Week 3 - Week 3 - Antenatal care tutorial - Foetal abnormality, Hypertension in Pregnancy, Rhesus disease

Question 1

Mrs Caroline Davis is 28 and became pregnant whilst taking the oral contraceptive.

Her Last Menstrual Period (LMP) was 21.08.13 and she has been offered and has accepted the blood test to screen for Down’s syndrome. As part of this test her serum α fetoprotein (MSAFP) is measured.

• * a) From where does α fetoprotein originate?
• * b) How does a-fetoprotein get into the maternal circulation?

Answer 1

A - Alfa-feto protein is produced by the placenta and the yolk sac

B - It crosses the placental membrane to enter the maternal circulation

Question 2

What is the gestational age calculator used to provide an estimate of the due date of the pregnancy? How does the calculation work?

Answer 2

Calculation is carried out using Naegele’s Rule for pregnancy The calculation works by adding 9 months to the first day of the Women’s LMP and then adding a further 7 days - this should be approx 40 weeks after the LMP - due date Remember -gestational age is taken from the first day of LMP

Question 3

Mrs Caroline Davis is 28 and became pregnant whilst taking the oral contraceptive. Her Last Menstrual Period (LMP) was 21.08.13 and she has been offered and has accepted the blood test to screen for Down’s syndrome. As part of this test her serum α fetoprotein (MSAFP) (maternal serum Alfa-feto protein) is measured. The level is reported as 110 on 12.12.13. c) Based upon the LMP, what was the gestational age at which the MSAFP was measured?

Answer 3

C - Based upon the LMP - gestational age at which the mothers MSAFP is thought to be 16 weeks

Question 4

Mrs Davis’ obstetrician expresses uncertainty about the gestational age of the pregnancy. Question 2 Why might this be?

Answer 4

There is uncertainty regarding the LMP as she fell pregnant whilst taking the oral contraceptive pill

Question 5

Because of this uncertainty, an ultrasound scan is performed and reported as follows: Single fetus - BPD - 47mm FH present

a) What is BPD? b) What is FH? c) Using the graph, what is the gestational age from the USS?

Answer 5

A - BPD - biparietal diameter

B - Foetal heartbeat - present in this case

C - Gestational age - gestational age could be 18-21 weeks

Question 6

Question 4 Why is it important to have an accurate knowledge of the gestational age?

Answer 6

To accurately chart foetal development and growth (and abortion cut offs) – gestational age wrong also may suggest that the baby is abnormal (best way to determine gestational age is from a first trimester scan)

Question 7

The following ultrasound images demonstrate conditions which can give rise to an elevated MSAFP. What type of pregnancy is this?

Answer 7

This is a monochorionic twin pregnancy - shared placenta elevated AFP is physiological in multiple pregnancies

Question 8

The following ultrasound imagesdemonstrate conditions which can give rise to an elevated MSAFP. Can you name the conditions?

Answer 8

Top one - Gastrochisis - Gastroschisis is a birth defect of the abdominal (belly) wall. The baby’s intestines are found outside of the baby’s body, exiting through a hole beside the belly button - can see intestines anterior to umbilicus

Bottom one - Spina bifida - Spina bifida is a type of birth defect called a neural tube defect. It occurs when the bones of the spine (vertebrae) don’t form properly around part of the baby’s spinal cord.

Question 9

What are the different types of spin bifida?

Answer 9

Spina bidifda occulta- mildest form Spina bifida cystica - in which there can be meningeocele (meninges herniate), myelpmeningeocele - spinal cord and meninges herniate

Question 10

The elevated MSAFP seen in multiple pregnancies is physiological, but what is the common feature of gastroschisis and spina bifida that results in elevated MSAFP?

Answer 10

High levels of AFP may suggest the developing baby has a neural tube defect such as spina bifida or anencephaly. High levels of AFP may also suggest defects with the esophagus or a failure of your baby’s abdomen to close.(gastrochisis) The AFP can also leak into the amniotic fluid from open neural tube defects, in which the fetal blood stream is in direct contact with the amniotic fluid.

Question 11

The combination of hypertension and proteinuria (pre-eclampsia) is a common and important complication of the second half of pregnancy. pre-eclampsia is essentially a multi-systemic disease of the endothelium – can get vasasopasm in the blood vessels leading to HBP Whereelse can the vasospasm affect?

Answer 11

Can also affect the liver and kidneys causing their function tests to be abnormal

Question 12

In pregnancy, what happens to the serum creatinine levels and why? What happens during pre-eclampsia?

Answer 12

The physiologic increase in GFR during pregnancy normally results in a decrease in concentration of serum creatinine, However in pre-eclampsia, the kidneys are not working properly and therefore the GFR doesnt increase and instead decreases causing the serum creatinine and other electrolytes to increase in the blood

Question 13

What is the syndrome associated with severe pre-eclampsia? Result is from abnormal coagulation screen and LFTs

Answer 13

HELLP syndrome It is characterized by Hemolysis (destruction of red blood cells), Elevated Liver enzymes (which indicate liver damage), and Low Platelet count.

