Transfusion Medicine Case Study: Fetal Maternal Hemorrhage in a Trauma Patient

A 31 year old woman, gravida 1 para 0, 35 weeks pregnant, arrived in the emergency room via ambulance following a fall down the stairs. The ER ordered a CBC, Type and Screen and a Kleihauer-Betke (KB) test and sent blood to the lab. The KB result was positive with 1.1 % fetal cells. Hypothetically, if this was an exam question, you might be asked, “How many doses of Rhogam should be administered?” But, before you grab your calculators, let’s explore that a bit.

Hemolytic Disease of the Fetus and Newborn (HDFN) has been described since the early 1600s, before blood groups were recognized. In the early 1900s, pioneers in blood banking, Landsteiner and Weiner, discovered the ABO and Rh blood groups, and, later, the Rh system became associated with HDFN. However, the antibody related etiology and pathogenesis of HDFN was not recognized until the late 1930s. Thus, the disease was written about in memoirs of midwives and physicians as early as 1609, but the mechanism involved was not described for another 300 years. The KB test was developed in 1957 by Enno Kleihauer and Klaus Betke to quantitate fetal maternal hemorrhage (FMH). The KB test allows physicians to diagnose and monitor and to initiate therapy to prevent the effects of HDFN. Finally, considered one of the most significant successes in medicine, prophylaxis for Rh HDFN, Rh immune globulin (RhIg), became available in 1968. The KB test is used to quantitate FMH in RhD negative mothers and the results can be used to calculate dosage for RhIg to prevent immunization. The KB test became one of the earliest examples of using a laboratory test to determine the appropriate dosage of a drug.1

KB testing has traditionally been used for RhD negative women to detect FMH and to determine the appropriate dose of RhIg to prevent immunization. In an RhD negative woman, we are concerned with immunization if the baby and mother are not antigenically similar. An RhD negative mother is given a prophylactic dose of RhIg at 28 weeks gestation. After delivery, when a newborn has a positive DAT and the fetal screen is positive, a quantitative test is needed to determine the appropriate dose of RhIg. In prenatal maternal trauma, there can also be a fetal bleed. Much as in childbirth, in a trauma, the baby’s blood can enter the mother’s circulation. This indicates placental hemorrhage and can be a prediction of preterm labor. In prenatal maternal trauma, the KB test has been used as aid in diagnosis and prognosis of HDFN, preterm labor and fetal demise. It can be used to determine if there has been a fetal bleed, and if so, to determine how much RhIg should be administered.

But, did you know that the KB test can also be used to determine FMH in RhD positive mothers? This is considered an alternative usage of the test. In the labs where I did KB tests, most fetal screens in Blood Bank were held until the following morning and performed on day shift. So, any KB tests on postpartum patients were also mostly done on day shift. I worked 2nd shift, and it was not uncommon to see KB tests ordered on RhD positive women. In fact, most of the KB tests ordered on 2nd and 3rd shift were from the ER and on RhD positive mothers. With RhD positive mothers, providers are not concerned with the mother producing anti-D, so RhIg is not a concern. Therefore, the answer to the hypothetical question posed above, is that this mother did not need any RhIg because, by checking the lab results it would be noted that this woman was Rh positive with a negative antibody screen.

A study performed in 2004 at the Shock Trauma Center, University of Maryland in Baltimore, reported that pregnant trauma patients with positive KB tests often had pre term contractions All patients in their study who experienced preterm contractions had positive KB tests. None of the patients with negative KB tests had uterine contractions. The conclusion was that “Kleihauer-Betke testing accurately predicts the risk of preterm labor after maternal trauma. Clinical assessment does not.” 2 They additionally concluded that, with a negative KB test, electronic fetal monitoring could safely be reduced. The major statement of the study, which has been incorporated into practice guidelines was that KB testing is important for all pregnant trauma patients, regardless of Rh status.2,3

In 2019 the College of American Pathologists Transfusion, Apheresis and Cellular Therapy Committee sent a survey with their proficiency testing program to determine how many participating laboratories perform KB tests on Rh positive pregnant females. 52% of the labs who responded noted that they performed quantitative fetal hemoglobin testing for RhD positive women, and about 39% reported performing more than 20 tests a year. The CAP group also reviewed literature detailing 16 observational studies and concluded that the literature supporting relying on the KB as a predictor of fetal distress was lacking evidence and nonconclusive. Despite the fact that doctors are ordering these and many laboratories are still performing this test STAT on RhD positive mothers, different guidelines for practice are mixed regarding if and how the KB should be used in these RhD positive trauma patients. Furthermore, many labs responded on the survey that doctors considered these results very important but that the labs were not sure how the results helped guide management of the mother or fetus.4

One of the problems some of these guidelines cite is that the KB test may not be rapid enough to use in trauma situations. Now, I have to start by saying that KB tests are probably no tech’s favorite test. The last hospital I worked at did KB tests in Hematology. Before that I worked at a hospital where we did KB tests in Blood Bank. There seems to be no way to avoid them! I would have to agree that a KB is not at all rapid. The test is both time sensitive, always ordered STAT, and very time consuming. Hands on time is considerable. I’ve gotten 2 in one night, on 2nd shift with only 4 or 5 techs manning the whole lab, and that makes for a busy night! Add a trauma or 2 to the mix, or a few units to wash for the NICU and you know why “Kleihaur-Betke” are not our favorite words.

