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PubMed This is a summary of 7 peer-reviewed journal articles Updated
Hematology

What is the Pesaro Score for Stem Cell Transplants?

At a Glance

The Pesaro Risk Classification is a grading system used to predict the success and safety of a stem cell transplant for beta-thalassemia major. It scores patients based on liver enlargement, liver scarring, and past chelation therapy to help doctors safely customize pre-transplant treatments.

When evaluating whether a stem cell transplant is a safe and effective option for beta-thalassemia major, doctors often use a grading system called the Pesaro Risk Classification (or Pesaro score). This system helps your care team predict the likelihood of transplant success, survival rates, and the risk of complications based on how much the body—specifically the liver—has been affected by iron overload from regular blood transfusions [1].

While it is normal to feel anxious about any “risk score” involving your child, this tool is actually used proactively to customize their care and make the transplant as safe as possible.

The Three Pesaro Criteria

The Pesaro system evaluates health based on three specific risk factors present before the transplant [1]:

  1. Liver Enlargement (Hepatomegaly): The doctor checks whether the liver is larger than normal. This is typically assessed during a simple physical exam by feeling just below the ribs, or with a painless ultrasound. In thalassemia, the liver can become enlarged due to a buildup of excess iron and because the body sometimes tries to produce blood outside of the bone marrow.
  2. Liver Fibrosis: This refers to the presence of scarring (portal fibrosis) in the liver tissue. Scarring is a sign of long-term damage caused by iron toxicity [2]. Historically, this was checked using a liver biopsy, but today, doctors frequently use non-invasive MRI scans to accurately measure the iron concentration in the liver and heart without needing painful procedures [2].
  3. Quality of Prior Chelation Therapy: Chelation is the daily medication used to remove excess iron from the body. The medical team evaluates the patient’s overall history of taking this medication. Note for parents: This is a clinical measurement of the body’s total iron exposure over several years—it is not a judgment on your parenting. An occasional missed dose does not cause a high risk score. This criterion typically looks at whether chelation was started early in childhood and maintained consistently over the long term.

The Three Risk Classes

Based on how many of the three criteria apply, a patient is placed into one of three risk classes [1]:

  • Class 1 (Low Risk): The patient has none of the three risk factors. Patients in Class 1 generally have the highest survival rates and the best chance of a successful cure (thalassemia-free survival) [3][4]. They face a very low risk of life-threatening complications from the transplant.
  • Class 2 (Intermediate Risk): The patient has one or two of the risk factors. Outcomes remain very favorable, with excellent survival and cure rates, though the risk of transplant-related complications is slightly higher than in Class 1 [3][4].
  • Class 3 (High Risk): The patient has all three risk factors. Historically, Class 3 meant a significantly higher risk for transplant-related mortality (severe complications from the transplant process itself) [5].

What This Means Today

If you or your child is classified as Class 2 or Class 3, it is completely normal to feel worried. However, it is important to know that the original Pesaro system was developed decades ago, and modern transplant medicine has significantly improved.

Today, knowing a patient is in Class 3 allows doctors to customize their treatment to make it safer. For example, the transplant team will often use modified conditioning regimens [5]. Conditioning is the chemotherapy given before the transplant to prepare the body to receive the new stem cells. For high-risk patients, doctors use carefully adjusted, less toxic drug combinations to reduce the strain on the liver and improve survival rates [5][1][6]. Families should still discuss the specific side effects of these modified regimens with their care team.

Additionally, modern risk assessment now goes far beyond the basic Pesaro score. Specialized MRI scans (like T2* MRI) provide precise, objective measurements of tissue iron, giving a much more accurate picture of a patient’s health [2]. Being younger (especially under 7 years old) and receiving care at a hospital that performs a high volume of stem cell transplants also strongly improve the chances of a successful, complication-free outcome [7].

