VTE Flashcards
Genetic risks of VTE
Low risk thrombophilia : heterozygotes for FVL, hertozygote Prothrombin mutation, C/S deficiency
High risk: Homozygous FVL, homozygous Prothrombin, double hetero FVL/Prothrombin, AT III deficiency (overall risk of recurrent VTE related to pregnancy was 26 percent per patient-year of observation)
IF low risk + prior VTW : anticoagulate
If High risk : Anticoagulate
Management of VTE in pregnancy
a) warfarin for DVT: substitute with UFH or LMWH
b) warfarin for mechanical valves: substitute with UFH (adjusted to aPTT 2 x control or anti-Xa level 0.35-0.7 U/mL) or LMWH (adjusted to anti-Xa levels) through pregnancy or until 13 wks then back to warfarin before substitution back to UFH or LMWH close to delivery
• if high risk valve (older generation in mitral position or Hx of thromboembolism) or concerns about efficacy or safety of heparin, warfarin throughout preferred over heparin until close to delivery + ASA (57-100 mg/d)
• SAFE IN BREASTFEEDING, SAFE in 1st 6 weeks. AVOID in 6-9 weeks.
1. considering pregnancy: if on warfarin, frequent pregnancy tests and substitute UFH or LMWH once confirmed
2. VTE while pregnant: LMWH over UFH for treatment continued throughout pregnancy and continued for at least 6 wks post-partum for total duration of at least 6 mo
• d/c at least 24 h prior to elective induction of labour
3. recurrent VTE prevention: previous VTE, not taking long-term anticoagulation
a) single episode VTE associated with transient risk factor: clinical surveillance antepartum and anticoagulant prophylaxis postpartum
b) VTE associated with pregnancy or estrogen exposure: clinical surveillance or prophylaxis with UFH or LMWH antepartum and prophylaxis postpartum
c) single idiopathic episode of VTE: clinical surveillance or prophylaxis with UFH or LMWH antepartum and prophylaxis postpartum
d) single episode VTE with thrombophilia: clinical surveillance or prophylaxis with UFH or LMWH antepartum and prophylaxis postpartum
e) high risk thrombophilias (antithrombin III deficiency, anti-phospholipid Ab, homozygosity for prothrombin 20210A or factor V Leiden or heterozygous for both): prophylaxis with UFH or LMWH antepartum and postpartum
f) multiple (>1) episode VTE: prophylactic of full dose UFH or LMWH antepartum and postpartum
• all of the above should have both antepartum and postpartum graduated compression stockings
4. prevention in patients with thrombophilia (no VTE):
a) anti-thrombin III deficiency: prophylaxis with UFH or LMWH antepartum and postpartum
b) all others: clinical surveillance or prophylaxis with UFH or LMWH antepartum and prophylaxis postpartum
5. risk and prevention of pregnancy complications with thrombophilia:
a) recurrent early pregnancy loss, recurrent preeclampsia or IUGR: screen for antiphospholipid Ab
b) recurrent pregnancy loss + antiphospholipid Ab: antepartum ASA + prophylactic UFH or LMWH
6. high risk of preeclampsia: low dose ASA throughout pregnancy (NOT UFH or LMWH)
Peripartum management of VTE
A. DVT: prevalence 5-10%
• significant amount is proximal to distal flow due to increased venous stasis
• Well’s model not validated in pregnancy
Dx: Gold Standard = serial ultrasounds
B. PE: prevalence 5%
• Well’s model not validated in pregnancy
• V/Q scan is preferred over CT due to high proportion of inadequate CT scans (up to 1/3, due to dye dilution) and increased risk of 2nd malignancy (150 x risk of breast cancer compared to V/Q)
• the radiation exposure in both CT and V/Q much less then teratogenic dose
Tx: LMWH full dose q12h (dosed to current pregnancy weight) with weekly anti-Xa levels to confirm not “sub-therapeutic” x 3-4 wks
• clearance and volume of distribution increased in pregnancy
• can consider ¾ dose reduction after 1st month with no monitoring as risk of 2nd clot considerably reduced
peri-partum management: planned C section or induction
• anticoagulation must be off prior to delivery
clot 1-14 d old: retrievable IVC filter, LMWH d/c day prior
clot 2-4 wks: IV heparin until cervix 3 cm, restart 6 h post-partum (assuming venous stasis achieved)
clot >4 wks: split final dose of LMWH with final dose 12 h prior to delivery, re-start 6 h post delivery (assuming venous stasis achieved)
anti-partum therapy: continue for at least 6 mo then reassess
High risk thrombophilia
antithrombin deficiency; double heterozygous for prothrombin G20210A mutation and factor V Leiden; factor V Leiden homozygous or prothrombin G20210A mutation homozygous. (These guys gets prophylactic UFH.)
Low risk thrombophilia
factor V Leiden heterozygous; prothrombin G20210A heterozygous; protein C or protein S deficiency. These guys you monitor.
Thrombocytopenia
Thrombocytopenia in pregnancy is a commonly encountered problem. Differential includes:
1) spurious
2) gestational
3) pre-eclampsia/eclampsia/HELLP
4) ITP
5) DIC
6) TTP / HUS
7) Hypersplenism
In general platelets are lower in pregnancy compared to normal. Gestational thrombocytopenia is defined by mild occurrence during late gestation with spontaneous resolution after delivery. Typically counts are above 70000. May have a possible immunologic etiology. Routine gestational management for both fetus and mother. There is no risk for fetal thrombocytopenia or intracranial hemorrhage after delivery.
For pre-eclampsia, gradual development of hypertension and proteinuria in pregnancy, typically become present in 3rd trimester and progress until delivery. Symptoms typically resolve within hours to a few days following delivery. Post-partum, main findings pointing towards TTP-HUS is the absence of DIC, with neurologic signs and hematologic abnormalities for more than three days after delivery, usually for preeclampsia, hematologic recovery is within three days of delivery. Patient should have plasma exchange if TTP-HUS felt likely, can try steroids until third day.
HELLP probably represents a severe form of pre-eclampsia. Symptoms typically in 3rd trimester, though 2nd and post-partum disease are also possible. Most common symptom is abdominal pain; also nausea / vomiting. In distinguishing between fatty liver of pregnancy, prolonged PT/PTT, low glucose, encephlopathy and high creatinine more common in fatty liver. For HELLP, if >34 weeks, or DIC, or non-reassuring baby tests, deliver. Otherwise, manage BP with labetaolol, hydralazine, nifedipine. Mg to prevent convulsions. Platelet transfusion if bleeding. For AFLDP, deliver.
DIC
high INR and PTT, low fibrinogen, low platelets, increased D-dimer, increased bleeding time
HELLP
- Microangiopathic hemolytic anemia with characteristic schistocytes (also called helmet cells) on blood smear. Other signs suggestive of hemolysis include an elevated LDH or indirect bilirubin and a low serum haptoglobin concentration (≤25 mg/dL).
- Platelet count ≤100,000 cells/microL
- Serum LDH ≥600 IU/L or total bilirubin ≥1.2 mg/dL
- Serum AST ≥70 IU/L
