Complications after blood transfusion: signs and tactics

Post-transfusion reactions (PTRs) are adverse events that occur during or at specific times after the transfusion of blood components. In developed hemovigilance systems, such reactions are recorded and classified according to standard criteria, allowing for comparison of data between institutions and improving safety. [1]

National hemovigilance protocols list standardized definitions of reactions, separate reporting forms, and severity and causality scales. It is important to understand that these are definitions for surveillance purposes, not clinical diagnoses. However, in practice, they correlate well with actual clinical presentations and help guide appropriate management. [2]

According to large registries and reports, serious reactions are rare, but they cannot be completely avoided. The greatest risks are associated with volume overload, acute pulmonary complications, hemolytic reactions due to incompatibility, severe allergic and anaphylactic reactions, and bacterial contamination of platelets. Systematic monitoring in national programs shows that some fatal outcomes are potentially preventable with strict adherence to patient and component identification procedures. [3]

Effective complication prevention is based on principles of patient blood management, moderate transfusion thresholds, and technical component safety measures. The fewer unnecessary transfusions and the better the processes, the less likely reactions and errors are to occur. [4]

Table 1. Classification of post-transfusion reactions by groups

Group	Examples	Timing of appearance	Key Features
Immunity immediate	Acute hemolytic syndrome, febrile non-hemolytic reaction, allergy and anaphylaxis, hypotensive reaction	Minutes or hours	Fever, chills, urticaria, drop in blood pressure, hemoglobinuria
Acute respiratory	Volume overload and acute lung injury	Within 6 hours	Dyspnea, hypoxemia, infiltrates on radiograph
Infectious	Bacterial, viral, parasitic transmission	Hours, days, weeks	Fever, sepsis, laboratory confirmation
Delayed immune	Delayed hemolytic reaction, post-transfusion purpura, graft-versus-host disease	Days and weeks	Decreased hemoglobin or platelet count, pancytopenia, rash
Metabolic and other	Iron overload due to multiple transfusions, hypocalcemia, hypothermia, hyperkalemia due to massive transfusions	Hours, days, months	Biochemical abnormalities, rhythm disturbances, signs of iron overload

Immediate immune complications

Acute hemolytic post-transfusion syndrome is most often caused by the transfusion of red blood cells incompatible with the ABO system. Classic signs include fever, chills, lumbar pain, hemoglobinuria, hypotension, and possible coagulopathy. Suspicion requires immediate cessation of the transfusion, verification of patient and component identification, collection of samples for a direct Coombs test, free plasma hemoglobin, and bilirubin, and reconfirmation of the blood type. Treatment is supportive, with correction of shock, diuresis, and referral of components and samples to the blood service laboratory. [5]

A febrile nonhemolytic reaction manifests as fever and chills without signs of hemolysis. The risk is reduced by total leukofiltration of components, and routine prophylactic administration of antipyretics or antihistamines prior to transfusion is not recommended as a universal measure, as it has not been demonstrated to significantly reduce the incidence of clinically significant reactions. In mild cases, after evaluation, transfusion can be completed under observation.

Allergic reactions range from isolated urticaria to anaphylaxis with bronchospasm, hypotension, and shock. In severe episodes and the presence of immunoglobulin A deficiency, the use of washed red blood cells and special plasma derivatives is considered, along with mandatory consultation with a transfusion specialist. Repeated episodes require a prophylaxis plan with optimal component selection. [6]

A hypotensive reaction is characterized by a sharp drop in blood pressure near the start of a transfusion, with a rapid response to discontinuation of the infusion and supportive care. Other, more specific reaction definitions are excluded. The mechanism is believed to be bradykinin-related and is more common with angiotensin-converting enzyme inhibitors. Diagnosis and severity are recorded using a standardized form with an assessment of causality. [7]

Table 2. Red flags of immediate reactions and initial actions at the bedside

Situation	What's alarming	First steps
Suspicion of hemolysis	Chills, fever, dark urine, lower back pain	Stop the transfusion immediately, maintain intravenous access with saline, verify identification, notify the blood service, and collect blood and urine for emergency testing.
Allergy and anaphylaxis	Rash, itching, wheezing, drop in blood pressure	Stop the transfusion, ensure airway patency, oxygen, adrenaline as indicated, antihistamines, call the resuscitation team
Febrile reaction	Fever without signs of hemolysis	Assess for hemolysis and bacterial contamination, symptomatic therapy, decision on continuation after excluding serious causes
Hypotensive reaction	Rapid pressure drop at the start of transfusion	Stop the transfusion, provide supportive care, rule out anaphylaxis and hemolysis, notify the blood service

Acute respiratory complications: volume overload and acute lung injury

Volume overload after transfusion is one of the most common and potentially severe reactions. It manifests as dyspnea, hypoxemia, tachycardia, signs of left ventricular overload, positive fluid balance, and a response to diuretics. Elevated brain natriuretic peptide levels, confirmation of the cardiogenic nature of pulmonary edema, and a relationship with the transfused volume and infusion rate aid in diagnosis. Prophylaxis in high-risk groups is performed with a slower infusion rate and diuretics as indicated.

