In 2021 we learned that there was ongoing variability in pediatric ECMO anticoagulation practices across the United States (2, 3). We also read that laboratory studies used to assess coagulation during ECMO correlated poorly with each other and with hematological complications (4, 5). Then, in 2022, general evidence about bleeding during ECMO was summarized in the Transfusion and Anemia EXpertise Initiative-Control/avoidance of Bleeding (TAXI-CAB) practice recommendations and expert consensus (6).Currently, in this issue of PCCM, investigators at the Murdoch Children's Research Institute in Australia describe their prospective study of coagulation in 25 infants and children who were supported by venoarterial-ECMO. In this unique report, we read about serial von Willebrand Factor (VWF) assay measurements-daily during the first 5 days of support, and alternate days thereafter (1). The accompanying editorial explores the meaning of these data in relation to bleeding risk (7). Like a previous editorial entitled "Anticoagulation in extracorporeal membrane oxygenation: a dilemma wrapped in an enigma" (5) the new editorial poses another question for PCCM readers: "VWF: the canary in the ECMO hemostasis coal mine?" In fact, the editorialist challenges the ECMO research community to consider a broader hematology landscape that includes ADAMTS13 (A Disintegrin And Metalloproteinase with ThromboSpondin type 1 motif, member 13) measurements, besides VWF, in order to better understand the complex interactions in coagulation factors that complicate hemostasis during ECMO (7). I recommend all this PCCM reading material (1−7).