Haematological assessment in non-accidental injury

The most challenging aspect for any clinician assessing a child presenting with bruising or bleeding and possible maltreatment is in deciphering whether the clinical signs are consistent with the stated mechanism. A thorough structured history from the child and relatives including a focused bleeding history is essential so that timely and appropriate investigations may be instigated. First stage investigations should include a full blood count and morphological examination of the blood film, a prothrombin time, activated partial thromboplastin time (aPTT), thrombin time and fibrinogen. First line investigations should include factor VIII and IX assays and a von Willebrand screen, as mild deficiencies may be masked by a normal aPTT. If these are normal or there is a clinical suspicion of a bleeding disorder further second-line tests should include additional factor assays, including factor XIII. If the von Willebrand screen is abnormal, further testing may be needed to further characterize to disease sub-type. The results of PFA-100 testing cannot be relied on to rule out von Willebrand disease or platelet function disorders. Platelet function should be assessed with platelet aggregation and nucleotide release studies in preference to PFA-100. Results must be interpreted in the context of the child's age and by a clinician experienced in paediatric haematology.