When to transfuse? study tests best blood strategy for heart patients after surgery

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Males and females older than 18 years of age who have postoperative Hb \< 10gm/dl within 15 days after the index operation * Patients who undergo an operation in either one of the three following categories: * Veterans who undergo PAD - related operations including but not limited to the following: * aortobifemoral or aortobiiliac bypass * open abdominal aortic aneurysm repair with simultaneous repair of aortoiliac occlusive disease * visceral bypass * iliofemoral bypass * femoral bypass or endarterectomy * infrainguinal bypass * thromboembolectomy * supra-aortic trunk bypass or endarterectomy * carotid endarterectomy * major lower extremity amputations (transfemoral, through the knee, or transtibial) * Veterans with past medical history of ischemic stroke or IHD or PAD who undergo the following general surgery procedures, defined as: * known prior MI * ECG findings consistent with prior MI * prior percutaneous coronary intervention * prior coronary artery bypass surgery * history of angina for which the patient is currently receiving treatment * stress test indicating myocardial ischemia * who undergo the following General Surgery operations: * Open cholecystectomy or other complex biliary reconstruction * such as open common bile duct exploration for stones * reconstruction as part of oncologic operations such as palliative pancreatic cancer procedures) * small bowel resection * pancreatectomy * colon resection * rectal resection * splenectomy * transhiatal esophagectomy * liver resection * gastric resection * open ventral hernia repair * Colostomies (reversals and takedowns) * Intestinal anastomosis takedowns and revisions * Gastric bypass * Adrenalectomies * Major diaphragmatic hiatal hernia repairs * Veterans with past medical history of ischemic stroke or IHD or PAD who undergo the following Vascular Surgery operations: * Open aneurysm repair, including but not limited to: * carotid * subclavian * abdominal aortic * iliac * femoral * popliteal aneurysms * and complex endovascular aneurysm repair, defined as: * fenestrated endograft * or endograft with need for iliac conduit * or endovascular aneurysm repair with simultaneous femoral artery reconstruction or bypass * Subclavian/vertebral bypasses and transpositions * Patients undergoing the above procedures will be included in the study regardless of their preoperative Hb level, and regardless of preoperative or intraoperative transfusion they might have received. Exclusion Criteria: * Veteran unable to consent * Veteran unwilling to follow protocol (such as Jehovah's witnesses) * Veteran with known history of hereditary anemias such as Thalassemia or Sickle cell disease * Veteran with known history of hereditary bleeding disorders, such as factor VIII or factor IX deficiency * Veteran with prior history of adverse reaction to blood administration, such as fever, rash, or hemolysis * Veteran does not speak or understand English * Veteran hemodynamically unstable or in cardiogenic shock for \>48 hours after the index procedure * Veteran participating in another interventional trial whose objective is to evaluate the effect of transfusion on outcomes * Pregnancy in female Veterans * Veteran is a prisoner or in custody of law enforcement * Prior randomization in the CSP#599 * Patients who are known to have tested positive for COVID-19 and have not recovered prior to consent will not be consented. Any participant who is known to have a positive COVID-19 test during the screening process and has not recovered will be excluded prior to randomization.