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Abstract

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

BACKGROUND: Pittsburgh's Centralized Transfusion Service (CTS) provides transfusion support to 16 hospitals and features an electronic database that contains patient transfusion and serologic histories. This database can be accessed from any hospital in the system. A major cause of ABO-incompatible transfusions is the “wrong blood in tube” (WBIT) phenomenon, that is, the sample is not from the recipient identified on the label. We hypothesized that having access to patient historical ABO types from anywhere in the CTS system can identify WBIT errors and prevent mistransfusions.

STUDY DESIGN AND METHODS: The transfusion committee records of the 16 CTS hospitals from March 2005 to September 2007 were reviewed for major collection errors, that is, the current ABO type differed from the historical type in the database. The patient's historical ABO type, the discrepant type, and the hospital(s) where these samples were collected were recorded.

RESULTS: In 6 of 16 major collection errors for which complete information was available, the current and historical ABO types were obtained from different hospitals within the CTS system. In 3 cases, selection of ABO type–specific blood based on the current sample would have led to an ABO-compatible transfusion (e.g., correct type A, current type O). In the other 3 cases, an ABO-incompatible transfusion would have resulted (e.g., correct type O, current type A).

CONCLUSIONS: Access to a centralized patient database detected 38 percent more ABO typing errors and prevented six mistransfusions, which would not have been prevented at a single institution. Centralization of patient transfusion data should be encouraged.

ABBREVIATIONS:
CTS

Centralized Transfusion Service

WBIT

wrong blood in tube.

Acute intravascular hemolytic transfusion reactions are consistently among the leading causes of transfusion-related morbidity and mortality.1,2 Of 97 transfusion-related fatalities reported to the FDA in fiscal years 2005 and 2006, 9 were due to ABO incompatibility.1 Over a 22-month period, 54 ABO-incompatible transfusions were reported to the New York State Department of Health, of which 3 had fatal consequences.3 At that rate there would be more than 40 ABO-incompatible transfusion-related deaths per year in the United States.

ABO-incompatible transfusions are preventable because they typically result from patient misidentification at the time of sample collection or blood administration. A 2000 report from the New York State Department of Health attributed approximately two-thirds of such errors to factors outside the blood bank: administration to the wrong patient (38%), phlebotomy errors (13%), and in 15 percent of cases multiple errors were identified.4 Patient misidentification at the time of collection can lead to two types of errors that result in the “wrong blood in tube” (WBIT): the intended patient's identification is applied to the tube but a different patient was actually phlebotomized (patient misidentification), or the intended patient is phlebotomized but a different patient's identification is applied to the tube (sample mislabeling).

The experience with mistransfusions in other countries is similar. Between October 1996 and September 1998, 191 “wrong blood to patient” episodes were reported in England involving multiple identification errors and causing 3 deaths due to ABO incompatibility.5 There were 130 ABO-incompatible transfusions between 1999 and 2003 reported by the British National Health Service in which 68 percent of the errors took place in clinical areas.6 Reports from Germany and Japan have shown similar results.7,8 Sample misidentification is a problem not limited to the blood bank but can affect other services, such as surgical pathology, that receive patient specimens from elsewhere in the hospital.9

Unlike other laboratory results reported on mistyped samples (e.g., electrolytes or blood cultures), ABO mistypings are rarely clinically apparent because there is usually no a priori expectation of the patient's ABO type. Thus the error might go unrecognized until an incompatible transfusion has occurred. To prevent such outcomes, hospital blood banks typically enforce stringent specimen labeling requirements. The AABB Standards require some method of double checking the patient's ABO type before issuing ABO-matched red blood cells (RBCs); this verification method might be a second typing of the initial sample (often by a different technologist), comparison with a historical type available from the blood bank's records, or ABO confirmation on a second, independently obtained sample from the intended patient.10 The College of American Pathologists' preferred methods for ABO type reverification includes the latter two methods.11

Thus historical ABO type information from previous encounters with the patient provides an extra layer of transfusion safety by potentially alerting the blood bank to a discrepancy with the current sample. Experience with historical-type information is widely reported.12-14 In 2006, Figueroa and colleagues12 reported on 17 years of using a second, independently drawn sample for ABO verification at a single institution. This policy detected 94 WBIT errors, averting five potential ABO-incompatible transfusions; 57 percent of the errors were found via comparison with a historical type.

