Obstetrics Flashcards
What is the expected weight gain during a normal pregnancy?
10-12 kgs total weight gain in pregnancy.
What are the main changes seen in the cardiovascular system during pregnancy?
Decrease in Total Peripheral Resistance due to progesterone
Decrease in BP by 5-10 mmHg systolic and 10-15 diastolic up to 24 weeks, then slow return to pre pregnancy level (but never above)
Increase by 30-50% in CO, max at 24 weeks
Increase in Heart Rate.
What are the changes to the respiratory system seen in pregnancy?
Increase in respiratory rate Increase in tidal volume Increase in arterial and alveolar O2 Decrease in total lung capacity (elevation of diagphragm) Decrease in alveolar and lung CO2 Decrease in residual volume
Describe normal nausea and vomiting in pregnancy.
Normal nausea and vomiting in pregnancy occurs in 70% of pregnancies up to 16 weeks. Caused by increased in progestorone, oestrogen, and BHCG, and decreased in BSL. Treat with metclopromide (Maxolon), prochlorperazine (stematil), adequate hydration, and frequent snacking.
What are the normal heamatological changes that occur in pregnancy?
Increase in plasma volume by 40%
Increase in RBC mass 25% (dilutional aneamia,- decreased Hb and heamatocrit)
Increse in WBCs (Normal range 6-16)
Increase in VTE due to increased fibrinogen and increased factors VII-X and vWF. INR and APTT normal.
Slight decrease in platelets
At what point in pregnancy does bHCG peak, and at what time would you expect it to level off?
bHCG approximately doubles every 48 hours, peaks at 100,000 at 10-12 weeks, levels off around 15 weeks.
What tests can be used to confirm pregnancy?
Pregnancy can be confirmed by measuring b-HCG, or via ultrasound. Trasnvaginal ultrasound can detect a gestational sac at 5-6 weeks, and a heart beat at 6-8 weeks. Doppler ultrasound can detect audible feotal heart sounds at 12 weeks.
What testing is available in the first trimester to screen for Down Syndrome?
There is a nuchal lucency ultrasound screening at 11-13 weeks that is combined with testing of beta HCG and Papp-A to predict risk of Trisomy 21 (Down Syndrome), Trisomy 18 (Edward’s Syndrome) and Trisomy 13 (Patau Syndrome). There is a 80-90% sensitivity.
What screening for Down Syndrome can be conducted in the second trimester?
The Triple Test is used to screen for Down Syndrome. It occurs in weeks 16-18 and tests bHCG, Oestriol, and aFP. It is less sensitive and has a higher rate of false positives than the nuchal translucency scan. Hence, it is generally only used for people who missed out on the first tests.
Describe Chorionic Villus Sampling?
Chorionic Villus Sampling is a diagnostic test that is carried out at 10-12 weeks by taking a villus sample from the placenta using a transcervical or transabdominal approach. It results in a 1% chance of miscarriage, and carries the risk of inducing limb defects. CVS cannot test for neural tube defects, will not pick up moscaism, and also tests maternal cells.
Describe the process of amniocentesis.
Amniocentesis is a diagnostic test that is carried out >15weeks. A needle is inserted transabdominally and is used to take an amniotic fluid sample containing foetal cells. Misscariage rate is 0.5%, can do a FISH to quickly detect chromosomes. Feotal blood sampling is done >18weeks.
What are the symptoms of early pregnancy?
Early symptoms of pregnancy include loss of menstrual cycle, nausea and vomiting, increased frequency of urination, increased size and sensitivity of breasts, and quickening (foetal movements starts between 16-20 weeks).
What are the signs of pregnancy?
Chadwick’s Sign: blue colour of the vagina and the cervix, increase in basal body temperature, abdominal enlargement, breast swelling, hyperpigmentation of the skin, telangiectasia, abdominal swelling.
What is Naegle’s rule?
Subtract three months and add 7 days
What is the schedule of antenatal visits?
7 weeks- Confirm and date pregnancy (measure crown rump length), exclude ectopic or molar pregnancy.
11-14 weeks: Nuchal translucency
18-20 weeks: FAS (Feotal abnormalitiies, detects multiple pregnancies, assess dates and growth and placental position)
22-42 weeks: feotal growth scan
32 weeks follow up: foetal growth and position, doppler
What is the role of peri-conceptual folate in reducing neural tube defects?
Take ~ 0.4mg/day (400micrograms) for 1-3 months prior to conception and 6-12 weeks into the pregnancy for a woman with no history of NTDs.
A women with a history of NTDs should take 0.5mg/day. Patients with IDDM and on anti-seizure medication need 2-3 times the normal amount.
What is feotal alcohol syndrome?
FAS occurs due to the itake of EtOH during pregnancy (2-5sd/day). Causes growth retardation, mental retardation, typical facies (smooth filtrum, palpebral fissures, vermillion, microcephaly, micropthalmia), VSD, horseshoe kidney, hypoplastic/aplastic kidney, strabismus.
Barbituates can be used to help maternal withdrawal.
