Transcript Blood bank/transfusion medicine lab

Second Year Medical Student
Fall Pathology Lab
and Indiana Blood Center Tour:
Transfusion Medicine and
Blood Banking
October, 2014
Outline
• Pre-test
• Major blood group basics
• Trauma
– Bag o’blood
– Massive blood transfusion protocol (MBTP)
• ABO incompatibility
– Acute hemolytic transfusion reaction
• Hemolytic disease of the fetus/newborn (HDFN)
• Post-test
What is blood
Blood has an interesting medical and philosophical
history, it permeates our lives and culture
was born show
withtreatment
music inside me.
Egyptian Ihieroglyphics
French physician Jean-Baptiste Denis
of patients
by
bleeding
from
the
neck
Music was one of my parts. Liketransfuses a teenage boy suffering
and ankle – circa 2500 BC
from a persistent fever with nine
my blood.
was
a force already
Christianity
teachesItthe
blood
ounces
of lamb'sDracula
blood –centralizes
1667
shed within
by Jesus me
Christwhen
formedI aarrived on the
Bram Stroker’s
new covenant and is the
around
a character who can drink
scene.
It
was
a
necessity
for
me
sacramental symbol of the
the blood of his victims and attain
Hippocrates
postulates
that
similar
to
the
like food
water. Ray Charles immortality - 1897 (with huge pop
Eucharist
- 0 AD or
to present
four elements,
the body is comprised of
culture implications)
1930-2004
four humors -- blood, phlegm, black bile,
“I was Macbeth
a queen, plays
and you
tookGlobal
away theater
my
at the
and yellow bile --Shakespeare’s
and their imbalance
Clara
Barton,
“Angelofofthe
theU.S. Army
Surgeon
General
crown;
a
wife,
and
you
killed
my
husband;
a character’s
causes disease –with
circathe
400theme
BC of blood representingbattelfield”
and
Navy,during
the American Red Cross
a mother,
and you– circa
deprived
of my
masculinity
and remorse
1600me
American
civil War,
agrees
children. My blood alone remains:
taketoit,organize a civilian blood
founded
the
American
Redblood
donor
service
to collect
but do not make me suffer long.”
Marie
Cross
- 1881
plasma
for the war effort -1941
Antoinette 1793
What the Blood Blanker does for the clinicians and patients
Transfusion therapy is a set of processes, not just a product
Medical reason to TX
Recruit donor
Screen donor
Pre-TX testing
Collect unit
Issue unit
Prepare components
Administer at bedside
Monitor & evaluate
Infectious diseases
testing
Product: Blood safety
Entire process: Blood transfusion safety
After S. Dzik, MD Blood Transfusion Service, MGH, Boston
Some blood bank basics
• Basically, there are 4 major blood groups
–
–
–
–
A
B
AB
O
• These groups are defined by surface antigens
present on the Red Blood Cell (RBC)
• Which antigens are present is determined by the
expression of genes which code for enzymes
found on the long arm of chromosome 9 (9q34)
• These genes are expressed co-dominantly
A gene
• If you have the A gene (N-acetyl
galactosyltransferase), you make the A antigen
– Thus you are blood Type A
N-acetyl GalT
A gene
A gene
A Blood type
B gene
• If you have the B gene (galactosyltransferase),
you make the B antigen
– Thus you are blood Type B
GalT
B gene
B gene
B Blood type
Both A and B genes
• If you have the A and B genes on separate
chromosomes, you make both the A and B antigens
– Thus you are blood group AB
AB Blood Type
GalT
A gene
B gene
N-acetyl GalT
Neither A or B genes
• If neither A or B genes are present, you will
make neither A no B antigens
– Thus you are blood group O
O Blood Type
Why do we care?
• Try to stay awake because it has to do with
immunology
– Recognition of self and non-self
• A and B like antigens are found constitutively
in nature
– We are exposed to them early in life
– As a result the body will make antibodies against
the antigens it doesn’t have (non-self) and not
make antibodies against the antigens it does (self)
Major antigens and antibodies
B
Type A
Type AB
B
B
B
B
B
B
A
A
B
B
A,B
A
A
A
A
B
A
A
A,B
A
B
Type B
A
A
B
A,B
A
Type O
A, B, and A,B allo-antibodies
• Allo-antibody is an antibody against an
antigen of the same species
• All potent activators of complement and the
membrane attack complex
– Cause massive intravascular hemolysis of RBCs
So what happens when…
We mix type A whole blood with…
B
B
B
B
B
B
B
B
Type AB whole blood
So what happens when…
We mix type A whole blood with…
B
B
Type AB whole blood?
