The MDU has assisted a number of members with complaints in relation to a missed or delayed diagnosis of deep vein thrombosis (DVT).

This can be a relatively common diagnosis in both general practice and hospital medicine, so it's worth being aware of the criticisms that may be made, for example by the Ombudsman¹ or the GMC, should a complaint be made to them if a diagnosis is missed. This presentation also highlights the importance of good history taking and documentation.

How does DVT present?

A DVT is a blood clot that develops in the deep veins of the body, usually in the legs.

• A patient will often present with pain and swelling in the affected leg, often the calf.
• On examination the leg may be tender, warm to the touch and red.
• It's important to diagnose a DVT, due to the risk of the clot breaking off and travelling in the bloodstream to the lungs, causing a pulmonary embolus (PE), which can be fatal.
• Where a DVT has resulted in a PE, the patient is likely to be breathless and complain of chest pain, particularly when they breathe in.
• There is also a risk of sudden collapse.

Where a patient presents with any of these symptoms or signs, it's important to take a detailed history to determine whether there are any risk factors to developing a DVT. This may include, for example, the oral contraceptive pill or hormone replacement therapy, obesity and immobility, either through illness or if the patient has been immobilised on a long journey or recently had surgery, such as a pelvic operation or hip replacement.

It's also important to check whether the patient has a past, or family, history of previous blood clots.

Not all patients will present with classic symptoms of a DVT and therefore a doctor's index of suspicion may be low. The patient may, for example, have a vague history of trauma which may lead the doctor to suspect the pain and/or swelling is mechanical. Another differential diagnosis may be that of a Baker's cyst; a fluid-filled swelling that can develop behind the knee causing similar symptoms of pain, swelling and tightness, as a DVT.

The importance of the Wells score

The Ombudsman has been critical where a doctor does consider the diagnosis of a DVT, even if this is very tentative, but does not take any further action to confirm or rule out the diagnosis. NICE guidance states that a Wells score² should be calculated and, based on the result of this, a management plan agreed with the patient.

Even where the Wells score is low, but a DVT has been considered a possibility, the patient should be offered a D-dimer test to help exclude the presence of a DVT. If the D-dimer test were to be raised this is not specific to a DVT but, taking into account the patient's presentation and the possibility of a clot being present, they should be started on anticoagulants until an ultrasound scan can be arranged.

When criticism occurs 

Doctors may be criticised where a Wells score has not been calculated and NICE guidance not followed, or where they state that they did calculate the Wells score but this has not been recorded and there is no indication of what the result was.

Even where a patient has not presented with the typical signs of a DVT, but where this has been considered as a remote possibility, the guidance should still be followed. As mentioned above, if the Wells score is low but a clot has been considered, the patient should be offered a D-dimer test and the patient managed according to the result. If a complaint is made, the doctor will need to be able to justify their clinical decision making.

Having seen a patient who has presented with signs of DVT, or the doctor has a suspicion of such, it's important to make sure that all relevant signs, symptoms and management advice are documented.

This includes the fact that a Wells score has been calculated and what the score was, and any relevant negative findings on examination. Where a patient has not reported any chest pain or breathlessness, this should be recorded in the records as evidence that these questions were asked.

Whether or not a D-dimer test was offered, based on the Wells score and index of suspicion, should also be noted and whether or not the patient accepted this offer. Clear safety netting advice should also be documented, and any follow-up plans.