Platelet transfusion: how low before you need to transfuse?

Myron Yaster MD, Shawn Jackson MD PhD, Susan Goobie MD, FRCPC

A couple of years ago I was assigned to the oncology center at the hospital I was working in to provide general anesthesia for patients undergoing surveillance bone marrow aspirations and lumbar punctures. One of the patients on my list had a platelet count of < 20 K. I spoke to the nurse practitioners and delayed the case, insisting that the child needed a platelet transfusion to prevent a spinal bleed or hematoma. The nurse said: “nobody else would demand this”. My response was “I don’t know who ‘nobody else’ is and I’m responsible and am certain my colleagues would agree for the need for a platelet transfusion.” About 15 minutes later the board runner called me and told me I was being reassigned to the general ORs and the section leader for oncology would take over my list. Obviously, the case proceeded without a platelet transfusion. What would you do?

Today’s PAAD by Metcalf et al.[1] is an updated clinical practice guideline on platelet transfusion from the Association for the Advancement of Blood and Biotherapies (AABB) and the International Collaboration for Transfusion Medicine Guidelines (ICTMG) based on 34 published studies “aimed to meet the need for updated recommendations for health care professionals and their patients, with practical advice on appropriate use of platelets”[1-3] .” I asked Drs. Shawn Jackson and Susan Goobie who are experts in this area to assist. Myron Yaster MD

Original article

Metcalf RA, Nahirniak S, Guyatt G, Bathla A, White SK, Al-Riyami AZ, Jug RC, La Rocca U, Callum JL, Cohn CS, DeAnda A, DeSimone RA, Dubon A, Estcourt LJ, Filipescu DC, Fung MK, Goel R, Hess AS, Hume HA, Kaufman RM, Kranke P, Louw VJ, Møller MH, Murphy MF, Muszynski JA, O'Kelly CJ, Pagano MB, Patidar GK, Pavenski K, Poston JN, Saifee NH, Stolla M, Szczepiorkowski ZM, Tobian AAR, Uberoi R, Waters J, Williams B, Wood EM, Zantek ND, Zeller MP, Grossman BJ, Stanworth SJ. Platelet Transfusion: 2025 AABB and ICTMG International Clinical Practice Guidelines. JAMA. 2025 May 29. doi: 10.1001/jama.2025.7529. Epub ahead of print. PMID: 40440268.

Platelet transfusions can be life-saving when needed to manage a hemostatic derangement or life threatening when given solely to treat an abnormal number. Platelets have a short half-life (5-7 days), are stored at room temperature (unlike other blood products), and have well known side effects some of which are unique to platelets like febrile non-hemolytic transfusion reactions (fever, chills), allergy, anaphylaxis, and have the highest risk of bacterial contamination among blood products due to their storage conditions which can result in serious infections. Other side effects are common to all blood products are relevant to platelet transfusions, such as transfusion mediated immunomodulation, transfusion associated circulatory overload (TACO) and transfusion-related acute lung injury (TRALI).

Many cancer patients, particularly those with lymphoproliferative diseases present for anesthesia and surgery, and like Myron’s patient have chronic thrombocytopenia. Are prophylactic platelet transfusions necessary in non-bleeding patients for procedures; especially those with a chronic over acutely low number? And if yes, what is a comfortable threshold to determine risk and finally what is platelet count that should trigger a transfusion for a high risk procedure ?

Here’s what the 2025 AABB and ICTMG guidelines now recommend (from Table 3 of the paper):

1. In nonbleeding patients with hypoproliferative thrombocytopenia actively receiving chemotherapy or undergoing allogeneic stem cell transplant (SCT): Transfuse only if platelets <10 × 10³/μL. (The < 10K rule lives on!)

2. Preterm neonates without major bleeding: Platelet transfusion should be administered when the platelet count is <25 × 10³/μL*

3. Patients undergoing lumbar puncture - Hold the platelets: The risk of spinal hematoma is extremely low. Transfuse only if < 20 × 10³/μL. No need to "top off" just in case.

4. Adult patients undergoing central venous catheter (CVC) placement at anatomic sites amenable to manual compression: Platelet transfusion should be administered when the platelet count is <10 × 10³/μL.

5. Adult patients undergoing interventional radiology procedures: Platelet transfusion should be administered when the platelet count is <20 × 10³/μL for low-risk procedures and <50 × 10³/μL for high-risk procedures

6. No routine platelets for surgery: For cardiac surgery patients without thrombocytopenia, or for ICH patients with platelets >100K, even if on antiplatelet meds: Platelets don’t help and may increase risks.

