Obstetrics

Front 1

What is EDD?

Back 1

280 days (40wks) from 1st day of last menstrual period to represent number of weeks of pregnancy

Front 2

What is Naegele's rule?

Back 2

EDD = LMP + 1 year - 3 months + 7 days (can use wheel)

Front 3

What are the maternal respiratory changes in pregnancy?

Back 3

• Increased O2 consumption (by 15-20%) due to increased maternal need (increased metabolic rate) and feto-placental unit (40%)
• increased ventilation (40%) above normal by increasing tidal volume NOT respiratory rate
• Decreased maternal CO2 allows transfer at placenta from fatal circulation
• Changes mediated by progesterone (similar effect with POP)

Front 4

What are the maternal cardiovascular changes in pregnancy?

Back 4

• Overall increased CO and reduced peripheral resistance
  
• CO increases from 3.5L/min to 6L/min
• Flow murmurs are common due to hyper dynamic circulation
• Blood pressure changes with gestation (slight fall in BP in 2nd trimester)
• These facilitate efficient transfer of nutrients and waste products. Heat loss to compensate for increased metabolism

Front 5

What maternal changes are present during pregnancy in terms of Blood, plasma and ECF volume?

Back 5

• Increased red cell mass by 25%
• Circulating plasma volume increased by 40%
• Haemodilution (hb >105gL normal)
• Osmotic pressure falls as fluid into extravascular compartment - thus peripheral oedema common in pregnancy
  

Front 6

What is haemostasis in pregnancy?

Back 6

Pregnancy is a hyper coagulable state which is an evolutionary advantage to reduce blood loss at delivery. However, there is an increased risk of thrombosis, because of increased fibrinogen, Factor VIII, Von willebrand factor, platelet aggrability and a reduced protein S and anti-thrombin.

Front 7

How is renal function affected in pregnancy?

Back 7

• Renal blood flow and GFR increase by 60% in first trimester
  
• Reduced urea and creatinine levels
• Hydronephrosis as a result of progesterone effect and back pressure from gravid uterus (increases stasis and thus has an increased risk of UTI)

Front 8

How is the GI system affected by pregnancy?

Back 8

• General reduction in motility and transit time for increased absorption of fatal nutrients
  
• Delayed gastric emptying and gastric relaxation - and increased risk of Mendelson syndrome if GA
  
• Relaxation of lower oesophageal sphincter and increased intrabdominal pressure (reflux/Heart burn)
• Constipation and haemorrhoids

Front 9

How is calcium homeostasis and skin affected by pregnancy?

Back 9

• Fetal skeleton requires calcium, which is usually met from increased maternal GI absorption. Bones of mother are not usually affected but Vit D deficiency is common and supplements are recommended.
• Placental melanocyte stimulating hormone causes darkening of parts of the skin (nipples, lines nigra) and rest in striae gravidarum
• Altered hair growth (95% in active growth cycle) and hair falling out after pregnancy which is temporary

Front 10

What are the 3 main aspects of antenatal care?

Back 10

1. Health Promotion
   
2. Preparation for labour and parenthood
3. Recognise and identify women who are more likely to develop problems in pregnancy before they happen

Front 11

What are high risk pregnancies?

Back 11

• Extremes of age
• Extremes of BMI
• Low socio-economic status
• Drug/Alcohol misuse
• Previous obstetric problems
• Vulnerable groups (e.g. asylum seekers)
• Pre-existing medical problems, e.g. diabetes, hypertension, epilepsy

Front 12

What health promotion is there for antenatal care?

Back 12

• Folic acid 400mcg (5mg in high risk pregnancies)

  
  

  Vitamin D

  
  

  Weight, exercise, healthy lifestyle and food hygiene

  
  

  Smoking cessation

  
  

  Alcohol intake

  
  

  Dental care

  
  

  Occupational therapist

Front 13

When are some important maternal blood tests done in pregnancy?

Back 13

• Sickle cell and thalassaemia 0-10wks
• Haemoglobin, group, rhesus and Abs 8-12wks
• Syphilis, HIV, Hep B, rubella at any stage, as early as possible 8-12wks
• Repeat Hb and antibodies at 28wks

Front 14

What are the important routine fatal scanning tests?

Back 14

• 11 - 14wks early pregnancy scan to support T21, T18 and T13 screening
• 16-25wks detailed USS for structural abnormality incl. T13 and T18

Front 15

What screening is available for T21?

Back 15

• Live birth incidence is 1:700
• Opt in testing offered to everyone in form of nuchal translucency at 11-13wks
• Identify a sub group and offer diagnostic testing
• Appropriate counselling/explanation
• CUBSS screening - (combined ultrasound and biochemical serum screening) combined measurement of nuchal translucency with biochemistry at 11-14wks, increases sensitivity from 75 to 90%
• Biochemical markers - free B-hCG, PAPP-A
• If have NT but low biochem markers, then could be T18 or 13

Front 16

What is the quadruple test?

Back 16

• 14-20wks
• 2nd trimester biochemical and maternal age screening
• Measures MSAFP, hCG, inhibit A and unconjugated estriol
• Combines information with maternal age and software algorithm
• cut off between high and low risk is 1 in 150, where high risk individuals will be offered amniocentesis.

Front 17

What is amniocentesis?

Back 17

• Invasive diagnostic test performed from 15wks onwards
• 10-15ml amniotic fluid is aspirated under continuous ultrasound control
• Offered to preselected group
• >1% miscarriage rate
• PCR results 48hrs
• Technically straightforward
• Anti D cover in Rh negative mothers

Front 18

What is CVS?

Back 18

• Invasive diagnostic test
• 11 weeks onwards
• technically more demanding than amniocentesis and more painful
• >2% miscarriage rate
• PCR results 48hrs
• Placental mosaicism may require repeat testing

Front 19

What is non-invasive prenatal testing?

Back 19

• Cell free fetal DNA (cffDNA)
  
• Identifies fetal DNA from maternal circulation
• Major advances in prenatal screening
• Commercially available for T21, T18, T13, X and Y
• Very accurate, results confirmed by invasive testing

Front 20

What is the fetal anomaly scan?

Back 20

• Sonographic examination of the bones, heart, brain, spinal cord, face kidneys and bladder and abdomen of fetus.
• This helps identify features associated with anencephaly, open spina bifida, cleft lip, diaphragmatic hernia, T18, T13, serious cardiac abnormalities, bilateral renal genesis or lethal skeletal dysplasia etc.
• Allows identification of anomalies and allows: Reproductive choice (termination of pregnancy), preparation for parents, managed birth in specialist centre, intrauterine therapy
  
• Routine USS detection rates vary by: Type of anomaly, woman's BMI and position unborn baby at the time of the scan