question 1

A woman with sickle cell anaemia is found to have an Anti-U alloantibody during her pregnancy booking bloods. She does not currently require blood. Later in the pregnancy she is found to have placenta praevia.

How will you manage this patient’s pregnancy?

Antenatal

  • Monitor titre (serial dilution IAT)

  • USS for MCA dopplers, amniotic fluid volume

  • Refer fetomaternal unit, MDT approach

Delivery

  • Planned C-section

  • Pre-op anaemia Mx

  • Cell salvage

What options do you have to source blood for this patient, and what would be your preferred choice?

  • 1st choice – Is there any fresh U neg in stock?

  • 2nd choice - Blood from a directed donor – fresh, longer shelf-life, better quality.

  • 3rd choice – Frozen blood bank

 

Could you use a relative as a directed donor?

Risk is the increased pressure to lie on the donor safety check forms.

Would need irradiating up to 2nd degree relatives. 

 

What are the risks to the baby and how will you manage these?

At risk of HDFN. (Anti-U can target U antigen even buried beneath S or s.)

  • Cord blood at birth – DAT (—> elution if positive), Group, FBC, Bilirubin

  • Monitor for jaundice

  • Will need U neg blood at birth if transfused due to maternal antibody

question 2

Define major & minor ABO incompatibility

Major - Presence in the recipient’s plasma of Anti-A, Anti-B or Anti-A,B antibodies incompatible with donor red cells, e.g. Group A donor, Group O recipient

Minor - Presence in the donor’s serum of Anti-A, Anti-B or Anti-A,B antibodies reactive with the recipient’s red cells, e.g. Group O donor, Group A recipient

State two potential risks following allogeneic stem cell transplant attributable to major ABO incompatibility between the recipient and donor.

Acute haemolysis at time of cell infusion

Delayed haemolysis due to production of antibodies by residual host lymphocytes

At day +10 Mr Grissom is anaemic with haemoglobin 70g/l, platelets 20x10e9/l and neutrophils 0.02x10e9/l. You prescribe one unit of packed red cells for transfusion. What ABO and Rh D blood group should the donor red cell unit be?

Group O Rh D negative, because patient is currently pre-engraftment

Six months later Mr Grissom is admitted to hospital following an upper GI bleed. He is symptomatically anaemic with haemoglobin 65g/l, platelets 210x10e9/l and neutrophils 2.7x10e9/l. The result of his transfusion investigations are given in the table.

You prescribe one unit of packed red cells for transfusion. What ABO and Rh D blood group should the donor red cell unit be?

Group A Rh D positive is the correct answer as per NHSBT guidelines. This is because patient has now fully engrafted and the blood bank investigations provided show group A+ with no evidence of mixed field reaction or reactions on IAT or DAT.

(However, for pragmatic reasons Group O Rh D negative will continue to be used by many hospitals so that would not be a wrong answer).

question 3

List your differential diagnosis for this patient

Warm Autoimmune haemolytic anaemia

Paroxysmal Cold Haemoglobinuria

With reference to Figure B, state the most likely full Rh type of this child, expressed in both the Fisher-Race and the Weiner nomenclature

CcDe (Fisher-Race)

R1r (Weiner). This is the most likely, although other combinations could account, e.g. R0ri

State the specification of the red cell units you would prefer to issue in this case

ABO, Rh and Kell matched blood - therefore Blood group O R1R1 Kell negative would be an appropriate choice.

Describe the principle of the Donath-Landsteiner test

Indirect D-L test preferred

  • Principle: Biphasic IgG binding at low temp but causing complement lysis as temperature rises.

  • Patient serum sample left to clot at 37 degrees

  • Pt serum : 50% suspension of washed O P+ red cells in a ratio of 9:1

  • Chill at 0 degrees for one hour. Then 37 degrees for 30 minutes

  • Centrifuge and examine for lysis – presence of lysis positive for D-L antibodies

  • Use positive and negative controls