Download Taking a Pregnant Pause: Radiologic Evaluation of Suspected Pulmonary Embolus in the Pregnant Patient

Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
April 2011
Taking a Pregnant Pause:
Radiologic Evaluation of
Suspected Pulmonary Embolus in
the Pregnant Patient
Jennifer Katz Eriksen, MSc
Harvard Medical School Year III
Gillian Lieberman, MD
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Agenda
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Discuss the presentation, pathophysiology and
differential diagnosis of pulmonary embolism (PE) in
pregnancy
Describe relevant anatomy
Present the menu of tests used in the diagnostic
evaluation of suspected PE
Discuss a diagnostic algorithm for PE and its
limitations in pregnancy
Present a proposed diagnostic algorithm for PE
diagnosis in pregnancy
2
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: Clinical Presentation
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36 year old pregnant woman at 12 weeks, 6 days
gestational age
Chief complaint: New onset exertional chest pain and
dyspnea
Also noted subtle atraumatic left lower calf swelling
without tenderness, stiffness or erythema
When asked if she had ever had similar symptoms
before, she noted…
3
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: Additional History

“This feels exactly like
when I had my
pulmonary embolism.”
4
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: Past Medical History
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12 months prior, she had developed exertional chest
pain and dyspnea and was found to have bilateral
pulmonary emboli
Work-up found no enviromental, genetic or modifiable
risk factors except oral contraceptives, which were
discontinued
She was on warfarin anticoagulation until 5 months
ago, when she began trying to conceive
Planned to initiate low molecular weight heparin
anticoagulation in 2nd trimester (the following day)
5
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Differential Diagnosis

Pulmonary Embolism
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Thromboembolic
Fat
Air
Amniotic fluid
Septic
Tumor
Foreign body
Parasite/Egg
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Pneumonia
MI
Pericarditis
CHF
Pleuritis
Pneumothorax
Pericardial tamponade
URI
Rib fracture
…or normal physiologic changes of pregnancy!
6
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Clinical Presentation of DVT and PE
Notoriously insensitive and non-specific
Symptoms
Signs
PE
PE
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Dyspnea
Pleuritic chest pain
Cough
Hemoptysis
DVT

Lower extremity
 Swelling
 Erythema
 Pain
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Tachypnea
Rales
Tachycardia
S4
Accentuated P2 of S2
Circulatory collapse
7
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Pulmonary Embolism: Epidemiology
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Most typically secondary to embolizing
thrombus from the deep venous system to the
pulmonary arterial circulation
600,000 cases annually in general population
Incidence ≈ 2-3/10,000 pregnancies
Responsible for 20% of the maternal mortality
in the US (most common non-obstetric cause)
Secondary to increased risk of DVT

Typically left sided, higher frequency in pelvic veins
8
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
PE Pathophysiology – Venous Stasis
Image from Bourjeily, 2010
9
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
PE Pathophysiology – Vascular Damage
Image from Bourjeily, 2010
10
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
PE Pathophysiology – Hypercoagulability
Image from Bourjeily, 2010
11
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Pulmonary Artery Anatomy: Illustration
Gray, 1918
12
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #1:
Normal Pulmonary Artery Anatomy
Axial Contrast
Enhanced CT
Right
Pulmonary
Artery
Pulmonary Trunk
Left
Pulmonary
Artery
PACS, BIDMC
13
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Menu of Tests