Transfusion-associated acute lung injury is divided into those without risk factors and those with preexisting conditions. Clinically, this is characterized by acute hypoxemia and bilateral infiltrates on imaging within 6 hours of transfusion in the absence of signs of volume overload. Management is supportive, with respiratory support, cessation of transfusion, and mandatory reporting to the blood service for investigation and measures to prevent recurrence. [8]

A key task at the bedside is to differentiate volume overload from acute lung injury, as the treatments are fundamentally different. In volume overload, diuretics and fluid management are important, while in acute lung injury, respiratory support and an assessment of the immune nature of the event, including possible donor antibodies to leukocyte antigens, are essential. Documentation using standardized forms facilitates further investigation.

Current reports from national safety programs confirm that both volume overload and acute pulmonary complications remain among the leading causes of severe outcomes. Guidelines emphasize the importance of correctly identifying patients with cardiac and renal failure and strict monitoring of infusion rates. [9]

Table 3. How to distinguish volume overload from acute lung injury

Sign	Volume overload	Acute lung injury
Time	Within 6 hours	Within 6 hours
Hemodynamics	Often hypertension, signs of overload	Often normal pressure or shock
Biomarkers	High natriuretic peptide	There is no specific marker
Response to therapy	Rapid response to diuretics	Respiratory support is needed
X-ray	Cardiogenic edema	Non-cardiogenic edema

Infectious complications

Septic reactions are most often associated with bacterial contamination of platelet components due to their storage at room temperature. Current risk mitigation strategies include extensive bacteriological testing, pathogen inactivation methods, and regulated platelet risk management options outlined in regulatory guidelines. These measures significantly reduce the incidence of septic transfusion reactions.

The risk of viral infection transmission through transfusions in high-income healthcare systems is currently extremely low thanks to strict donor selection and molecular screening, but it cannot be completely eliminated. The emergence of new pathogens continually necessitates a review of safety measures and surveillance protocols in blood services.

Rapid recognition of a septic reaction is critical: fever, chills, or hypotension during or shortly after transfusion require immediate cessation of the infusion, blood cultures of the patient and the remaining component, initiation of empirical antibacterial therapy, and notification of the blood service. Local surveillance protocols should be consistent with national guidelines.

Regular safety program reports emphasize the importance of a safety culture and error analysis throughout the entire supply chain, from procurement to transfusion. This includes minimizing the time between blood collection and testing, proper logistics, and maintaining proper storage temperatures, which reduces the likelihood of contamination and other violations. [10]

Table 4. Infection risks and control measures

Component	The most likely risk	Key reduction measures
Platelets	Bacterial contamination	Advanced testing, pathogen inactivation, compliance with time limits and temperatures
Red blood cell mass	Viral agents with extremely low residual risk	Strict donor selection, molecular screening
Plasma	Viral agents with extremely low residual risk	Pool pasteurization or inactivation for derivatives, strict screening
All components	Errors in identification, storage and issuance	Scan-identification, double-checking at the bedside, process audit

Delayed immune complications

A delayed hemolytic reaction develops over several days or weeks, when the patient already has or is developing an antibody to the donor red blood cell antigen. Clinically, it presents with an unexplained drop in hemoglobin, jaundice, and sometimes fever. Diagnosis relies on a direct Coombs test, detection of a specific antibody, and laboratory evidence of hemolysis. Antigen-negative components are then selected for subsequent transfusions. [11]

Post-transfusion purpura is a rare but severe reaction with a sharp drop in platelets 5-10 days after a transfusion, most often in women with immune sensitization. The mainstay of treatment is intravenous immunoglobulin, with prompt involvement of a hematologist and blood service. [12]

Transfusion-induced graft-versus-host disease (GVHD) in immunocompromised patients presents with fever, rash, diarrhea, liver damage, and pancytopenia. This event has a high mortality rate; the key prevention is the use of irradiated components for high-risk groups and for related donations. Timely differentiation from infections and drug-induced injuries is critical. [13]

Alloimmunization to red blood cell or platelet antigens remains a separate issue, complicating the selection of components and increasing the risk of transfusion failure. Prevention relies on a thorough transfusion history, an antibody database, and the selection of phenotypically compatible units in high-risk groups.

