Antenatal care and screening

Question 1

Any screening programme should be

Answer 1

• highly sensitive
• highly specific
• have a high positive predictive value
• easily used in a large population
• safe and cheap
• quick and straightforward to perform
• able to detect a disease with a known natural history and where early diagnosis has a proven benefit

Question 2

What is sensitivity

Answer 2

True positive /(positive + false negative)

Question 3

What is specificity?

Answer 3

True negative/(negative + false positive)

Question 4

What happens at the booking visit?

Answer 4

• History:
  
  • Menstrual
  • Medical
  • Obstetric
  • Family
  • Social
• Examination:
  
  • Ht; Wt; BP; CVS; Abdomen
• Investigation
  
  • Hb
  • ABO; thesus
  • syphillis; HIV; hep B&C
  • Urinalysis; MSSU C&S
  • Ultrasound

Question 5

What is the purpose of the US at the booking visit

Answer 5

• confirm viability
• singleton/multiple pregnancy
• estimate gestational age- explain most accurate time/method to establish EDD
• detect major structural anomalies that may be identified in early pregnancy
• offter DSS

Question 6

What is done at antenatal follow up visits?

Answer 6

• History:
  
  • Physical and mental health
  • Fetal movements
• Examination:
  
  • BP and urinalysis
  • Symphysis- fundal height
  • Lie and presentation
  • Engagement of presenting part
  • Fetal heart auscultation

Question 7

What are the objectives of ultrasound screening for foetal anomaly?

Answer 7

• reduction in perinatal mortality and morbidity
• potential for in utero treatment
• identification of conditions amenable to neonatal surgery

Question 8

Major structural abnormalities occur in _-_% of pregnancies

Answer 8

Major structural abnormalities occur in 2-3% of pregnancies

Question 9

What do the NHS Fetal anomaly screening programme guidelines say?

Answer 9

“All pregnant women should be offered the 18+0 to 20+6 weeks fetal anomaly scan by a midwife or clinician (at first contact visit and/or booking visit).”

Question 10

What is placenta praevia?

Answer 10

When the placenta is low lying in the womb and covers all or part of the entrance (the cervix)

Question 11

If an early ultrasound scan between 18 weeks and 20+6 weeks detects placenta praevia what should be done?

Answer 11

Offered another abdominal scan at 32 weeks and if this is unclear a vaginal scan

Question 12

How is the down’s risk assessment carried out in first trimester?

Answer 12

Measure of skin thickness behind fetal neck using ultrasound (nuchal thickness)

Measured at 11- 13+6 weeks

Combined with HCG and PAPP-A

A value of <3.5mm would be considered normal with the CRL is between 45 and 85mm

Question 13

What sould all pregnant woman undergoing down’s screening have before blood is taken?

Answer 13

A dating USS to accurately establish gestation

CRL is only used up to 13 weeks and HC should be used after this

Question 14

What is done in down’s assessment in 2nd trimester?

Answer 14

Blood sample at 15-20 weeks

Assay of HCG and AFP

Question 15

What should be done for women who miss 1st trimester down’s screening

Answer 15

• Maternal Age + Biochemical Markers
  
  • Alpha-fetoprotein (AFP)
  • human Chorionic Gonadotrophin (hCG)
  • unconjugated oestradiol (UE3)
  • inhibin A

Question 16

What are the specific antenatal diagnostic tests?

Answer 16

Amniocentesis

Chorionic villus sampling

Question 17

When is amniocentesis performed and what is the miscarriage rate?

Answer 17

after 15 weeks

1%

Question 18

When is chorionic villus sampling performed and what is the miscarriage rate?

Answer 18

After 12 weeks

2%

Question 19

What are the major haemoglobin disorders?

Answer 19

HbS and thalassemias

Question 20

What is maternal anaemia?

When is it screened for?

Answer 20

Iron deficiency, folate deficiency, B12 deficiency

Screened at booking and 28 weeks

Question 21

What is important in the management of maternal anaemia?

Answer 21

Hb should be optimised prior to birth

Question 22

When should all women have their blood group antibody status determined?

Answer 22

At booking and at 28 weeks gestation

Question 23

How does Rh haemolytic disease develop?