Common questions in this guide

What are the three criteria for the Pesaro score?
The Pesaro classification evaluates three specific risk factors present before a transplant: liver enlargement, the presence of liver scarring or fibrosis, and your overall history of taking chelation therapy to remove excess iron.
What does a Class 3 Pesaro score mean?
A Class 3 score means a patient has all three risk factors. While this indicates a higher historical risk for complications, modern doctors use this score to customize and lower the toxicity of conditioning treatments, making the transplant much safer.
Will my child need a liver biopsy to determine their Pesaro score?
Not necessarily. While liver biopsies were traditionally used to check for scarring, doctors today frequently use non-invasive MRI scans to accurately measure iron concentration in the liver without the need for painful procedures.
How is a stem cell transplant modified for higher-risk patients?
For patients with a higher Pesaro risk score, the transplant team will often use modified conditioning regimens. They carefully adjust the chemotherapy drugs given before the transplant to reduce strain on the liver and improve overall survival chances.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is my child's current Pesaro score, and how many of the three criteria do they meet?
  2. 2.Will my child need a liver biopsy to check for fibrosis, or can we use a specialized MRI scan to measure liver iron?
  3. 3.If my child is in Class 2 or Class 3, exactly how will their conditioning regimen be modified to reduce the risk of complications?
  4. 4.What are the specific side effects of the modified conditioning drugs you plan to use for my child?
  5. 5.How does my child's age factor into your evaluation of their transplant risk?

Questions For You

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Related questions

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References

References (7)
  1. 1

    Hematopoietic Stem Cell Transplantation in Thalassemia.

    Algeri M, Lodi M, Locatelli F

    Hematology/oncology clinics of North America 2023; (37(2)):413-432 doi:10.1016/j.hoc.2022.12.009.

    PMID: 36907612
  2. 2

    Magnetic resonance imaging during management of patients with transfusion-dependent thalassemia: a single-center experience.

    Karakas Z, Yilmaz Y, Bayramoglu Z, et al.

    La Radiologia medica 2018; (123(8)):572-576 doi:10.1007/s11547-018-0889-0.

    PMID: 29663188
  3. 3

    Comparison of Hematopoietic Stem Cell Transplantation Results in Patients with β-Thalassemia Major from Three Different Graft Types.

    Aydogdu S, Toret E, Aksoy BA, et al.

    Hemoglobin 2021; (45(1)):25-29 doi:10.1080/03630269.2021.1872611.

    PMID: 33478286
  4. 4

    Unrelated Donor Transplantation in Children with Thalassemia using Reduced-Intensity Conditioning: The URTH Trial.

    Shenoy S, Walters MC, Ngwube A, et al.

    Biology of blood and marrow transplantation : journal of the American Society for Blood and Marrow Transplantation 2018; (24(6)):1216-1222 doi:10.1016/j.bbmt.2018.01.023.

    PMID: 29374585
  5. 5

    Endothelial Activation and Stress Index-Measured Pretransplantation Predicts Transplantation-Related Mortality in Patients with Thalassemia Major Undergoing Transplantation with Thiotepa, Treosulfan, and Fludarabine Conditioning.

    Kulkarni UP, Pai AA, Kavitha ML, et al.

    Transplantation and cellular therapy 2022; (28(7)):356.e1-356.e6 doi:10.1016/j.jtct.2022.05.001.

    PMID: 35550442
  6. 6

    Optimal Outcomes in Young Class 3 Patients With Thalassemia Undergoing HLA-Identical Sibling Bone Marrow Transplantation.

    Gaziev J, Isgrò A, Sodani P, et al.

    Transplantation 2016; (100(4)):925-32 doi:10.1097/TP.0000000000000928.

    PMID: 26457600
  7. 7

    Thalassemia-free and graft-versus-host-free survival: outcomes of hematopoietic stem cell transplantation for thalassemia major, Turkish experience.

    Yesilipek MA, Uygun V, Kupesiz A, et al.

    Bone marrow transplantation 2022; (57(5)):760-767 doi:10.1038/s41409-022-01613-w.

    PMID: 35210564

This information explains the Pesaro Risk Classification for educational purposes only. Always consult your transplant team for personalized risk assessments, test interpretations, and treatment decisions.

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