PHYSIOLOGICAL CHANGES IN COAGULATION & FIBRINOLOYTICS SYSTEMS IN PREGNANCY

Coagulation system : Increase in levels of coagulation factors, mainly fibrinogen and factor VII, VIII, IX and X from the beginning of the second trimester.

Fibrinolytic system : Inhibition of the system, due to increase in the levels of plasminogen inhibitors.

Platelet count : No change

Anticoagulant system : levels of anti-thrombin III, no change in the levels of protein C & S The result of these changes is hypercoagulable state in pregnancy

The benefit of these changes is protection of mother from severe haemorrhage after delivery

The risk of these changes is the increased risk of thromboembolism

DISSEMINATED INTRAVASCULAR COAGULOPATHY

MAIN CAUSES IN PREGNANCYDIAGNOSISMANAGEMENT

Placental abruption

Preeclampsia & eclampsia

Endotoxic shock septic abortion, chorioamnionitis and puerperal sepsis

Amniotic fluid embolism

Prolonged shock

Prolonged retention of dead fetus missed abortion or IUFD for >5 weeks Clinical observation

Vaginal bleeding, oozing from venepuncture sites & surgical incisions.

History of any of the above risk factors.

Whole blood clotting time prolonged ( Normal 5-10 minutes)

Coagulation profile :

Platelet count reduced (Normal 150,000 350,000)

Fibrinogen level reduced ( Normal 2-4 gm/L)

APTT prolonged (Normal 35-43 seconds)

PT prolonged (Normal 10-14 seconds)

TT prolonged (Normal 10 seconds)

FDPs levels increased Insertion of at least 2 large infusion lines Send at least 20ml of blood for cross-matching & coagulation profile, and request at least 6 units of blood & 4 units of FFP.

Correct hypovolaemia by fluids & whole blood

Correct coagulation disorder by FFP NB:- platelet transfusion only indicated in presence of active bleeding if platelet count is less than 50,000 , and if no active bleeding, if platelet count less than 20,000.

Empty the uterus as rapidly as possible by delivery or D&C.

NB- DIC is always a 2ry phenomenon to an underlying stimulus, and is usually self-limiting if the stimulus producing it is removed therefore the uterus should be emptied as rapidly as possible

THROMBOEMBOLISM

RISK FACTORSDIAGNOSIS

Pregnancy hypercoagulate state .

Maternal age > 35 years.

Parity > 4

Obesity > 80 kg.

Caesarean section, particularly emergency C.S

Previous history of thromboembolism

*the risk of recurrence of thromboembolism is 12%, & the majority occur after delivery .

Prolonged hospital stay.

Family history of thromboembolism.

Thrombophilia ie. Congenital deficiency of antithrombin III, protein C or protein S, & presence of factor V leiden.

Anti cardiolipin syndrome or presence of lupus inhibitor

Cardiac disease such as valvular prosthesis or atrial fibrillation.

Sickle cell disease.

Gross varicose veins.

Blood groups other than O

Suppression of lactation with estrogen DVTPE

1- Sx: Pain & swelling in the leg

2- Signs: temp of the leg, tender calf muscles, a difference of >2cm in the circumference at identical sites of legs, and +ve Homan's sign.

*in 50% of patients there are no clinical symptoms & signs referable to the limbs & pulmonary embolism may be the 1st indication of thromboembolism .

*Over 80% of DVT are left-sided.

3-Investigations :

I. Doppler U/S Noninvasive, safe, accurate in 95%, more accurate if DVT above the knee due to absence of collaterals than if DVT below the knee due to presence of collaterals.

II. Ascending venography Contraindicated in the 1st trimester, and maybe indicated after that if Doppler U/S is not informative.

*There may be (50%) or may be not (50%) prior clinical evidence of DVT.

1. Sx: Sudden onset of dyspnoea, chest pain, cough & haemoptysis, and sudden collapse in massive PE

2. Signs: Cyanosis, rapid breathing & jugular veins distention.

3. Investigations:

CXR: May be helpful ie. Consolidation, infarction & elevated hemidiaphragm on affected side, but can be totally normal.

ECG: Usually normal except when the embolus is large.

Respiratory alkalosis and low Pco2 - due to hypoxia hyperventilation with blowing off of CO2 and respiratory alkalosis.

Ventilation & perfusion lung scan

Pulmonary angiography.

ANTICOAGULANTS

LMWH HEPARINHMWH HEPARINORAL WARFARIN

Low molecular weight heparin (LMWH) e.g Enoxaparin sodium (Clexane).

The preferred type used now.

Given by S.C route. The therapeutic dose is 2 mg/kg/day, given in two divided doses.@ High molecular weight heparin

Rarely used ( if LMWH is not available ).

