What To Know About Deep Vein Thrombosis (DVT) in Pregnancy

Health Line

2 days ago

The changes that happen in the body during pregnancy can cause blood clotting, but the risk of deep vein thrombosis (DVT) is low. Symptoms of DVT include swelling, warmth, and pain in a leg.
Deep vein thrombosis (DVT) is a blood clot that develops in a deep vein in the:
DVT is not common during pregnancy, but pregnant people are at least 5 times more likely to develop DVT than people who aren't pregnant, according to the Centers for Disease Control and Prevention (CDC).
Blood-clotting protein levels increase during pregnancy, while anti-clotting protein levels decrease. This helps reduce the amount of blood lost during delivery.
The enlarging uterus during pregnancy may also increase the risk because it puts the veins of the lower body under additional pressure to return blood to the heart.
This article takes a closer look at DVT during pregnancy, including symptoms, risk factors, how it affects the baby, and more.
What are the symptoms of deep vein thrombosis (DVT) in pregnancy?
The most obvious symptom of DVT is swelling and heavy pain or extreme tenderness in one of your legs. Approximately 82% of DVT cases in pregnancy occur in the left leg.
Other symptoms of DVT can include:
pain in the leg when standing or moving around
pain in the leg that worsens when you bend your foot up toward your knee
warm skin in the affected area
visible veins that appear enlarged
discoloration or red skin at the back of the leg, typically below the knee
bluish toes
slight to severe swelling
Around 50% of people with acute DVT may be asymptomatic. It occurs more often in post-op patients, particularly those who have undergone orthopedic surgery.
The chances of having asymptomatic DVT before or after pregnancy are unlikely. But those with multiple risk factors should receive adequate screening for DVT, especially after cesarean delivery.
When should you see a doctor?
See a doctor as soon as possible if you suspect DVT. Diagnosed DVT is not a medical emergency and is unlikely to harm you or your baby unless there are serious complications. It's best to get checked early to begin DVT treatment.
Is it a muscle cramp or a symptom of DVT?
You may experience muscle cramps during pregnancy. They typically affect the calf during the second and third trimesters, particularly at night. Muscle cramps during pregnancy are not a medical emergency.
They can be prevented or relieved with:
stretching and movement
hydration
massages
magnesium supplements
comfortable, supportive footwear
Swelling is a symptom of DVT
Muscle cramps do not cause leg swelling. Unlike muscle cramps, stretching and moving around will not improve pain from DVT.
Pulmonary embolism vs. DVT
A pulmonary embolism (PE) is a blood clot that travels to the lungs. DVT commonly causes it.
PE is rare during pregnancy but more common compared with people who are not pregnant. Symptoms of PE can include:
sudden shortness of breath
chest pain or tightness in the chest
a cough that produces blood-streaked sputum (mucus)
rapid heartbeat
Pulmonary embolism (PE) is a medical emergency
If you or someone you know has PE symptoms such as shortness of breath or chest pain, contact 911 or your local emergency services immediately.
How do doctors diagnose deep vein thrombosis during pregnancy?
It's not always easy to diagnose DVT in pregnancy from symptoms alone. A doctor may order multiple tests to confirm the diagnosis, including:
D-dimer test: This blood test identifies pieces of a blood clot that have broken off into your bloodstream. D-dimer levels above a certain threshold may indicate a higher risk of PE, but doctors typically conduct further testing because levels normally fluctuate during pregnancy.
Doppler ultrasound: This scan determines how fast blood flows through a blood vessel. A Doppler ultrasound helps a healthcare team establish whether blood flow is slowed or blocked, a possible sign that indicates a blood clot.
Venogram: If a D-dimer test and ultrasound cannot confirm a DVT diagnosis, a doctor may use a venogram or magnetic resonance imaging (MRI). A venogram involves injecting a liquid called a contrast dye into a vein in your foot. The dye moves up the leg. The dye shows on an X-ray, which pinpoints a gap in the blood vessel where the clot stops the blood flow.
According to a 2019 review of over 40 studies, a venogram is the 'gold standard' for a DVT diagnosis.
How do doctors treat deep vein thrombosis during pregnancy?
