You’re covering a night shift and are asked to prescribe a blood transfusion for Robbie, a 4-year-old boy with an Hb of 68 and tachycardia post-surgery. You assess him and discuss the decision with a senior clinician, and you decide to transfuse.
Out of habit, you reach for the adult transfusion chart you keep on hand, then realise it won’t contain the information you need.
You don’t know the thresholds for paediatric transfusions or the recommended volume for the child’s age or size.
You know we tend to transfuse children less often than adults. To complicate matters, you must also remind yourself of the nuances of gaining consent for procedures in children and young people.
Blood product transfusion in children may be less common, but it is often lifesaving. For many resident doctors, it’s something we learn on the job and often isn’t covered in medical school.
As a general rule, transfusion is a clinical decision, not a numerical one; i.e., it is situation-dependent and guided by a senior doctor. It is always a good idea to consult a senior paediatrician and/or haematologist when there are special considerations (more on this below).
This blog post acts as a map, and I hope it keeps you from getting lost in transfusion confusion.
The Guideline Landscape
Clinical guidance on paediatric transfusion comes from a few overlapping sources, often depending on the country and region you work in. Below are a few brief resources to signpost, depending on your background:
Trust Guidelines – Your first port of call should be your trust’s intranet for local guidelines. This will inform you of any hospital-specific nuances.
United Kingdom
- NICE NG24 – This is the main general UK guideline, covering assessment and management of transfusion in children aged 1 year and over. It does not provide any condition-specific guidance1.
In February 2026, the guidance was updated to recommend offering tranexamic acid to children with high bleeding risk undergoing surgery, aged 1 to 15 years.
Neonates and infants under 1 year fall outside NG24’s scope. This group is particularly vulnerable due to a small circulating volume and immunological immaturity. Neonatal-specific guidance and local trust protocols set thresholds and practice for this group separately. - Joint UK Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee (JPAC) – JPAC has created a ‘Handbook of Transfusion Medicine’, which has more detailed, paediatric-specific guidance. This includes guidance for transfusion-dependent children with inherited conditions, paediatric cardiac and PICU/NICU patients, and those on chemotherapy2.
- The British Society for Haematology (BSH): BSH offers guidance on clinical indications, blood product selection, and pre-transfusion testing protocols tailored to foetuses, neonates, and children3.
Australia/New Zealand
- National Blood Authority Patient Blood Management Guidelines: Module 6 (Neonatal and Paediatrics) – this guideline is currently being updated, so check for current status before citing4.
- Australian and New Zealand Society of Blood Transfusion (ANZSBT) – ANZSBT have created a very clear guideline on indications, volumes and infusion rates for neonates and children5.
International
- Association for the Advancement of Blood and Biotherapies (AABB) 2023 International RBC Transfusion Guideline: This is based on 45 adult RCTs and 7 paediatric RCTs (2,730 children) comparing restrictive vs liberal thresholds. It explicitly excludes pre-term neonates and outpatient transfusion, and the full text includes a comparison against other international guidelines6.
It is important to consider the underlying causes of anaemia when dealing with a case of low Hb:
When to Transfuse
Indications for transfusion
Let’s reflect on our initial case. Does an Hb of 68 on Robbie’s blood test mean that transfusion is indicated? The answer is, not necessarily. Consider the clinical context.
Generally, there are three clinical scenarios where you may consider transfusing children and young people. These are:
- Acute blood loss: trauma, peri- or post-operative bleeding, or less commonly GI bleeding. The priority is haemodynamic stability, not a specific Hb target.
- Chronic anaemia: haemoglobinopathies (sickle cell disease, thalassaemia), oncology patients on chemotherapy, or chronic kidney disease, where regular transfusion is often planned in advance.
- Perioperative transfusion: particularly cardiac surgery, where reduced physiological reserve means there is a higher risk of intra-operative haemodynamic instability. Again, this requires senior advice and guidance.
General rule: The decision to transfuse is always clinical and not based on a fixed threshold!
