Availability of the Kleihauer-Betke test for work up of fetal bleeding following maternal trauma

A colleague who works at a trauma center in Southern California wants to know the availability of the Kleihauer-Betke (KB) test for work up of fetal bleeding following maternal trauma. For example, at his hospital, the KB test is only available on day shift, so that the turnaround time for the test can be a full day, depending on when a specimen is submitted to the laboratory. The inquiring colleague would like to know what is the practice at other institutions, and if the KB test is not available around the clock, what other tests are used to assist in the rule out of significant fetal bleeding following traumatic injury to a pregnant patient.

The following comments have been submitted in response.

ADDENDA Dec. 30, 2009

1. At the academic center in Michigan at which the responding colleague works, the KB testing is available in that facility 24/7.
   
   
2. At the university hospital in Virginia at which the responding physician works, the KB test is available at all times.
   
   
3. A transfusion medicine physician in New York reports that they have the Kleihauer-Betke (KB) test available 24/7 at their 750 bed university hospital/trauma center. Their OBs like to have one more indicator of possible large fetal bleeds, although the responding physician believes there are better techniques for assessing fetal anemia/distress, particularly ultrasound. The KB can be misleading as a large fetal blood volume in the maternal circulation can be a result of a slow constant bleed, not just an acute traumatic bleed (usually the question being asked). So the responding physician would rather be guided by what the OBs really need. The KB test is a difficult test to do well, particularly if you use something other than flow (which probably isn't going to be available 24/7). But if you're a level 1 trauma center and do high risk OB, the responding physician suspects it's reasonable to have the KB test available in large tertiary care hospitals. Obviously it is not needed 24/7 to assess Rh immune globulin dose, because there is usually no real urgency about giving Rh immune globulin in most instances.
   
   
4. At the VA hospital at which the responding physician currently works, the KB test is not performed on site because the patient population (almost exclusively men and a few older woman at this point) does not warrant it. In the rare instance in which this testing would be indicated (and the responding physician expects this need to increase with time) it is sent to a local reference lab. The local labs available for such testing are able to perform the testing STAT if the clinical need for such testing requires STAT testing. In terms of the need for STAT testing, a little background first. The package insert for RHIG indicates that it should be administered within three days of delivery. This is based on scientific studies, well referenced in Mollison's text, that a short delay in RHIG administration even to Rh- volunteers administered large quantities of Rh+ blood, still provides complete protection against alloimmunization. So, in the case of trauma of an Rh-pregnant women, the issue of a delay in calculating the dose of RHIG should not be a reason for STAT testing. More germane, of course, is to calculate the quantity of fetal hemorrhage as a way of assessing the extent of trauma to the fetus and to make appropriate clinical decisions based on this (? early delivery perhaps; ? need for intrauterine transfusion). These are legitimate concerns and the clinical assessment of the mother and fetus by various monitoring techniques would provide much needed information. In such cases the KB test can add important supplementary information to the clinical assessment. Whether the results of the KB test are critical to patient management such that it must be performed STAT is a question the responding physician would refer to the high risk OB-GYN specialists.

ADDENDA Jan. 3, 2010

5. A transfusion medicine physician at a teaching hospital in Southern California is quite surprised that so many other institutions make the KB test available around the clock. At her institution the K-B is available 7 days/week, but on a routine (day shift only) basis. There has been disagreement between the Transfusion Medicine service and the Obstetric service as to the utility and need for this test. As most blood bankers know, the KB test is highly subjective and difficult to reproduce. Additionally, certain patient populations may normally retain fetal hemoglobin, giving false positive results. In general, most pregnant trauma victims will have too little fetal blood in the maternal system to detect reliably and major bleeds will result in fetal distress causing either death or delivery before a KB test can be done. However, their Obstetrician colleagues tell her that the KB is part of the standard of care for their pregnant patients who have suffered trauma. They agree that they would be unlikely to act on a KB test result alone (example: high % of fetal cells but no ultrasound, heart rate or movement abnormalities would not result in an emergency delivery; conversly a negative KB test result in a patient with ultrasound abnormalities, erratic heart rate or sudden cessation of fetal movements would result in intervention.) Because of community standards, however, it is a service that her Blood Bank provides. To strike a balance between practical and useful, the responding colleague's transfusion service laboratory has agreed to do KB tests on trauma patients as routine tests only. This is for documentation in the chart. STAT KB tests are avoided because the test result is unlikely to change treatment. If a STAT is felt to be warranted it is only approved when an OB Attending specifically requests it, not an intern or resident. So far, in the 4 years that they have taken the aforementioned approach, they have never had an Attending OB request a STAT KB and the routine, next day run has been sufficient.
   
   
6. A colleague in Iowa reports that the KB test is available on a stat basis 24 hr/day at his ~ 50 bed, rural hospital. It is used the vast majority of the time by their sole OB/GYN physician and occasionally by a handful of general practitioners who do deliveries. Referring 'difficult' cases to their urban medical centers that are about 40 miles away; the test's availability offers more prompt service to their patients. They have a lab staff of about 10 MT/MLTs who feel comfortable with the procedure and who have scored well on CAP surveys.

ADDENDA Jan. 20, 2010

7. The medical director of a transfusion service at an academic medical center in Ohio reports that her laboratory does not perform Kleihauer-Betke (KB) testing, but rather, it performs flow cytometry testing to quantify FMH, following a positive fetal screen. If testing for FMH was requested on an Rh positive patient pregnant patient following trauma, the same flow cytometry testing would be done, since no KB testing is done by their lab. This testing is available Monday-Friday on day shift; off hours there is an ‘on call’ tech who may be brought in to perform the flow cytometry during those times with physician approval. Their patient population is such that the testing is performed infrequently.

ADDENDA Feb. 15, 2010

8. Transfusion medicine physicians at an academic medical center in Los Angeles report that they send their KB test to a reference lab when the fetal screen test is positive. Since they will not get results back for a couple of days, they would issue 2 vials of RHIG (300 µg/vial) to Rh negative patients when the fetal screen is positive. In case of a positive KB test, they would contact the attending physician to recommend additional dosing with RHIG. In the last 3 years, at their institution with a level I trauma center, they have only had one patient who needed more than 2 vials of RHIG based on calculation following receipt of KB results.

Submit Comments to the e-Network Forum below:

Items marked with an asterisk (*) are required entries. Please note that there is a 60 minute time-out on this form. if one anticipates taking more than 30 minutes or so to compose the submission, we recommend composing your comments in a word processing application, and performing a copy and paste of your text into the comments field.
* Name
Title
Affiliation
* email address
* Enter email address again to verify
* Do you wish to have attribution for your comments?	Yes No
* Your Comments
*Please indicate if this is a new question, or if you are commenting on an existing discussion:	New Question Existing, Name:
File Attachments (2MB limit)
To help us prevent SPAM, you must enter the the validation code EXACTLY AS IT IS DISPLAYED in the image directly to the right of the text entry field below in order to submit this form. Please note that the validation code is CASE SENSITIVE.

Ira A. Shulman, MD
CBBS e-Network Forum Editor & Moderator

W. Tait Stevens, MD
CBBS e-Network Forum Assistant Editor & Moderator