A doctor can form a treatment plan if you develop DVT during pregnancy. They may refer you to a specialist, such as a hematologist (blood specialist) and a maternal medicine or obstetric medicine specialist.
To treat DVT, a doctor may recommend once or twice daily injections of the blood-thinning agent low-molecular-weight heparin. This treatment may help to:
stop the clot from getting bigger
help the clot dissolve in the body
reduce the risk of further clots
You'll likely have regular checkups and blood tests to ensure the clot dissolves and no further clots appear.
A doctor may recommend at-home practices for DVT in addition to medication. These may include daily walks, keeping the affected leg elevated when sitting, and following your prescribed anticoagulant medication schedule.
How does deep vein thrombosis during pregnancy affect the baby?
DVT during pregnancy typically does not affect the baby unless there are serious complications. Doctors and researchers consider heparin safe to use during pregnancy because it doesn't cross the placenta, so there is no risk to your baby.
Depending on your anticoagulation regimen, you must stop taking injections as soon as you begin labor, or at least 12 to 24 hours before inducing labor or a planned cesarean delivery.
If you want to nurse your baby, you will have to stop the injections after birth. For those with a mechanical heart valve, a doctor may prescribe warfarin (Jantoven) to ensure the baby's blood doesn't thin.
This medication carries significant risks for you and your baby, particularly before birth. Fetuses exposed to warfarin may develop congenital disabilities.
Discuss whether the benefits outweigh the risks with a doctor. Together, you may decide not to breastfeed or to stop taking anticoagulants while nursing your baby.
What are other complications of deep vein thrombosis during pregnancy?
Untreated, DVT can have lasting effects on the body.
Long-term DVT can lead to permanent swelling of the veins and fluid retention.
In rare cases, a clot can dislodge and move to the lungs, resulting in a PE.
Another rare complication from DVT is venous gangrene of the toes or fingers.
Irreparable damage to the veins from DVT may result in chronic post-thrombotic syndrome. This is a collection of symptoms associated with leg pain and ulcers.
Finally, taking anticoagulants raises the risk of side effects like bleeding. Report any unusual bleeding, such as nose bleeds, bloody stool/urine, or bruising, to a doctor if you take these medications.
Who's at risk for deep vein thrombosis during pregnancy?
Factors that can increase your risk for DVT during pregnancy include:
having a previous history of clots or DVT
having a family history of DVT
being over 35
having a BMI of 30 or higher
carrying twins or multiple babies
having fertility treatment
having had a previous, recent cesarean delivery
sitting still or being bedridden for long periods
smoking
having preeclampsia
having certain chronic conditions, such as high blood pressure (hypertension) and inflammatory bowel disease (IBD)
having severe varicose veins
Race and DVT risk
Research indicates that DVT and PE occur more frequently in Black Americans than in white Americans. The researchers speculate that this disparity has to do with increased risk factors, such as higher BMI and blood clotting protein levels. The data did not take pregnancy into account.
What can you do prevent deep vein thrombosis during pregnancy?
There isn't a way to definitively prevent DVT in pregnancy. But taking certain steps can help to reduce your risk:
Stay active with pregnancy-safe exercises.
Wear compression socks during air travel and walk around at least once every hour.
Move your legs when sitting down, for example, by raising and lowering your heels and your toes and flexing your ankle.
Wear support hose.
Quit smoking, if you smoke.
See a doctor immediately if you notice any pain, tenderness, redness, or swelling in your legs.
Pregnant people at high risk for DVT may receive a preventive dose of heparin, either during the entire pregnancy or for 6 to 8 weeks postpartum.
What's the outlook for people who develop deep vein thrombosis (DVT) during pregnancy?
While DVT isn't common in pregnancy, it's a serious condition that can be fatal if the clot dislodges and moves into the lungs.
Be aware of the symptoms and risk factors if you are pregnant or at risk for DVT. Let a medical professional know right away if you suspect DVT.
Early treatment and ongoing management can help keep you and your baby safe.