Some final thoughts. Myron’s fear of performing a lumbar puncture in the face of a low platelet count (< 20 × 10³/μL) are still reasonable even though the risks are astonishingly low. Several adult studies have further demonstrated that platelet counts of between 20 and 50 × 10³/ μL do not have a higher incidence of clinically significant post–lumbar puncture complications[4, 5]. Finally, a word of caution in adopting these guidelines as the pediatric and neonatal recommendations were made without any pediatric experts in the guideline review, nor were the most recent pediatric specific transfusion guidelines (TAXI-CAB) referenced[6] in the article. Fortunately, the authors between these two guidelines came to similar conclusions regarding the recommended threshold platelet count of 20 x 10³ / μL to be considered for patients undergoing neuraxial procedures.

*With particular focus on the neonatal guidelines we have asked our expert colleague, Patricia Davenport, MD of our BCH NICU to opine. Here is what she replied:

“With the publication of the PlaNet-2 Trial, we agree that it is essential to implement more restrictive platelet transfusion practices in the NICU, and we have done so in our level IV NICU at Boston Children’s Hospital. However, due to the heterogeneity of the NICU population and nuanced differences in the care between the US and Europe (specifically, the availability of point-of-care bedside head ultrasound to evaluate for new hemorrhage that is not common practice in US NICUs), there are some NICU populations that we have chosen to keep at a higher transfusion threshold of <50,000/mcL, including patients about to undergo a major bedside or surgical procedure and those who are immediately post-operative. It is also important to recognize that while the certainty of the evidence for this guideline was considered high (leading to a strong recommendation), the results of the meta-analysis were largely driven by a single trial. Currently, a second trial focusing on the highest risk population of extremely preterm neonates (23-26 weeks gestation) is underway and two international groups of neonatologists, pediatric transfusion medicine specialists, and pediatric hematologists are starting to work on joint guidelines that will focus exclusively on neonates. While we await the results of the second large platelet transfusion trial in neonates and the consensus statements from these neonatology-focused organizations, we agree that implementation of restrictive neonatal platelet transfusion practices is needed, but it may be too early for a one-size-fits-all approach.”

While expert consensus can guide practice, reduce variability and prevent over transfusion or unnecessary transfusion, large prospective pediatric and neonatal trials are needed to take into consideration not just the platelet count but also platelet function, and the dynamic and individual hemostatic status of the neonate, infant child or adolescent.

Send your thoughts and comments to Myron (myasterster@gmail.com) and he will post in a Friday reader response.

References

1. Metcalf RA, Nahirniak S, Guyatt G, Bathla A, White SK, Al-Riyami AZ, Jug RC, La Rocca U, Callum JL, Cohn CS et al: Platelet Transfusion: 2025 AABB and ICTMG International Clinical Practice Guidelines. Jama 2025.

2. Kaufman RM, Djulbegovic B, Gernsheimer T, Kleinman S, Tinmouth AT, Capocelli KE, Cipolle MD, Cohn CS, Fung MK, Grossman BJ et al: Platelet transfusion: a clinical practice guideline from the AABB. Annals of internal medicine 2015, 162(3):205–213.

3. Nahirniak S, Slichter SJ, Tanael S, Rebulla P, Pavenski K, Vassallo R, Fung M, Duquesnoy R, Saw CL, Stanworth S et al: Guidance on platelet transfusion for patients with hypoproliferative thrombocytopenia. Transfus Med Rev 2015, 29(1):3–13.

4. Chung HH, Morjaria S, Frame J, Riley M, Zhang AW, Martin SC, Bhatia A, Fenelus M, Fallah F, Inumerables F et al: Rethinking the need for a platelet transfusion threshold of 50 × 109/L for lumbar puncture in cancer patients. Transfusion 2020, 60(10):2243–2249.

5. Kozak M, Hallan DR, Stoltzfus M, Rizk E: Lumbar Puncture in Thrombocytopenia: The Floor Is Not Firm. Cureus 2023, 15(7):e42019.

6. Nellis ME, Karam O, Valentine SL, Bateman ST, Remy KE, Lacroix J, Cholette JM, Bembea MM, Russell RT, Steiner ME et al: Executive Summary of Recommendations and Expert Consensus for Plasma and Platelet Transfusion Practice in Critically Ill Children: From the Transfusion and Anemia EXpertise Initiative-Control/Avoidance of Bleeding (TAXI-CAB). Pediatr Crit Care Med 2022, 23(1):34–51.