B
B
B
B
B
B
When transfusing whole blood the blood
types must be identical.
But if we just…
Mix type A RBCs…
B
B
with type AB whole blood…
B
B
B
B
B
B
And if we apply this to patients…
Donor
Recipient
It is the basis for blood component
therapy
Blood Component Therapy
For RBC units
For plasma based units
Donor blood type
Recipient blood type
Recipient blood type
Donor blood type
• Who is the universal RBC donor?
• Who is the universal plasma donor?
• Type O
• Type AB
• Who it the universal RBC recipient?
• Who it the universal plasma recipient?
• Type AB
• Type O
Approximately 45% of the population is Type O, 40% type A, 11% type B, and 4% AB.
Case presentation #1
• You have been accepted to Emergency
Medicine residency in Washington DC and are
enjoying a nice day off of sight seeing
following three days on 16 hour shifts when
you walk past a TV wall and see this….
Olympus Has Fallen!
https://www.youtube.com/watch?feature=pla
yer_detailpage&v=kWPNediW79I
Case presentation
• Within a minute your pager goes off.
• You return the page and you are informed that
Emergency Response Plan has been initiated
and you are to report to your training hospital
for assignment.
Yes, this could happen to you!
Case presentation
• You are assigned to trauma management as a
team leader
• You meet the EMS at the ED entrance to accept
your first patient
– As you take the patient the driver quickly states “this
is a 27 year old male with proximal lower limb injuries
secondary to large caliber gunshot, GCS 15/15, vitals
are 98.0F, 135, 32, 108/62, O2 sats 95% NC.
Approximately 2 liters of blood loss at the scene.
Intraosseous lines placed – patient has received
approximately 1000ccs NS”
What do you Do?
• ABCDEs
–Airway assessment and protection possible cervical
spine stabilization
–Breathing and Ventilation assessment for oxygenation
–Circulation assessment to control hemorrhage and
maintain end organ perfusion
–Disability assessment by basic neurologic evaluation
–Exposure by undressing patient and searching for
additional injury while preventing hypothermia
A&B
• As you move the patient into the ED you ask
the patient his name – He states “Channing
Tatum” between rapid breaths
– Besides realizing that’s the wrong movie, you just
covered your A and B (patient’s ability to
“mentate” & phonate generally indicates an ability
to breath and protect his/her airway)
– You note the tachypnea and maintain a low
threshold for intubation
C &D
• Pulse in upper extremities is 1+ weak and thready with
regular tachycardic, approximately 130, while the posterior
tibia and dorsus pedis pulses are absent bilaterally.
– An abnormality is identified in the lower extremities (C), now
you must look for a cause while assessing for disability (D) of the
injury which may change treatment
• Blood soaked gauze is present at the upper thigh bilaterally
• You remove the patient’s socks to reveal two pale, grey feet
and 10 pale toes.
– You run the sharp end of you reflex hammer up the plantar
aspect of the patient’s feet – the toes curl in and the patient
groans – you just assessed for disability
E
• You order your staff to start undressing the
patient as you arrive in Triage and demand a
trauma room.
– To which they respond “All of the trauma rooms are
full!”
• You turn your attention to the blood soaked
gauze at the thighs
– Removing the gauze reveals two entrance and exit
puncture wounds with pulsatile blood
– A scan of the rest of the body including back reveals
no other injuries but the patient’s skin is cold and
clammy
Diagnosis and additional management
• Diagnosis: Traumatic laceration of bilateral
femoral arteries complicated by probable
hemorrhagic shock
• What can you do for this patient?
– What studies or labs should you order?
– Intravenous access?
– Environment?
Traumatic laceration of bilateral
femoral arteries
•
Studies
– EKG with telemetry
– Continuous pulse ox
•
Labs
–
–
–
–
–
–
CBC stat
CMP stat
Blood gas stat
Lactate stat
Type and Cross stat
Thromboelastography (TEG)?
•
Interventions
– Oxygen therapy
– Two large-bore 16 gauge catheters
with continuous NS push
– Direct pressure/turniquet/BP
cuff/upstream occlusion
– Arterial line
– Warm blankets to prevent
hypothermia
– Elevate extremities/ Trendelenburg
– Foley catheter
Can you manage this patient on your own?
