Char Witmer, MD, MSCE

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Char Witmer, MD, MSCE, is the Assistant Director of the Hemostasis and Thrombosis Center at Children’s Hospital of Philadelphia. 

Areas of Expertise: Bleeding and clotting disorders, Sickle cell disease, General hematology

Appointments and Referrals: 1-800-TRY-CHOP (1-800-879-2467)

Education and Training

Medical School

MD - University of Rochester School of Medicine and Dentistry, Rochester, NY


Pediatrics - The Children's Hospital of Philadelphia, Philadelphia, PA


Hematology/Oncology - The Children's Hospital of Philadelphia, Philadelphia, PA

Board Certification

Pediatric Hematology/Oncology
Pediatrics – American Board of Pediatrics

Graduate Degree

MS in Clinical Epidemiology - University of Pennsylvania Center for Clinical Epidemiology and Biostatistics, Philadelphia, PA

Titles and Academic Titles

Assistant Director, Hemostasis and Thrombosis Center

Attending Physician

Clinical Associate Professor of Pediatrics, Perelman School of Medicine at the University of Pennsylvania

Conditions Treated

Departments and Services




McDonnell A, Bride KL, Lim D, Paessler M, Witmer CM, Lambert MP: Utility of the Immature Platelet Fraction in Pediatric Immune Thrombocytopenia: Differentiating from Bone Marrow Failure and Predicting Bleeding Risk. Pediatr Blood Cancer 65(2), Feb 2018 Notes: Epub ahead of print.


Galvez JA, Pappas JM, Ahumada L, Martin JN, Simpao AF, Rehman MA, Witmer C: The use of natural language processing on pediatric diagnostic radiology reports in the electronic health record to identify deep venous thrombosis in children. J Thromb Thrombolysis Aug 2017 Notes: Epub ahead of print.

Witmer CM, Sauck E, Raffini LJ: A Survey of Pediatric Hematologist/Oncologist Regarding the Management of Central Line Associated Venous Thrombosis. Pediatric Blood & Cancer 64, Jul 2017.

Lambert MP, Witmer CM, Kwiatkowski JL: Therapy Induced Iron Deficiency in Children Treated with Eltrombopag for Immune Thrombocytopenia. American Journal of Hematology 92: E88-E91, Jun 2017.


Wong, TE, Nguyen, T, Shah, SS, Brogan, TV, Witmer, CM: Antithrombin concentrate use in pediatric extracorporeal membrane oxygenation (ECMO): a multi-center cohort study. Pediatr Crit Care Med 17: 1170-1178, Dec 2016. PMCID:  27662567

Sood S, James A; Ragni MV, Shapiro A,  Witmer, C, Vega R, Bolgiano D, Konkle B: A Prospective Study of von Willebrand Factor Levels and Bleeding in Pregnant Women with Type 1 von Willebrand Disease. Haemophilia 22: e562-e564, Nov 2016. PMCID: 26206486

Witmer, CM, Lambert, MP, O'Brien, SH, Neunert, C: Multicenter Cohort Study Comparing U.S. Management of Inpatient Pediatric Immune Thrombocytopenia to Current Treatment Guidelines. Pediatr Blood Cancer 63(7): 1227-31, Jul 2016. PMCID: 26929009

Malec LM, Moore CG, Bujnicki HL, Yee DL, Kerlin BA, Witmer CM, Kulkarni R, Gupta S, Gunawardena, S, Kouides PA, Brown D, Bennett CM, Ragni MV: Validation Study of the Composite Score To Identify Von Willebrand Disease in Children. Journal of Pediatric Hematology Oncology 38(2): 139-42, Mar 2016. PMCID: 26535774


Blevins, EM, Glanz, K, Huang, YV, Raffini, L, Shinohara, RT, Witmer, C: A Multicenter Cohort Study of Inferior Vena Cava Filter Use in Children. Pediatric Blood and Cancer 62(12): 2089-2093, Dec 2015.