Another concern is that the KB test is marketed as a quantitative test. The problem with this is that it is not very precise due to technical difficulty. In the KB acid elution test the mother’s blood is treated with acid and then stained and counterstained. Fetal cells contain HbF which is resistant to acid and these cells will remain bright pink. The mother’s cells, which are primarily HbA, will appear as faint ‘ghost’ cells. 2000 cells are counted and the percent of fetal cells is determined. The test is complicated and needs precision in staining, counting and calculations. A slide that’s too thick, poor timing of steps, slides that are not adequately dried, or fetal cells that fail to stain can all affect results and cause false negative results. In pregnant women HbF may be increased, and in women with hemoglobinopathies such as sickle cell anemia and thalassemia Hb-F can be increased, leading to false positive results. As well, late in pregnancy it would be considered normal to have some fetal cells in the mother’s circulation. Thus, both false negative and false positive KB results are not uncommon, and a positive report on a KB test may not accurately predict fetal distress.

Image 1. Kleihauer-Betke stain showing dark ink fetal cells and ‘ghost’ like pale maternal cells

In the CAP survey article, it was noted that, of participating labs, about 96% did KB tests and 4% use flow cytometry.4 Flow cytometry is accurate, sensitive and reliable for HbF determination. Flow cytometry uses antibodies directed against fetal hemoglobin and antibodies directed against adult RBCs. A clear separation of populations can be identified and quantitated. Despite the fact that it is well known that flow cytometry is a much more precise test for FMH, many laboratories continue to do KB testing. This is likely due to the fact that only a small percentage of labs have flow cytometers. If, in trauma situations, physicians want HbF determination with a “fast” turnaround time, KB testing can be done in house with no equipment necessary. This is not fast, but would, in most circumstances, be faster than sending a test to a reference lab.

The KB test has historically been validated and used to estimate the total amount of FMH, and the results used to calculate if additional doses of RhIg are indicated. The test has high specificity for HbF but can be subjective. Precision between techs and even with the same tech repeating the test can be relatively low. Because of this, the formula used to calculate RhIg dosage has a factor built in to make up for any imprecision. An alternate usage of the test, and the one used in this case example, is to predict outcomes and guide treatment in maternal trauma victims, regardless of Rh status.

While there is some controversy on using the KB test in these cases, it is none the less still recommended by many authors and included in medical guidelines.5 Providers are using the KB test more and more for assessing placental hemorrhage in cases of trauma and premature labor. Though immunophenotyping by flow cytometry has a greater accuracy, the KB test can give reliable results at a lower cost and with a faster turnaround time.

As always, this blog led me off on several tangents while writing. When I have an idea for a blog, I start with a case study or an interesting sample I have seen in the lab. The case study itself is the easy part, then I start researching and reading articles about the disorder, test or phenomenon that I am writing about. Often, when I read one article, I ask myself another question and say, “what if…?” and that leads to another article and another and another. Days later I can still find myself reading articles and chasing after more information. I love my job, I love being a Medical Laboratory Scientist and educator, and in true form of the curious MLS, I always want to investigate and never want to stop learning. Thus, this simple case about an alternative usage of Kleihauer-Betke (KB) test kept developing as I wrote. As a side note, it was interesting to see that the studies have had different conclusions and the guidelines for this use of the KB test have swayed over the years. It will be interesting to see what the future will bring. I have seen some articles about adding the HbF determination to hematology analyzers—wouldn’t that be nice!

References

  1. Reali G. Forty years of anti-D immunoprophylaxis. Blood Transfus. 2007;5(1):3-6. doi:10.2450/2007.0b18-06
  2. Muench MV, Baschat AA, Reddy UM, Mighty HE, Weiner CP, Scalea TM, et al. Kleinhauer-betke testing is important in all cases of maternal trauma. J Trauma 2004;57(5):1094-8.
  3. Michael V. Muench, Joseph C. Canterino, Trauma in Pregnancy, Obstetrics and Gynecology Clinics of North America, Volume 34, Issue 3, 2007, Pages 555-583.
  4. Matthew S. Karafin, Chad Glisch, et al, for the College of American Pathologists, Transfusion, Apheresis, and Cellular Therapy Committee; Use of Fetal Hemoglobin Quantitation for Rh-Positive Pregnant Females: A National Survey and Review of the Literature. Arch Pathol Lab Med 1 December 2019; 143 (12): 1539–1544.
  5. Krywko DM, Yarrarapu SNS, Shunkwiler SM. Kleihauer Betke Test. [Updated 2020 Sep 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan.

