Issues in diagnosis of VTE in Pregnancy Ng Heng Joo Department of Haematology Singapore General Hospital

Does she or does she not….. Doctor, My legs are getting more swollen. Maybe a little bit more on one side…..

Suspected VTE in pregnancy– Diagnostic Difficulties Physiological changes commonly mimic symptoms/signs of VTE Clinical diagnosis insensitive and non-specific Predictive scoring systems have not been validated in pregnant women (e.g Wells) Clinicians and parents may be reluctant to subject patients/fetus to radiation from diagnostic test

Outline Diagnosis of DVT – Compression ultrasound – D-dimers – Predictive scores Diagnosis of Pulmonary Embolism – VQ scans vs CT scans – Predictive scores

What would we do if she were not pregnant? Consider the clinical likelihood of DVT – pre-test probability score (Wells score… D-dimer if score is low Scan if score is high

Wells Score

Ann Intern Med 2009

L – Symptoms in the left leg E – Edema, calf circumference difference >2 cm Ft – First trimester Score 0 – 0% Score 1 – 16% Score 2-3 – 58%

LEFt validation

LEFt Clinical Prediction Rule Cannot be used as a standalone Needs further validation in larger study populations

D-dimers in normal pregnancy

Using higher cut-points than those used in non- pregnant patients, the specificity of D-dimer assays for the diagnosis of DVT in pregnancy can be improved without compromising sensitivity. Validation in prospective management studies is needed

Imaging techniques Compression ultrasound Magnetic resonance venography Ascending contrast venography

Compression ultrasound Current standards High sensitivity and specificity (>95%) for thigh DVT Less sensitive for pelvic vein and calf vein DVT Colour Doppler, Valsava maneuver, decubitus position etc improves diagnostic sensitivity for pelvic vein thrombus Calf vein thrombus – serial scans may detect progression to proximal vessels

Magnetic resonance venography High sensitivity for thigh and pelvic vein thrombosis in non-pregnant Limited data in pregnant women Some evidence of potential value in pregnant women

Diagnostic algorithm for DVT ACCP 2012

Diagnostic Algorithm for PE M. Tan, M.V. Huisman / Thrombosis Research 127 (2011)

Suspected pulmonary embolism

Modalities Pre-test probability scores – Not validated for pregnancy D-dimers – similar issues with suspected DVT Imaging studies

Compression ultrasound of lower limbs Rationale – Treatment of DVT and PE is going to be the same – Potential to avoid exposure to radiation with PE specific scans Reality – Compression ultrasound as first investigation only if there is clinical suspicion of DVT – Negative scans does not preclude other imaging studies if PE symptoms present

CT scan vs VQ scans

Radiation exposure concerns - Fetus threshold of mGy or higher Malformations have a threshold of mGy or higher and are typically associated with central nervous system problems Fetal doses of 100 mGy (0.1Gy) are not reached even with 3 pelvic CT scans or 20 conventional diagnostic x-ray examinations Perfusion scintigraphy exposes the fetus to around 0.2 mSv Multi detector row helical CT: mSv ICRP 84

Radiation exposure to fetus by procedure

Radiation exposure concerns - Mother Radiation absorption by maternal breast tissue CT scan: 10 mGy V/Q scan: 0.28 mGy 1 mGy of radiation exposure is associated with an increase of breast cancer by an additional 1 in 50,000 women

CT scan vs VQ scans Diagnosing pulmonary embolism in pregnancy using computed- tomographic angiography or ventilation-perfusion.Cahill AG, Stout MJ, Macones GA, Bhalla S. Obstet Gynecol. 2009;114(1):124. Pulmonary embolism in pregnancy: comparison of pulmonary CT angiography and lung scintigraphy. Ridge CA, McDermott S, Freyne BJ, Brennan DJ, Collins CD, Skehan SJ. AJR Am J Roentgenol. 2009;193(5):1223 Pulmonary embolism during pregnancy: diagnosis with lung scintigraphy or CT angiography? Revel MP, Cohen S, Sanchez O, Collignon MA, Thiam R, Redheuil A, Meyer G, Frija G. Radiology. 2011;258(2):590. Pulmonary embolism in pregnancy: CT pulmonary angiography versus perfusion scanning. Shahir K, Goodman LR, Tali A, Thorsen KM, Hellman RS. AJR Am J Roentgenol. 2010;195(3):W214. CT scan = VQ scan

MRI scan No ionizing radiation Misses subsegmental PE Not well validated Uses gadolinium which crosses placenta

RCOG 2015

Thank you