To whom do you need to communicate this patient?
Transition of care and support
• You page the trauma/vascular surgery team
– Nurse returns the page and says that due to the volume
the soonest they can evaluate the patient is in 20 minutes
• You call the blood bank and they haven’t received the
specimen for type and cross.
– They say, due to the volume, it will take 5-10 minutes
before a type can be done.
– Still, they ask what products you want?
– You try to think back to
medical school and recall if
anyone ever taught you anything
about blood therapy.
Options
• Whole blood
• Packed red blood cells
– Leukocyte reduced
– Washed RBC
– CMV negative
• Platelets
– Pooled random donor
– Apheresis
• Plasma
–
–
–
–
–
Fresh Frozen Plasma
Plasma frozen <24 hrs
Thawed Plasma
Liquid plasma
Plasma cryoprecipitate
reduced
• Cryoprecipitate
Irradiated or not irradiated?
Whole Blood
A. Description:
–
500+/- 50 ml mixed with 70
ml CPD
B. Storage:
–
21 days stored at 1-6º
C. Indications:
–
–
Recently used in military
hospitals in combat areas
settings
Proposed clinical trials to
examine feasibility and
efficacy in civilian setting
Packed Red Blood cells
A. Description:
–
–
200 ml of RBC with 111 ml of
additive solution
Packed cell volume = 60%
B. Storage = 42 days
C. Indications:
–
–
Acute blood loss exceeding 1520% of blood volume (pediatric
patients - 10-15 ml/Kg) and
failure to obtain hemodynamic
stability with reasonable volume
of crystalloid and/or colloid
solutions
Acute blood loss of any amount if
there is clinical evidence of
inadequate oxygen carrying
capacity
Packed Red Blood cells
C. Indications:
–
–
–
Hemoglobin of ≤ 7 gm/dl
(hematocrit ≤ 21%), if not due to a
treatable cause (treatment of
underlying case is preferable if
patient is not symptomatic)
Symptomatic anemia regardless of
hemoglobin level
Hemoglobin ≤ 8 gm/dl (hematocrit
≤ 24% ) and acute cardiac disease /
or shock
D. Contraindications:
–
–
–
–
For volume replacement
In place of a hematinic
To enhance wound healing
To improve general “well-being”
Leukocyte reduced pRBC
A. Description:
–
Packed red cells with leukocytes
reduced (residual leukocyte count
less than 5x106)
B. Processing of Product:
–
–
Product made during transfusion
with filter attached to unit
Pre-storage leukocyte reduction
at blood center
C. Indications:
–
–
–
Prevention of HLA/WBC
alloimmunization
Prevention of recurrent nonhemolytic febrile reactions
Prevention of CMV transmission
in select groups of patients
Saline washed pRBC
A.
Description: packed red cells washed
with saline
–
–
–
B.
C.
D.
99% of plasma proteins are removed
85% of leukocytes are removed
Post-wash K + is 0.2 meq/L
Processing: manual and automatic
methods
Storage: once washed, 24-hour
outdate
Indications:
–
–
–
History of allergic or febrile reactions
secondary to plasma proteins not
prevented by pre-transfusion
administration of antihistamines and
leukocyte reduction
IgA deficiency with documented IgA
antibodies
History of anaphylactic reaction to
blood components
Platelet Concentrates
A. Description:
–
–
–
Random donor unit contains 5.5 X
1010 platelets suspended in 30-50
ml of plasma
Apheresis donor unit contains
3.0 X 1011 platelets suspended in
300-400 ml of plasma
B. Dosage:
–
–
–
–
4-6 platelet concentrates
1 apheresis unit
Platelet count should increase
25,000 – 30,000/cc3
Each dose has equivalent of one
unit of fresh plasma*
C. Storage:
–
–
Stored at 20-24º C on a rotator
5-day outdate
Platelet Concentrates
D. Indications: prevention and cessation
of bleeding
–
–
–
–
–
–
E.