-Becky Socha, MS, MLS(ASCP)CM BB CM graduated from Merrimack College in N. Andover, Massachusetts with a BS in Medical Technology and completed her MS in Clinical Laboratory Sciences at the University of Massachusetts, Lowell. She has worked as a Medical Technologist for over 30 years. She’s worked in all areas of the clinical laboratory, but has a special interest in Hematology and Blood Banking. When she’s not busy being a mad scientist, she can be found outside riding her bicycle.

Patient Advocacy in Transfusion Medicine

Since 2008 I have served as the Associate Medical Director and the Medical Director of Transfusion Medicine in a large academic medical center. In addition to overseeing the operations of our transfusion service, I also spend several days per week in our apheresis unit. We currently see between 10-20 patients daily for a wide range of therapeutic apheresis procedures performed by our 5 apheresis nurses including stem cell collection and lymphapheresis procedures for stem cell transplant and CarTcell therapy, respectively. These procedures can last from 90 minutes to 6 hours and includes both outpatients as well as acutely ill patients in our critical care units. Typically we perform procedures from 8 AM to 6 PM but there are frequent requests for procedures that last beyond these hours and occasionally in the middle of the night for life threatening conditions. Despite the long hours and unpredictable days, this provides an opportunity to bond with patients over the hours and days they spend in our apheresis unit.

I remember the first time I met Reed. He was sitting on the side of his hospital bed and was bald and pale in stark contrast to his dark blue pajamas. Although he was thin, I could tell that he was a much bigger man before chemotherapy and the transplant ravaged his body. I introduced myself and he was pleasant and engaging despite how ill he was. He had recently undergone 2 autologous stem cell transplants and now with recurrence of the multiple myeloma he had received his brother’s stem cells and was suffering severe acute graft vs. host disease (GVHD). His entire gastrointestinal (GI) tract was under assault as he was diagnosed with Grade IV GI GVHD and was losing liters of bloody stool daily. Despite the abdominal pain and cramps, I never saw him without a smile on his face. He had been treated with high doses of immunosuppression but his GVHD was unresponsive and now we were called in to perform photopheresis, which has great results for skin and pulmonary GVHD but has not been as effective for GI GVHD. In fact, all our previous patients with Grade IV GI GVHD lost their battle.

The bone marrow transplant physician advised Reed that his prognosis was poor and that he should get his affairs in order. His response to the BMT physician was, I am not leaving my wife to raise our three children by herself and I am going to walk out of this hospital. We performed photopheresis twice a week every week and gradually his symptoms improved. His hair started growing back, his color returned, and he kept his word and walked out of the hospital. He continued photopheresis twice a week every two weeks for 2 years. During that time, he met my son who was only 8 at the time and I met his wife and children. He always asked how my son was every time he came for his treatment and what activities he was involved in. When he finished his 2 years of photopheresis, he brought every pathologist and nurse a long stem red rose and thanked us for saving his life.  

Several years later, Reed started to experience renal failure as another complication of GVHD and again he was referred to our clinic for plasmapheresis. We picked up where we left off during his weekly treatments. Again, his positive attitude and compliance with treatment were successful in saving his kidneys. This past summer I went to an outdoor concert. At the end of the night, when everyone was leaving, I saw Reed and his wife! I was so happy to see him looking healthy and strong. I introduced him to everyone who was with me, telling them that Reed was our miracle patient, the only patient that survived Grade IV GI GVHD. This fall, a card was delivered to my office. It was a birthday card from Reed to celebrate my 50th birthday! That is so typical of Reed, still thinking about others and wanting to do what he can to show how important others are to him!!

-Kimberly Sanford, MD is the Medical Director of Transfusion Medicine at Virginia Commonwealth University Health.

Review: Blood Supplies During the COVID-19 Pandemic

When I first thought of writing a blog on blood supplies amid the COVID-19 pandemic, it was early March. Fast forward a couple months and a lot of things have changed. So, where were we, and where are we now?

January 6, 2020

At this time, most people in the US were not even aware of the novel coronavirus. (unless you were taking my Introduction to Human Disease course and were searching online for media articles about infectious disease!)

I first became aware of this ‘mystery’ virus in early January, when I was teaching an online Winter session course called Introduction to Human Disease. I developed this course a number of years ago as a STEM course for non-science majors. The intent of the course is to familiarize students with diseases and disease terminology that they will use in their everyday lives. The course gives students a chance to learn basic medical concepts that will enable them to become their own (or their family’s) medical advocate. In addition, the course covers many diseases that are ‘in the news’ and allows students to gain some knowledge and insight into the myths and facts surrounding these diseases. Topics covered include general mechanisms of disease, including inflammation, infectious disease, immunity, heredity, and cancer. Emphasis is placed on emerging and pandemic …. so, when this disease emerged, we were right there to take note!

