VTE Flashcards
Prevalence of PE in pregnancy?
2-6%
At what stage (ante/intra/postpartum) is the risk of a VTE highest?
Postpartum
What are the symptoms of a DVT and PE?
DVT - leg swelling, tenderness, erythema, pain, lower abdominal pain ( if extension into pelvic vessels)
PE - dyspnoea, chest pain,
haemoptysis and collapse
Low grade pyrexia and leucocytosis can alconoccur with both
How do u diagnosis acute DVT?
Compression lower limb duplex ultrasound
What percentage of patients with untreated DVT will develop PE?
15-24%
In what percentage of pregnant patients is PE fatal?
15%
- of these 66% will die within 30mins of embolic event
What is the sensitivity and negative predictive value of serial compression ultrasonography in detecting DVT?
Sensitivity - 94.1%
Negative Predictive Value- 99.5%
How do u diagnosis an acute PE?
- Computerized Tomography Pulmonary Angiogram
- more readily available than V/Q, shows other lung pathology
- low radiation to fetus, relatively high dose to maternal breast tissue (20mGy) = increased risk breast ca
- bismuth Shields over breast decrease risk by 20-40%
- Ventilation/Perfusion lung scan
- neg predictive value of 99%
- slight increased risk of childhood cancers
If CTPA not available:
- Cxray: normal in 50%, features of PE include atelectasis, effusion, focal opacity, pulmonary oedema (kurly b lines - indicate thickened, oedematous interlobular septa)
- helps to exclude lung infection, pneumothorax and lobar collapse.
*negligible radiation dose <0.01mSv
ECG is of limited diagnostic value and is abnormal in 41% of pts with PE.
- most common abnormalities: T wave inversion, S1Q3T3 pattern and Rt bundle branch block.
- Also helps to exclude other causes
T/F. Tranexamic acid is assoc with an increased risk of VTE?
False
How many current risk factors (other than prev VTE or Thrombophilia) are required for thromboprophylaxis/lmwh throughout the antenatal period?
4 or more
How many current risk factors (other than prev VTE or Thrombophilia) are required for thromboprophylaxis/lmwh from 28 weeks gestation?
3
Patient has 2 current risk factors for VTE (other than prev VTE or Thrombophilia). What’s your advice ?
CONSIDER prophylactic LMWH for at least 10 days postpartum
T/F. All women requiring antenatal prophylactic LMWH should continue prophylaxis for 6 weeks postnatally?
True - usually this is true, however a postnatal assessment should always be made.
How should a pt with a single previous VTE (not related to a major surgery) be managed?
-Prepregnancy counselling
-Management plan for VTE in pregnancy should be made
- should be offered thromboprophylaxis with LMWH throughout antenatal period.
If pregnant refer to an expert in thrombosis in pregnancy
Management of a pt with a previous thrombophilia-asscoiated VTE?
Thrombophilias may be HERITABLE or ACQUIRED.
For VTEs due to Antithrombin deficiency a Multi-disciplinary team approach is needed.
- MFM specialist with collaboration with a haematologist with expertise w/ thrombosis in pregnancy.
– consider antenatal anti-Xa monitoring
— consider potential need for antithrombin replacement at START of labour or PRIOR to csection. - Offer thromboprophylaxis with higher dose LMWH (either 50%, 75% or full therapeutic dose) antenatal and for 6 weeks postpartum OR until returned to oral anticoagulant therapy post delivery.
— as most pts would have been managed on oral anticoagulation.
For other heritable thrombophilic defects can be managed with standard doses of thromboprophylaxis as they are lower risk.
ACQUIRED thrombophilia
- Pts with Antiphospholipid syndrome/APS are usu on long term anticoagulation.
- manage with haematologist and rheumatologist w/ expertise in this area.
- Offer thromboprophylaxis with higher dose LMWH (either 50%, 75% or full therapeutic dose) antenatal and for 6 weeks postpartum OR until returned to oral anticoagulant therapy post delivery.