Severely thrombocytopenic (less than
10,000 or 20,000 depending on
institution)
Moderately thrombocytopenic and
bleeding (less than 50,000)
Surgery or invasive procedure (less
than 50,000)
Diffuse microvascular bleeding
following cardiopulmonary bypass or
with intra-aortic balloon pump (less
than 100,000)
Bleeding with qualitative platelet
defect
Massive Transfusion Protocols (MTP)
Contraindications:
–
–
Idiopathic Thrombotic
Thrombocytopenic Purpura (ITP)
Thrombotic Thrombocytopenic
Purpura (TTP)
Plasma
A. Description:
–
–
–
–
225-275 ml of plasma and
CPDA-1, including 25 meq of
citric acid
Jumbo plasma 400 cc or
greater
Frozen within 8 hrs = FFP
Frozen within 24 hrs = 24FP
B. Storage: 1 year at -18ºC
C. Outdate once thawed (1-6ºC)
–
–
24 hours for FFP or 24FP
72-120 hours if relabeled as
Thawed Plasma
Plasma
D. Indications:
–
–
–
–
–
E.
Treatment of coagulopathy due to
clotting factor deficiencies
Patient is bleeding actively with
PT and/or PTT greater than 1.5
normal (INR > 1.8) and platelet
count above 50,000
Coumadin overdose with major
bleeding or impending surgery
Treatment of TTP
Massive Transfusion Protocol
(MTP)
Contraindications:
–
–
Volume expansion
Treatment of nutritional
deficiencies
Cryoprecipitate
A. Description: each unit
consists of 10-30 ml
residual plasma
–
–
80 units of factor VIII
250 mg of fibrinogen
B. Storage: 1 year at -18ºC
C. Indications:
1.
2.
3.
4.
Hypofibrinogenemia (≤ 100
mg/dl)
Dysfibrinogenemia
Factor XIII deficiency - rare
MTP
Irradiated Units
A.
Products irradiated:
–
B.
Indications: preventing graft versus host
disease
–
–
–
–
–
C.
Immunocompromised patients
Directed donations from blood relatives
Premature infants ≤ 1200 gms
Fetuses receiving intrauterine
transfusions
Neonatal exchange transfusions
Processing and final product:
–
–
D.
Whole blood, packed red cells, platelets,
and granulocyte concentrates
Irradiate with 2500cGy
Mitotic capacity of lymphocytes is
reduced or eliminated without significant
functional damage to other cellular
elements
Storage:
–
Red cells outdate 28 days from
irradiation (or original expiration if less
than 28 days)
Confused?
• As you are running through the options in
your head…. you hear the technician, still on
the line, ask…
“Would you like to initiate a Massive Blood
Transfusion Protocol?”
Massive Blood Transfusion Protocol
(MBTP)
• Massive blood transfusion – transfusion of 10 or more
blood components within a 24 hour window
• Blood bank maintains an adequate inventory of typespecific and type compatible units for emergent
situations
– When the patient’s blood type is unknown O Rh positive
red blood cells and AB plasma products will be released
– Special component processing cannot be provided due to
urgency
– Once blood type has been identified type specific units will
be released; if incompatible blood has been released the
clinician will be notified retrospectively
Massive Blood Transfusion Protocol
(MBTP)
• Since the patient is bleeding whole blood each
component of the blood must be replaced
– At IU Health components are released in the
following ratios
• 8 units packed, leukoreduced red blood cells
• 4 units plasma
• 1 unit leukoreduced, apheresis platelets
Back to the case
• You initiate that massive blood transfusion
protocol
– You order rapid infusion as units arrive
• Lab results come back
Labs/Studies
Venous blood
Total white blood cell (WBC) count = 7,400 WBCs /mm3
Differential WBC count revealed 59% neutrophils
Hematocrit = 46%
Hemoglobin = 15.0 gm / dl
Sodium (Na+) = 138 mEq / L
Potassium (K+) = 5.1 mEq / L
Chloride (Cl-) = 104 mEq / L
BUN = 27 mg / dl
Creatinine = 1.9 mg / dl
Glucose = 165 mg / dl
SGPT = 41 IU / L
SGOT = 48 IU / L
Lactate = 4.2 mmol/L
(normal = 4,000 to 11,000)
(normal = 55-70%)
(normal = 42-54%)
(normal = 14-18 gm / dl)
(normal = 136-145 mEq / L)
(normal = 3.5-5.1 mEq / L)
(normal = 96-106 mEq / L)
(normal = 6 - 23 mg / dl)
(normal = 0.7 - 1.5 mg / dl)
(normal = 70 - 160 mg / dl)
(normal = 0-33 IU / L)
(normal = 0 41 IU / L)
(normal = 0.6-2.3 mmol/L)
Arterial blood
Blood pH = 7.28
pCO2 = 31 mm Hg
pO2 = 78 mm Hg
Hemoglobin - O2 saturation = 88%
[HCO3-] = 14 mEq / L
(normal = 7.35-7.45)
(normal = 40 mm Hg)
(normal = 90-100 mm Hg)
(normal = 94-100%)
(normal = 22-26 mEq / L)
Urinary output in first 60 minutes in ER was 20 ml (color was dark yellow).