I asked the students to find an article in the media on an infectious disease, and to summarize and answer questions about the article and the mechanism of the disease. Three students chose different articles about this yet unnamed mystery illness affecting people in Wuhan, China. We had active discussion board conversations about this emerging severe respiratory disease and pneumonia, that at the time had infected around 40 people, with no reported deaths, and no human to human transmission. In my comments, I compared this novel virus to seasonal influenza, H1N1, SARS and MERS and tried to reassure students that this would hopefully follow the same path as H1N1 or SARS and MERS.

Feb 21, 2020

The first confirmed case in the United States was on Jan 21 in Washington state. (CDC)1 On Jan 31, the Health and Human Services Secretary declared Coronavirus a Public Health Emergency in the US. (HHS.gov)2 We began hearing news of restrictions on flights from China, passengers affected on Princess Cruise ships and outbreaks at a long term care facility in Washington State. 

As a Medical laboratory Scientist, I became concerned with this virus early on, and started watching statistics. I was concerned not only for the health of my family, friends and coworkers, but also for the health or our laboratories and our blood supply.

The first journal articles I read about COVID-19 and blood safety were published in Transfusion Medicine Reviews on Feb 21, 2020. In the very early days of this novel coronavirus, researchers in China reviewed publications about SARS and MERS to help give us a better understanding of SARS-CoV-2, the virus that causes our current pandemic of COVID-19. When discussing blood safety, one of the first things to consider is if the virus is transmittable via blood transfusions. If the virus is transmittable, we also must consider if there is an asymptomatic time when there is virus in the blood. One review stated that SARS, MERS and SARS-CoV-2 can all be found in the serum or plasma, but, at the time of this review, it was still uncertain if SARS-CoV-2 could be transmitted from those with pre-symptomatic or asymptomatic infections.3

March 18, 2020

On March 18, Blood Transfusion published an article written by a group at several Blood Centers in a few provinces in China. This article discussed efforts to minimize the impact of blood shortages due to COVID-19. It was noted that the rising pandemic had had a profound impact on the number of blood donations, and on blood safety. Because it was now recognized that there is a long incubation period and a significant number of asymptomatic cases, this posed a huge challenge in recruiting blood donors. In China, strictly restricted mobility led to a decrease in donations across the country. Donors were recruited through various methods, including the use of social media. Social distancing during blood donations and thorough cleaning and disinfecting of donor areas were enforced. Screening procedures were enhanced to include temporary isolation of blood products for 14 days after collection and delaying release for clinical use. At the same time, donors were followed up until the expiration of the products. If a donor was found to test positive for COVID-19 after donation, the blood products were recalled. These new protocols in place were helping to insure adequate donations and the safety of blood products. ne interesting note is that this article referred to the epidemic as “effectively controlled” and that “normal medical services had been resumed”.4

Meanwhile, in the US, American Red Cross was pleading for blood donors. On March 17 it was reported that 2,700 mobile blood drives had been cancelled at a loss of 86,000 units of blood potentially collected. On March 21, 4 days later, that number had risen to more than 5,000 blood drives canceled at a loss of 170,000 units. As more schools, workplaces, churches and college campuses closed down in response to the pandemic, those institutions had to cancel their blood drives. Social distancing guidelines and shelter in place orders resulted in fewer people donating blood. In addition, an FDA mandate from February, that people who had traveled to areas with COVID-19 outbreaks should wait at least 28 days before donating blood, most likely contributed to the shortage. Dr. Justin Kreuter, from the Mayo Clinic Blood Donor Center, stated that the blood shortage was not due to more COVID-19 patients needing blood products. Rather, “it’s a lack of donations coming in.”5

April 1, 2020

procedures that the Chinese had instated. Mobile blood drives were shut down, but collection centers remained open. TV commercials, radio ads, You Tube videos and social media called for blood donors, assuring them that this was essential and that donating blood was safe. Donations were arranged through appointments only, and potential donors contacted and verbally screened for symptoms and risk factors before appearing to donate. On arrival at the centers, temperatures were taken and travel and symptoms questions were asked before a donor was allowed to enter the center. The use of masks and social distancing, along with extra cleaning and donor chair decontamination between donors were all implemented.

