<unk> 's<unk>  paients traditionally refuse allogenic blood and whole blood products.
This includes:  RBCs, plasma, platelets, white cells) 
HOWEVER, they are able to choose to accept BLOOD COMPONENT FRACTIONS (includes recombinant factor VII, PCC), though this decision may still vary per individual. 
This can make cases of life threatening bleeding difficult to address.  However, multiple options exist to temporize and treat bleeding which are acceptable to<unk> 's<unk>  patients. These include:
Erythropoesis stimulation
Iron supplementation
Oxygen carriers
Whole blood conservation
It is important to note that individual<unk> 's<unk> es may not strictly adhere to this doctrine; up to 49% of<unk> 's<unk>  patients in one study would be willing to accept blood products in certain circumstances.  It's worth carefully discussing the risks/benefits with the patient (without visitors present), especially if the need is truly critical.
Severe anemia in Jehovah's Witness patients
Asplenic patient
Multisystem inflammatory syndrome in children
Bacteremia vs contaminated blood cultures
Healthcare occupational exposure to blood or other body fluids
Seizures in patients with HIV-AIDS
The obese patient
Urethritis in men