Platelets are the components of blood that are the first on the scene when you cut your finger, lodging themselves in the microscopic openings of blood vessels giving the other clotting proteins a place to attach and stop your bleeding. A normal platelet count is between 150,000-450,000. Platelet counts are routinely checked 3 times during pregnancy: with your initial blood work, glucose test, and at delivery.
Low platelets can occur in up to 7% of pregnancies, but rarely are the platelets low enough to result in bleeding (<20,000). The three most common causes of low platelets in pregnancy are ITP, Pre-eclampsia and Gestational Thrombocytopenia.
ITP (Immune Thrombocytopenia) is a chronic medical condition (one that the patient has before pregnancy) characterized by the immune system attacking the body’s platelets. A woman would likely already be diagnosed with ITP before pregnancy, but if not it would be discovered with her initial pregnancy blood work. ITP usually occurs after a viral infection in childhood and continues into adulthood. It is treated with steroids if the platelet count drops below 50,000. Platelet transfusions do not work well with ITP, because the body will attack the foreign platelets as well. There is a 10% chance of the baby having low platelets, so a cesarean section is often recommended in cases of ITP.
If associated with high blood pressure and protein in the urine, low platelets can be a sign of a severe form of pre-eclampsia known as HELLP syndrome and is usually seen in the third trimester. HELLP syndrome is usually an indication for immediate delivery of the baby, but it does not have to be by cesarean section. The baby’s platelets are normal with HELLP syndrome. After delivery, mom’s platelets return to the normal range within a couple weeks.
By far the most common cause of low platelets in pregnancy is Gestational Thrombocytopenia, which occurs in 5% of normal pregnancies in the third trimester. These women will have normal platelets on their first blood count in early pregnancy. Sometimes the low platelet count is picked up on a routine blood draw in the third trimester, and other times it is not noted until the patient arrives for delivery. The platelets return to normal shortly after delivery and do not cause any issues with the baby, so a vaginal delivery is recommended.
The main concern with Gestational Thrombocytopenia is that if the platelets drop too low (usually below 100,000) then it is not considered safe to administer an epidural. The overall risk associated with epidurals is extremely low, but the most serious complication that can occur is bleeding in the epidural space which can lead to permanent paralysis and injury. Since platelets are involved in stopping bleeding at the earliest stage, most anesthesiologists do not feel it’s safe to administer an epidural if the platelets are too low (the exact platelet count cut off varies by hospital). Also if you require a cesarean section, general anesthesia will be used instead of spinal anesthesia.
When a woman arrives in labor anxiously awaiting her epidural, only to discover that no relief is in sight due to an unforeseen issue of low platelets, drama can ensue. This does not happen very commonly, but when it does, it can be a quite unpleasant conversation.
Low platelets are a common complication of pregnancy that rarely causes any permanent issues. However, it is always good to be mentally prepared for the possibility than an epidural might not be an option if your platelets are too low.
Have you had a natural childbirth even though you were planning on epidural?