Falling haemoglobin after chronic transfusion in sickle cell disease
A 27-year-old woman with sickle cell disease (HbSS) enrolled in a chronic simple-transfusion programme (target Hb 90-100 g/L, HbS <30%) is admitted in vaso-occlusive crisis. Pretransfusion Hb is 58 g/L, reticulocytes 2.1%, LDH 1240 U/L, bilirubin 68 micromol/L. She has received 6 units in the past 5 weeks, the most recent 9 days ago. Her record lists anti-C and anti-S; the last four units were C-negative, S-negative and compatible by AHG gel. Today Hb is 52 g/L, reticulocytes 0.8%, LDH 1890 U/L, haptoglobin <0.1 g/L, DAT 1+ IgG with a panreactive eluate. The antibody screen is negative at immediate spin and AHG. She is febrile, tachycardic and increasingly hypoxic.
1. What is the most likely diagnosis, and which findings separate it from a delayed haemolytic transfusion reaction? What else must you exclude?
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Hyperhaemolysis syndrome (HHS) is the leading diagnosis. The post-transfusion Hb (52 g/L) is lower than the pretransfusion value (58 g/L), the reticulocyte count has fallen rather than risen, LDH is climbing and haptoglobin is undetectable: brisk haemolysis with failed marrow compensation. HHS destroys both donor and autologous red cells, gives a panreactive eluate, and the DAT may be only weakly positive or genuinely negative. The absence of a new alloantibody does not exclude it, and a negative screen must not be allowed to reassure anyone.
A delayed haemolytic transfusion reaction usually shows a newly identified alloantibody, a reticulocytosis, and an eluate with defined specificity; here we see none of those, though a weak alloantibody masked by the panreactive eluate cannot be fully excluded until warm autoadsorption and phenotyping/genotyping are complete.
Before committing, exclude alternatives that also lower reticulocytes or distort the biochemistry: parvovirus B19, occult bleeding, splenic sequestration, sepsis-associated haemolysis, and microangiopathy (schistocytes, platelet trend). The fever and hypoxia raise concurrent acute chest syndrome, which independently demands urgent treatment and makes the Hb threshold for transfusion a clinical, not numerical, decision.
2. Should she be transfused today? If so, with what, and what adjunctive therapy would you give?
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Transfusion in HHS is hazardous: further units can precipitate fulminant haemolysis of both donor and residual autologous cells. Reserve it for life-threatening anaemia (Hb roughly <40 g/L), cardiac or cerebral ischaemia, or worsening acute chest syndrome, and give one unit at a time with clinical and laboratory reassessment before any second unit.
If transfusion is unavoidable, select units that are extended-phenotype or genotype matched (at minimum C, E, K, and Jka/Jkb if feasible) and 'least incompatible' by AHG; do not delay life-saving transfusion chasing a compatible crossmatch, but document the reasoning. Simple exchange transfusion is not a reflex solution here: it loads more donor cells and can aggravate the process.
Give IVIG 1 g/kg/day for 2-5 days plus high-dose corticosteroids, involve haematology and transfusion medicine immediately, and consider rituximab or eculizumab in refractory or recurrent disease. Treat acute chest syndrome concurrently (oxygen, antibiotics, incentive spirometry, cautious hydration) and avoid iron supplementation during the active haemolytic phase. Place a permanent alert in the blood bank record so any future transfusion is planned electively.
3. Three weeks later she has recovered (Hb 92 g/L, reticulocytes 6%). Haematology asks whether and how to restart the chronic transfusion programme.
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Restarting is reasonable but must be a planned, jointly owned decision rather than a resumption of routine ordering. First, complete the immunohematology workup: extended red cell genotype, warm autoadsorption to unmask any underlying alloantibody, and formal documentation of the HHS episode.
Preferred strategy is to reduce donor exposure per unit of benefit: switch from simple transfusion to erythrocytopheresis/exchange, which achieves the same HbS target with fewer donor units and less iron loading, and continue extended-matched units indefinitely. Where the transfusion indication is primarily stroke prevention, confirm the programme is still required and consider hydroxyurea as a co-therapy to lower the transfusion burden.
If simple transfusion continues, use single-unit, genotype-matched transfusions with a longer interval, pre-transfusion IVIG/steroid prophylaxis in patients with a prior severe episode, and explicit instructions that any fever, falling Hb or dark urine triggers immediate review. Record the plan in the chart and blood bank, and counsel the patient, since the greatest risk is an emergency-room transfusion given without knowledge of the history.