A previously well child who has lost blood acutely is transfused based on signs of shock – tachycardia, poor perfusion, altered consciousness, rather than a fixed Hb threshold. Hb can be falsely reassuring in the first hours after acute bleeding before haemodilution catches up (do not take the capillary gas reading as Gospel!).
Thresholds
You go to review Robbie, and he is tachycardic but otherwise clinically well. There are no signs of acute bleeding or haemolysis. You discuss with the consultant on call, who advises you to prescribe a weight-based transfusion.
The decision to transfuse a child is always a clinical decision. Hb thresholds alone do not dictate when transfusion is indicated, as they may in adults. A decision to transfuse should always be made with a senior and will be child- and situation-specific. It is likely to follow a more conservative approach.
For example, a stable, asymptomatic child with an Hb of 60 due to iron deficiency may not be transfused, but rather given iron as their treatment.
A rough illustration: (please always check with current guidelines and trust protocols before using clinically):
Evidence Behind Haemoglobin Thresholds
The restrictive Hb thresholds now considered standard practice have a fairly recent history. The adult Transfusion Requirements in Critical Care (TRICC) trial in 1999 first showed that a restrictive strategy (transfusing at Hb 70g/L rather than higher) was safe in critically ill adults8.
It took until 2007 for the Transfusion Requirements in Paediatric Intensive Care Units (TRIPICU) trial to confirm the same threshold could be safely applied to critically unwell but haemodynamically stable children9. Much of what is now routine paediatric practice is built on a small number of international trials, not decades of accumulated paediatric-specific evidence.
Outside of these landmark trials, paediatric transfusion evidence remains minimal. To date, the TRIPICU trial is the main RCT informing PICU transfusion practice; however, a larger international pilot trial, Pilot Optimising Transfusion Thresholds in Critically ill Children with Anaemia (P-OpTTICCA)10, is currently underway.
Special Considerations
A few groups generally require more considered pathways – it is always a good idea to check with the duty haematologist when the situation is a more complex one:
- Neonates and infants under 1 year: usually considered in a guideline of their own – check local policies for more guidance.
- Children with haemoglobinopathies (sickle cell disease, thalassaemia): often on planned, regular transfusion programmes, sometimes exchange transfusion rather than simple top-up, usually specialist-team-led.
- Haem-Onc patients: thresholds and product requirements (e.g. irradiated products) often differ from general paediatric practice, set by trust-specific protocol.
- Children with religious or family objections to blood products: requires early senior and legal involvement, as above.
Confirming Blood Type
Before any transfusion, confirm the child’s identity and send blood samples to the lab for ABO and RhD typing with an antibody screen. Practice varies between countries, so always check your national and local policies.
For example, in the UK, two valid samples confirming blood grouping are required prior to ordering blood from the lab (e.g. one historic sample and one recent sample). There are varying rules for how long each sample result remains valid for (e.g. if the patient is pregnant or has been recently transfused), therefore it is important to check with your lab.
For any special requirements (e.g. CMV-negative blood) or any uncertainty about the indication for transfusion, it is vital to consult an on-call haematologist/the transfusion lab itself.
Consent for Transfusion
Robbie’s mum is at the bedside. You explain the plan for transfusion and remind yourself of the consenting process for children and young adults, including Gillick Competence guidelines.
DFTB has a great Gillick Competence guideline which can be read here!
Consent for transfusion usually sits with parents or those with parental responsibility, but it is important to know, rather than assume, the practicalities. A few guidelines cover the intricacies of consenting for paediatric procedures, including the UK-based Safety of Blood, Tissues and Organ (SaBTO) guidelines11, and the more international Association for the Advancement of Blood and Biotherapies (AABB) guidelines12.
For older children and adolescents, Gillick competence applies as it does for other medical decisions. This allows a competent young person to consent to transfusion themselves. This is particularly relevant in adolescent oncology or chronic disease settings.
