Hematology Week 5 Summary

Question 21

What are the major blood groups and how are they determined? What is involved in a “group and screen” and in a “cross-match” for blood? What blood group is universally transfusable?

Points for discussion:

• Major blood groups: A, B, O representing the antigenic oligosaccharide chains anchored to glycoproteins on the RBC membrane. A and B antibodies in the serum result from “naturally occurring” isohemaglutinins produced in the absence of RBC exposure (i.e. The serum from a Group A red blood cell patient contains anti-B)
• O negative blood = RBC has no immunogenic antigens on its surface to cause an ABO incompatible transfusion. Universal blood type (and should be given to all women of childbearing age in case of critical emergency where group and screen is not possible)
• The Rh(D) blood group is included with the blood group due to its high rate of immunogenicity and implications with hemolytic disease of the newborn and hemolytic transfusion reactions

• Group and Screen
  • Group = ABO and Rh group
  • Screen = detects any non-ABO alloantibodies in the serum acquired through prior transfusion or pregnancy
• Cross Match
  • Assesses ABO compatibility between recipient plasma and donor red blood cells

Question 22

A 31 year old healthy woman (G2P2) is seen in the ER post motor vehicle accident. She has numerous contusions, is conscious and can move her limbs. She complains of severe abdominal pain. A FAST ultrasound illustrated a liver laceration and splenic rupture. Her BP is 74/40 and her HR is 148 bpm. She is on a face mask and is becoming increasingly delirious.

What type of blood should she be transfused immediately and why?

Ideally, female patients of childbearing age should be given Rh negative blood to minimize allo-immunization to the Rh factor in case of future pregnancy and risk of hemolytic disease of the newborn.

Patients who cannot wait for a group and screen or cross match should be given group O blood. This blood has no A or B antigen on its RBC surface. Thus blood group “O” patients are universal donors and there should be no risk of ABO mismatch.

She required an urgent splenectomy. What immunizations are required?

Immunizations are required to protect against encapsulated organisms against Strep pneumonia, N. Meningitides, and H. flu.

Question 23

A 50 year old male with previously normal blood work presents to the emergency department with complaints of his skin turning yellow over the past 3 to 4 days. He’s become increasingly dyspneic and tired. His blood work is below with his peripheral blood work showing spherocytes. His DAT is positive.

What is your differential diagnosis and how should he be treated?

Discussion points: treatment of a Warm IgG causing autoimmune hemolytic anemia:

1. Transfuse only when necessary (note: every donor blood product will react in the cross match)
2. Steroids (often started at >1 mg/kg) with prophylaxis (i.e. PPI, Ca, Vit D)
3. Investigate for the underlying cause (i.e. SLE, lymphoproliferative disorder)
4. If steroids are ineffective, second line therapy has traditionally been splenectomy
5. Alternative therapies for refractory cases: Rituximab (anti-CD 20), immunosuppressants, IVIG

Question 24

Blood transfusions come with risks and complications. What are the major issues to consider in consenting a patient for a blood transfusion and are the infectious risks of transfused blood product?

• Common:
  • FNHTR (5% with platelets, <1% with RBCs), allo-immunization to red cell antigens
• Serious:
  • TACO (1 in 700)
  • TRALI (1 in 5,000)
  • Acute hemolytic transfusion reaction (1 in 40,000)
  • Anaphylactic reaction
  • Bacterial contamination (1 in 40,000)
• Uncommon:
  • Hepatitis B (1:153,000), Hepatitis C (1:3 million), WNV, HTLV, HIV (1:7.8 million)
  • Emerging pathogens: Chagas
  • PTP, TaGVHD, TRIM
  • Error (1:19,000)

Callum JL et al. Bloody Easy 3. ORBCN; 2011

Question 25

A 32 year old G1P1 patient has delivered her first child with the complication of severe postpartum hemorrhage. She has required 2 units of pRBCs; however, one hour post her second unit she starts to complain of fever, tachycardia, dyspnea and has crackles on her chest exam.

What is the differential diagnosis of her condition? How should she be managed?

Points for discussion:

The differential diagnosis of acute dyspnea post transfusion is broad and includes: Pulmonary embolism, infection, TRALI, TACO, AHTR, and anaphylaxis.

This patient should be kept in a monitored setting, with IVF and oxygen given. Immediate investigations include CXR, ABG, septic work-up (i.e. blood cultures), CBC, group and screen, and hemolytic indices (retic count, LDH, haptoglobin).

The blood bank should be immediately notified to investigate for transfusion-related pulmonic causes, such as TRALI and complete blood cultures, on the transfused sample.