The Centralized Transfusion Service (CTS) in Pittsburgh is a large, integrated hospital blood transfusion service which supplies blood products, testing, and transfusion medicine expertise to 16 area hospitals serving a metropolitan population of 2.4 million people. On an annual basis the CTS performs approximately 150,000 type-and-screen procedures and 220,000 cross-matches and oversees the transfusion of approximately 120,000 units of RBCs. The CTS is thus responsible for conducting more than 90 percent of all transfusion activity in the Pittsburgh region.15 The CTS uses the SafeTrace blood bank information system (Wyngate Technologies, El Dorado Hills, CA), which maintains electronic records of patient ABO types performed at any of the hospitals in the system, such that the results of an ABO type performed at any of the 16 CTS hospitals are available at any of the other CTS hospitals, regardless of where they were typed initially. An ABO typing discrepancy between the current sample and the historical type on file would be investigated and resolved before ABO-matched RBCs are issued.

We hypothesized that having the historical ABO type information readily available on a regional basis through the CTS system would improve transfusion safety through enhanced detection of ABO typing errors.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

This study was approved by the quality improvement branch of the University of Pittsburgh's Institutional Review Board. Records of the 16 CTS-serviced hospital transfusion committees between March 2005 and September 2007 were reviewed to identify all reported major ABO typing errors. Such errors are routinely reported to and monitored by each hospital's transfusion committee. Major ABO typing errors included any laboratory errors that resulted in mistyping, as well as collection errors leading to WBIT.

Each major ABO mistyping error (“event”) was investigated to determine what historical ABO type was listed in the patient's electronic blood bank file at the time when an ABO-discrepant sample was received, the ABO type of the erroneous current sample, and at which hospital(s) the historical and the current samples were obtained.

RESULTS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Twenty-eight major ABO typing errors occurring between March 1, 2005, and September 14, 2007, were reported to the transfusion committees of the 16 hospitals serviced by the CTS. Of these 28 reports, complete event information was available for 16 patients. The causes of these mistypings are depicted in Fig. 1. There were no laboratory errors that led to ABO mistypings in this series of patients.

image

Figure 1. The underlying causes of the 16 ABO mistyping errors included in this study.

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In 6 of 16 (38%) ABO mistyping events, the historical and erroneous types had been obtained at different hospitals. In the other 10 cases, the historical and current ABO types had been collected at the same hospital (Fig. 2).

image

Figure 2. Description of the 16 mistyping errors (“events”) for which complete information was available. The dashed arrow indicates the three potential ABO-incompatible transfusions that were averted by having the patient's historical ABO type, drawn at a different hospital from where they were to be transfused, available in the electronic database. See text for details.

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In 8 of 16 cases (50%), the collection error could potentially have led to an ABO-incompatible transfusion. In 3 of 8 cases, the potentially life-saving historical ABO type had been obtained at a different hospital, but was available to the blood bank through the common electronic patient database of the CTS. In the remaining 5 cases both the historical and the erroneous current ABO types had been obtained at the same hospital (Fig. 2).

DISCUSSION

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES

Hospital blood banks routinely compare historical ABO type information available from their own internal records to current samples for the purpose of detecting major ABO collection errors before a mistransfusion occurs.12 Notably, our areawide CTS system has documented a 38 percent enhancement of detection of major ABO collection errors over a 2½-year period using data acquired from different blood banks in the system without the need for additional samples. In the absence of ABO verification on a second sample, these 6 errors would not have been detected by a single-institution blood bank and could have led to an ABO-incompatible transfusion. This represents a large proportionate increase in transfusion safety directly attributable to using a centralized database of patient ABO types. Since almost half (12/28) of the collection error cases were not included in our analysis due to incomplete documentation, we may have actually averted even more potential hemolytic reactions by comparing the patient's current ABO type to his or her historical type on file in the CTS record. Furthermore, it is only by chance that half of the mistransfusions prevented by historical information would have been ABO-compatible. Thus the ability of the CTS system to prevent ABO-incompatible transfusions might have been underestimated in this study. Few other transfusion safety initiatives could offer such an immediate improvement in serologic safety and could substantially reduce the burden and potential delays associated with a second “check” sample.

The underlying causes of the ABO mistypings in this study were the same as those identified in numerous other reports: patient misidentification and specimen mislabeling. Efforts to reduce these types of errors by employing bar-code or radio frequency identification device (RFID) technology,14 or even an overhaul of blood specimen collection and processing systems,16 may reduce these errors, but they cannot completely counter human fallibility; in one patient for which we did not have complete event information, the identification error occurred at the time of hospital registration, that is, the intended patient was registered under a different patient's name. Both patients coincidentally had identical ABO types, and the registration error was identified by other means.

We believe that the historical ABO type information, collected and stored in the CTS system, is an important public health advantage of a centralized transfusion service and that centralization of patient transfusion data should be encouraged. Other models of centralization could simply involve the sharing of patient serologic information amongst hospitals in the same geographic region.

REFERENCES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. REFERENCES