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Aplastic crisis

What is an aplastic crisis?

An aplastic crisis occurs because the bone marrow suddenly no longer makes red blood cells. It is a health problem caused by sickle cell disease.

Bone marrow is the soft, spongy tissue at the center of most of your bones. It constantly makes new red blood cells. These cells go into your blood supply and carry oxygen through the body.

An aplastic crisis is a medical emergency for children with sickle cell disease. Your child needs treatment to avoid serious health problems, including death. Your child needs to make a lot of new red blood cells if they have sickle cell disease.

During an aplastic crisis, the bone marrow stops making red blood cells for a short time. This is called a transient (temporary) aplastic crisis. It normally lasts 7-10 days. Then the bone marrow starts making red blood cells again.

An aplastic crisis is not a problem for most people because healthy red blood cells last 90-120 days. But red blood cells in sickle cell patients only last 7-20 days. If your child stops making red blood cells for a few days, they might develop severe anemia (too few red blood cells).

What causes an aplastic crisis?

A virus usually causes this condition. Parvovirus B19, or "fifth disease," is one of the most common causes. This virus causes the bone marrow to stop making new red blood cells for 7 to 10 days.

Symptoms of aplastic crisis

Your child might have:

  • Fever
  • Cough
  • Fatigue
  • Flu-like symptoms
  • Low energy level
  • Pale skin

They will get worse each day instead of better. Their energy level will be low, and they will look tired and pale.

Diagnosis of aplastic crisis

The care team will take a sample of your child’s blood.

They will do 2 tests: a complete blood count (CBC) and a reticulocyte count.

  • What the CBC tells your child’s doctor: This test shows your child’s hemoglobin level. Hemoglobin is the part of the blood that carries oxygen. People with sickle cell disease have what is called sickle hemoglobin, or hemoglobin S. It does not last as long as normal hemoglobin. So, people with sickle cell disease have too little hemoglobin in their blood. A person with sickle cell disease becomes even more anemic during an aplastic crisis. Hemoglobin levels can be dangerously low during an aplastic crisis.
  • What the reticulocyte count tells your child’s doctor: This test shows how many young red blood cells are in the blood. A reticulocyte is a new red blood cell forming in the bone marrow. Normally, these cells stay in the bone marrow until they become mature red blood cells. Then they leave the bone marrow and move into the bloodstream. A person with sickle cell disease usually has a high reticulocyte count. In an aplastic crisis, the reticulocyte count can go as low as zero.

Knowing your child’s CBC and reticulocyte counts tells the doctor how severe the anemia is. This helps them decide on treatment. The doctor will probably check these counts every day during an aplastic crisis.

When to call the doctor

Call your child’s care team if you think your child is in aplastic crisis.

When to seek emergency care

Take your child to the emergency room right away if they have any of these symptoms:

  • Trouble breathing
  • Won't wake up
  • Looks extremely pale
  • Act extremely tired

Do not wait to talk to your care team if you see these signs. Go to the emergency room or call emergency services by phone if your child has a medical emergency and needs help right away.

What is the treatment for aplastic crisis?

Your child might need a blood transfusion if they have severe anemia. The donated red blood cells will give the body oxygen until the bone marrow starts making new red blood cells again.

Your child will go into isolation during treatment. This means a room away from other patients. This is needed because parvovirus can spread from person to person. It is not dangerous to most people, but it can cause problems for pregnant women and other people with sickle cell disease. People who come into your child’s room must wear a mask and a gown.

Once a child has had parvovirus, they rarely get it again.

Prevent infection

Parvovirus spreads easily. Your doctor should check any other children in your family who have sickle cell disease. Pregnant women should stay away from a child who is having an aplastic crisis. The virus can harm an unborn baby. If a pregnant woman has been near someone who has parvovirus, she should tell her doctor right away.

Other viruses besides parvovirus can cause an aplastic crisis. Children under 15 with sickle cell disease are most likely to get parvovirus and have an aplastic crisis. Your child can’t avoid every virus, but you can do things to lower their chances of getting one.

Follow these steps to keep germs from spreading:

  • Clean your hands often. Use soap and water or an alcohol-based hand sanitizer. Germs on your hands can spread to things you touch.
  • Cover your face if you cough or sneeze. Use your arm or a tissue. Throw the tissue away and clean your hands.
  • Avoid touching your eyes, nose, or mouth if you have flu-like symptoms.
  • Getting the COVID-19 and flu vaccines as often as recommended.

Key Points

  • An aplastic crisis happens when the body does not make enough new red blood cells to replace the ones that are already in the blood. It can be a serious health problem in children with sickle cell disease.
  • A virus usually causes this condition. Parvovirus B19, or "fifth disease," is one of the most common causes.
  • Take your child with sickle cell to the emergency room if they have trouble breathing, won't wake up, look very pale or act very tired.


Reviewed: August 2022