1. The act of pouring from one container into another one; hence, transference, or the transmission of something: Frank tipped the pitcher of lemonade in order to complete the transfusion of the drink from the container to his glass.
2. In medicine, the transfer of a body fluid from one person, or animal, to the veins of another person, or animal: A transfusion involves the injection of blood or a blood component into the bloodstream.

The transfusion of large volumes of life-saving liquid into the bloodstream is also done primarily to remedy someone who has bled severely after an accident or has lost a lot of blood during surgery.

During a transfusion, the patient's pulse, blood pressure, and temperature are measured regularly and, if there are any signs of bad reactions, the transfusion is discontinued.

A procedure for collecting and storing a patient's own blood several weeks before its expected need by the patient: This method of providing blood, or autologous transfusion, for an individual is done in order to prevent the transmission of diseases which can take place with the use of donor blood.

Blood that is lost during a surgical procedure can be recovered from the operation site and processed for the circulatory system when a patient's autologous transfusion is available.

A transfer of vital bodily fluid that is obtained from a dead body within a short time after a person's death: Cadaver blood transfusion is acceptable for movement into other living humans.

The movement of blood directly from one person to another one: Direct transfusion is the medical process of a person’s vital body fluid being given straight from the donor to the recipient by using an interconnecting hollow tube.

The transfer and withdrawal of small amounts of blood that is repeated until the blood volume is almost entirely exchanged: "Exchange transfusions are used for infants who are born with hemolytic disease (the abnormal breakdown of red blood cells) and in patients with uremia (a form of blood poisoning caused by the accumulation in the blood of products that are normally eliminated in the urine)."

A rare condition that occurs only in identical twins while the babies are still in the womb and involves the transfer of blood from one twin to the other one.

A transfusion of blood from a donor to a suitable storage container and then to the patient.

A condition consisting of fever, splenomegaly, atypical lymphocytes, abnormal liver function tests, and occasionally a skin rash that develops following a blood transfusion or perfusion of a organ during surgery.

One of a variety of reactions that can occur as a result of blood transfusions.

The most serious is the response of the recipient when incompatible blood is administered, in which case massive intravascular (occurring within blood vessels) clumping and lysis (destruction) of red blood cells occur.

1. Twin-to-twin transfusion syndrome (TTTS) is the result of an intrauterine blood transfusion from one twin to another twin.

TTTS occurs in monochorionic, monozygotic twins. The donor twin is often smaller and anemic at birth. The recipient twin is usually larger and plethoric at birth.

2. Also known as Feto-Fetal Transfusion Syndrome (FFTS) and Twin Oligohydramnios-Polyhydramnios Sequence (TOPS) is a complication with high morbidity and mortality that can affect identical twins or higher multiple pregnancies where two or more fetuses share a common (monochorionic) placenta.

In twin-to-twin transfusion syndrome, the twins share not only the same placenta but some of the same blood circulation; in other words, they essentially share a single blood supply. This allows the transfusion of blood from one twin (the donor) to the other (the recipient).

The donor twin becomes small and anemic, and the recipient twin becomes large and overloaded with blood.

The transfusion causes the donor twin to have decreased blood volume, retarding the donor's development and growth, and also decreased urinary output, leading to a lower than normal level of amniotic fluid (becoming oligohydramnios).

The blood volume of the recipient is increased, which can strain the donor's heart and eventually lead to heart failure, and also higher than normal urinary output, which can lead to excess amniotic fluid (becoming polyhydramnios).