Pulmonary embolism in pregnancy

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Background

  • Incidence of VTE in pregnancy and postpartum is 1.72 per 1000[1]
  • The risk is significantly elevated in the 6 wks postpartum
    • Risk of DVT equal in 1st and 2nd trimesters, higher risk in 3rd trimester and 3 weeks postpartum. [2]
    • PE most commonly occurs in postpartum. [2]
    • Common risk factors include: Advanced maternal age, C-Section, Obesity, multiple gestations, thrombophilia, prior VTE
  • Risk returns to baseline by 12 wks postpartumm[3]
  • Consider MI in differential as risk can increase 3-6 times during the postpartum period

Clinical Spectrum of Venous thromboembolism

Only 40% of ambulatory ED patients with PE have concomitant DVT[4][5]

PE Types

Massive

  • Cardiac arrest
  • Sustained hypotension (sys BP <90 for at least 15min or requiring inotropic support)
  • Persistent profound bradycardia (HR <40 with signs of shock)

Submassive

  • Sys BP >90 but with either RV dysfunction or myocardial necrosis
  • RV dysfunction
    • RV dilation or dysfunction on TTE
      • "D Sign" on bedside echo (LV takes on a "D" shape due to RV dilation)
    • RV dilation on CT
    • Elevation of BNP (>90)
    • ECG: new complete or incomplete RBBB, anteroseptal ST elevation/depression or TWI[6]
    • Myocardial necrosis: Troponin I >0.4

Non-Massive

  • No hemodynamic compromise and no RV strain

Sub-Segmental

  • Limited to the subsegmental pulmonary arteries

Clinical Features

Symptoms

According to the PIOPED II study, these are the most common presenting signs[7]

  • Dyspnea at rest or with exertion (73%)
  • Pleuritic chest pain (44%)
  • Cough (37%)
  • Orthopnea (28%)
  • Calf or thigh pain and/or swelling (44%)
  • Wheezing (21%)
  • Hemoptysis (13%)

Signs

  • Tachypnea (54%)
  • Calf or thigh swelling, erythema, edema, tenderness, palpable cord (47%)
  • Tachycardia (24%)
  • Rales (18%)
  • Decreased breath sounds (17%)
  • Accentuated pulmonic component of the second heart sound (15%)
  • JVD (14%)
  • Fever (3%)

Differential Diagnosis

Chest pain

Critical

Emergent

Nonemergent

Evaluation

Clinical Decision Rules

  • Limited utility as no studies (PERC, Wells) have proven effective in pregnancy
    • 8% (9/114) of PERC Negative patients with CT or V/Q proven PE were pregnant or post-partum [8][9]

If clinical features suggestive of PE and lower extremity swelling then:

  • Bilateral LE Ultrasound
    • if Positive→treat empirically for PE
    • if Negative→CTA
      • CTA and V/Q scans yield approximately 0.025 rad and 0.040 rad respectively to the fetus[10]
      • >5 rads is considered teratogenic[11]
      • However, 20-100 times more radiation is delivered to maternal breast tissue with CT, increasing the risk of breast cancer[12]
  • Up to 17% of pregnant patients have isolated pelvic DVT(not found with ultrasound)[13]
CT (with shield) vs. V/Q is roughly equivalent radiation exposure to fetus, but CT confers increased radiation to maternal breast tissue

American Thoracic Society In Pregnancy[14]

  • D-dimer is not recommended for excluding PE (weak recommendation, very-low-quality evidence).
  • If signs and symptoms of deep venous thrombosis (DVT), first perform bilateral venous compression ultrasound (CUS) of lower extremities, followed by anticoagulation treatment if positive and by further testing if negative (weak recommendation, very-low-quality evidence).
  • If no signs and symptoms of DVT, pulmonary vascular imaging should be used over bilateral lower extremity ultrasounds(weak recommendation, very-low-quality evidence).