Antun A, Monahan P, Manco-Johnson M, Callahan M, Young G, Kanin M, Knoll C, Carpenter S, Davis JA, Guerrera M, Kruse-Jarres R, Ragni M, Witmer C, McCracken CE, Kempton CL: Inhibitor Recurrence after Immune Tolerance Induction: a Multicenter Retrospective Cohort Study. J Thromb Haemost 13: 1980-8, Nov 2015. PMCID: 26382916

Witmer, CM: Low Mortality from Intracranial Hemorrhage in Pediatric Patients with Hemophilia.  Haemophilia 21(5): e359-e363, Sept 2015.

McGee, S, Raffini, L, Witmer, C: Organized sports participation and the association with injury in pediatric patients with haemophilia. Haemophilia 21(4): 538-542, July 2015.


Lin K, Kerur B, Witmer C, Beslow L, Licht DJ, Ichord RN, Kaufman BD: Thrombotic Events in Critically Ill Children with Myocarditis. Cardiology in the Young 24(5): 840-7, Oct 2014.

Bruno C, Beslow L, Witmer C, Vossough A, Jordan LC, Zelonis S, Licht DJ, Ichord RN, Smith SE: Hemorrhagic Stroke in Term and Late Preterm Neonates. Archives of Disease in Childhood Fetal and Neonatal Edition 99(1): F48-F53, Jan 2014. PMCID: 23995383


Wong TE, Huang YS, Weiser J, Brogan TV, Shah SS, Witmer CM: Antithrombin Concentrate Use in Children: A Multicenter Cohort Study. The Journal of Pediatrics 163(5): 1329-1334, Nov 2013.


Elden L, Reinders M, Witmer C: Predictors of bleeding disorders in children with epistaxis: value of preoperative tests and clinical screening. International Journal of Pediatric Otorhinolaryngology 76(6): 767-71, Jun 2012.

Puetz J, Witmer C, Huang YS, Raffini L: Widespread use of fresh frozen plasma in US children's hospitals despite limited evidence demonstrating a beneficial effect. The Journal of Pediatrics 160(2): 210-215, Feb 2012.


Witmer CM, Huang YS, Lynch K, Raffini LJ, Shah SS: Off-label recombinant factor VIIa use and thrombosis in children: a multi-center cohort study. The Journal of Pediatrics 158(5): 820-825.e1, May 2011. PMCID: PMC3075379

Witmer C, Presley R, Kulkarni R, Soucie JM, Manno CS, Raffini L: Associations between intracranial haemorrhage and prescribed prophylaxis in a large cohort of haemophilia patients in the United States. British Journal of Haematology 152(2): 211-6, Jan 2011.


Raffini L, Huang YS, Witmer C, Feudtner C: Dramatic increase in venous thromboembolism in children's hospitals in the United States from 2001 to 2007. Pediatrics 124(4): 1001-8, Oct 2009.

Witmer CM, Manno CS, Butler RB, Raffini LJ: The clinical management of hemophilia and head trauma: a survey of current clinical practice among pediatric hematology/oncology physicians. Pediatric Blood & Cancer 53(3): 406-10, Sep 2009.

Witmer CM, Elden L, Butler RB, Manno CS, Raffini LJ: Incidence of bleeding complications in pediatric patients with type 1 von Willebrand disease undergoing adenotonsillar procedures. The Journal of Pediatrics 155(1): 68-72, Jul 2009.


Witmer CM, Raffini LJ, Manno CS: Utility of computed tomography of the head following head trauma in boys with haemophilia. Haemophilia  13(5): 560-6, Sep 2007.

Witmer CM, Steenhoff AP, Shah SS, Raffini LJ: Mycoplasma pneumoniae, splenic infarct, and transient antiphospholipid antibodies: a new association? Pediatrics 119(1): e292-5, Jan 2007.




Jaffray J, Witmer C: Pediatric Venous Thromboembolism  Patient Safety and Quality in Pediatric Hematology/Oncology and Stem Cell Transplantation.  Dandoy CE, Hilden J, Billett AL, Mueller BU (eds.). Springer, 1: 377, 2017.


Giglia, T, Witmer, C: Hematologic Aspects of Pediatric and Adolescent Heart Disease: Bleeding, Clotting and Blood Component Abnormalities. Moss and Adams' Heart Disease In Infants, Children and Adolescents: Including the Fetus and Young Adult. 9th edition. Allen HD, Shaddy RE, Penny DJ, Feltes TF and Cetta F (eds.). Wolters Kluwer, 2016 Notes: Also an author for the 8th Edition.

