OB-GYN Revision 14

Question 2

When determining the type of twins using an ultrasound scan.

Which findings regarding placentas and amniotic sacs would determine the type of twins occuring? [3]

Answer 2

Dichorionic diamniotic twins
- have a membrane between the twins, with a lambda sign or twin peak sign

Monochorionic diamniotic twins
- have a membrane between the twins, with a T sign

Monochorionic monoamniotic
- twins have no membrane separating the twins

Question 3

What does the T sign refer to? [1]

Answer 3

The T sign refers to where the membrane between the twins abruptly meets the chorion, giving a T appearance. This indicates a monochorionic twin pregnancy (single placenta).

Question 4

What does the lambda / twin peak sign show? [1]

Answer 4

The lambda sign, or twin peak sign, refers to a triangular appearance where the membrane between the twins meets the chorion, as the chorion blends partially into the membrane. This indicates a dichorionic twin pregnancy (separate placentas).

Question 5

What are the risks to the mother of twins? [+]

Answer 5

Anaemia
Polyhydramnios
Hypertension
Malpresentation
Spontaneous preterm birth
Instrumental delivery or caesarean
Postpartum haemorrhage

Question 6

Describe the risk to the fetusesus and neonates of being twins [+]

Answer 6

Miscarriage
Stillbirth
Fetal growth restriction
Prematurity
Twin-twin transfusion syndrome
Twin anaemia polycythaemia sequence
Congenital abnormalities

Question 7

Describe what is meant by twin-twin transfusion syndrome [+]

Answer 7

Twin-twin transfusion syndrome occurs when the fetuses share a placenta
- When there is a connection between the blood supplies of the two fetuses, one fetus (the recipient) may receive the majority of the blood from the placenta, while the other fetus (the donor) is starved of blood
- the recipient gets the majority of the blood, and can become fluid overloaded, with heart failure and polyhydramnios
- The donor has growth restriction, anaemia and oligohydramnios

Question 8

Describe what is meant by Twin Anaemia Polycythaemia Sequence [1]

Answer 8

Twin anaemia polycythaemia sequence is similar to twin-twin transfusion syndrome, but less acute. One twin becomes anaemic whilst the other develops polycythaemia (raised haemoglobin).

Question 9

When do additional US scans in multiple pregnancy? [2]

Answer 9

2 weekly scans from 16 weeks for monochorionic twins
4 weekly scans from 20 weeks for dichorionic twins

Question 10

What can be used to suppress lactation after stillbirth? [1]

Answer 10

Dopamine agonists (e.g. cabergoline) can be used to suppress lactation after stillbirth.

Question 11

What are the resus council’s list of reversible causes of adult cardiac arrest? [8]

The RCOG guideline advises to the list: [2]

Answer 11

4 Ts:
* Thrombosis (i.e. PE or MI)
* Tension pneumothorax
* Toxins
* Tamponade (cardiac)

4 Hs:
* Hypoxia
* Hypovolaemia
* Hypothermia
* Hyperkalaemia, hypoglycaemia, and other metabolic abnormalities

The RCOG guideline advises adding to the list:
* Eclampsia
* Intracranial haemorrhage

Question 12

The three major causes of cardiac arrest in pregnancy to remember are [3]

Answer 12

Obstetric haemorrhage
Pulmonary embolism
Sepsis leading to metabolic acidosis and septic shock

Question 13

Obstetric haemorrhage is a major cause of severe hypovolaemia and cardiac arrest.

What are the causes of massive obstetric haemorrhage? [5]

Answer 13

Ectopic pregnancy (early pregnancy)
Placental abruption (including concealed haemorrhage)
Placenta praevia
Placenta accreta
Uterine rupture

Question 14

Describe what is meant by aortocaval compression [3]

How do you avoid this? [1]

Answer 14

After 20 weeks gestation, the uterus is a significant size.

When a pregnant woman lies on her back (supine), the mass of the uterus can compress the inferior vena cava and aorta.

This reduces the cardiac output, leading to hypotension.

In some instances, this can be enough to lead to the loss of cardiac output and cardiac arrest.

The solution to aortocaval compression is to place the woman in the left lateral position, lying on her left side, with the pregnant uterus positioned away from the inferior vena cava.

Question 15

Resuscitation in pregnancy follows the same principles as standard adult life support, except for which differences? [1]

Answer 15

• A 15 degree tilt to the left side for CPR, to relieve compression of the inferior vena cava and aorta
• Early intubation to protect the airway
• Early supplementary oxygen
• Aggressive fluid resuscitation (caution in pre-eclampsia)
• Delivery of the baby after 4 minutes, and within 5 minutes of starting CPR

Question 16

When is immediate c-section performed for a pregnant women when CPR has been performed? [2]

Answer 16

• There is no response after 4 minutes to CPR performed correctly
• CPR continues for more than 4 minutes in a woman more than 20 weeks gestation

Question 17

Describe how VTE prophylaxis used in pregnancy? [1]

Answer 17

All women recieve a risk assessment at booking clinic. If deemed high risk - recieve LMWH prophylaxis
- e.g. enoxaparin, dalteparin or tinzaparin
- Prophylaxis is started as soon as possible in very high risk patients and at 28 weeks in those at high risk
- Continues till 6 weeks post-natally

Question 18

To examine for leg swelling measure the circumference of the calf 10cm below the tibial tuberosity. More than [] cm difference between calves is significant.

Answer 18

To examine for leg swelling measure the circumference of the calf 10cm below the tibial tuberosity. More than 3cm difference between calves is significant.

Question 19

A patient presents with ?DVT.

How do you investigate? [1]

Answer 19

Doppler ultrasound initially, and if a DVT is present, they do not require a VQ scan or CTPA to confirm a PE.

TOM TIP: The Wells score is not validated for use in pregnant women. D-dimers are not helpful in pregnant patients, as pregnancy is a cause of a raised D-dimer.

Question 20

How do you calculate the dose of a LMWH for tx in pregnancy? [1]

How do you manage VTE in pregnany? [1]

Answer 20

The dose is based on the woman’s weight at the booking clinic, or from early pregnancy.
- LMWH should be start before the dx for suspected DVT or PE
- When the diagnosis is confirmed, LMWH is continued for the remained of pregnancy, plus six weeks postnatally, or three months in total (whichever is longer)

Question 21

Which pathologies are specific to MC twins? [4]

Answer 21

• Twin to Twin Transfusion Syndrome (TTTS)
• Selective Intrauterine Growth Restriction (s-IUGR)
• Twin Anemia Polycythemia Sequence (TAPS)
• Twin Reverse Arterial Perfusion (TRAP) sequence

Question 22

Lecture:

When should you deliver [3]
DC twins
MC twins
Triplets

Answer 22

Intrapartum care of multiple pregnancy
* DC: Delivery by 38 weeks
* MC: Delivery by 37 weeks
* Triplets: Delivery by 34 weeks

Question 23

Describe the difference in egg / sperm etc in the different types of twins

Answer 23

Identical twins are always the same sex, so if your twins are identical, you’ll have 2 girls or 2 boys.