Urine specific gravity = 1.029 (normal = 1.003 - 1.030).
Central venous pressure ranged from 1 to 3 cm H2O throughout the cardiac cycle
(normal = range = 5.5 to 13 cm H2O).
ECG revealed normal sinus rhythm with slight ST-depression in most leads
Final Diagnosis and Treatment
• Hemorrhagic shock
– Anion gap secondary to lactate acidosis from glycolytic pathway,
indicating poor oxygenation and end organ dysfunction.
• As units are infused and new labs are ordered the trauma
surgery team arrives to evaluate the patient.
– They commend you for your excellent work and indicate that
they are taking the patient to surgery now.
Case presentation #2
• You decided Emergency medicine just wasn’t for
you so you transfer into General Surgery at a
small community hospital outside Seattle, WA
that didn’t fill.
• You are asked to admit a 35 year old female for
non-urgent cholecystectomy for symptomatic
cholelithiasis confirmed by ultrasound.
You’re thinking “Now this is more like it!”
Case Presentation #2
• HPI
– Started feeling intermittent RUQ pain with fatty meals
during her third trimester. Pain brief and resolves
spontaneously. Last attack was 3 weeks ago. No
fevers, N/V, change in bowel habits. Wants the surgery
preformed while on maternity leave.
• PMHx
– Just gave birth to her second child 1 month ago, she
claims to have lost some blood during birth but felt
fine, did not get transfused, and was discharged at
48hrs
– No other significant history
Case Presentation #2
• Medication:
– multivitamin
• FmHx/SocHx/RoS: unremarkable
• Physical exam: unremarkable
– Vitals within normal limits
– Pertinent positives/negatives
• Abd: Soft non-distended, normal bowel sounds; No guarding
or rebound tenderness
• You order standard pre-op labs
– CBC, CMP, Type & screen
Labs
• CBC
5.2
• CMP
• Normal Hemoglobin levels
140
4.9
9.8
29.4
102
25
220
Ca: 9 mg/dL
Alk: 100 U/L
Bili: 0.4mg/dL
19
80 AST: 5 U/L
0.80
ALT: 2 U/L
Protein: 7g/dL
Albumin: 4g/dL
– Men: 13.8 – 18.0 g/dL
– Female 12.1 – 15.1 g/dL
• Hematocrit is the proportion of whole blood
occupied by RBC, calculated %
– HCT = RBC volume/total blood volume (or Hgb x 3)
Diagnosis
• Mild anemia, otherwise ready for surgery
• You discuss the patient with your staff on
rounds.
– He tells you to change the Type & Screen to a Type
and Cross
– He says transfuse two units when available… He
never operates on a patient with a Hgb < 10 g/dL
• A single unit of packed RBC will increase a normal
adults hemoglobin 1gm/dL
T&C vs T&S
• Type and Screen – used in patients without and immediate need for
transfusion (pregnant and pre-surgical patients)
– Identify blood and Rh type (with RBC and serum)
– Screen serum for minor blood group antibodies which
could cause hemolysis
• Type and Cross – used in patients with an imminent need for
transfusion (trauma patients, sickle cell crisis, invasive surgical patients)
– Perform a Type and screen
– Identify compatible units for transfusion and mix
patient serum with RBC product to prove there is no
reaction/hemolysis (CROSS-match)
– Units are then reserved for that patient if needed
Patient’s T&C
• Red blood cell typing – done two ways, remember ABO antigen and
antibodies correlate
• Forward – Patient’s red blood cells with known anti-sera
• Reverse – Patient’s serum with known red blood cell types
Forward
Anti-A
4+
Anti-B Anti-Rh Type?
0
4+ A+
Reverse
A Cell
B Cell
Type?
