Final answer:
Type O negative blood is transfused in critical emergencies due to its universal donor status, lacking A/B antigens and Rh factor. Visible agglutination in both wells during blood type testing indicates a normal response for blood type AB.
Step-by-step explanation:
The type of blood transfused in a critical emergency where there is no time to determine the patient's blood type is type O negative blood. This blood type is known as the universal donor because it does not contain A or B antigens on the surface of the red cells, and it has Rh-negative status which is compatible with any recipient's blood. Therefore, it is the safest choice to transfuse in an emergency when the patient's blood type is unknown.
In the scenario of a lab technician testing a patient's blood for their blood type and observing agglutination in both the anti-A and anti-B serum wells, this indicates a normal response for blood type AB. Patients with blood type AB have both A and B antigens on the surface of their red blood cells, which is why the blood will agglutinate in the presence of anti-A or anti-B antibodies.