Confirming the diagnosis of DVT in pregnancy

The part of the limb (usually the calf or inner thigh) affected by DVT will be painful and tender. The pain may be continuous or throbbing. The area may also be swollen, red and turgid.

If it is in the calf, movements of the ankle joint may cause shooting pain. If you have any of the above symptoms, even in isolation, seek prompt medical attention. Not all episodes of calf pain will be due to DVT, but it is best to leave it to the experts to make the distinction.

Tests to confirm diagnosis of thrombosis

In pregnancy, ultrasound is the first choice. However, while it is good for the thigh vein thrombosis, it is not so accurate if the suspected site is the calf. For this, a rather invasive method called venography may have to be used.

Where facilities allow, MRI imaging may be used. This is very accurate and safe to use in pregnancy.

Even for a suspected calf vein thrombosis, the clinical impression, coupled with ultrasound results, may be judged to be enough to start treatment. If venography is used, the fetus will be shielded to minimize exposure to radiation - which is low, to begin with.

DVT and risk of Pulmonary Embolism

Of the two main areas commonly affected by thrombosis in the lower limb, the upper inner thigh (femoral vein) thrombosis is potentially much more dangerous when compared to the calf thrombosis.

While it is true that calf thrombosis rarely leads to pulmonary embolism, untreated, the thrombosis in the vein could extend upwards into the thigh, thereby changing the outlook quite dramatically.

Treatment for thrombosis in pregnancy

Once the diagnosis is established, treatment will be commenced immediately. The aim is to prevent extension of the clot as well as the complication of embolism.

The treatment is also to facilitate the existing clot to dissolve. There are various types of ‘heparins’ used in pregnancy. The treatment is decided on the basis of the individual patient's circumstances. Generally, in the medium term, the mother should expect to be on heparin injections daily.

The patient will be taught to give herself the injections. The majority of patients grasp the technique easily and quickly. Alternatively, a partner or another adult may take up the task. Once all this is in place and her condition is stable, she can attend hospital as an outpatient with regular and frequent reviews.

Alternatives to heparin injections

Until a few years ago, heparin had to be administered twice or three times daily. Now, the so-called low molecular weight heparins (LMWH) are available. These offer a distinct advantage to the traditional heparin in that they are administered the same way but usually only once or at most twice daily. Examples include Dalteparin (Fragmin) and Enoxaparin (Clexane or Lovenox).

Even though LMWH are more expensive, virtually all obstetricians and obstetric units have increasingly switched to these because of their user-friendliness. They also seem to have milder side effects. They are just as effective as traditional heparin.

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