Incompatibility with which procedure is an absolute contraindication to allotransplantation?

Allotransplantation is a medical procedure that involves the transplantation of organs or tissues from one individual to another of the same species, and compatibility between the donor and recipient is crucial for the success of the transplantation.

ABO grouping is fundamental for determining blood type compatibility between the donor and recipient. If there is an incompatibility in ABO blood groups, there is a high risk for severe hemolytic reactions following transplant due to pre-existing antibodies in the recipient against the donor's blood group antigens. Such reactions can lead to acute rejection of the transplanted organ, often resulting in serious complications or even death.

While other factors such as Rh factor typing, HLA typing, and crossmatch testing are important for assessing compatibility and minimizing rejection risks, ABO incompatibility stands out as an absolute contraindication because it can lead to immediate and life-threatening immune reactions. Thus, a mismatch in ABO grouping necessitates abstaining from allotransplantation, making it essential for safe and successful procedure planning.