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VENOUS THROMBOEMBOLISM DURING PREGNANCY

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A-MOWAFY 2013

VTE = Venous thromboembolism

Includes; Deep venous thrombosis DVT, Pulmonary embolism PE

INCIDENCE :

2-3 in 1000 pregnancies

DVT 80% PE 20%

2/3 of DVT are antepartum

Caesarean section increases the risk 3-5 fold than vaginal delivery

PATHOGENESIS

Virchow’s triade =

1. Circulatory stasis

2. Vascular damage

3. Increased blood co-agulation

AETIOLOGY

Risk factors:

1. Pregnancy itself is a risk factor

2. Previous VTE in patient on hormonal contraception

3. Previous VTE during pregnancy ( risk is 12 % )

4. Rheumatic heart disease and patients with heart prosthesis

5. Thrombophilias (congenital and acquired?!)

6. Age ˃ 35 years old

7. Obesity ; BMI ˃ 30

8. Multiparity ; parity ˃ 4

9. Recurrent miscarriage

10. Bed rest and physical immobility

11. Hyperemesis gravidarum

12. Shock and dehydration

13. Infections

Venous thromboembolism

during pregnancy Venous thromboembolism during pregnancy

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VENOUS THROMBOEMBOLISM DURING PREGNANCY

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A-MOWAFY 2013

14. Pregnancy-induced hypertension

15. Excessive blood loss

16. Prolonged labour

17. Instrumental delivery

18. Cesarean section

19. Pelvic surgery in peri-partum period

20. Sickle cell anemia

21. Gross varicose veins

22. Fetal demise with remaining viable fetus

23. Intra-uterine gross restriction IUGR

Q: What is thrombophilia?

It is abnormalities in the blood co-agulation that is increases the risk of thrombosis;

(congenital, Acquired?)

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VENOUS THROMBOEMBOLISM DURING PREGNANCY

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A-MOWAFY 2013

RISKY GROUPS AND THEIR MANAGEMENT:

Very high risk

Criteria Previous VTE with thrombophilia

Long term warfarin therapy

Antepartum High prophylactic dose or therapeutic dose of LMWH

Postpartum LMWH for 5 days + Warfarin

High risk Criteria Previous recurrent VTE

VTE once with thrombophilia

VTE once with positive family history

Diagnosed important thrombophilia

Valvular mechanical prosthesis

Antepartum prophylactic dose LMWH

Postpartum LMWH for 5 days + Warfarin for 6 weeks

Moderate risk

Criteria Single provoked VTE without thrombophilia

Thrombophilia + Anti-thrombin III deficiency

Mitral stenosis

Antepartum Antenatal aspirin

Postpartum LMWH for 5 days + Warfarin for 6 weeks

Low risk Criteria Two or more of the following :

Obesity

Age ˃ 35

Parity ˃ 4

Gross varicose veins

Recurrent hypertensive disorders

Antepartum Antenatal aspirin

Postpartum Warfarin for 6 weeks

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VENOUS THROMBOEMBOLISM DURING PREGNANCY

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A-MOWAFY 2013

ANTI-COAGULANT DRUGS:

Heparin

Types I. Unfractionated heparin → UFH “Cal-heparin” II. Low molecular weight heparin → LMWH “Clexan”

Onset Within 10 minutes

Half-life 6 hours

Doses I. Unfractionated heparin

Normal body weight → 5000 IU/day

Body weight ˂ 50 kg → 2500 IU/day

Body weight ˃ 90 kg → 5000 IU/12 h

High prophylactic dose→ 100 IU/kg/12h

II. Low molecular weight heparin

Normal body weight → 40 mg/day

Body weight ˂ 50 kg → 20 mg /day

Body weight ˃ 90 kg → 40 mg / 12h

High prophylactic dose→ I mg/kg/12h

Monitoring 1. Activated partial thromboplastin aPPT twice weekly 2. Plattlets concentration monthly 3. Bone mineral density every 3 months

Advantages 1. No effect on the fetus ( does not cross placental blood barrier ) 2. Not secreted on milk ( no effect on lactation )

N.B : advantages of LMWH over UFH

o Fewer side effect o Prolonged half-life o Greater inhibitory effect on factor X o Prophylactic dose once daily o No need for continuous laboratory monitoring

Drawbacks Increase bleeding tendency

Osteoporosis ( improved by adding calcium , hence name “ Cal-heparin “

Fat necrosis at site of injection

Alopecia

Anti-dot Protamine sulphate 1mg/100IU

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VENOUS THROMBOEMBOLISM DURING PREGNANCY

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A-MOWAFY 2013

Oral anti-coagulant drugs

Types I. Coumarine → Warfarin sodium “Marevan”

II. Indandione → phenoidione “Dindevan”

Onset Full effect after 5 days

Half-life Warfarin → 44 hours

Phenoidione → 5 hours

Doses 2 to 5 mg/day

Monitoring 1. INR = “ international randomized ratio “→ should be 2 to 3 2. PT = “ prothrombine time “→ 30–50 % of normal control

Advantages Oral route , potent and long acting

Drawbacks Maternal : 1. Skin: allergy, fever, rash, urticarial and dermatitis 2. Blood: agranulocytosis 3. Liver: liver disturbances; jaundice 4. Renal: renal disturbances; hematuria 5. Over dose → bleeding tendency

Fetal : 1. Warfarin embryopathy; nasal hypoplasia, depression of nasal bone, mental

retardation, optic atrophy, skeletal defect ‘ bone splitting’ 2. Can cross placental-blood barrier; bleeding tendency and increases the risks

of intracranial hemorrhage and accidental hemorrhage

Drug interactions : 1. drugs increases the effect : salicylates, quinine, steroids 2. drugs decreases the effect : hepatic enzyme inducers

Anti-dot Vitamin K IM. , SC.

For rapid effect : 1. Fresh blood , fresh frozen plasma 2. Vitamin K to the mother and baby

PROTOCOLS FOR ANTI-COAGULATION DURING PREGNANCY

Frist trimester → only heparin for fear of warfarin embryopathy

Second trimester → warfarin starting from 13 weeks

Continue till:

33 weeks if risk of preterm laobour exist

36 weeks if no risk of preterm labour

However, oral anti-coagulants are not absolutely safe as delayed warfarin

embryopathy is recorded

Late in pregnancy: at 33 – 36 weeks → shift to heparin again

Postpartum: Vitamin K to the mother and baby and readjust the dose