In an effort to open up the pool of potential donors, the FDA reviewed current studies and epidemiological data and concluded that certain donor eligibility criteria could be modified without compromising the safety of the blood supply. On April 2, 2020 the FDA approved several important changes in donor qualifications. These revisions included the following:

  • For male donors deferred for having sex with another male: the recommended deferral period changed from 12 months to 3 months.
  • For female donors deferred for having sex with a man who had sex with another man: the recommended deferral period changed from 12 months to 3 months
  • The deferral period for recent tattoos and piercing was changed from 12 months to 3 months
  • For people who have traveled to malaria-endemic areas, the recommended deferral period was changed from 12 months to 3 months. In addition, the guidance notes that deferral can be waived for these donors, provided the blood components are pathogen-reduced using an FDA-approved pathogen reduction device.
  • For donors who spent time in European countries or on military bases in Europe who were previously deferred due to potential risk of transmission of Creutzfeldt-Jakob Disease or Variant Creutzfeldt-Jakob Disease, the FDA has eliminated the deferrals and these individuals may now qualify to donate.6

Despite loosening requirements, advertising, and calls from the blood centers for additional donors, the shortages remained. To address the decline in blood product availability, it became essential to review the principles of patient blood management (PBM). PBM is defined as “the timely application of evidence-based medical and surgical concepts designed to maintain hemoglobin concentration, optimize hemostasis and minimize blood loss in an effort to improve patient outcome.”7 Firstly, elective procedures were put on hold, thus freeing up units for the most needy patients. Despite this, many blood banks still had their standing orders decreased. In many cases, Blood bank Medical Directors approved changes in transfusion triggers. At the hospital where I work, the transfusion trigger was changed from a hemoglobin of 8g/dL to 7 g/dL. New changes of SOP were approved to issue to all patients, except females of child bearing age, Rh positive units instead of more scarce Rh negative units. We also have a large NICU unit and baby units were not available from ARC, so we were using the newest units available, when necessary for these patients.

By April 8, 15,000 blood drives had been cancelled across the US, at a potential loss of almost 500,000 donated units. One technologist reported in an online Blood bank professionals group, that “Our supplier downgraded us in terms of standard inventory (about 40%), but our transfusion numbers have dropped at least as much.”8 With the decrease in usage and the careful patient blood management, blood needs were met.

May 12, 2020

AABB began sending out a weekly COVID impact survey for hospital transfusion services survey in late March. Many questions on the survey, and the resulting charts and graphs, are related to COVID convalescent plasma practices and procedures (details in my next blog!), but one important graph produced by this survey shows the increase in inventory wastage due to changes related to COVID-19. These changes due to COVID-19 can be a decrease in patients and elective surgeries or changes in transfusion protocols. In early April, in the first few weeks of the survey, 25%-28% of hospitals responding reported an increase in inventory wastage. This corresponds to when donors started coming back to donate, and usage dropped. This percent of hospitals reporting wastage increased each week until the week of May 4-7 when 54% of hospitals reported inventory wastage. This may be due to several factors. The units collected at the end of March and early April, have reached their 42 day expirations. Donors came out initially in response to the call for blood, but now, these units have expired, and it has not yet been 56 days when these donors can donate again. Usage also decreased during this time. COVID patients have not generally had heavy use of red cells, in particular, and doctors have been very conservative in usage with all patients. For the week of May 11-14, as more hospitals are planning to resume elective surgeries, and for the first time in the 8 weeks, fewer hospitals (52.0%) reported an increase in wastage due to changes related to the pandemic. Of the 100 respondents, 59% reported they are resuming “some” elective surgeries before mid-May and 28.0% are doing so after mid-May.9

What does this mean for the future of our blood supply during this pandemic? On May 12, a group of Blood bank professionals, when asked in an informal online survey, had had varying answers. These were likely dependent on location, both geographic and city vs. rural, and size of the hospital. One comment was that “We have gone from huge shortages to throwing away massive units not being used. Hospital is empty.” Another tech said “We were way overstocked a week ago, now we’re dipping way below average.” Technologists in Florida, Oregon and Pennsylvania reported low inventory. Techs in Ohio and Maryland reported their inventory to be very healthy. But these reports could easily vary between areas of the individual state, and even different hospitals in the same city. Another technologist commented “We had a mass of donors when this all started and now all those units are expiring!” The shortage of donors will likely continue, but may relax a bit with some states beginning to lift restrictions. We likely won’t see a huge drove of donors, all at once, which is actually good because it will spread out expiration dates. But, though things may be opening up, it is unlikely that we will see blood drives at schools, workplaces and churches for some time, and this is a huge source of our countries blood supply.

We have seen a big swing in both inventories and usage. After elective and with surgeries have been put on hold for months, we may see an increase over the typical number of elective surgeries, which will mean we will see an increase in blood usage, and with a lack of donors, inventories may drop again.

As far as blood safety, we know now that SARS-CoV-2 did not follow the path of SARS and MERS. We know that it can definitely be transmitted from person to person, and can be transmitted by people who are asymptomatic. But, we also know that, in general, respiratory viruses are not known to be transmitted by blood transfusion. So, from what we know at this time, it is likely not necessary to routinely screen blood products for SARS-CoV-2, and not necessary to isolate blood products after collection and delay release of the products. It is recommended that blood centers encourage self-deferral for donors who have traveled to a COVID-19 affected area or been in contact with an infected person in the past 14 days and to screen donors carefully for fever and respiratory symptoms. With these practices in place, we can ensure an adequate and safe blood supply. We will continue to see swings in volumes, but with careful patient blood management, we will ride these waves and come out on top. Thanks to all our wonderful Blood Bank Technologists who are helping manage our country’s blood supplies!