Management of a pt with a previous recurrent VTE?
- MDT; seek advice re dose of anticoagulant by a haematologist
- higher doses of LMWH required
- Patients on long term wafarin or other anticoagulants should be counselled about the risks to the fetus.
- should stop oral anticoagulant and switch to LMWH as soon as pregnancy is confirmed - ideally before GA 6 weeks.
- Women NOT on oral anticoagulants should start LMWH as soon as she has a positive pregnancy test.
Advice for a pregnant women with a h/o a prior VTE that was unprovoked/ due to a transient/oestrogen related (OCPs/pregnancy) risk factor?
Prophylaxis with LMWH throughout the antenatal period.
- if it was unrpovoked, we don’t know what caused it so better safe than sorry. She’s pregnant again, so if it was oestrogen related before it can occur again
Advice for a pregnant woman with a h/o a VTE due to major surgery. She had recovered and has no other risk factors.
Start LMWH at 28 weeks if no other risk factors are identified.
– monitor for development of other risk factors
- Other risk factors found? Give throughout antenatal period.
What are the pre-existing risk factors for VTE in pregnancy and the puerperium?
There are 9:
1. Previous VTE
2. Thrombophilia
3. >35yrs
4. Medical comorbidities [active SLE, cancer, heart failure, IBD, inflamm polyarthropathy, T1DM w/nephropathy, sickle cell, current iv drug user]
5. Obesity BMI>30
6. Parity 3/more
7. Smoking
8. Gross varicose veins
9. Paraplegic
What are the obstetric risk factors for VTE in pregnancy and the puerperium?
There are 8:
1. Multiple pregnancy
2. Current preeclampsia
3. Prolonged labour >24hrs
4. Mid-cavity or rotational operative delivery
5. Preterm birth
6. Stillbirth
7. C-section
8. PPH >1L/requiring transfusion
What are the new onset/transient risk factors for VTE in pregnancy and the puerperium?
There are 7:
1. Ovarian hyperstimulation
2. Hyperemesis, dehydration
3. Long-distance travel >4hrs
4. Admission/Immobility 3/more days
5. Current systemic infection (requiring admission/ iv antibiotics)
6. Any surgical procedure in pregnancy/puerperium
–perineal repair excluded
7. Bone fracture
30 wks, 12hr flight to UK, with chest pain and dyspnoea. Booking wt 66kd, current wt 76kg. What dose of:
1. enoxaprin
2. dalteparin
Booking wt 66kg, therefore in second wt class [50-69kg] for both drugs.
■Enox:
▪︎60mg sc bd (first class is 40mg bd & increases by 20 to 120mg bd)
▪︎90mg sc od (60 +30; remember od increments [20, 30, 40, 50, 60] are added to the bd dose to get the od dose)
▪︎▪︎Doses >120mg = haematologist
■Dalteparin
Od Doses are double the bd Doses
66kg = 6,000iu bd or 12,000iu od
Remember bd dosing starts at 5,000iu and stops at 12,000iu. >12,000 = Haematologist
Pt with PE at 38 weeks. Received bolus dose and on 18mg/kg/hr unfractionated heparin. APTT ratio 6hrs after bolus dose is 1.3. Next step?
40units/kg bolus + 20units/kg/hr infusion.
Why 20 units?
▪︎18+2=20units
If APTT:
▪︎ <1.2: Add 4 units
(18+4=22units/kg/hr)
1.2-1.5: add 2 units = 20 units
1.5-2.5: no change
2.5-3.0: minus 2 units (18-2=16u)
>3.0: minus 3 units (18-3=15units)
What is the target APTT ratio when on unfractionated heparin infusion?
1.5-2.5 times lab control value
How often is APTT measured when on unfractionated therapy?
- 4-6hrs after loading dose
- 6 hours after any dose adjustment
- Daily once in therapeutic range
Incidence of VTE in pregnancy and puerperium?
1-2/1000 (0.1-0.2%)