D-Dimer

  • D-Dimer MAY BE used with following limits with very poor evidence[15][16][17]
    • 1st trimester: <750 ng/mL (+50% increase from normal lab threshold)
    • 2nd trimester: <1000 ng/mL (+100% from normal)
    • 3rd trimester: <1250 ng/mL (+150% from normal)

Management

  • Heparin and Enoxaparin are safe (coumadin is not)
    • Heparin 80 units/kg IV bolus followed by continuous infusion 18 units/kg/hr [18]
    • Enoxaparin 1 milligram/kg (100 IU/kg) SC every 12 or 24 h [18]
  • Perimortem cesarean delivery with cardiac arrest with no ROSC in 5 min
  • Consider thrombolysis in severely unstable post-partum pulmonary embolism[19](see Adult pulseless arrest for tPA dosing in pulmonary embolism)

Disposition

  • Admit

See Also

References

  1. James AH, et al. Venous thromboembolism during pregnancy and the postpartum period: Incidence, risk factors, and mortality. 2006; 194(5):1311–1315.
  2. 2.0 2.1 Chan et al. Venous Thromboembolism and Antithrombotic Therapy in Pregnancy. SOGC Guidelines. 2014.
  3. Kamel H, et al. Risk of a thrombotic event after the 6-week postpartum period. N Engl J Med. 2014; 370:1307-1315.
  4. Righini M, Le GG, Aujesky D, et al. Diagnosis of pulmonary embolism by multidetector CT alone or combined with venous ultrasonography of the leg: a randomised non-inferiority trial. Lancet. 2008; 371(9621):1343-1352.
  5. Daniel KR, Jackson RE, Kline JA. Utility of the lower extremity venous ultrasound in the diagnosis and exclusion of pulmonary embolism in outpatients. Ann Emerg Med. 2000; 35(6):547-554.
  6. David Da Costa. Bradycardias and atrioventricular conduction block BMJ. 2002 March 2; 324(7336): 535–538
  7. Stein PD et al. Clinical characteristics of patients with acute pulmonary embolism: data from PIOPED II. Am J Med. 2007;120(10):871.
  8. Kline JA, et al. Clinical Features of Patients With Pulmonary Embolism and a Negative PERC Rule Result. Ann Emerg Med. 2013 January 60(1): 122-124
  9. West, J. “When the PERC Rule Fails”. ALiEM. Feb 2014[1]
  10. Astani SA, et al. Detection of pulmonary embolism during pregnancy: comparing radiation doses of CTPA and pulmonary scintigraphy. Nucl Med Commun. 2014; 35(7):704-711.
  11. Bentur Y, Horlatsch N, and Koren G. Exposure to ionizing radiation during pregnancy: perception of teratogenic risk and outcome. Teratology. 1991; 43(2):109-112.
  12. Greer IA. Pregnancy complicated by venous thrombosis. N Engl J Med 2015; 373:540-547
  13. Chan WS, Spencer FA, Ginsberg JS. Anatomic distribution of deep vein thrombosis in pregnancy. CMAJ. 2010; 182(7):657- 660.
  14. Leung, A et al. An Official American Thoracic Society/Society of Thoracic Radiology Clinical Practice Guideline: Evaluation of Suspected Pulmonary Embolism PDF
  15. Kovac M. The use of D-dimer with new cutoff can be useful in diagnosis of venous thromboembolism in pregnancy. Eur J Obstet Gynecol Reprod Biol. 2010 Jan;148(1):27-30
  16. http://blog.ercast.org/2013/04/pulmonary-embolism-in-pregnancy/
  17. D-Dimer Concentrations in Normal Pregnancy: New Diagnostic Thresholds Are Needed. Kline et all. Clinical Chemistry May 2005 vol. 51 no. 5 825-829 http://www.clinchem.org/content/51/5/825.long
  18. 18.0 18.1 Tintinalli's 7th edition
  19. Stone SE and Morris TA. Pulmonary embolism during and after pregnancy. (Crit Care Med 2005; 33[Suppl.]:S294 –S300.