Blevins E, Witmer C: Hematology  Philadelphia Guide to Inpatient Pediatrics. Shah SS, Zaoutis LB, Catallozzi MC, Frank G (eds.). McGraw Hill Education, Page: 169-188, 2016 Notes: Also participated in the 1st edition release in 2005.


Witmer CM: Bleeding, Disseminated Intravascular Coagulation, Hemophilia, Thrombosis, and von Willebrand Disease. The 5-Minute Pediatric Consult, 7th ed. Cabana MD, Brakeman P, Curran ML, DiMeglio LA, Golden WC, Goldsby RE, Hartman AL, Kind T, Lee CKK, Lightdale JR, Sabella C, Tanel RE (eds.). Wolters Kluwer  Page: 8-9, 304-305, 428-429, 920-921, 992-993, 2015 Notes: Also authored in the 4th, 5th and 6th editions.


Bickert Poon B, Witmer CM and Pruemer J: Coagulation Disorders. Pharmacotherapy: A Pathophysiologic Approach, 9th ed.  DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM  (eds.). McGraw-Hill Education, Page: 1625-1642, 2014 Notes: Also an author in the 7th and 8th Editions.


Witmer C, Gallagher S, Wong C, Litman R: Hematologic Diseases. Basics of Pediatric Anesthesia. Ronald S. Litman (eds.). Ronald S. Litman, Page: 69-76, 2013.

Posters and Presentations


Mamdouhi T, Witmer CM, Ichord R, Billinghurst L: Association Between Thrombophilia and Childhood Arterial Ischemic Stroke Subtype and Clinical Outcome. Oral presentation by Ms. Mamdouhi at the annual Eastern Society of Pediatric Research (ESPR) meeting 2017.

Kamdar AB, Raffini LJ, Witmer CM: Children with CVC-VTE: A very high risk group for recurrent thrombosis. Poster presentation American Society of Hematology Annual Meeting, Abstract #1098 Dec 2017.


Kozyak B, Costarino A, Raffini L, Witmer C, Petrosa W, Glatz A, Giglia T: Low/Medium-dose Systemic Thrombolysis Achieves Resolution of Critical Thrombosis in Pediatric Heart Disease with Acceptable Risk Profile. Poster presentation Pediatric Cardiac Intensive Care Society Annual Meeting  2016.

Invited Lectures


Witmer CM. "Sports in Hemophilia: Keeping It Safe. The Hemophilia Perspective." Mid-Atlantic/Region III Federally-Funded Hemophilia Treatment Centers 2018 Annual Meeting. Alexandria, PA. Apr, 2018.

Witmer CM. "Treatment of Pediatric Venous Thromboembolism." Association of Pediatric Hematology Oncology Nurses Greater Philadelphia Area Chapter Annual Meeting. Radnor, PA. Mar, 2018

Witmer CM. "Disorders in Hemostasis." 2018 Highlights of American Society of Hematology, Asia-Pacific. Bali, Indonesia. Mar, 2018.

Witmer CM. "VTE Prevention in Hospitalized Pediatric Patients." Hematology Seminar, St. Jude Children's Research Hospital. Memphis, TN. Feb, 2018.

Witmer CM. "Disorders in Hemostasis." 2018 Highlights of American Society of Hematology, North America. Washington, DC. Jan, 2018.

Witmer CM. "Disorders in Hemostasis." 2018 Highlights of American Society of Hematology, North America. Chicago, IL. Jan, 2018.


Witmer CM. "Prevention of Venous Thromboembolism in Hospitalized Pediatric Patients." Children's Mercy Hospital and Clinics, Kansas City, MO. Oct, 2017.

Witmer CM. "VTE Prevention in Hospitalized Pediatric Patients."  Children's Mercy Hospitals and Clinics. Hematology Oncology Seminar. Kansas City, MO. Oct, 2017.

Witmer CM. "Venous Thromboembolism in Pediatric Patients." Virtua Voorhees Hospital Pediatric Conference. Voorhees, NJ. Sep, 2017.

