100 Cases in Clinical Medicine

ANSWER 80

The most likely clinical diagnosis in this patient is a left deep vein thrombosis(DVT). The
main differential diagnoses of an acutely swollen leg are a ruptured Baker’s cyst, trauma
and acute cellulitis. Other causes of chronically swollen legs are obesity, lymphoedema,
congestive cardiac failure and previous DVTs (postphlebitic). The knee cartilage problems
raise the possibility of ruptured Baker’s cyst, and the active lifestyle is compatible with
muscle trauma such as a ruptured plantaris but there is no story of an acute onset.

The raised D-dimers are not helpful since there are many causes. D-dimers are helpful
when negative in making the diagnosis of DVT much less likely. The history of miscarriage
and the raised activated partial thrombopastin time suggest the presence of antiphospho-
lipid syndrome (lupus anticoagulant) which should be investigated together with serological
tests for systemic lupus erythematosus.

In assessing the clinical likelihood of a deep vein thrombosis scoring systems are

available:

Active cancer 1 point

Paralysis or recent plaster immobilization 1 point

Major surgery or confined to bed for#3 days in last 4 weeks 1 point

Local tenderness along venous system 1 point

Swelling of entire leg 1 point

Calf#3 cm larger than other side 1 point

Collateral superficial veins 1 point

Oedema greater than in contralateral leg 1 point

Alternative diagnosis as or more likely than DVT –2 points

Pretest clinical probability

0 or less)low

1–2)intermediate

# 2 )high

This patient has a score of 3.

! Scoring system for DVT diagnosis

• Dehydration, prolonged inactivity, bedrest, post-surgical, obesity.


• Malignancy: cancers of the lung, pancreas, breast, prostate and gut are particularly
  associated. Pelvic malignancy causing compression can directly lead to venous
  thrombosis.


• Oral contraceptives: oestrogens increase the risk.


• Genetic causes: protein C/S deficiency, antithrombin III deficiency, homocystinuria
  and factor V Leiden mutation.


• Behçet’s syndrome: a diagnostic triad of iritis, orogenital ulceration and DVTs.


• Antiphospholipid antibody syndrome.

! Major risk factors for DVTs

When a patient presenting with a DVT is young, or where there is no obvious underlying
cause or where there is a strong family history or a history of recurrent events, underly-
ing risk factors should be investigated. This woman had oral contraceptive use and the
presence of antiphospholipid antibodies as risk factors for her DVT. Antiphospholipid anti-
bodiesmay be present as part of systemic lupus erythematosus (SLE) or may be an isolated