Laboratory Studies

CBC count

The platelet count is frequently less than 50 X 10⁹/L ( 15-30 X 10⁹/L.) Platelet morphology looks normal on blood smear examination. Large platelets are not a feature. Eosinophilia is observed in 50% of patients.

Leukocytosis may be present, with a WBC count >35 X 10⁹/L with a left shift and picture of leukemoid reaction.

Anemia may be present secondary to bleeding.

Genetic findings

Chromosomes are normal. Findings on chromosomal breakage studies with clastogenic agents are normal.

Imaging Studies

Characteristic skeletal involvement (ie, absent radii) is detectable during prenatal transvaginal ultrasonography as early as 13 weeks' gestation, when sufficient fetal skeletal ossification is present.

Upper-limb abnormalities on prenatal sonograms suggest numerous syndromes in the differential diagnosis.

After radial aplasia is observed, ultrasonography of the extremities, face, and kidneys is indicated.

Other Tests

Sampling of the bone marrow (which is not required to make the diagnosis) reveals the following findings:

Normal or hypercellular bone marrow
Decreased, absent, or immature megakaryocytes
Small, basophilic, vacuolated megakaryocytes
Erythroid hyperplasia

Procedures

Cordocentesis can be performed to confirm known genetic conditions. Cordocentesis poses a 1-2% risk of fetal loss and a risk of prolonged bleeding from the umbilical puncture site.

Weinblatt and associates performed in utero platelet transfusion of a fetus with radial aplasia at 37 weeks' gestation after cordocentesis revealed a platelet count of 40 X 10⁹/L.^[22]The infant was delivered within 24 hours of the transfusion with no complications.

Treatment & Management

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Media Gallery

Infant with thrombocytopenia-absent radius syndrome. The arms and forearms are shortened, with radial deviation of both hands because of the absence of bilateral radii. The legs are normal. See also Media files 2 and 3.
Same infant as in Media files 1 and 3. Close-up photograph of arm and forearm (volar aspect). Note the petechiae.
Same infant as in Media files 1 and 2. Close-up photograph of arm and forearm (dorsal aspect).

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Author

John K Wu, MBBS, MSc, FRCPC Clinical Professor, Department of Pediatrics, Division of Hematology-Oncology-BMT, University of British Columbia Faculty of Medicine, British Columbia Children's Hospital, Canada

John K Wu, MBBS, MSc, FRCPC is a member of the following medical societies: American Society of Hematology, International Society on Thrombosis and Haemostasis, Canadian Medical Association

Disclosure: Nothing to disclose.

Coauthor(s)

Christopher Wu, MD Resident Physician, Department of Urology, McMaster University School of Medicine, Canada

Christopher Wu, MD is a member of the following medical societies: American Urological Association, Canadian Urological Association

Disclosure: Nothing to disclose.

Michelle P Wong, MD Staff Physician, Department of Hematopathology, University of British Columbia Faculty of Medicine, Canada

Disclosure: Nothing to disclose.

Suzan Williams, MD, MSc, FRCPC Staff Physician, Division of Hematology, The Hospital for Sick Children, Canada

Suzan Williams, MD, MSc, FRCPC is a member of the following medical societies: American Academy of Pediatrics, American Society of Hematology, Canadian Medical Association, Royal College of Physicians and Surgeons of Canada, Canadian Paediatric Society, College of Physicians and Surgeons of Ontario, Ontario Medical Association

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

James L Harper, MD Associate Professor, Department of Pediatrics, Division of Hematology/Oncology and Bone Marrow Transplantation, Associate Chairman for Education, Department of Pediatrics, University of Nebraska Medical Center; Associate Clinical Professor, Department of Pediatrics, Creighton University School of Medicine; Director, Continuing Medical Education, Children's Memorial Hospital; Pediatric Director, Nebraska Regional Hemophilia Treatment Center

James L Harper, MD is a member of the following medical societies: American Society of Pediatric Hematology/Oncology, American Federation for Clinical Research, Council on Medical Student Education in Pediatrics, Hemophilia and Thrombosis Research Society, American Academy of Pediatrics, American Association for Cancer Research, American Society of Hematology

Disclosure: Nothing to disclose.

Chief Editor

Hassan M Yaish, MD Medical Director, Intermountain Hemophilia and Thrombophilia Treatment Center; Professor of Pediatrics, University of Utah School of Medicine; Director of Hematology, Pediatric Hematologist/Oncologist, Department of Pediatrics, Primary Children's Medical Center

Hassan M Yaish, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, American Society of Hematology, American Society of Pediatric Hematology/Oncology, Michigan State Medical Society, New York Academy of Sciences

Disclosure: Nothing to disclose.

Additional Contributors

J Martin Johnston, MD Associate Professor of Pediatrics, Mercer University School of Medicine; Director of Hematology/Oncology, The Children's Hospital at Memorial University Medical Center; Consulting Oncologist/Hematologist, St Damien's Pediatric Hospital

J Martin Johnston, MD is a member of the following medical societies: American Academy of Pediatrics, American Society of Pediatric Hematology/Oncology, International Society of Paediatric Oncology

Disclosure: Nothing to disclose.