0
4+
A
Transfusion
• Screen is negative and serum sample crossmatched with two units
– Units arrive in the OR as the patient receives
anesthesia prior to intubation
• The nurse checks the patient labels and
everything matches, confirms that they are A+
units which is witnessed by the anesthesia tech,
and takes the patient’s vitals which are normal
• She starts the transfusion and goes about her
pre-op routine
– As she places the foley catheter she notes dark urine
Transfusion
• There is no one besides the anesthesia tech in the
room, so the nurse pages you
– On the phone the nurse tells you about the urine
• You quickly request an update on her vitals
– The patient is now intubates but otherwise vitals show
increased temperature of 1.9˚C, increased heart rate, and
decreased blood pressure
– She includes that the patient is now oozing from all IV sites
• What is the next, MOST important step you need to
take to decrease morbidity and mortality for your
patient?
Suspected Transfusion Reaction
STOP THE
TRANSFUSION
Suspected Transfusion Reaction
• The nurse stops the transfusion
• You tell her to call a code, start a transfusion
reaction work-up, and you will be there as
soon as possible
• You arrive in the midst of aggressive
resuscitation efforts
– Ultimately the team is unsuccessful and the
patient is pronounced dead
Transfusion reaction work-up
• Post-mortem labs are drawn
– Direct anti-globulin test
– Plasma free hemoglobin
– Urine for hemoglobin testing
– Blood bank receives a specimen for retyping and
cross match
• Body bank notes the serum is pink that does not
change with centrifugation
• Clerical paper work review revealed no errors
Transfusion reaction work-up
Forward
Anti-A
0
Reverse
Anti-B Anti-Rh Type?
0
0
O-
A Cell
B Cell
Type?
4+
4+
O
• What is the patient's blood type?
– Original pretransfusion specimen retyped A+
•
•
•
•
DAT is positive
Repeat cross-match strongly positive (4+)
Plasma free hemoglobin elevated
Urine hemoglobin elevated
What is the diagnosis and how did this happen?
Acute hemolytic transfusion reaction
• Rapid destruction of donor RBC by recipient Ab
• Medical emergency
– Most severe transfusion reaction
– Can be fatal, thus treat all transfusion reactions as possible
AHTR (Stop the transfusion for all possible reations)
• Pathophysiology
– Ab bind donor RBCs  Complement activation  formation of
MAC  RBC lysis
– Ag-Ab complexes  coagulation cascade activation 
intravascular thrombi and consumption of coag factors  DIC
and schistocytes
– Both pathways result in the release of numerous cytokines
causing symptoms
– All dose dependant
Acute hemolytic transfusion reaction
Signs and symptoms
• Triad
– Fever/Chills (>2˚F or >1 ˚C)
– Flank pain
– Dark urine
• Additional
–
–
–
–
–
–
Tachycardia
Dyspnea
N/V
Bleeding
Hypotension
Feeling of impending doom
Laboratory findings
• Hemoglobinemia (pink or red
serum/plasma)
• Hemoglobinuria (NOT hematuria)
• Usually positive direct
antiglobulin test (DAT) but can be
negative (all Ab coated cells
already lysed)
• Elevated indirect bilirubin and
LDH
• Decreased haptoglobin
• Hyperkalemia
• Peripheral smear: Schistocytes
Acute hemolytic transfusion reaction
• Treatment is supportive
• Case resolution
– Patient in a two person room
– Patient asked to switch beds with roommate because she liked
to be by the window
– When nurse came to draw Type and Cross specimen, she drew
the specimen from the patient in the door bed (where the
patient was assigned) without checking patient ID
– The patients roommate typed A+ while our patient was actually
O– Anti-A, Anti-B, and Anti-A,B antibodies in patient destroyed A+
transfused cells
Risk of transfusion reaction
Carson J L et al. Ann Intern Med doi:10.1059/0003-4819-156-12-201206190-00429
Case Presentation #3
• You decide that General Surgery isn’t for you
either. You love babies, so you figure Ob/Gyn is
the place for you.
• You transfer into a residency program in a large
metropolitan city with a diverse population.
You think, its just catching babies – They’re about as
big as a blood bag and inside someone else. I’m
finally done with these pesky transfusions!!
Case presentation #3
• A 25 year old pregnant Chinese female
presents to your clinic for her first obstetric
appointment. She just immigrated from China
and is late in her second trimester. She
received her prenatal care in rural China.