Chest x-ray (CXR)
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Lower extremities non-invasive studies (LENIS)
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CT of the pulmonary arteries with contrast
(CTPA)
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Ventilation/perfusion lung scan (V/Q scan)
14
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Chest X-Ray Overview
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First imaging modality for chest pain
Only 12% of patients with PE have normal chest x-ray
Findings in PE usually non-specific and not diagnostic:
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Focal peripheral alveolar opacification
Linear atelectasis
Cardiomegaly, pleural effusion, elevation of hemidiaphragm,
PA enlargement, discoid atelectasis
Rare findings: Westermark’s Sign, Palla’s Sign, and
Hampton’s Hump
15
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Chest X-Ray – Rare Findings
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Westermark’s Sign: Local peripheral oligemia
Palla’s Sign: Prominent descending pulmonary
artery with a sharp cutoff
Hampton’s Hump: Peripheral wedge-shaped
opacity indicating infarction and atelectasis
Now we’ll look at each of
these findings on CXR…
16
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #2
Discoid Atelectasis
Upright Frontal
PA CXR
Discoid
Atelectasis
PACS, BIDMC
17
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #2
Focal Alveolar Opacification
Upright
Left Lateral
CXR
Hazy RLL
Opacity
PACS, BIDMC
18
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #3
Westermark’s and Palla’s Signs
Westermark’s
Sign
Upright Frontal
PA CXR
Palla’s Sign
Sreenivasan, 2007
19
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #4:
Hampton’s Hump and Palla’s Sign
Supine Frontal
AP CXR
Hampton’s
Hump
Palla’s
Sign
Taylor, 2010
20
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Lower Extremity Non-Invasive Studies
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Ultrasound of the lower extremity venous system with
duplex Doppler
Assesses patency and drainage of veins, as well as blood
flow through the veins and around any obstructions
Strengths: Non-invasive, cost-effective study, at bedside
Limitations: Operator dependent, less reliable above
inguinal canal and below knee, can’t assess pelvic veins
21
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
CT-PA: Overview
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Multidetector CT pulmonary angiography with
contrast is the standard of care diagnostic test
for pulmonary embolus
Strengths: high sensitivity and specificity for
detection of PE, high intra- and inter-observer
reliability, when combined with D-dimer and
clinical suspicion, PPV and NPV are very high
Limitations: cannot reliably detect subsegmental
PE
22
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
CTPA: Characteristic Findings
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Arterial occlusion – low attenuation on CT
Non-obstructive intraluminal filling defects
Evidence of R heart strain
Polo mint sign: partial filling defect surrounded by
contrast on images of the vessel perpendicular to its
long axis
Tram track sign: partial filling defect surrounded by
contrast on images of the vessel parallel to its long axis
Peripheral wedge shaped infarcts
23
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #5:
Polo Mint Sign
Axial Contrast
Enhanced CT
of the Chest
Polo
Mint
Sign
Wittram, 2004. Polo mint image from: www.royalanecdotes.com/wp-content/uploads/Polo.jpg
24
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #6:
Tram Track Sign
Axial Contrast
Enhanced CT
of the Chest
Tram
Track
Sign
Wittram, 2004
25
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #7:
Peripheral Wedge Shaped Infarct
Axial Contrast
Enhanced CT
of the Chest
Peripheral Wedge
Shaped Infarct
Wittram, 2004
26
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: CTPA #1
Axial Contrast
Enhanced CT
of the Chest
PACS, BIDMC
27
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: CTPA #2
Axial Contrast
Enhanced CT
of the Chest
PACS, BIDMC
28
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Do you see anything
unusual? Let’s look at a
few more sections…
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: CTPA #3
Axial Contrast
Enhanced CT
of the Chest
PACS, BIDMC
30
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: CTPA #4
Axial Contrast
Enhanced CT
of the Chest
31
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: CTPA #5
Axial Contrast
Enhanced CT
of the Chest
PACS, BIDMC
32
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our patient’s CT-PA showed no
abnormalities. There was no
evidence of pulmonary embolus.
Let’s look at imaging from our
companion patients to see some
classic findings…
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #2: Pleural Effusion
Axial Contrast
Enhanced CT
of the Chest
Pleural effusion
PACS, BIDMC
34
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #2: Bilateral Emboli
Axial Contrast
Enhanced CT
of the Chest
Emboli
PACS, BIDMC
35
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Companion Patient #8: Pleural Effusion and Infarct
Axial Contrast
Enhanced CT
of the Chest
Peripheral
Wedge Shaped
Infarct
Pleural
Effusion
PACS, BIDMC
36
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Ventilation Perfusion (V/Q) Scan
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Uses 2 different radiotracers, one inhaled and
one intravenous, to measure alignment of
ventilation and circulation
Scan showing ventilation without perfusion
indicates a decrease in regional blood flow
The differential for an abnormal exam includes
PE, pneumonia, COPD, or airway obstruction
Scans must be interpreted in the context of a
current CXR
37
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
V/Q Scan Images
Image from: Lung SPECT. Southern Nuclear Imaging. http://www.nuclearimaging.com.au/lung_spect.htm. Accessed on April 14, 2011
38
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
CTPA vs. V/Q Scan
Patient
population
Time
Alternate dx
Subsegmental?
Breast radiation
CTPA
V/Q Scan
All
Normal lung
function
Hours
No
Yes
Low
Minutes
Yes
No
High
39
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Now that we’ve
discussed the different
tests, let’s discuss how
to use them to evaluate
a suspected PE
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Diagnostic Algorithm for Suspected PE
in the Non-Pregnant Patient (1)
Schwartz, 2011
41
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Limitations of the Diagnostic
Algorithm in Pregnancy
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It is difficult to determine pretest probability of
PE in pregnant patient
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There is limited utility of D-dimer study during
pregnancy
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Concerns about fetal and maternal breast
radiation from CT-PA and V/Q scans
42
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Diagnostic Algorithm for Suspected PE
in the Non-Pregnant Patient (2)
Schwartz, 2011
43
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Determining Pretest Probability
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Determining if a patient is “likely” or “unlikely”
to have a PE is typically done with diagnostic
criteria, such as the Modified Wells’ or Geneva
Criteria
These do not account for the increased risk of
44
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Modified Wells’ Criteria
Clinical Symptoms of DVT
PE is most likely diagnosis
3.0
3.0
Heart rate >100bpm
1.5
Immobilization/surgery in previous 4 weeks
1.5
Previous DVT/PE
Hemoptysis
1.5
1.0
Malignancy
1.0
PE likely
PE unlikely
>4.0
≤4.0
45
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Diagnostic Algorithm for Suspected PE
in the Non-Pregnant Patient (3)
Schwartz, 2011
46
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
D-Dimer
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Breakdown product of cross-linked fibrin
High sensitivity (82-95%)
Low specificity (40-60%)
Negative predictive value depends on clinical
suspicion
D-dimer is progressively elevated in
uncomplicated pregnancy
47
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Diagnostic Algorithm for Suspected PE
in the Non-Pregnant Patients (4)
Schwartz, 2011
48
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Radiation Exposure Concerns
in Pregnancy
 Fetal radiation dosing
 Breast radiation dosing
49
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Fetal Radiation Risks
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Carcinogenesis
Baseline risk = 0.05%
 50mGy has RR =2.0
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Teratogenesis
Risk is dependent on dose and gestational age
 >100mGy:

 Induced abortion (3-4w GA)
 Organogenesis defects (5-10w GA)
 IQ deficits/mental retardation (11-17w)
50
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Fetal Radiation Exposure of
Diagnostic Tests (mGy)
CXR (PA and lateral)
<0.01
CTPA chest
0.3
Perfusion lung scan
0.06-0.12
Ventilation lung scan
0.01-0.19
Combined CTPA, V/Q scan and conventional
pulmonary angiogram
1.5-2.0
Schwartz, 2011
51
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Breast Radiation Exposure
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Breast radiation exposure is associated with increased
risk of breast cancer
Younger women are more susceptible than older
women
CTPA
 10-50 mGy
 = 15 mammograms
 0.7-1.0% lifetime excess
RR of breast cancer per
exposure at 25 years old
V/Q Scan
 0.28 mGy
 = 0.1 mammogram
 =0.01 CTPA
 No detectable increased
risk of breast cancer
52
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Strategies to Reduce Radiation Dose
CTPA
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Reduce current and
voltage
Bismuth breast shield
Oral barium prep for
fetal shielding
Strategies to improve
quality to reduce nondiagnostic films
V/Q Scan
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Appropriate patient
selection
Decrease perfusion dose
Eliminate ventilation
exam
Frequent post-exam
voids
53
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Proposed Diagnostic Algorithm for Suspected PE
in the Pregnant Patient
Litmanovich, 2009
54
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Our Patient: Clinical Conclusion
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Given scheduled initiation of Lovenox on the
following day, and lingering concern for
unvisualized subsegmental PE, patient was given
a prophylactic dose of low molecular weight
heparin and told to follow-up as scheduled with
her hematologist the following day
She is now 25 weeks 6 days pregnant
She has had no further respiratory complaints or
complications in her pregnancy
55
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
Acknowledgements
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
Gillian Lieberman, MD
Diana Litmanovich, MD
Emily Hanson
Carole Ridge, MD
Christopher Aderman, Jasmine Barrow, and Kelsey
Sunderland
Thank you!
56
Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
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Jennifer Katz Eriksen, MSc, MSIII
Gillian Lieberman, MD
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