Question 14

The definitive management of pre-eclampsia is delivery, but various drugs are often also used . Examples of drugs used in the management of this condition are given below. Name 4 drugs that can be used in the treatment of pre-eclampsia (1 is for the treatment of the seizures)

Answer 14

Labetalol Hydralazine Betamethasone Magnesium sulfate - helps to prevent seizures

Question 15

Betamethasone is a steroid How to hydralazine and labetalol work?

Answer 15

Labetanol - dual alpha and beta adrenergic antagonism (alpha/beta blocker so anti-hypertensive) – safe to use in pregnancy Hydralazine - It is a direct-acting smooth muscle relaxant and acts as a vasodilator primarily in resistance arterioles

Question 16

What does betamethasone act to prevent?

Answer 16

Betamethasone is given if the baby is premature - helps to produce surfactant to keep the lungs inflated and prevent neonatal respiratory distress sydnrome

Question 17

Following the introduction of effective prevention and treatment by anti-D immunoglobulin, perinatal mortality from haemolytic disease of the newborn has now been reduced to 1-2 per 100,000 births in the UK. How does the rehsus disease process wor?

Answer 17

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Question 18

(1) What is meant by Rhesus -ve? (2) What would you expect to find in the blood of a sensitised mother? (3) In an affected Rhesus +ve baby, what would happen to the following cord blood parameters:(a) Haemoglobin(b) Bilirubin(c) Coombs test?

Answer 18

a - Red blood cells have a protein coat. Most of us are rhesus positive and have a big D protein on it and our immune system doesn’t attack the blood cells. If a mother who is rhesus negative gets the babies rhesus positive blood, this triggers an immune response (sensitisation). b - in a sensitised mother, would expect to find anti-D antibodies c - Haemoglobin - decreased, bilirubin - increased, coombs test - this is a haemagglutination test and will be positive

Question 19

Question 1

• When can Anti D be given to prevent Rhesus isoimmunisation following even of feto-maternal transfusion ?

Question 2

• What is the ideal site and route of Administration of Anti-D? Can you describe origin and insertion anatomically for this site ? When can it be given via .other route ?

Answer 19

• 1. Anti-D immunoglobulin would be given to mop up any of the babies blood cells that have entered the mothers circulation and prevent sensitisation occurring – ideally anti-D immunogloblin given within 72 hours but can be given up to 10 days
• 2. Ideal site is deltoid and IM route - origin is the clavicle/spine of scapula/acromion proces and insertion is deltoid tuberosity of the humerus Can be given IV or subcut if patient contraindicated to IM

Question 20

Question 3 What is the dose of Anti-D based on gestational age? What are the prophylactic regimens for administration of Anti D in pregnancy? Question 4 List three events in pregnancy where you will administer Anti –D?

Answer 20

* Less than 20 weeks would give 250units (ie someone who has a TOP at 12 weeks) * Over 20 weeks would give 500 units (ie someone has a fall onto tummy at 22 weeks) Prophylaxis * Single big dose at 28 weeks or double dose at 28 and 34 weeks 4. Ectopic pregnancy/TOP, abdominal trauma or unexpected bleeding, post pregnancy if there was bleeding

Question 21

Using the information given about preventing the sensitisation of Rh -ve mothers after delivery by the administration of anti-D immunoglobulin, decide for each of the following cases whether the maternal administration of anti-D post delivery is indicated, and give reasons for your decision. Case 1 - RhD- mother, ABO compatible, RhD+ baby, Coombs test negative, Infant Bilirubin lvl nromal

Answer 21

Coombs test negative which means she is not sensitised yet and normal bilirubin – would give Anti-D after delivery or would give prophylactic anti D- one big shot at 28 weeks or two doses - at 28 and 34 weeks

Question 22

Using the information given about preventing the sensitisation of Rh -ve mothers after delivery by the administration of anti-D immunoglobulin, decide for each of the following cases whether the maternal administration of anti-D post delivery is indicated, and give reasons for your decision. Case 2 - RhD- mother, ABO incompatible, RhD- baby, Coombs test negative, INfant Bilirubin lvl nromal

Answer 22

rhesus negative mum and rhesus negative baby – no risk of sensitisation

Question 23

Using the information given about preventing the sensitisation of Rh -ve mothers after delivery by the administration of anti-D immunoglobulin, decide for each of the following cases whether the maternal administration of anti-D post delivery is indicated, and give reasons for your decision. Case 3 - RhD- mother, ABO compatible, RhD+ baby, Coombs test positive, Infant Bilirubin lvl increased

Answer 23

Coombs test positive and bilirubin of infant is increased - mother is already sensitised and therefore no point in anti-D immunoglobulin administration

Question 24

Using the information given about preventing the sensitisation of Rh -ve mothers after delivery by the administration of anti-D immunoglobulin, decide for each of the following cases whether the maternal administration of anti-D post delivery is indicated, and give reasons for your decision. Case 4 - RhD+ mother, ABO compatible, RhD- baby, Coombs test positive, Infant bilirubin lvl increased

Answer 24

rhesus positive mother and rhesus negative baby , there is no risk of anti-D antibodies here but There is ABO incompatibility which can cause HDFN (tends not to be severe)