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December 2008
Feature Story

A 28-year-old woman delivered a term infant by vaginal delivery. There was little bleeding during delivery, and the patient was discharged 1 day postpartum. At day 3 postpartum, the patient developed extensive vaginal bleeding, with a hemoglobin of 9 g/dL, requiring hospitalization and transfusion. The patient related a similar delayed bleeding episode after a tonsillectomy at the age of 7 years, but no coagulation evaluation had been performed at that time.

At the time of admission, the PT was 10.0 seconds (reference range, 9.9–13.0) and the aPTT was 28.9 seconds (reference range, 24.6–32.8) with a normal platelet count. After the initial coagulation study results were obtained, repeat testing of PT and aPTT was performed, with similar normal results. Further testing showed a normal Clauss fibrinogen of 325 mg/dL (reference range, 200–400), a normal D-dimer of 280 ng/mL fibrinogen equivalent units (FEU) (normal level, <500), and a normal platelet function screen with the PFA-100 (collagen/epinephrine closure time, 175 seconds [normal level, <198] and collagen/adenosine diphosphate [ADP] closure time, 115 seconds [normal level, <118]). These results do not suggest a coagulation protein disorder in the common, intrinsic, or extrinsic pathways, nor do they suggest a fibrinolytic or platelet disorder. For this reason, a qualitative factor XIII urea solubility assay was performed, which was abnormal. Sub­sequent quantitative factor XIII assay sent to a reference laboratory showed a decreased factor XIII activity of 3%, and a diagnosis of factor XIII deficiency was rendered. This case illustrates that significant clinical bleeding can be seen with normal PT and aPTT results in the setting of a factor XIII deficiency because factor XIII is responsible for cross-linking fibrin.