References

  1. First Travel-related Case of 2019 Novel Coronavirus Detected in United States – CDC, January 21, 2020
  2. https://www.hhs.gov/about/news/2020/01/31/secretary-azar-declares-public-health-emergency-us-2019-novel-coronavirus.html
  3. L. Chang, Y. Yan, L. Wang Coronavirus disease 2019: coronaviruses and blood safety. Transfus Med Rev (2020)
  4. Xiaohong, et al. Blood transfusion during the COVID-19 outbreak, Blood Transfusion (2020)
  5. https://newsnetwork.mayoclinic.org/discussion/critical-blood-shortages-because-of-covid-19/
  6. https://www.fda.gov/media/92490/download
  7. http://sabm.org
  8. Facebook Blood Bank professionals page, May 12, 2020
  9. http://www.aabb.org/advocacy/regulatorygovernment/Documents/AABB-COVID-19-Impact-Survey-Snapshot.pdf

-Becky Socha, MS, MLS(ASCP)CM BB CM graduated from Merrimack College in N. Andover, Massachusetts with a BS in Medical Technology and completed her MS in Clinical Laboratory Sciences at the University of Massachusetts, Lowell. She has worked as a Medical Technologist for over 30 years. She’s worked in all areas of the clinical laboratory, but has a special interest in Hematology and Blood Banking. When she’s not busy being a mad scientist, she can be found outside riding her bicycle.

Transfusion Medicine Case Study: Positive Pretransfusion Test

A 72 year old man was admitted to the hospital for an aneurysm repair. The physician ordered a type and crossmatch for 6 units of blood in preparation for surgery. The patient history included surgery in 2016 during which he was transfused with 4 units of RBCs.

patient’s blood type: A positive

antibody screen: negative

history: anti Jkb  (2016)

6 Jkb negative units were found and full crossmatches were performed. One of the 6 donor units was incompatible. What is the most probable explanation for these findings?

If the patient has a negative antibody screen, and no history of an antibody, most facilities would do an electronic crossmatch or an immediate spin crossmatch. The immediate spin (abbreviated) crossmatch will simply verify ABO compatibility. However, if the patient has a positive antibody screen, we must identify the antibody, phenotype the patient, and do a full AHG crossmatch with donor units that are antigen negative for the corresponding antibody. In this case, the patient had a history of an antibody, so the antibody must be honored, and antigen negative units must be chosen for transfusion.

Kidd antibodies demonstrate dosage, are often weak, and can be found in combination with other antibodies. Because if this, they can be notoriously difficult to detect. They are usually IgG and are made in response to transfusion or pregnancy. Jkb has an antigen frequency of about 73% in the white population and about 43% in the black population. To find antigen negative blood, we consider that about 27% of units would be antigen negative. The tech working on the sample screened 21 units and found 6 that were Jkb negative.

AHG crossmatch results:

unit 1: compatible

unit 2: compatible

unit 3: compatible

unit 4: 3+ at AHG

unit 5: compatible

unit 6: compatible

There are 2 possible scenarios for the above results. A crossmatch is a test between donor’s red blood cells and patient’s plasma. Antigens, we know, are on red blood cells and antibodies are detected in the plasma. So, with a negative antibody screen, crossmatch incompatibility is due either to a patient antibody to a low incidence antigen on the donor red blood cells, or a donor cells with a positive direct antiglobulin test. We can easily rule in or out a positive donor DAT by performing a DAT on the segment. If the donor unit has a positive DAT, the unit should be quarantined and the positive DAT reported to the collecting facility. If the donor unit has a negative DAT, the patient likely has an antibody to a low incidence antigen.

Low frequency antigens are uncommon, but antibodies that recognize them are less rare. Fortunately, for patients with these antibodies to low frequency antigens, finding antigen negative compatible blood is easy. As we can see, 5 of the 6 chosen units were negative for the unknown low frequency antigen and were antiglobulin crossmatch compatible. The low prevalence of the antigen makes compatible blood readily available. If transfusion is necessary, it should not be delayed while waiting for identification of the antibody.

In this case, the antibody screen was repeated and the negative result was verified. In many cases, it may not be possible for a lab to identify the antibody because the lab may not have the necessary panel cells or typing reagents. Yet, these antibodies to low incidence antigens that react at AHG can be clinically significant and cause severe hemolytic transfusion reactions. To identify the antibody, you may need to send the sample to a reference lab for testing against a panel of reagent red cells that express low incidence antigens. Alternately, the donor red cells that were incompatible can be tested against known antibodies to low prevalence antigens  to help identify the antibody.

