What is Thrombocytopenia in Pregnancy?
Thrombocytopenia is a condition where the number of platelets (cells that help blood clot) in the blood is below 150 x 109/L. It’s the second most common blood-related abnormality during pregnancy. The International Working Group sets a lower limit for platelets at 100 x 109/L to define immune thrombocytopenia, a condition observed in fewer than 1% of all pregnancies.
This drop in platelets can result from pregnancy-related issues such as gestational thrombocytopenia (a condition that reduces platelets during pregnancy) or pre-eclampsia/eclampsia (conditions known to raise blood pressure in pregnant women). It can also be secondary to other whole-body disorders.
The treatment for thrombocytopenia depends on which trimester of pregnancy the condition starts to develop and the cause behind it. Understanding these two factors helps guide treatment. While thrombocytopenia is a common pregnancy abnormality, it rarely causes life-threatening issues by itself. Instead, the treatment primarily focuses on addressing the root cause. It’s rare for patients to need a platelet transfusion unless there’s bleeding happening.
Local hospital rules guide how many platelets they aim to have in the blood, and this can vary from hospital to hospital. Regardless, it’s important to involve a hematologist (a doctor who specializes in blood conditions) in managing thrombocytopenia during pregnancy. This is especially true when platelet counts drop below 70 x 109/L, or if other bleeding disorders are expected or identified.
What Causes Thrombocytopenia in Pregnancy?
Thrombocytopenia is a condition where there is a lower-than-normal number of blood platelets in the blood. During pregnancy, this can happen for several reasons, and each reason has its own unique characteristics and symptoms. To summarize, the reasons can include:
1. Gestational thrombocytopenia: a decrease in platelets specifically related to pregnancy
2. Immune thrombocytopenia: an autoimmune disorder where the body attacks its own platelets
3. Thrombotic microangiopathy (TMA): a blood condition marked by small clots in the blood vessels, which can be specifically related to pregnancy or not
4. Disseminated intravascular coagulation (DIC): abnormal blood clotting and bleeding simultaneously happening throughout the body
5. Hereditary thrombocytopenia: a genetic disorder causing reduced platelets
6. Other causes like bone marrow failure syndromes (including anemia, leukemia, lymphoma, and others), disorders that are related to blood cell production, and some drug-induced conditions
Interestingly, the cause of thrombocytopenia can often depend on the stage of pregnancy. For instance,
In the first trimester, thrombocytopenia is most commonly caused by immune thrombocytopenia, hereditary thrombocytopenia, and others.
In the second trimester, if platelet count is above a certain level, gestational thrombocytopenia and immune thrombocytopenia are more common causes. If the count drops, the causes could include conditions like pre-eclampsia and HELLP syndrome – both serious pregnancy complications that involve high blood pressure.
In the third trimester, the most common cause for a lowered platelet count is gestational thrombocytopenia. However, if the count drops severely, pre-eclampsia or HELLP syndrome become the most common causes.
Remember that the exact cause can sometimes change depending on the stage of pregnancy and the level of platelets in your blood.
Risk Factors and Frequency for Thrombocytopenia in Pregnancy
Thrombocytopenia, or low platelet count, affects 7-11% of all pregnancies. But, less than 1% of pregnancies see platelet levels dropping below 100 x 109/L. This condition makes it the second most common blood abnormality in pregnancy, after anemia. The leading cause of low platelets during pregnancy is gestational thrombocytopenia, followed by pre-eclampsia, ITP, and other less frequent conditions accounting for less than 1% of cases. Though rare, these less common causes are serious and can lead to significant health risks for the mother.
- Gestational thrombocytopenia, the primary reason for low platelets, is found in about 75% of pregnancies presenting with thrombocytopenia. It’s especially prevalent in the third trimester.
- ITP is the most common cause of low platelets in the first trimester. It affects 1 to 4% of all pregnancies and 1 to 2 per 1000 pregnancies yearly. Roughly two-thirds of women are diagnosed with ITP before pregnancy.