Given by I.V route. The therapeutic dose is 10,000 units bolus dose , followed by 24,000 units / day, given via infusion pump. The dose is 2.5-5 mg/twice daily

Monitored by International Normalized Ratio ie. INR (which should be around 2 ) & by PT (which should be 2-2.5 times of control.)

MOA: Inhibition of the synthesis of Vit-K dependent factors: II, VII, IX & X.

Monitored therapeutic dose (1mg/kg/day 2x/day) by APTT; should be 2 times of control. Monitor maintenance (40mg/ml 1x/day) & prophylactic (20-40mg/ml 1x/day) dose by plasma heparin level; should be 0.2-0.4 units/ml. The action of therapeutic heparin is inhibition of thrombin & factors IX, X, XI & XII. Heparin DON'T cross the placental barrier & so can be used safely during pregnancy

The side effect is bleeding. If bleeding occur, stop the treatment, and in practice this is enough. Rarely if bleeding not stopped, give specific antidote ie. Protamine sulphate.

The advantages of heparin compared to warfarin - are:-

1. Does not cross the placenta

2. Small dose prophylaxis- no haemorrhagic hazard

3. Easily and rapidly reversed as heparin disappears from the circulation in 6 hours.

The disadvantages:-

1. Osteoporosis if given for more than 6 months

2. Thrombocytopenia.Disadvantages of warfarin are:

1. Bleeding

2. Teratogenic - if given in 1st trimester during the period of organogenesis coz warfarin cross the placenta: chondrodysplasia punctata, cerebral haemorrhage, calcification & microcephaly.

3. Fetal & Neonatal cerebral haemorrhage if given after 36 weeks.

4. Effect not easily or rapidly reversed as warfarin disappears from the circulation in 3 days.

In case of bleeding, antidote is FFP.

*Neither heparin nor warfarin are excreted in breast milk, so that they are safe to be used during lactation.

MEDICAL TREATMENT OF THROMBOEMBOLISM

ACUTE PHASE

Therapeutic dose of heparin. Either LMWH or HMWH. LMWHs duration of acute phase therapy 2 3 months.

LMWH (Clexane)HMWH

The therapeutic dose is 2 mg/kg/day, given in two divided dosesThe therapeutic dose is 10,000 units bolus dose, followed by 24,000 units / day, given via infusion pump.

LONG TERM THERAPY

Either LMWH (S/C) heparin or Oral Warfarin

- If thromboembolism occurs during pregnancy the best after acute phase therapy for 2-3 months, is to give S/C heparin in the maintenance dose for the rest of pregnancy ( in order to avoid side effects of warfarin during pregnancy) & for 12 weeks postpartum of either S/C heparin or warfarin.

- If thromboembolism occurs after delivery S/C heparin in therapeutic dose for 4 weeks, then either S/C heparin in maintenance dose or oral warfarin , for 3 months.

HEPARINWARFARIN

Given by SC route. The best is LMWH, if not available, HMWH.

Dose of LMWH (Clexane) 40mg/ 1x/day. HMWH 5000IU 2x/day.

Monitored by plasma heparin level; should be between 0.2-0.4 units/ml.

*Monitoring of maintenance or prophylactic dose of SC heparin by APTT is of no value, coz maintenance & prophylactic dose doesnt level of coagulation factors & so doesnt cause prolongation of clotting time. Given orally.

Dose is 2.5-5mg 2x/day

COUNSELING AFTER AN ATTACK OF THROMBOEMBO DURING PREGNANCY

1. Explain the risk of recurrence in future pregnancies which is about 12 %

2. Explain the need for prophylactic anticoagulatnts in future pregnancies

3. Avoid the use of combined contraceptive pill.

4. Consider screening for thrombophilia in absence of other risk factors

POLICY OF PROPHYLAXIS

No hx.

Did c-section.

With 1 risk factor. Delivery 1wk postpartum

1 hx of DVT

No risk factor. Delivery 6wk postpartum

1 hx of DVT.

Other risk factor (e.g. admitted to hospital)

Admission Delivery 6wks postpartum

Hx of 2DVT or 1PE or anticardiolipin or lupus inhibitors presence or cardiac indication for prophylactic anticoagulants (eg AF, valvular prosthesis)Pregnant Delivery 2months postpartum

*The policy of prophylactic anticoagulant during pregnancy in previous history of pulmonary embolism or DVT or thrombophilia is by LMWH once daily throughout pregnancy up to 12 hours before delivery .

*The policy of prophylactic anticoagulant during pregnancy in cardiac indication : warfarin in the 1st trimester & up to 36 weeks and then by HMWH, I.V, 6000 units/6hrs up to 12 hours before delivery.

*S/C heparin is not effective in prevention of cardiac thrombosis, and so warfarin given in the 1st trimester in spite of its known teratogenic effects.