Answer 23

When father is Rh positive and mother is Rh negative

Baby is Rh+, at birth Rh positive babies blood cells enter mother’s bloodstream

Invading Rh +ve blood cells cause the production of Rh antibodies

Rh antibodies remain in mothers bloodstream

The Rh antibodies attack the babies blood cells, causing Rh disease.

Question 24

What mental health screening questions should be asked to mothers?

Answer 24

• Do you have new feelings and thoughts which you have never had before, which make you disturbed or anxious?
• Are you experiencing thoughts of suicide or harming yourself in violent ways?
• Are you feeling incompetent as a mother, as though you can’t cope or feeling distanced or estranged from your baby? Are these feeling persistent?
• Do you feel you are getting worse?

Question 25

How should risk of gestational diabetes be assessed?

Answer 25

At the booking appointment; * BMI above 30kg/m² * previous macrosomic baby weighing 4.5kg or above * previous gestational diabetes * family history of diabetes (first-degree relative with diabetes) * minority ethnic family origin

Question 26

If women have risk factors for gestational diabetes what test should be done?

Answer 26

2 hour 75g oral glucose tolerance test +ve if woman has; a fasting plasma glucose of 5.6mmol/litre or above OR a 2 hour plasma glucose level of 7.8mmol/litre or above

Question 27

What are the major risk factors for SGA?

Answer 27

* maternal age \> 40 * smoker \>11 cigarettes a day * paternal SGA * cocaine * daily vigourous exercise * previous SGA baby * previous stillbirth * maternal SGA * chronic hypertension * diabetes with vascular disease * renal impairment * antiphospholipid syndrome * heavy bleeding similar to menses * PAPP-A \<0.4 MoM

Question 28

What are the minor risk factors for SGA?

Answer 28

* Maternal age \>35 * IVF singleton pregnancy * nulliparity * BMI \<20 * BMI 25-34.9 * smoker 1-10 cigarettes per day * low fruit intake pre-pregnancy * previous pre-eclampsia * pregnancy interval \< 6 months * pregnancy interval \> 60 months

Question 29

If mum has 3 or more minor risk factors then what should be done?

Answer 29

Reassess at 20 weeks UAD at 20-24 weeks If normal then assessment of fetal size and umbilical artery doppler in third trimester

Question 30

If mum has one major risk factors then what should be done?

Answer 30

Reassess at 20 weeks PAPP-A \<0.4 MOM Fetal echogenic bowel (major)

Question 31

What is PAPP-A

Answer 31

Placental associated plasma protein A

Question 32

What is foetal echogenic bowel?

Answer 32

observation in antenatal ultrasound imaging fetal bowel appears to be brighter than it is supposed to be. It is a soft marker for trisomy 21 and has several other associations. needs to be interpreted in the context of other associated abnormalities

Question 33

What is recommended at each antenatal appointment to predict SGA neonate

Answer 33

serial measurement of symphysis fundal height from 24 weeks of pregnancy

Question 34

Which women should be considered for ultrasound measurement of fetal size?

Answer 34

women with a **single SFH which plots below the 10th centile** or **serial measurements** which demonstrate slow or static growth by **crossing centiles**

Question 35

What is important about the plotting of SFH?

Answer 35

Needs to be plotted on a personalised chart

Question 36

In which women is measurement of SFH inaccurate?

Answer 36

BMI \> 35 Large fibroids Hydraminos

Question 37

What should women at high risk of pre-eclampsia be asked to do?

Answer 37

Take 75mg of aspirin daily from 12 weeks until the birth of the baby

Question 38

Which women are at high risk of preeclampsia?

Answer 38

Women with any of; - hypertensive disease during a previous pregnancy - chronic kidney disease - autoimmune disease such as systemic lupus erythematosis or antiphospholipid syndrome - type 1 or type 2 diabetes - chronic hypertension

Question 39

Which women are at moderate risk of pre-eclampsia?

Answer 39

Women who have more than one of; - first pregnancy - age 40 or older - pregnancy interval of more than 10 years - BMI of 35kg/m² or more at first visit - family history of pre-eclampsia - multiple pregnancy