- Pre-eclampsia affects 2% to 8% of all pregnancies globally and is responsible for 20% of thrombocytopenia cases in pregnancies. It mainly occurs in the second and the third trimester, affecting up to half of the women with pre-eclampsia.
- HELLP syndrome impacts 0.2 to 0.8% of all pregnancies, and it’s often associated with pre-eclampsia. Up to 20% of HELLP cases are identified 24 to 48 hours after delivery, with low platelet counts persisting for up to 4 days after delivery.
- Acute fatty liver of pregnancy is a rare cause of thrombocytopenia, affecting roughly 1 in 5000 to 20,000 pregnancies.
- Other conditions like TTP, atypical HUS, DIC, and hereditary thrombocytopenia are among the rarest causes of thrombocytopenia in pregnancy, affecting a minimal fraction of pregnancies.
- Conditions such as bone marrow failure, antiphospholipid antibody syndrome, autoimmune conditions, and type II VWD are also among the rare causes of thrombocytopenia in pregnancy. Less than 1% of patients develop thrombocytopenia because of these ‘other’ causes.
Signs and Symptoms of Thrombocytopenia in Pregnancy
Thrombocytopenia, a condition characterized by low platelet count, can be diagnosed through a careful history and physical exam. It’s important to know that symptoms don’t typically appear unless platelet levels are extremely low, or the patient is exhibiting symptoms of a related disorder. A number of factors aid in pinpointing the cause of thrombocytopenia. These include other diseases the person may have, such as autoimmune disorders or infections, any medications they’re taking, their recent health history, and any high-risk behaviors like smoking or drug use.
- Past medical history of diseases
- History of different medications
- Recent health history
- High-risk behaviors
Further, a detailed family history is crucial in identifying inherited thrombocytopenia, which can sometimes appear for the first time in adulthood.
A physical examination provides additional clues, such as mucocutaneous bleeding, which is commonly associated with low platelet count. Serious bleeding, potential signs of liver enlargement or spleen enlargement, skeletal deformities, and skin issues can also serve as indicators. Diagnosing certain conditions like gestational thrombocytopenia relies on several factors, including its onset in the mid-second to the third trimester, lack of symptoms, and effect on pregnancy. Numerous other factors may clue a doctor in on the underlying issues causing thrombocytopenia.
- Mucocutaneous bleeding
- Potential signs of liver or spleen enlargement
- Skeletal deformities
- Skin issues
For example, preeclampsia can be indicated by severe high blood pressure after 20 weeks of pregnancy, or persistent severe upper stomach pain that doesn’t respond to medication. In more challenging cases, such as distinguishing between AFLP and HELLP syndromes, it’s important to note signs of conditions such as encephalopathy, hypoglycemia, and severe coagulopathy.
Finally, previous exposure to certain medications, like heparin, can point towards specific types of thrombocytopenia such as HIT. Recognizing such specific signs and symptoms can greatly help in accurately diagnosing the underlying cause of thrombocytopenia.
Testing for Thrombocytopenia in Pregnancy
To check if someone has thrombocytopenia, which is a decrease in blood platelets, scientists study a blood sample. Sometimes, the platelets stick together, making it seem like there are fewer platelets than there actually are. This false appearance of low platelet count can happen to up to 1% of pregnant women. This can be corrected by collecting the blood in a different type of tube and counting the platelets manually.
A complete blood count test also helps measure the degree of thrombocytopenia and suggests possible causes. Sometimes the platelet count is low along with changes in red or white blood cells. This pattern helps identify specific causes of the low platelet count.
For instance, if the patient also has anemia, a condition where the blood lacks enough healthy red cells, it could suggest TMA, a group of rare blood disorders characterized by abnormal blood clot formation in small blood vessels. To diagnose TMA, doctors would perform a panel of additional tests. They might also test for TTP and HUS, two types of TMA, or PNH, another rare blood disease.
