Blood & platelet transfusions during treatment — what to expect

Chemotherapy works by targeting rapidly dividing cells — including cancer cells, but also the healthy cells inside the bone marrow that produce blood. As a result, after chemotherapy the bone marrow temporarily cannot make enough red blood cells, platelets, or white blood cells. This period is called the nadir (the lowest point of blood counts). When red blood cell levels fall below a safe threshold, the child may receive a red blood cell transfusion to restore oxygen-carrying capacity. When platelet levels fall too low, a platelet transfusion helps reduce the risk of serious bleeding. These transfusions are a planned, well-understood part of cancer treatment — they are not a sign that treatment is failing.

Red blood cells carry oxygen from the lungs to every organ and tissue in the body. When a child’s red blood cell count drops too low (anaemia), tissues do not receive enough oxygen, causing symptoms such as pallor, fatigue, rapid breathing, and a fast heartbeat. A red blood cell transfusion restores this oxygen supply. Platelets are tiny cell fragments that help blood to clot after an injury or a small bleed inside the body. When the platelet count falls too low (thrombocytopenia), even a minor bump or a small internal bleed may not stop on its own. A platelet transfusion temporarily raises the platelet count to reduce this bleeding risk. The two types of transfusion are given separately, and a child may need one, the other, or both at different points during treatment.

The care team monitors your child’s blood counts through regular blood tests. Many transfusions are given based on the count result alone, before obvious symptoms develop. That said, there are signs you can watch for at home. For low red blood cells: unusual paleness, extreme tiredness, fast or laboured breathing, a racing heartbeat, or your child becoming very weak during normal activity. For low platelets: unexpected bruising, tiny pinpoint red dots on the skin (called petechiae), bleeding gums, nosebleeds that are hard to stop, or blood in the urine or stool. Any of these signs should prompt you to call the oncology team immediately rather than waiting for the next scheduled appointment.

The blood or platelets are given through the same central line or port your child already has for chemotherapy, so there is no extra needle. A red blood cell transfusion typically takes two to four hours. A platelet transfusion is usually faster, often completed within thirty to sixty minutes. The transfusion itself is not painful. The nurse will check your child’s temperature, blood pressure, and heart rate at the start and at intervals throughout, to watch for any early reaction. Most children tolerate transfusions well. Some feel drowsy or cold; a warm blanket usually helps. Serious reactions are uncommon, but the team is trained and prepared to manage them if they arise.

Transfusion reactions can happen, though serious ones are uncommon. The most common reaction is a mild fever or chilling, sometimes with mild discomfort, which the nursing team manages with medication and by temporarily slowing or stopping the transfusion. All blood products used in paediatric cancer care are carefully screened and matched to your child’s blood type. Children who receive many transfusions may over time develop antibodies that make careful matching more important — the blood bank team tracks this and selects products accordingly. If your child has had a reaction before, tell the team before the next transfusion so they can pre-medicate and monitor more closely. The benefits of correcting very low blood counts far outweigh the small risk of a mild reaction.

Not necessarily for the entire course of treatment. The need for transfusions is highest during and just after the most intensive chemotherapy cycles, when the bone marrow is most suppressed. As treatment progresses through lower-intensity phases, blood counts often recover between cycles and transfusions may become less frequent. After treatment ends, the marrow gradually recovers and most children no longer need transfusions. The team will track blood counts at every visit and only recommend a transfusion when the count falls to a level where the benefit clearly outweighs the small inconvenience of the infusion. Your oncologist can give you a more specific picture based on the type and stage of treatment your child is receiving.