Case presentation #3
• PMHx
– None, reports always being healthy
• Medication
– None
• FmHx/SocHx/RoS
– Unremarkable
• Birth history
– G3 P2002
• First pregnancy uncomplicated
• Second child born “golden” which resolved after several weeks
• Her husband is the father of all children
Case presentation #3
• Physical exam
– Vitals within normal limits
– Pertinent physical exam findings: Fundal height 26cm
(correlates with weeks of gestation)
• Routine labs and exams ordered
–
–
–
–
–
–
CBC, CMP
Infectious serology (ToRCHeS)
Group B strep screen
Type and Screen
Fetal heart rate by doppler
Fetal ultrasound
Lab and Exam results
• Fetal heart rate: 170 bpm (normal 120-150
bpm)
• Awaiting ultrasound findings
• Laboratory work up shows a mild anemia but
is otherwise unremarkable
– Remember pregnant patients will develop a
physiologic anemia due to a disproportionate
increase in blood volume over red blood cell
volume
Type and Screen Results
Forward
Anti-A
0
Reverse
Anti-B Anti-Rh Type?
0
0
O-
A Cell
B Cell
Type?
4+
4+
O
• Antibody screen is positive
– Reflex red blood cell panel is performed and an Anti-D
antibody was identified
• What diagnosis do these findings suggest?
– What does the Rh +/- mean?
– Does it have anything to do with the Anti-D antibody?
Hemolytic Disease of the
Fetus/Newborn (HDFN)
Defined as the destruction of fetal and neonatal red blood cells by maternal antibodies
Historically IgG anti-Rh (anti-D) minor blood group alloantibodies were first identified
Other Minor blood group antibodies are implicated as well – however Anti-D
alloantibodies are the most immunogenic/potent
Hemolytic Disease of the
Fetus/Newborn (HDFN)
The Rh Minor blood group antigen system contains multiple antigens
However during typing the Rh +/- demarcation refers only to the Rh(D) antigen
Thus Anti-Rh allo-Ab are often incorrectly used interchangeably with Anti-D allo-Ab
Minor blood groups
• Genetics
– Similar to Major ABO genes
– Minor blood group genes code for surface
proteins (Rh system), enzymes, or nothing
(silent/amorph)
– Minor genes are also inherited in a
Co-dominant pattern
• Each parent contributes half of the
inheritance
• Individual traits are inherited
independent of each other
• Serology
– Allo-antibodies can be formed against any
minor blood group antigen
– Requires exposure which is often by unnatural
means, i.e. exposure to blood
e
A
k
D
Jka
B
E
Fyb
A
Fya
c
K
bB
Jk
C
Development of fetal allo-antibodies
1.
Mother must be antigen negative
– Antigen positive individuals will not form antibodies to self
2.
Mother must be exposed to minor antigen
–
–
–
–
3.
Feto-maternal hemorrhage
Transfusion with ABO compatible, minor group incompatible blood
Injection with needles contaminated with minor group antigen positive blood
Minor blood group mismatch allogeneic stem cell transplant
Minor antigen exposure induces antibody formation
– Exact volume unknown (varies between individuals) but as little as 0.1 mL of Rh+ RBC have
been shown to stimulate antibody production
– Larger volume of exposure tends to produce a more robust response
4.
Following antibody production mother must become pregnant with an antigen
positive fetus
– The initial response will be IgM which will not cross the placenta
•
In most cases, the first minor group incompatibility between mother and fetus will not be affected,
with exceptions
– Subsequent exposure will induce memory cells to produce IgG antibodies which will in turn
cross the placenta and cause hemolysis or clearance
Development of fetal alloantibodies
Unlike A and B antibodies,
many minor antibodies are
not naturally occurring
First Rh + child sensitizes Mother
Rh+
Rh -
Dd
dd
Dd
Dd
First
Child
IgG Alloantibodies have
developed which
cross placenta and…
Rh +
Second
Child
Mother develops Anti-D antibodies
- First round IgM antibodies
Second child conceived
Rh +
dd
Rh -
dd
Rh -
IgG antibodies
• Only IgG type antibodies
can cross the placenta
• Actively transported via a
receptor specific to IgG Fc
region
• Starts in the second trimester
and continues until birth
(passive immunization )
Pathophysiology of HDFN
• Maternal IgG antibodies cross the placenta and attach to fetal red
blood cells
• Red blood cells hemolyzed or removed via reticulo-endothelial
system
• Resultant anemia causes accelerated production of RBCs by bone