Table 5. Delayed immune responses: key differences

Reaction	Deadlines	Main manifestations	Confirmation	Tactics
Delayed hemolytic	Days or weeks	A drop in hemoglobin, jaundice	Direct Coombs test, antibodies, hemolysis markers	Antigen-negative components, maintenance therapy
Post-transfusion purpura	5-10 days	Severe thrombocytopenia, bleeding	Antibodies to platelet antigens	Intravenous immunoglobulin, support
Graft-versus-host disease	Days or weeks	Fever, rash, diarrhea, pancytopenia	Clinical and laboratory criteria, leukocyte chimerism	Prophylaxis with irradiation of components, intensive care

Metabolic and other complications

Repeated red blood cell transfusions lead to chronic iron overload, leading to damage to the liver, heart, and endocrine organs. Management strategies include regular serum ferritin assessment and magnetic resonance imaging to quantify iron in the liver and heart, followed by the selection of chelation therapy according to current guidelines. [14]

Massive transfusions can cause citrate-induced hypocalcemia, hypothermia, acidosis, and hyperkalemia. Prevention involves warming the components, monitoring electrolytes and acid-base balance, and, if necessary, administering calcium and adjusting potassium according to department protocols. These measures are especially important in newborns and during prolonged surgeries.

Some patients exhibit platelet refractoriness due to immune sensitization, requiring antigen-based matching and a transfusion strategy using components matched to platelet antigens. Management should be coordinated with the blood service using standardized definitions of transfusion efficacy. [15]

Rare reactions include hypothermic hemolysis due to improper storage, mechanical hemolysis, and other technical issues. Their incidence is reduced by strict adherence to storage and transportation procedures, as well as through a culture of safety and staff training. [16]

Table 6. Who needs special preventive measures and what exactly

Patient group	The main risk	What to consider in advance
Elderly, heart or kidney failure	Volume overload	Slow rate, diuretic as indicated, careful fluid monitoring
Immunocompromised, transplantation	Graft-versus-host disease	Irradiated components, strict control of readings
History of immunoglobulin A deficiency or anaphylaxis	Severe allergy and anaphylaxis	Washed red blood cells, special plasma products, emergency care plan
Chronic transfusions	Iron overload	Ferritin and magnetic resonance imaging monitoring, selection of chelators
Newborns and children	Metabolic complications	Warming of components, monitoring of calcium and potassium, individual protocols

What to do if you suspect a reaction

The first and most important action to take if any suspicious symptoms occur is to immediately stop the transfusion, maintain intravenous access for saline infusion, assess vital signs, ensure airway patency, and notify the blood service. At the same time, the patient and component are matched and symptomatic treatment is initiated based on the clinical situation.

Next, blood and urine samples are collected for laboratory verification: direct Coombs test, plasma free hemoglobin, total bilirubin, plasma hemolysis, and a blood smear if hemolysis is suspected; blood cultures from the patient and from the remaining component if a septic reaction is suspected. The remaining component and all accompanying documentation are returned to the blood service for investigation. [17]

In cases of dyspnea and hypoxemia, signs of volume overload and acute lung injury are assessed, chest X-ray or CT scan is performed, brain natriuretic peptide is measured, and fluid balance is analyzed. Specific therapy is decided based on differential criteria.

All cases must be documented using standard forms, with severity and causality categories assigned. This is important for internal analysis, prevention of recurrence, and participation in the national hemovigilance system. [18]

How to reduce the risk of complications before and during transfusion

Reducing unnecessary transfusions is one of the most effective ways to reduce risk. Current guidelines support moderate thresholds for red blood cell transfusion in stable patients and emphasize individualization of indications, which reduces exposure to donor components and the incidence of reactions. [19]

Component safety is enhanced through total leukofiltration, irradiation for at-risk groups, platelet bacteriological testing, and the use of pathogen inactivation technologies. Regulatory documents and industry standards detail acceptable strategies and requirements for their use.

At the clinical process level, key factors include bedside scanning, a mandatory "safety pause" before starting an infusion, double-checking of patient and component information, monitoring of the infusion rate, and staff training in recognizing early signs of reactions. These simple steps prevent the vast majority of errors and serious outcomes. [20]

For patients with chronic transfusion requirements, iron overload monitoring and prevention are planned in advance, antibodies are recorded, and phenotyping databases are used. This systematic approach reduces the likelihood of reactions and makes treatment predictable and safe. [21]