Refusal is the situation juniors find hardest. It is most commonly seen with Jehovah’s Witness families. Most international guidelines are clear that, in an emergency, treatment to preserve life takes precedence over parental refusal.
The practical route matters: escalate early to the on-call consultant, and if unresolved, to the hospital/trust’s legal team, with an out-of-hours application to the High Court/Court of Protection available for emergency treatment if needed. Once again, please check your national policies.
This is not a situation for a resident doctor to navigate alone; please seek help from your seniors.
How much to prescribe
It’s time to prescribe and order the blood from the lab. You must first calculate the volume of blood needed – but how do you do this?
Practical points
- Unlike the fixed units used in adult practice, paediatric transfusion volumes are weight-based. This is a common cause of prescribing errors for doctors used to adult charts. Trust protocols will specify the calculation, typically in ml/kg.
- Paediatric transfusions are always requested and prescribed in volume (mLs) and not units
- This is due to the well-acknowledged risk of over-transfusion leading to overload as a result of doctors prescribing transfusions by units rather than millilitres to infants and young children.
Volume calculations
There is no single unifying international calculation for the volume prescribed for transfusing children, so check your local guidelines first.
UK calculation example
In the UK, we use the UK-based British Society for Haematology (BSH) guidelines13 equation below, which is reflective of most standard equations used in local hospitals worldwide:
Volume to transfuse (ml) = Desired Hb (g/L) – Actual Hb (g/L) x Weight (kg) x 4/10
A transfusion factor of 3 or 4 is usually used. In this calculation, we have used 4.
To prevent over-transfusion, clinicians should generally double-check that the final volume is no more than 20ml/kg for top-up transfusion; however, please check your local policies.
It is recommended that the rate of transfusion of red cells should be no faster than 5ml/kg/hour. Each unit must be completed within a maximum of 4 hours from removal from the temperature-controlled blood fridge13.
A worked example for Robbie’s case:
Let’s assume Robbie weighs 18kg, and that we want to raise his Hb to 80
= (80 – 68) x (18 x 4) /10
= 86.4 mL of packed red blood cells
Australian calculation example
Another example is the Royal Children’s Hospital (RCH) Melbourne’s guidelines, which specify volume calculation based on weight thresholds14:
Weight < 20 kg:
Calculated using the formula: mL = weight (kg) × 0.5 × (desired Hb g/L – actual Hb g/L)
Typical starting rate is 5 mL/kg/hr (max ~150 mL/hr)
Weight > 20 kg: Transfuse 1 standard unit and re-assess.
They also have a guideline for neonatal volumes.
A worked example for Robbie’s case:
Let’s assume Robbie weighs 18kg, and that we want to raise his Hb to 80
= 18 x 0.5 x (80-68)
= 108mL of packed red blood cells
Key point
In children over ~20 kg, if the calculated volume exceeds one adult unit (~260-300 mL*), chart one unit, specify a maximum mL/h rate, and reassess before giving more. If the volume is less than one unit, as in both examples (86.4 mL and 108 mL), prescribe that calculated volume. Labs may issue a smaller paediatric pack (~60 mL), if a match is available, to reduce wastage.
*This is based on Australian RCH guidelines; please remember to correlate with your local lab as unit volume varies.
Complications of transfusion
Twenty minutes after the nurses start the transfusion, you are called to review as Robbie has developed a fever of 37.8 °C. What do you do next?
Most transfusions in children are uneventful, but recognising reactions matters. Transfusion reactions can present non-specifically in younger children who cannot describe symptoms or tell you about subtle changes. During transfusion, children should have regular observations.
These are typically at baseline, 15 minutes after baseline, and then as per local protocol.
If you are worried about a reaction, stop the transfusion and escalate to your registrar and on-call consultant.
Key Point
If a child becomes unwell during transfusion: stop the transfusion, call for senior help, and work through ABCDE. If you are worried it is a serious reaction, it is reasonable to put out a paediatric arrest call so the right seniors can support you.
