Diagnosis of acute VTE

Question 1

What % of untreated VTE becomes PE?

Answer 1

15-24%

Question 2

What % PE can be fatal in pregnancy?

Answer 2

15% patients

66% within 30 minutes of the embolic event

Question 3

What is the role of Duplex USS in diagnosing VTE?

Answer 3

• Gold standard
• If neg and low suspicion, stop LMWH
• If neg, but high suspicion, stop LMWH but repeat USS at day 3 and day 7

Question 4

What are the symptoms of iliac vein thrombosis?

Answer 4

• Back and buttock pain
• Whole leg swelling
• Needs uss venography for diagnosis

Question 5

Compare VQ scan and CTPA

Answer 5

• If chest Xray abnormal, CTPA instead of VQ scan
• VQ scan slightly higher risk of childhood cancer.The fetal radiation exposure associated with CTPA and V/Q is
  approximately 0.1 mGy and 0.5 mGy respectively. The increased risk of cancer is 0.006% per mGy.
• Absolute risk is very small for both
• CTPA is more readily available, delivers a low radiation dose to the fetus (see section below) and can identify other pathology including pneumonia (5–7%), pulmonary oedema (2–6%) and rarely aortic dissection.
• VQ scanning high negative predictive value and its substantially lower radiation dose to pregnant breast tissue (CTPA 20-100 times higher exposure)
• The delivery of 10 mGy of radiation to a woman’s breast
  has been estimated to increase her lifetime risk of developing breast cancer by 13.6% above her background risk.

Question 6

ECG abnormalities in PE

Answer 6

• T wave inversion 21%
• SQT pattern 15%
• RBBB: 18% in pregnancy, 4.2% in the puerperium

Question 7

Chest Xray abnormalities in PE

Answer 7

• Atelectasis
• Pleural effusion
• Focal opacities
• Regional oligaemia
• Pulmonary oedema