///2012 Abstract Details
2012 Abstract Details2019-08-02T19:38:42-06:00

Recombinant Factor IX for Labor Epidural Placement in a Hemophilia B Carrier.

Abstract Number: T-49
Abstract Type: Case Report/Case Series

Farheen Mirza M.D.1 ; Edward Riley MD2; Alexander Butwick MBBS, FRCA, MS3

Introduction: Women with hemophilia B (HB), an X-linked disorder, are predominantly carriers, with a minority (3%) affected with a bleeding phenotype.[1] Patients with HB may have reduced factor IX (FIX), which potentially increases the risk of bleeding during pregnancy. We describe the use and dosing strategy for recombinant factor IX (rFIX) prior to uncomplicated neuraxial blockade for labor analgesia in a known HB carrier.

Case: A 29 year-old G1P0, a known HB carrier (baseline FIX level=37%), presented with vaginal bleeding to the emergency room at 7 weeks’ gestation. Prior to pregnancy, she had never experienced any signs of bleeding. During pregnancy, the patient had gum bleeding and prolonged bruising. ER labs were:INR=1.0, PT=12.7, PTT=34.6, Hct=39.1 and platelet count=215. The patient was evaluated by hematology and given 5,000 IU of rFIX (Benefix), which was calculated to raise the FIX level ≥90%. After receiving rFIX treatment, patient’s FIX level was 97% and her vaginal bleeding resolved. At 34 weeks, the patient’s FIX level=44%, and repeat rFIX treatment was recommended by hematology prior to induction of labor (IOL) and consideration for regional anesthesia. The calculated dose was based on a dosing algorithm: formula dose (Ukg -1) = [100 x (required rise in Uml-1 of FIX)]. A rFIX dose of 4,000 IU was estimated to increase her 3rd trimester level to 80%, which was deemed safe for regional anesthesia. After admission at 40 weeks for IOL, she was given 4,000 IU rFIX with no allergic reaction. Sixty minutes post-infusion, she received a labor epidural (using a 17 Tuohy needle;19G polyurethane epidural catheter; single attempt). She underwent a spontaneous vaginal delivery (EBL=500 ml), but sustained a second degree vaginal tear that was repaired. Her postpartum course was uncomplicated with no post-partum hemorrhage. She was discharged 42 hours post-rFIX infusion from the labor and delivery unit to the postpartum unit and had an uncomplicated postpartum admission. The patient did not sustain any neurologic deficit post-neuraxial blockade.

Discussion: There is limited data on the use rFIXa for increasing FIX levels prior to regional anesthesia for pregnant women who are HB carriers. Only one prior report describes the use of rFIX prior to neuraxial blockade in a pregnant patient with hemophilia, however no dosing information was provided [2]. Prior to regional anesthesia, FIX levels should be checked in the 3rd trimester for all HB carriers with FIX levels > 50%.[3] Our patient had a baseline FIX level=37%, which was in the mild disease category (5-40%). We closely liaised with hematology experts at our institution to formulate our anesthetic plan for the peripartum period. We advise early consultation, and careful planning for neuraxial anesthesia in pregnant patients who are HB carriers.

Refs:1)Brit J Obstet Gynaecol 1997;104:803-10. 2) Thromb Hemost 2009;101:1104-11. 3)Anesth Analg 2009;109:648-60.

SOAP 2012