Ms. Wu, whose blood type is O−, requires a blood transfusion. Her family members volunteer to donate blood. Their blood types are as follows: her son, type B−; her husband, type B+; her daughter, type O+. Which family members could safely donate blood to Ms. Wu? Who could not? Explain.

Video transcript

Hi, everyone. Let's take a look at this practice problem together. After her surgery, Miss Cruz suffered significant blood loss which required an urgent blood transfusion. Four of her friends have volunteered to donate their blood. If Miss Cruz has blood type a negative, what blood type among them can be safely donated to her. The answer options are a type A positive B type O negative C type A B negative and D type O positive. Recall. The two things determine blood compatibility, the A bo blood group and the Rh Factor ab blood group types are determined by what surface antigen is present on red blood cells. Rh Factor compatibility is determined by whether Rh Factor antigen is present or absent. If the Rh antigen is present, blood types will have a positive sign and if Rh is absent, the blood types will have a negative sign. Now, our age factor compatibility is easier to assess if both blood types are positive or if both blood types are negative, then that is compatible. But if you have one blood type is positive and one blood type is negative, that would be incompatibility for Miss Cruise. Remember she has type a negative blood. Therefore, she can only safely receive blood from those that are also Rh factor negative. Looking at the answer options, both A and D are blood types that are positive for Rh factor. So they would not be, be compatible with Miss Cruise's blood. So we can eliminate both options A and D. Now determining the A bo blood group compatibility is a bit more complicated on the screen. I am putting up a chart that summarizes the A bo blood groups, what antigens are present and what antibodies are present? Miss Cruise has type a blood. So I'm going to highlight that group type on the chart. So type A blood has surface a antigen present and has antibodies against the bee surface antigen. That means that her blood type will attack any blood type that has the surface antigen. Now we have two answer options left to choose from. Option cab negative blood that is compatible with her Rh factor. However, A B blood remember contains the B surface antigen. So this blood type and Miss Cruise's type A blood are incompatible. So option C cannot be the correct answer. The correct answer is option B type O negative blood has the Rh compatibility. And in addition, it doesn't type O blood does not contain any surface antigens. So it's compatible with type a negative blood. Now, wait a second, you may be thinking but type O blood does have the anti A antibodies So, shouldn't it be incompatible? Well, the answer is that it is still compatible. The donor blood type is o and so it is given in much smaller quantities than the blood that is in the recipient type. A. So there's only a small amount of those anti a antibodies in the type of donor blood and it's not enough to cause damage or cause incompatibility. So the correct answer is type or is, excuse me, the correct answer is option B type O negative. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.