In this patient, anti-Wra was identified. The incompatible donor unit was verified to be Wra positive. Wra is part of the Diego system, usually IgG, and has ben implicated in hemolytic transfusion reactions.

One of the reasons I have written up this case is questions my Transfusion Medicine students often ask about exam and exam prep questions concerning incompatibility. Below are 2 questions to give examples of the confusion.

“At the indirect antiglobulin phase of testing, there is no agglutination between patient serum and screening cells. One of 3 donor units was incompatible.. The most probable explanation for these findings is that the:

  1. patient has an antibody directed against a high incidence antigen
  2. patient has an antibody directed against a low incidence antigen
  3. donor has an antibody directed against donor cells
  4. donor has a positive antibody screen”5

answer: b

“Which of the following would most likely be responsible for an incompatible antiglobulin crossmatch?

  1. recipient’s red cells possess a low incidence antigen
  2. anti-K antibody in donor serum
  3. recipient’s red cells are polyagglutinable
  4. donor red cells have a positive direct antiglobulin test”4

answer: d

I am asked why is one answer “low prevalence antigen” and one answer “positive DAT”? I typically ask questions of my students to let them reason out the answer. Take a careful look at the words antigen and antibody. Remember that a DAT is a test of red cells, the IAT tests for antibodies in plasma. A crossmatch uses donor red cells against patient plasma. Therefore, even though these are both reasons for the incompatibility of one out of multiple units, each question only has one answer of a common reason for such incompatibility. Be sure to read questions and use your theory and knowledge of testing when encountering discrepancies and problems in Blood Bank. To all of my students: Happy Studying for your ASCP exam!

References

  1. Fung, Mark K., Technical Manual 18th ed, Bethesda: AABB, 2014.
  2. Harmening, Denise M. Modern Blood Banking and Transfusion Practices, 7th edition, 2019.
  3. Schonewille, Henk, et al. “The importance of antibodies against low‐incidence RBC antigens in complete and abbreviated cross‐matching”. The Journal of AABB. 20 June 2003.
  4. BOC Study Guide, 5th edition. Clinical Laboratory Certification Examinations.  ASCP, 2016
  5. BOC Study Guide, 6th edition. Clinical Laboratory Certification Examinations.  ASCP, 2018

-Becky Socha, MS, MLS(ASCP)CM BB CM graduated from Merrimack College in N. Andover, Massachusetts with a BS in Medical Technology and completed her MS in Clinical Laboratory Sciences at the University of Massachusetts, Lowell. She has worked as a Medical Technologist for over 30 years. She’s worked in all areas of the clinical laboratory, but has a special interest in Hematology and Blood Banking. When she’s not busy being a mad scientist, she can be found outside riding her bicycle.

The Best Gift of the Season: A Gift of Self

We few, we happy few, we band of brothers;

For he today that sheds his blood with me

Shall be my brother.

Henry V (Act 4, scene 3), Shakespeare.

Good morning! We’re entering the holiday season, and it’s an exciting time for all. I love seeing the ethnic and cultural diversity as we all celebrate our favorite holidays with family and friends. I myself look forward to the holiday season. It’s a festive time and a season of giving and sharing. It’s a favorite time of year to share traditions and create new ones. However, at a time when stores have Christmas candy on the shelves, holiday lights up and holiday music playing on the day after Halloween, I feel a bit rushed and want to slow down and find better ways to celebrate and enjoy the season. Over the past few years I have been making a special effort to become more environmentally conscious; remembering my reusable bags at stores, purchasing more reusable products, and reusing, recycling, and upcycling whenever I can. I belong to a community ‘buy nothing’ group and am warmed by the generosity of strangers to others in the community. It’s wonderful to give from our abundance and to receive wish list items from neighbors without having to exchange money. And it’s great for the environment, too. Used items are being put to use by others, and not into landfills. People in the community have asked for or gifted furniture, clothing, tools, toys and many other goods and services. I have gifted no longer needed clothing, household items, excess fabric from my fabric stash, and donated my time to participate in a career fair at a local high school. I have been given a car set for my grandchildren when they visit, toys, and someone even loaned me a bike trailer so we could take my granddaughter out for a bike ride. The generosity makes it feel like the holiday season all year round.

So, you may be asking, “where is this blog going?” I saw a memo from Red Cross this week that there is a critical need for blood and platelets and thought that giving to our community with the gift of blood would be a wonderful way to make this holiday season even better! It’s one of the most generous gifts we can give, and costs nothing. Every 2 seconds in the US, someone needs a blood product. That’s about 36,000 units of red blood cells, 7,000 units of platelets and 10,000 units of plasma needed every day. 21 million blood products are transfused every year.1 That’s a lot of blood. And, these blood products cannot be manufactured, so must come from volunteer donors.

