Testing for Blood Clots During or After Pregnancy: You have been given this leaflet because you are pregnant or have recently been pregnant and your doctor suspects that you may have a blood clot in your leg or lung.
Leaflet Details
| Title | Testing for Blood Clots During or After Pregnancy: Information for women with a suspected blood clot |
| Department | Maternity |
| Author(s) | Dr Jo Hale |
| Review Date | April 2021 |
| Next Review | April 2023 |
| Download | A4 Handout PDF |
| Accessibility Options | Click on the Recite Me button to show our accessibility resources |
Patient Information
Introduction
You have been given this leaflet because you are pregnant or have recently been pregnant and your doctor suspects that you may have a blood clot in your leg or lung
Terms
- Thrombus / thrombosis - blood clot that forms in a blood vessel
- Embolus / embolism - part of a thrombus that breaks off and travels through your blood to another part of your body
- Deep vein thrombosis (DVT) - blood clot that forms in your legs
- Pulmonary embolism (PE) - blood clot that breaks away from your leg and travels to your lungs
Pregnancy and blood clots
In pregnancy blood clots are up to 5 times more common. However it is still uncommon and happens in 1-2 pregnant women in every 1000.
A blood clot can occur at any time in pregnancy and up to 12 weeks after you have had your baby.
What is a Deep Vein Thrombosis (DVT)?
In your leg a blood clot forms and blocks the blood flow
Symptoms can include
- Pain
- Swelling
- Tenderness
- Redness or warm skin in affected area
- Heavy ache in affected area
How is a DVT diagnosed?
The main way to look for a blood clot in your leg is to use doppler ultrasound. This is an ultrasound scan of your leg (like the ultrasound that is used to scan your baby)
Sometimes if the blood clot is higher up then other scans may need to be used to look at this. This may include using an MRI (magnetic resonance imaging) scan which is safe in pregnancy.
Blood thinning medication is used to treat this.
What is a Pulmonary Embolism (PE)?
A PE develops when some of the clot breaks off from the clot in your leg and travels to your lungs. This clot then blocks the blood vessels in your lung preventing blood getting to that part of the lung.
Symptoms include
- Sudden onset shortness of breath
- Tightness in the chest / chest pain
- Coughing up blood
- Feeling very unwell or collapsing
Blood thinning medication will be started to treat this.
How is a PE diagnosed?
A PE can be life-threatening. If you have symptoms in your legs then we will do an ultrasound of your legs to look for clot. If this is clear we will consider whether we need to do a scan of your chest.
In our hospital we use computerised tomography pulmonary angiography (CTPA) to diagnose a PE. This involves a low dose of x-ray radiation – it cannot be performed without the low dose of radiation.
We only carry out these tests when absolutely necessary and the benefits to you (and your unborn child) outweighs the risks of not having it
Chest X-ray
Before performing a CTPA a chest X-ray is usually required. This uses an extremely small dose of x-rays to create the image of your lungs and chest. It can diagnose other conditions which cause symptoms similar to a PE such as pneumonia.
The radiation dose from a chest X-ray is not thought to be significant. It is the equivalent to 3 days of the natural background radiation1 which occurs all around us, or eating 140g brazil nuts2.
CTPA Scan
This is a special scan of your lungs which x-rays to create detailed images.
You will need to have a small drip inserted in your arm so that some colourless contrast can be injected during the scan. The contrast shows the blood vessels in the lungs and allows any to be clot identified.
What are the risks of this scan?
The CTPA does expose your baby to a low dose of ionising radiation (x-rays) but it is lower than other tests that also look for PE.
The CTPA also scan gives a slightly higher dose of ionising radiation to your breasts. While you are pregnant or breast feeding, the breast tissue is growing or producing milk making the cells more susceptible to damage from radiation.
Studies suggest that the use of a CTPA scan whilst pregnant or breast feeding increases the risk of developing breast cancer by a small amount. Breast cancer is the most common cancer affecting women in the UK and 1:8 women will be affected by breast cancer during their lifetime.
The radiation is from the X-rays not the contrast.
The dose of radiation that you will receive is similar to the natural radiation dose from living in a city for 15 months, as background radiation occurs all around us.
You can have this test if you are breastfeeding.
In some cases, we may also do an ultrasound scan of your heart called an ECHO (Echocardiogram), the same way that we scan your baby.
Treatment of a blood clot
The treatment for a blood clot involves blood thinning medication. Whilst you are pregnant this is given in the form of an injection called low molecular weight heparin (LMWH). In our trust we use Enoxaparin (Clexane). This is given as an injection twice a day for a length of time.
They are safe to take in pregnancy as the molecule is too big to cross the placenta and affect the baby. It is important to determine if a blood clot is present before starting LMWH. With all blood thinning medications there is an increased of bleeding when these medications are used for any length of time.
There are other medical conditions that can present in a similar way to PE so it is important that we do the correct tests to look for a PE, so that if it is not a PE then we can give you the correct treatment.
