Editorial

The New Guideline of the Dutch Institutefor Health Care Improvement (CBO) on theDiagnosis of Venous Thromboembolism

Diagnosing venous thromboembolism (VTE) is of great

importance, as especially pulmonary embolism is a

potentially fatal disorder. In the last decade, the diagnostic

methods for both venous thrombosis and pulmonary

embolism have greatly been improved by the introduction

of clinical decision rules (CDR), D-dimer testing, and

multidetector computed tomography (CT) scan. In the

recently published guideline of the Dutch Institute for

Health Care Improvement (CBO) ‘diagnosis, prevention

and treatment of VTE and secondary prevention of arte-

rial thrombosis’, the value of several diagnostic methods for

deep-vein thrombosis (DVT) and pulmonary embolism

is discussed and an integrated diagnostic approach is

advocated.

In this issue of Imaging Decisions, the most important

subjects of this guideline are reviewed, all written by

authors who were important contributors. First, we

summarize the recommendations for the diagnosis of

venous thrombosis and pulmonary embolism. The value of

noninvasive diagnostic tests, namely CDR in combination

with D-dimer testing, is highlighted, as a combination of

these tests can rule out VTE in a considerable number of

patients, without the need for additional imaging. In the

CBO guideline, a simple diagnostic algorithm for both

diagnoses is the cornerstone of the diagnostic process in

patients with suspected VTE. After a first round of

noninvasive testing, only patients with a ‘likely’ Wells

score or an abnormal D-dimer concentration undergo

additional testing, like ultrasonography of the leg veins for

DVT, or multidetector CT scanning for suspected pulmo-

nary embolism. These diagnostic algorithms considerably

simplify the diagnosis of VTE in daily clinical practice.

Subsequently, Douma and colleagues focus on the

several score systems that categorize the probability for

pulmonary embolism. In general, clinical symptoms of

patients with suspected pulmonary embolism are often

nonspecific and have a low sensitivity for this diagnosis.

Several CDR have been developed to stratify the patient’s

risk for pulmonary embolism. CDRs that have been

evaluated in management studies are either implicit (or

‘gestalt’) or explicit, more standardized. Comparative

studies between these different methods show similar

accuracy in the determination of the pre-test probability

for pulmonary embolism. It seems however that

a standardized clinical decision score has a lower inter-

observer variability and can be used by less experienced

doctors. The two most important CDRs, Wells and

Geneva, are discussed and new developments that simplify

these scores are described.

D-dimer testing plays a crucial role in the diagnosis of

VTE. Several tests for the measurement of D-dimer

antigen are available on the market. These include

enzyme-linked immunosorbent assay and whole plasma

agglutination measurements, which differ in sensitivity and

specificity. The article by Haas describes the different tests

and discusses the pitfalls of their use in patients with

suspected VTE. In general, in combination with the

clinical rule, D-dimer is an effective diagnostic tool to rule

out VTE. On the other hand, an abnormal D-dimer test

has a too low specificity to indicate the presence of

thromboembolism.

Next, Donkers discusses the value of the CT scan in

diagnosing pulmonary embolism. Multidetector CT scan is

becoming the preferred imaging modality for suspected

pulmonary embolism in most countries. It directly visual-

izes a thrombus in the pulmonary arteries and is capable of

detecting other diseases that can mimic pulmonary embo-

lism. Several management outcome studies have shown

that it is safe to withhold anticoagulant treatment in

patients with a normal multidetector CT scan. In this

article, the technique of the CT scan is discussed and the

accuracy among patients with suspected pulmonary embo-

lism in the literature is reviewed.

Subsequently, van Loon and Stekkinger focus on the

diagnosis of VTE during pregnancy and puerperium,

where the incidence of VTE is much higher than in non-

pregnant women. Making a clinical diagnosis in these

circumstances is often difficult and diagnostic tests are

jeopardized by concerns regarding radiation exposure of

the fetus. Furthermore, the common diagnostic tests, like

D-dimer, compression ultrasonography, ventilation-perfu-

sion scintigraphy and helical CT, have not been appro-

priately validated in pregnancy. This article will review the

role of various diagnostic tests in case of suspected VTE in

3/2007 n IMAGING DECISIONS

pregnancy and puerperium, and issues such as radiation

risk are discussed. Recommendations for the use of

D-dimer and imaging techniques in pregnant and

postpartum patients with a clinically suspected DVT or

pulmonary embolism are presented.

The last article by Karami Djurabi et al. highlights the

Christopher Study. This landmark trial used a diagnostic

algorithm of a modified CDR according to Wells, followed

by a D-dimer test, and, in the case of a likely decision score

or an abnormal D-dimer, a CT scan. The Christopher

study included 3305 consecutive patients with suspected

PE referred to five academic and seven general non-

academic teaching hospitals in the Netherlands. When

patients who had a combination of a Wells score ‘unlikely’

and a normal D-dimer test results were not treated with

anticoagulants, the 3-month recurrence rate of VTE was

very low [0.5% (95% CI 0.2–1.1%)]. This strategy safely

excluded pulmonary embolism in 32% of the patients.

A normal CT scan (mostly MDCT) reliably excluded

pulmonary embolism in patients who either had a likely

probability or an abnormal D-dimer test [3-month

incidence of VTE 1.3% (95% CI 0.7–2.0%)]. Karami

Djurabi et al. conclude that in patients with clinically

suspected pulmonary embolism the use of a diagnostic

algorithm consisting of a dichotomous decision rule,

D-dimer testing and CTPA, or as alternative V-Q lung

scanning, can guide treatment decisions with a low risk for

false-negative outcome.

I would like to thank all contributors for the excellent

articles, which offer a balanced look at the current state of

the art in the diagnosis of VTE. I hope that this issue will

give guidance in the diagnostic approach of patients with

suspected DVT or pulmonary embolism.

P. W. KamphuisenDepartment of Vascular Medicine

Academic Medical CenterAmsterdam

The NetherlandsE-mail: p.w.kamphuisen@amc.uva.nl

2 n E D I T O R I A L

IMAGING DECISIONS n 3/2007