marrow, termed erythroblastosis fetalis
• In severe disease, bone morrow inevitably falls short of necessary
RBC production
• Body responds with extramedullary hematopoesis in the spleen and
liver
• Hepato-splenomegaly causes portal hypertension and
hepatocellular damage
• Anemia coupled with hypoproteinemia (decreased osmotic
pressure) leads to massive, diffuse edema (hydrops fetalis) and high
cardiac output heart failure
Hydrops and Erythroblastosis Fetalis
Sequelae of HDFN
• Hyperbilirubinemia
– RBC destruction does not cease with delivery
• IgG due to its small size as a monomer distributes throughout
tissues (intravascular and extravascular)
• IgG has a half life of 25 days
– Prior to delivery bilirubin is transported across placenta
and conjugated by maternal liver preventing
hyperbilirubinemia in utero
– Bilirubin conjugation system in a neonate is immature
• Without therapy unconjugated/indirect bilirubin can reach toxic
levels (18-20 mg/dL) and diffuse into the brain causing
kernicterus and acute bilirubin encephalopathy
Acute Bilirubin Encephalopathy and
Kernicterus
Risk Stratification and Management
for Anti-D HDFN
• Type and screen at first prenatal visit
• If Rh(D) positive there is no risk of alloimmunization
• If Rh(D) negative, fetus may be at risk
• Determine biological fathers Rh(D) status and zygocity
– If dd homozygote there is no risk of allommunization – fetus is Rh(D) negative
– If DD homozygote fetus is Rh positive – fetus may be at risk depending on screen results
– If Dd heterozygote risk of fetus being Rh(D) positive is 50% - fetal DNA studies can be
performed to confirm status – fetus may still be at risk depending on screen results
• Fetus Rh(D) positive and screen is negative – no antibodies have developed,
but may yet
–
Repeat screen at 28 weeks and following any incident in which there is increased risk of
feto-maternal hemorrhage
• Fetus Rh(D) positive and screen is positive, fetus is at risk
–
–
Perform titer of Anti-D antibodies (>1:32 is clinically significant)
Perform diagnostic techniques followed by treatment if indicated
Diagnosis and Treatment of
Intrauterine fetal anemia
• Diagnostic techniques:
–
–
–
–
Ultrasound
Doppler assessment of MCA peak velocity
Percutaneous umbilical cord sampling for fetal hematocrit
Allele-specific PCR on fetal cells in amniotic fluid
• Treatment:
– Intrauterine fetal transfusion
• Transfuse when fetal hematocrit falls below 2 standard deviations of
mean hematocrit for gestational age
• Can be performed between 18 and 35 weeks
• Intraperitoneal transfusions not as effective as intravascular
transfusions in hydropic fetus due to congested lymphatics
• ABO type O, Rh- packed RBC utilized
• Fetal loss 1-2% with overall survival of 85% after transfusion
Algorithm
for HDFN
Prevention of Rh Alloimmunization
• Anti-D immune globulin/RhIG
– IgG anti-D manufactured from human plasma (primarily
male who undergo repeat injections of Rh+ blood)
– Preparation methods
• HyperRho S/D®, RhoGAM®
– Cohn cold ethanol fractionation followed by viral-clearance
ultrafiltration – intramuscular only as IgA and other plasma proteins
have the potential to produce anaphlyaxis
• Rhophylac®, WinRho SDF®
– Ion-exchange chromatography isolation – intramuscular or IV
Prevention of Rh Alloimmunization
• Anti-D immune globulin/RhIG
– Mechanism of action: not well understood, epitope
masking?, rapid clearance of fetal RBC?
– Guidelines
• Weak D positive managed as Rh• Mother Rh-, fetus confirmed or suspected Rh+
– 300 micrograms early in third trimester
– 300 micrograms if there is increased risk of feto-maternal
hemorrhage
» Repeat doses if risk is ongoing, guided by titers or KleinhauerBethke test
– 300 micrograms within 72 hrs after delivery
» If inadvertently not administered, give ASAP – partial protection
has been seen up to 13 days after birth
Case Presentation
• Finalizing the case
– What do you order?
• Maternal Anti-D titer
– 1:64
• US of fetus and MCA peak
velocity
– Slightly hydroptic fetus
– MCA peak velocity elevated
• Fetal CBC
– Moderate anemia
• Intrauterine fetal transfusion
performed by IR
– Mom transferred to high
risk OB service where last
you heard she was doing
very well and expecting to
be discharged
Questions
?
All of these blood bank situations and
complications have driven you so crazy......
…You decide to go into psych.