tested
- USS before + during, allows to check position of baby + find best place to remove some fluid and ensure needle can pass safely through walls of belly + womb
- area cleaned w/ antiseptic solution + local anaesthetic injected into skin to numb area
- using USS, needle passed into amniotic sac + syringe used to remove small sample of fluid:
- in 8/100 women, not enough fluid removed first time so needle inserted again
- isn’t painful but may feel uncomfortable
- takes around 10 mins + monitored for up to an hour afterwards for SE
What are the important risks associated with amniocentesis?
- MISCARRIAGE → estimated to be 0.5-1%; higher risk if carried out before 15wks; most occur within 3days of procedure
- INJURY FROM NEEDLE → placenta may be punctured by needle; sometimes necessary for needle to go through placenta to access amniotic fluid; usually heals without any problems
- INFECTION → lower than 1 in 1000
- RHESUS SENSITISATION → if mother’s blood type RhD negative but baby’s RhD positive
What happens if the condition is found (Down’s) following CVS or amniocentesis?
- can speak to specalists → midwife, consultant paediatrician + geneticist
- able to give detailed info about condition, symptoms child may have, treatment + support
- main options are → CONTINUE with pregnancy or TERMINATION
- difficult decision but never alone
- several charities can also offer support + information
- Antenatal Results + Choices (ARC)
- Down’s Syndrome Association
What is non-invasive prenatal testing (NIPT)?
- expensive - costs around £700 privately
- being introduced as second line screen under NHS
- non-invasive: detects cell-free foetal DNA in maternal circulation
- sensitivity 99% for Down’s + 97% for Edward’s
- occasionally no free DNA detected + test repeated
- remains a screening test
- higher sensitivity + specificity reduced need for CVS/amniocentesis
What are common teratogenic drugs?
- ACE inhibitors
- acne meds: isotretinoin/accutane
- alcohol
- androgens
- tetracyclines + doxycycline
- warfarin
- anticonvulsants
- lithium
- methotrexate
- carbimazole
- cocaine
- thalidomide
What are the teratogenic effects of specific anticonvulsants in pregnancy?
- sodium valproate → neural tube defects
- carbamazepine → least teratogenic of older antiepileptics
- phenytoin → cleft palate
- lamotrigine → safe?
What happens in a rhesus negative pregnancy?
- along w/ ABO system, the rhesus system is the most important antigen found on RBCs
- the D antigen is the most important antigen of the rhesus system
- around 15% of mothers are rhesus negative (Rh -ve)
- if a Rh -ve mother delivers a Rh +ve child, a leak of foetal red blood cells may occur
- this causes anti-D IgG antibodies to form in mother
- in later pregnancies, these can cross placent and cause haemolysis
- this can also occur in first pregnancy due to leaks
What is the management of Rhesus iso-immunisation?
- identification → screen for unsensitised women at 28; antibody testing + obstetric history
- assess severity of foetal anaemia → done using doppler USS
- treatment in utero → transfusion into umbilical vein if severe, or if >36 weeks deliver
- monitor → neonatal FBC + LFTs
All babies born to Rh -ve mother should have cord blood taken at delivery for FBC, blood group + direct Coombs test. Coomb’s test: direct antiglobulin - will demonstrate antibodies on RBCs of baby.
What are the three categories of hypertension in pregnancy?
What is the pathophysiology of pre-eclampsia?
What is HELLP syndrome?
- Haemolysis
- Elevated Liver enzymes
- Low Platelets
What is the pathophysiology of gestational diabetes?
Pregnancy is a diabetogenic state
What are the diagnostic thresholds for gestational diabetes?
What is the management of gestational diabetes?
- newly diagnosed women to be seen in joint diabetes + antenatal clinic within a week
- target cap glucose <5.3 mmol/l fasting and <7.8mmol/l 1hr after food
- check targets every 2wks
- if fasting plasma glucose <7mmol/l a trial of diet + exercise offered
- if glucose targets not met within 1-2ws of altering diet/exercise → add metformin → then add insulin
- if at time of diagnosis fasting glucose > 7mmol/l → insulin straight away
- if plasma glucose between 6-6.9mmol/l + complications (macrosomia, hydramnios) → insulin straight away
- glibenclamide only for those who cannot tolerate metformin + those who fail to meet glucose targets w/ metformin but decline insulin
- treatment discontinued after delivery
- if large for gestational age → consider C-section
- if not, plan induction for 38-40wks
- be alert for possible shoulder dystocia
- fasting glucose @ 6wks postpartum to exclude underlying DM
Placenta praevia is a placenta that is wholly or partially implanted in the lower segment of the uterus. It affects 0.5% of pregnancies at term.
What are the features of placenta praevia and what should be avoided?
- typically causes painless bright red vaginal bleeding
- blood on toes (usually indicates significant blood loss)
- severe bleeds ⇒ hypovolaemic shock
- foetus relatively unaffected unless massive haemorrhage
- women w/ placenta praevias who bleed often advised to remain inpatient until delivery
- major placenta praevias: delivery by C-section @ 39wks (or before if significant bleed)
- avoid internal examination until placental site has been determined - may precipitate heavier bleed in placenta praevia
