You are lying in a hospital bed when your nurse walks into the room carrying a tiny syringe.

Then you hear:

“This is your blood thinner.”

And before you know it, you’re getting a small injection in your abdomen.

For many patients, this comes as a surprise.

You may not have a blood clot. You may never have had a blood clot. You may not take blood thinners at home.

So why are you suddenly getting one now?

In many cases, the answer is prevention.

Being in the Hospital Can Increase Your Risk of Blood Clots

Hospitalization changes how much you move.

You may be recovering from surgery, weak from illness, experiencing pain, attached to medical equipment, or simply spending far more time in bed than you normally would.

When you move less, blood moves more slowly through the veins in your legs.

That slower circulation can contribute to the development of a deep vein thrombosis (DVT)—a blood clot that forms in a deep vein, most commonly in the leg.

If part of that clot breaks away and travels to the lungs, it can cause a pulmonary embolism (PE).

That’s why preventing blood clots is an important part of hospital care.

Why Give a Blood Thinner If I Don’t Have a Clot?

This is where patients sometimes get confused.

A blood thinner can be used to treat an existing blood clot, but smaller preventive doses may also be given to reduce the chance that one develops in the first place.

This is sometimes called DVT prophylaxis or VTE prophylaxis.

You don’t have to remember those terms.

What matters is understanding that the medication may have been ordered because your healthcare team believes your current situation puts you at increased risk for developing a clot.

In other words:

They’re trying to prevent a problem rather than waiting for one to happen.

What Medication Am I Getting?

Two medications commonly used for blood clot prevention in hospitalized patients are heparin and enoxaparin (Lovenox).

They’re usually given as small injections under the skin.

Depending on the medication and your individual situation, you may receive an injection once or several times during the day.

Not every hospitalized patient receives the same medication or dose.

Your healthcare team considers things such as your medical condition, mobility, surgery, kidney function, bleeding risk, other medications, and personal history when deciding what’s appropriate for you.

Why Does the Shot Go in My Stomach?

These medications are given into the fatty tissue just beneath the skin rather than deeply into a muscle.

The abdomen is a common place to give them because it usually provides an accessible area of subcutaneous tissue.

The needle itself is quite small.

But that doesn’t mean you won’t feel it.

Some injections sting.

And yes, they can leave bruises.

If you’ve been in the hospital for several days, you may end up with a collection of little bruises across your abdomen.

Your nurse will generally rotate injection sites rather than repeatedly using exactly the same spot.

What About Bruising?

Some bruising around an injection site can occur with these medications.

After all, the purpose of an anticoagulant is to reduce the blood’s ability to clot.

But that doesn’t mean all bleeding or bruising should automatically be ignored.

Tell your nurse if you notice unusual or significant bleeding, rapidly increasing bruising, blood in your urine or stool, prolonged bleeding from another site, or anything else that concerns you.

Your healthcare team needs to know about changes that could suggest you’re bleeding more than expected.

Can I Refuse the Injection?

As a patient, you can ask questions about any medication being offered to you.

And you should.

Before refusing something because you don’t understand why you’re receiving it, ask:

“Why was this ordered for me?”

You can also ask:

“What is my risk of developing a blood clot?”

“What are the risks of this medication?”

“Are there other ways we’re preventing blood clots?”

There may be a good reason the medication was ordered, and there may also be a reason it isn’t appropriate for a particular patient.

The important part is making an informed decision rather than simply assuming you don’t need it because you’ve never had a blood clot before.

The Shot Is Only Part of the Plan

Blood thinner injections are often just one part of preventing clots during a hospital stay.

You may also have Sequential Compression Devices (SCDs) wrapped around your legs.

You may wear compression stockings.

Your nurse or physical therapist may encourage you to get out of bed and walk.

And if you’re unable to walk yet, you may be encouraged to move your feet and ankles while you’re in bed.

Each approach works a little differently, but the goal is the same:

Keep blood moving and reduce the chance of a clot developing while your body recovers.

Will I Need Blood Thinners When I Go Home?

Some patients do. Many don’t.

It depends on why you were hospitalized, the type of surgery or treatment you had, your mobility, and your individual risk factors.

If anticoagulation is supposed to continue after discharge, make sure you understand exactly what medication you’re taking, how and when to take it, how long you’ll need it, and what signs of bleeding should prompt a call to your healthcare provider.

Never assume the injections automatically stop—or automatically continue—just because you’re leaving the hospital.

A Nurse’s Perspective

I’ve given a lot of these little injections over the years.

And I’ve heard some version of this many times:

“I don’t have a blood clot. Why do I need a blood thinner?”

It’s a reasonable question.

Hospital care can sometimes feel as though people are constantly doing things to you without anyone stopping long enough to explain why.

But this little injection is a good example of something happening quietly in the background.

We’re not waiting for a blood clot to appear.

We’re trying to prevent one.

The injection, the SCD sleeves, the ankle exercises, and that walk down the hallway may seem like completely separate parts of your day.

They’re not.

They’re different pieces of the same prevention plan.

And sometimes one of the most important things we do for patients is prevent the complication they never knew they were at risk for.