A Note on the Importance of Haemovigilance
Haemovigilance is the global system for tracking what happens after blood leaves the fridge, so that adverse reactions and near misses can be reported, studied and fed back into practice. It also tracks the safe use of blood products, and areas where wastage could be minimised. Reporting is mandatory in most countries, and national systems feed into the International Haemovigilance Network15, which runs a shared database so that countries can benchmark their data against each other.
In the UK, that system is SHOT16, whose data consistently shows that children are over-represented in transfusion errors, usually from preventable causes such as misidentification, calculation mistakes and poor communication with the lab, rather than gaps in knowledge.
The practical point for resident doctors: every report you make, including near misses, feeds into a pipeline that shapes future guidance, from international standards down to your trust’s local policy.
Key practical take-home points
When it comes to transfusion, children are not small adults.
Transfusion is always a clinical decision and never a numerical one. The decision to transfuse should always be led by a senior paediatrician or haematologist.
When in doubt over special considerations for transfusion, call the duty haematologist.
Paediatric transfusions are prescribed in volume (mLs), not units.
Where the total transfusion volume calculated exceeds one packed red cell unit volume (~300 mL), transfuse one unit at a time and re-assess (as you would in adults). The only exception is when transfusing children with haemoglobinopathies, where multiple units may be indicated.
Many guidelines do not cover neonates or infants <1. Double-check your local policies.
Consent is a shared decision-making process, ideally started at the point of group and save, not as an afterthought.
If a family refuses transfusion, escalate early rather than navigating it alone.
If a child’s clinical status changes during a transfusion, STOP the transfusion and seek senior support.
References
National Institute for Health and Care Excellence. Blood transfusion (NG24). London: NICE; 2015, updated 2026.
Joint UK Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee. Handbook of Transfusion Medicine. JPAC.
https://www.blood.gov.au/module-6-neonatal-and-paediatrics-patient-blood-management-guidelines
https://www.aabb.org/docs/default-source/default-document-library/resources/patient-blood-management-in-pediatrics.pdf?sfvrsn=19bfb520_4
Hébert, P.C., Wells, G., Blajchman, M.A., Marshall, J., Martin, C., Pagliarello, G., Tweeddale, M., Schweitzer, I., Yetisir, E. and Transfusion Requirements in Critical Care Investigators for the Canadian Critical Care Trials Group, 1999. A multicenter, randomized, controlled clinical trial of transfusion requirements in critical care. New England Journal of Medicine, 340(6), pp.409-417.
Lacroix, J., Hébert, P.C., Hutchison, J.S., Hume, H.A., Tucci, M., Ducruet, T., Gauvin, F., Collet, J.P., Toledano, B.J., Robillard, P. and Joffe, A., 2007. Transfusion strategies for patients in pediatric intensive care units. New England Journal of Medicine, 356(16), pp.1609-1619.
Tucci, M., Sarfatti, A., Leteurtre, S., Du Pont-Thibodeau, G., Fontela, P., Ray, S., Stanworth, S.J., Hébert, P.C., Roumeliotis, N., Sauthier, M. and Spinella, P.C., 2025. Pilot-Optimizing Transfusion Therapy in Critically Ill Children With Anemia: A Pilot Multicenter Electronic Health Record-Enabled Randomized Controlled Trial on Red Blood Cell Transfusion in Critically Ill Children. Pediatric Critical Care Medicine, 26(10), pp.e1218-e1230.
Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO). Consent for blood transfusion. 2025.
https://marketplace.aabb.org/PRODUCTFILES/18202826/243080_sam.pdf
New, H.V., Berryman, J., Bolton-Maggs, P.H., Cantwell, C., Chalmers, E.A., Davies, T., Gottstein, R., Kelleher, A., Kumar, S., Morley, S.L. and Stanworth, S.J., 2016. Guidelines on transfusion for fetuses, neonates and older children. British Journal of Haematology, 175(5), pp.784-828.
https://www.rch.org.au/clinicalguide/guideline_index/Blood_product_prescription
