This pathophysiology diagram illustrates the two primary mechanisms of red blood cell (RBC) destruction in Autoimmune Hemolytic Anemia (AIHA). The top section depicts Warm AIHA (wAIHA), characterized by IgG autoantibodies. These monomeric antibodies weakly activate the complement system and do not cause spontaneous RBC agglutination; instead, agglutination occurs only with an anti-IgG reagent, resulting in a positive Direct Antiglobulin Test (DAT + IgG). This pathway leads to extravascular hemolysis via phagocytosis of IgG-opsonized RBCs primarily in the spleen. The bottom section depicts Cold Agglutinin Disease (CAD), mediated by pentameric IgM autoantibodies. These antibodies cause spontaneous RBC agglutination and strongly activate the complement cascade. The diagram shows the binding of C3, C5, and the formation of the Membrane Attack Complex (MAC), leading to intravascular hemolysis. Additionally, it highlights extravascular hemolysis occurring via phagocytosis of C3b-opsonized RBCs in the liver, with a positive Direct Antiglobulin Test for complement (DAT + C). Key anatomical landmarks include the spleen for IgG-mediated clearance and the liver for C3b-mediated clearance.

Summary : This image shows two process steps related to allergy management in the context of DAT (Direct Antiglobulin Test) administration, each presented as a separate node with directional connectors. flowchart: Nodes : • "Perform allergy testing, and (if necessary) desensitisation before DAT is given" (text node) • "Give DAT and manage subsequent allergy and reactions as they arise*" (text node) Connectors : • Each node has a diagonal arrow pointing away from it, suggesting a sequence or branching, but the destination of the arrows is not visible in the crop. Layout : • Two horizontally aligned nodes, each with an outgoing diagonal arrow. Analysis : • The diagram outlines two alternative or sequential steps in allergy management for DAT: pre-administration testing/desensitisation, and post-administration management of allergic reactions. The arrows indicate process flow, but the next steps are not shown in this crop.

This diagnostic clinical image displays a close-up, grayscale view of the bottom portion of a laboratory test tube containing a liquid sample. The image illustrates a state of incomplete dissolution or insolubility, characterized by clear stratification of the contents. A distinct, highly opaque, and dark region is concentrated at the base of the tube, indicating the presence of a heavy precipitate or sedimented particulate matter. The upper portion of the liquid appears relatively lighter and less dense, though it remains non-homogeneous. This visual is used in medical laboratory science to teach the identification of insoluble samples, often in the context of hemolysis detection or serum/plasma quality assessment. The educational focus is on recognizing physical properties such as precipitation and density-based layering, which are critical for determining specimen integrity and the suitability of a sample for diagnostic testing.

<table> <tr> <td>Aggregate Evidence Quality</td> <td>C</td> </tr> <tr> <td>Benefits</td> <td>Use of IVIG during escalation of care may reduce hemolysis and thereby stabilize or reduce TSB concentrations, preventing the need for exchange transfusion.</td> </tr> <tr> <td>Risk, harm, and cost</td> <td>The effect of IVIG for immune-mediated hemolytic disease has been understudied with conflicting evidence supporting a reduction in exchange transfusions. Recent investigations using routine single early dose prophylactic IVIG do not demonstrate benefit in reducing the need for exchange transfusion and the routine use of prophylactic IVIG in DAT + neonates should be discouraged. However, targeted dosing may be more effective. Although observational studies suggest that IVIG may be associated with necrotizing enterocolitis, the risk of necrotizing enterocolitis with exchange transfusion is well documented so the benefits of IVIG may outweigh this potential harm when exchange thresholds are approached.</td> </tr> <tr> <td>Benefit-harm assessment</td> <td>The benefits of IVIG are not clear, and there is a small risk of harm. Treatment with IVIG may be more strongly considered if there is a poor response to phototherapy and there is difficulty in obtaining an exchange transfusion.</td> </tr> <tr> <td>Intentional vagueness</td> <td>None</td> </tr> <tr> <td>Role of patient preferences</td> <td>Some families may want to avoid IVIG treatment given limited evidence for its effectiveness, especially for Rh+ infants and the potential risk of necrotizing enterocolitis.</td> </tr> <tr> <td>Exclusions</td> <td>None</td> </tr> <tr> <td>Strength</td> <td>Option</td> </tr> <tr> <td>Key references</td> <td>Technical report and 66–75</td> </tr> </table>