If the low platelet count is accompanied by unusual bleeding, it’s essential to evaluate the blood’s ability to clot. DIC, a condition that affects the blood’s ability to clot and stop bleeding, is sometimes associated with low platelet count. A system developed by the International Society of Thrombosis and Hemostasis can predict DIC.
Other conditions might be involved if thrombocytopenia is found in isolation. Immune thrombocytopenia usually shows as low platelets with patches of tiny, red spots on the skin (petechiae) or bleeding. Tests for infections like hepatitis B and C, HIV, and Helicobacter Pylori would be conducted, along with assessments of the immune system. Heparin-induced thrombocytopenia (HIT), a reaction to the drug heparin, can also cause thrombocytopenia in pregnancy and can be diagnosed based on clinical presentation and specific tests.
During pregnancy, low platelet count or gestational thrombocytopenia can also be simply due to pregnancy itself. This is usually a diagnosis of exclusion, meaning other causes have been ruled out. It doesn’t usually drop the platelet count to very low levels, so if that happens, other causes should be investigated.
Treatment Options for Thrombocytopenia in Pregnancy
During pregnancy, a condition called thrombocytopenia can occur, which is a lower than normal number of platelets (blood cells that help blood clot) in the blood. Even in severe cases, such as Immune thrombocytopenic purpura (ITP), the risk of bleeding remains low. The way a baby is delivered, either naturally or by caesarean section, does not hinge on this condition, especially as natural births tend to have a lower risk of bleeding. Putting in an epidural for pain relief during labor can be a bit tricky, but the American College of Obstetrics and Gynecology suggests it’s safe if the platelet count is kept above a certain level.
Now, there are different ways to manage thrombocytopenia in pregnant patients, depending on what causes it.
In ‘Gestational Thrombocytopenia’, the platelet count seldom dips significantly and the condition clears up on its own 4 to 8 weeks after delivery. If the count drops below a certain level, though, it might actually be a sign of ITP. Steroids and certain infusions don’t help with gestational thrombocytopenia but might help if ITP is also present. Babies born to mothers with this condition do well and don’t develop thrombocytopenia.
ITP is a complex condition with various treatments for non-pregnant adults. But treatment during pregnancy focuses on limiting risks to mother and baby. Unless the platelet count drops very low, or there’s bleeding, most treatments can wait. If treatment becomes necessary, steroids are generally the first option, although they might lead to side effects like diabetes, weight gain, or high blood pressure. Intravenous infusions can also quickly improve platelet counts for a short period. Other treatments include a drug called rituximab, or in rare, severe cases, even removing the spleen through a minimal invasive surgery during the second and third trimester of pregnancy.
‘Thrombotic Microangiopathy’ or TMA, where blood clots start clogging small vessels, is managed based on its cause. In some cases, the aim is to deliver the baby, in others, to start plasma infusion treatments to restore the balance in the blood. In case of ‘Atypical Hemolytic-Uremic Syndrome’, a subtype of TMA, a certain medication has shown promising results, even though its safety during pregnancy isn’t fully established yet. Disseminated intravascular coagulation, a condition where the body’s clotting abilities are impaired, is managed by targeting the cause and providing supportive care. In severe cases, some might need blood clotting medications or clot inhibitors, depending on whether they’re at risk of excessive bleeding or clot formation.
If pregnant patients receive heparin and develop ‘Heparin-induced Thrombocytopenia’, they shouldn’t take heparin anymore and instead use alternative anticoagulants, for example, direct thrombin inhibitors for immediate management, and a drug named fondaparinux for ongoing treatment is an option for pregnant patients.
What else can Thrombocytopenia in Pregnancy be?
Thrombocytopenia during pregnancy is all about figuring out why the platelet count is low. A variety of diagnoses may be responsible for this issue, as mentioned earlier. It’s key to determine the underlying cause to guide the treatment approach.