Witmer CM. "VTE Prevention in Hospitalized Pediatric Patients." Boston Children's Hospital, Cancer and Blood Disorders Center Special Hemostasis/Thrombosis Seminar. Boston, MA. Jun, 2017.

Witmer CM. "Non-factor Treatments of Bleeding Disorders." Mid-Atlantic/Region III Federally-Funded Hemophilia Treatment Centers 2017 Annual Meeting, Alexandria, VA. Mar, 2017.


Witmer CM. "A Look Into the Crystal Ball: Future Treatments of Inhibitors and Hemophilia." National Hemophilia Foundation Regional Inhibitor Conference. Salt Lake City, UT. Nov, 2016.

Witmer CM. "What are Clinical Trials and Can I Participate?" National Hemophilia Foundation Regional Inhibitor Conference. Salt Lake City, UT. Nov, 2016.

Witmer CM. "Approach to Anemia." 17th Annual Advanced Practitioner Nurse Conference. Philadelphia, PA. May, 2016.

Witmer CM. "New VTE Improvement Strategies." Children's Hospitals' Solutions for Patient Safety National Learning Session. Denver, CO. May, 2016.

Witmer CM. "Pediatric Central Venous Catheter Related Thrombosis: Management." Thrombosis and Hemostasis Society of North America (THSNA) Meeting, Chicago, IL. Apr, 2016.

Witmer CM. "My Path in Clinical Research." North American Society of Thrombosis and Hemostasis (NASTH) Trainee Workshop, Chicago, IL. Apr, 2016.

Awards and Honors

2017, Alan R. Cohen Master Clinician Award, Children's Hospital of Philadelphia
2017, Distinguished Teaching Award for Hematology, Children's Hospital of Philadelphia
2017, Faculty Teaching Honor Roll, Children's Hospital of Philadelphia
2003, Senior Resident Humanitarian Award, The Children's Hospital of Philadelphia
2000, The Janet M. Glasgow Memorial Achievement Citation - American Medical Women's Association
2000, Alpha Omega Alpha, University of Rochester School of Medicine
1996, Phi Beta Kappa, University of Rochester

Editorial and Academic Positions

Editorial Positions

2013-present, Review Editorial Board Member, Frontiers in Obstetric and Pediatric Pharmacology
2007-present, Editorial Advisory Board Member, National Hemophilia Foundation publication HemAware

Ad Hoc Reviewer

2017-present, Research and Practice in Thrombosis and Haemostasis
2016-present, Therapeutic Advances in Drug Safety
2015-present, Pediatric Blood and Cancer
2014-present, British Journal of Haematology
2013-present, Archives of Pathology
2012-present, European Journal of Pediatrics
2012-present, Thrombosis and Haemostasis
2008-present, Journal of Pediatric Hematology/Oncology
2008-present, Pediatric Emergency Care
2008-present, Journal of Pediatrics
2008-present, Blood
2008-present, Thrombosis Research
2008-present, Pediatrics
2008-present, Haemophilia

Academic and Institutional Committees

2017-present, Harm Prevention Line Indicator Alignment Committee, CHOP, Physician Leader
2017-present, Revenue Cycle Committee, CHOP
2016-present, Pediatric Hematology Oncology Fellowship Committee, CHOP
2016-present, Values and Standards Committee, CHOP
2014-present, Venous Thromboembolism (VTE) Steering Committee, CHOP
2013-present, Perelman School of Medicine Medical Student Clinical Research Paper Prize Committee
2013-present, EPIC SUGr (Super Users Group) Initiative, CHOP
2011-present, Alumni Committee, CHOP

Leadership and Memberships

Memberships in Professional Organizations


2005-present, International Society on Thrombosis and Haemostasis


2016-present, American Board of Pediatrics
 - 2016-present, Subboard of Pediatric Hematology-Oncology
2012-present, Centers for Disease Control and Prevention
 - 2012-present, Presentation and Publication Committee
 - 2012-present, Blood Disorders Universal Data Collection Project, Committee Member
2005-present, The American Society of Pediatric Hematology/Oncology
 - 2016-present, Nominating Committee
2005-present, Hemostasis and Thrombosis Research Society
2004-present, American Society of Hematology