What is the effect of caffeine on pregnancy?
> 150mg per day can increase the risk of 2nd and 3rd trimester miscarriage.
30-179mg 1 cup of coffe
10-100mg I cup tea
60mg per can soft drink
What are the effects of maternal smoking during pregnancy?
Increased risk of spontaneous abortions, decreased birthweight, placental abruption, decreased birthweight, IUGR, placentra previa, placenta acreta, SIDS, respiratory illness in childhood, reduced performance at school, increased leukaemia,. Nicotine replacement is safe in pregnancy.
What are the effects of maternal use of cocaine?
Maternal use of cocaine causes maternal and feotal vasoconstriction, causing HTN -> placental abruption and cerebral infarction. Cocaine use is associated with IUGR, preterm labour, preterm delivery and developmental delay.
What is the effect of maternal use of opiates?
Most commonly used opiates are methodone and heroin. No teratogenic effects, can be more harmful to the foetus if there is withdrawal.
What screening tests are performed on all patients during their first booking visit?
FBC (Hb, MCV), blood group, antibodies, HIV 1,2 ,(pre and post test counselling), Hep B and C, syphilis, urine microscopy, rubella seroloy, BP
NB: BP and urine is consistently measured throughout pregnancy.
What additional tests might you consider to screen a mother for on her first booking test if indicated?
Iron studies and thalasseamia screen (if indicated)
Glucose Tolerance Test
Syphilis, Chlamydia, Gonorrhoea screen
Iodine, Vitamin D
When are women given a Glucose Tolerance Test?
Women are screen for gestational diabetes using a glucose tolerance test at 28 weeks?
When are women tested for GBS?
Women are tested for GBS using a lower vaginal swab at 35-37 weeks.
How is hypertension in pregnancy defined?
Hypertension in pregnancy is defined as >140/90, or >30/15 from admission bookings.
How is hypertension catergorised in pregnancy?
a) Preexisiting hypertension. should have no proteinuria and no oedema
b) Gestational/ Pregnancy Induced Hypertension: no proteinuria, no oedema, occurs after 20 weeks, resolves following birth, Women at increased risk of preclampsia for following births.
c) Preeclampsia: Pregnancy induced hypertension associated with proteinuria (>0.3g/day), may also have oedema
How do you manage pre-existing diabetes during pregnancy?
- weight loss for women with BMI of > 27 kg/m^2
- stop oral hypoglycaemic agents, apart from metformin, and commence insulin
- folic acid 5 mg/day from pre-conception to 12 weeks gestation
- detailed anomaly scan at 18-20 weeks including four-chamber view of the heart and outflow tracts
- tight glycaemic control reduces complication rates
- treat retinopathy as can worsen during pregnancy
How do you manage gestational diabetes?
- responds to changes in diet and exercise in around 80% of women
- oral hypoglycaemic agents (metformin or glibenclamide) or insulin injections are needed if blood glucose control is poor or this is any evidence of complications (e.g. macrosomia)
- there is increasing evidence that oral hypoglycaemic agents are both safe and give similar outcomes to insulin
- hypoglycaemic medication should be stopped following delivery
- a fasting glucose should be checked at the 6 week postnatal check
What is Feotal varicella syndrome?
- risk of FVS following maternal varicella exposure is around 1% if occurs before 20 weeks gestation
- studies have shown a very small number of cases occurring between 20-28 weeks gestation and none following 28 weeks
- features of FVS include skin scarring, eye defects (microphthalmia), limb hypoplasia, microcephaly and learning disabilities
How do you manage a women with varicella exposure during pregnancy?
- if there is any doubt about the mother previously having chickenpox maternal blood should be checked for varicella antibodies
- if the pregnant women is not immune to varicella she should be given varicella zoster immunoglobulin (VZIG) as soon as possible. RCOG and Greenbook guidelines suggest VZIG is effective up to 10 days post exposure
- consensus guidelines suggest oral aciclovir should be given if pregnant women with chickenpox present within 24 hours of onset of the rash
What is the definition of antepartum heamorrhage?
Antepartum heamorrhage is defined as bleeding after 24 weeks. Vaginal exam should not be performed in primary care for women with an antepartum heamorrhage as women with placenta previa may heamorrhage.
What are the common causes of bleeding during each trimester?
First trimester: Spontaneous aborption, hydatiform mole, ectopic pregnancy
Second Trimester: Spontaneous abortion, hydatiform mole, placental abruption.
Third Trimester: Bloody Show, Placental abruption, placenta previa, vasa previa.
Also consider STDs and cervical polyps.
How does a threatened miscarraige present?
Painless vaginal bleeding at 6-9 weeks.
How does a delayed (missed) miscarriage present?
Light vaginal bleeding and symptoms of pregnancy dissapear.
How does an incomplete miscarriage present?
Heavy bleeding and crampy lower abdominal pain.
How does an ectopic pregnancy present?
Typically 6-8 weeks of lower abdominal pain (usually unilateral), and then vaginal bleeding later. Shoulder tip pain and cervical excitation may be present.
