Hemorrhage is a feared and potentially life-threatening complication following cardiac catheterization and coronary angiography. This may reflect retroperitoneal hemorrhage, pericardial bleeding including cardiac tamponade, gastrointestinal, intracranial, or hemolysis. It is important post-procedure to monitor for overt bleeding, hemodynamic changes, symptomatic anemia, and hemoglobin drops. However, a hemoglobin drop does not always reflect clinically significant hemorrhage, or possibly any hemorrhage at all.

A hemoglobin drop without evidence of hemorrhage may reflect the preprocedural preparations or procedural techniques. Patients that have been NPO prior to the procedure may start out relatively hypovolemic and hemoconcentrated. Additionally, some institutions aggressively hydrate their catheterization patients prior to diagnostic and interventional procedures to counter the effects of sedative/vasodilatory medications and renal protection for contrast induced nephropathy. Nitrate medications used during the procedure can cause vasodilation, which expands the vascular space. These combined effects may lead to a post-procedural dilutional change in the hemoglobin that does not represent any true hemorrhage (BARC 0, see table below)

During the procedure itself, there are plenty of opportunities for blood loss. Blood draws for frequent ACT checks including the blood waste from the manifold (20 mL) prior to the ACT blood draw. There is also blood loss from the arteriotomy, catheter flushing/leakage. This is true blood loss which is often not tracked well, may or not but can exaggerate