What to expect with Thrombocytopenia in Pregnancy
The outlook or prognosis for thrombocytopenia (a condition that results in low platelet count in the blood) depends on its underlying cause. While low platelet count itself doesn’t usually lead to complications in pregnancy, the cause behind it could present significant challenges. The method of childbirth (vaginal birth or c-section) is usually chosen based on the specific situation related to pregnancy.
Gestational thrombocytopenia is when the platelet count decreases during pregnancy. This condition is temporary and generally gets better on its own within 4 to 8 weeks after the baby is born. However, the condition might recur (happen again) in future pregnancies. It’s usually a harmless condition that rarely leads to complications in the mother.
Immune thrombocytopenia, abbreviated as ITP, can potentially cause serious bleeding problems in the mother. ITP in the mother can also affect the newborn and result in neonatal thrombocytopenia (low platelet count in the newborn). In spite of low platelets, the mother’s risk of bleeding is usually quite low. Babies with low platelet count due to their mother’s ITP very rarely (less than 1% of cases) experience severely dangerous bleeding events, such as bleeding inside the skull (intracranial hemorrhage).
Thrombotic microangiopathy, or TMA, includes conditions that specifically arise during pregnancy (like PEC, HELLP syndrome, and AFLP) and those unrelated to pregnancy (like TTP and Atypical HUS). These conditions are linked with high rates of illness and death in both the mother and the newborn. However, low platelet count due to these conditions rarely causes problems in the mother or the newborn. The main treatment goal for these conditions is to safely deliver the baby. Although the recovery of platelet count might be slower than the recovery from delivery, it usually gets better as the underlying cause improves. Other causes of thrombocytopenia (like bone marrow failure syndrome, PNH, etc) should be managed according to their primary cause, and again, the outlook will depend on the underlying cause.
Regarding the newborn’s outcome in women with thrombocytopenia:
1. Babies born to mothers with gestational thrombocytopenia generally have excellent outcomes. They do not develop thrombocytopenia or face any risk of bleeding.
2. Babies born to mothers with ITP may experience a temporary low platelet count. Although the transfer of antibodies from mother to baby may lead to this temporary condition, this theory is not entirely proven. The lowest point of platelets appears within 24 to 48 hours. Reports of severe bleeding events like intracranial hemorrhage appear in less than 1% of babies who develop thrombocytopenia due to their mother’s ITP.
Possible Complications When Diagnosed with Thrombocytopenia in Pregnancy
Low platelet count or thrombocytopenia during pregnancy doesn’t generally cause bleeding. However, some complications can occur due to the reasons which have led to thrombocytopenia. These complications are mentioned in the section discussing management of the condition.
Preventing Thrombocytopenia in Pregnancy
Even though low platelet count, or thrombocytopenia, during pregnancy is usually harmless for most women, it should be carefully examined, particularly if platelet levels fall less than 70 billion per liter. Thrombocytopenia that’s related to pregnancy is typically harmless, and women should be reassured about this. Prompt and suitable treatment for whatever is causing the thrombocytopenia should begin as soon as possible, and correct education should be given to both patients and their families.
Patients should undergo regular monitoring of platelet levels every 2 to 4 weeks to observe any trends in their counts and every 2 weeks when the due date is near. Patients and family need to understand that the delivery method – either normal delivery or cesarean section – will be chosen based on the obstetric need rather than the platelet count. In addition, it’s important to know that platelet transfusions are not regularly used for managing thrombocytopenia during pregnancy. Normally, the delivery will proceed without complications if the platelet count is above 50 billion per liter. For the safe application of epidural anesthesia, however, the goal should be to have a platelet level greater than 80 billion per liter.
If the platelet count falls less than 70 billion per liter or if any bleeding occurs, a hematologist – a specialist in blood disorders – should be consulted to care for pregnant women with thrombocytopenia.