In the US, we need to collect about 13,000 units a day to meet demand. Approximately 14 million units of whole blood are collected each year from roughly 7 million donors.1 The blood is processed into components and used in the treatment of surgical, obstetric, oncology, and other patients. One unit of whole blood can be made into up to 3 components and used to help up to 3 patients. Yet, even with all these donations we still cannot keep up with demand. Weather, holidays, illness and travel can all affect blood donations. Shortages are not just apparent during the winter holiday season. This past summer, the Red Cross announced a critical blood shortage around the July 4th holiday. Compared to other weeks, there were 17,000 fewer blood donations during the week of July 4th. As of July 9, the Red Cross had less than a three-day supply of most blood types and less than a two-day supply of Type O blood. 2 During the summer, and particularly during the holiday week, people are busy with other activities or traveling. In the winter, busy schedules, holiday travel, winter weather and seasonal illnesses contribute to fewer blood and platelet donations. Severe weather can also cause the cancellation of blood drives which greatly impact the blood supply.

Some people donate blood because they see this critical need and hear the calls for blood. Others donate because a classmate or friend asked them to. Some people feel it’s their civic duty. For some, it just makes them feel good to help another person. And, others donate for the cookies and tee shirt. Yet, for all donors, it is a form of volunteerism and giving to the community. But, did you know that, other than the benefits from helping others, there are benefits to the donor, as well? Helping others can improve our emotional and physical health. It can help reduce stress, improve emotional well-being and help people feel a sense of belonging. A study conducted in Sweden concluded that regular blood donors enjoy better than average health.Blood donors had an overall mortality 30% lower and a cancer incidence 4% lower than the control population.3 Donating blood may help reduce high iron stores, a risk factor for heart attack. In addition, there have been several studies over the past few years, exploring the hypothesis that regular blood donations may help in the management of hypertension and high cholesterol.

Another interesting benefit of blood donation is being able to contribute to science and research. For example, there is currently a study being conducted on donor blood to test an investigational nucleic acid test for Babesia microti. Babesia microti is responsible for most transfusion-transmitted babesiosis cases in the United States, but there is no licensed test for screening for B. microti in donated blood. Participation in this study can help obtain FDA approval for a screening test. By giving your consent to use your blood sample, there is no additional blood taken and no further time commitment, but you can help protect the public health by supporting the development of a new blood safety test.

How can we, as individuals, help? About 38% of the population is eligible to donate blood, but less than 10% of the population actually donates. To be eligible to donate, you should be in good general health and feeling well. You must be at least 17 years old in most states (16 years old with parental consent in some states) but there is no age limit to donation. Adult doors must weigh 110 lbs, but there are additional height and weight requirements for donors 18 years old and younger. There have also been some recent changes to blood donor requirements. I will not be able list all of them here, but some of them don’t change a deferral, only the reasoning behind the deferral. One of the most prominent changes is, as of 2016, the indefinite deferral for men who have had sex with men, has been changed to a 12 month deferral since the last sexual contact with another man . Also changed is the minimum hemoglobin for male donors. This has been raised from 12.5g/dl to 13.0 g/dl. Until this time, the cutoff was the same for both males and females. Males with a Hgb below 13.0 g/dl are considered anemic and are no longer eligible to donate blood. On the other hand, the criteria for females to be mildly anemic is a Hgb below 12.0 g/dl, so females between 12.0 g/dl and 12.5 g/dl, though not considered anemic, are still not eligible to donate. The minimum hemoglobin for females has not changed and remains 12.5 g/dl. To review other eligibility requirements, visit https://www.redcrossblood.org/donate-blood/how-to-donate/common-concerns/first-time-donors.html

So, in this busy season, we often find ourselves with little time to get our own “to do” lists done, yet alone volunteer our time for others. But most of us would welcome an hour to reduce stress and improve our emotional well-being. Please consider a gift of self this season. It takes about an hour of your time, you get to sit and relax with your feet up, to feel good about yourself, and you’ll even get a snack!

Happy Holidays!

References

  1. redcrossblood.org
  2. https://news.azpm.org/p/news-splash/2019/7/19/155196-fourth-of-july-donation-slowdown-leads-to-blood-shortage/
  3. Edgre, G et al. Improving health profile of blood donors as a consequence of transfusion safety efforts. Transfusion. 2007 Nov;47(11):2017-24.
  4. Kamhieh-Milz S, et al.Regular blood donation may help in the management of hypertension: an observational study on 292 blood donors. Transfusion. 2016 Mar;56(3):637-44. doi: 10.1111/trf.13428. Epub 2015 Dec 8.

-Becky Socha, MS, MLS(ASCP)CM BB CM graduated from Merrimack College in N. Andover, Massachusetts with a BS in Medical Technology and completed her MS in Clinical Laboratory Sciences at the University of Massachusetts, Lowell. She has worked as a Medical Technologist for over 30 years. She’s worked in all areas of the clinical laboratory, but has a special interest in Hematology and Blood Banking. When she’s not busy being a mad scientist, she can be found outside riding her bicycle.