A study of critical value analysis and notification at hematology section of Central laboratory in a tertiary care hospital.

For good laboratory practice, timely identification and communication are essential elements and has gained importance in the recent years for the patient safety and timely treatment. Accreditation bodies require standardized laboratories to establish critical values [1]. Dr. George Lundberg first described the critical value in the year 1972 [2]. CVs are reported both for high and low values for selected analytical test. Recent studies and guidelines for CV have provided best contribution to the timely management, monitoring and safety of the patient care. Lack of clarity in communication and delays can cause frustration, anxiety and may threaten the life of the patient. According to The Joint Commission, a critical test result is one that must be communicated without delay because it falls far outside the expected range and could indicate a life‑threatening situation. Similarly, the College of American Pathologists requires laboratories to document not only the identification of such results but also the process of notifying the appropriate caregivers.[3]

The College of American Pathologists (CAP) checklist requires the percentage of CV results with documentation that the results have been reported to caregivers.

A summary of the CAP and TJC guidelines on CV notification is seen in Table 1.

Selection of critical value limit ranges in small to medium size laboratories and preparation of a standard list or target turn around time (TAT) for reporting of critical results is difficult due to the absence of consensus in laboratory community. Therefore, an agreement on the list of parameters and the critical value limits of each of them should be made, established and followed by each laboratory section which will help in eliminating the problem of diluting the urgency of the critical value call due to expansion of critical call out lists [4].

There is a pressing need to report these values accurately and rapidly because of its importance. Although there are no regulatory requirements to verify critical values by repeat analysis, the practice of repeating all critical values is longstanding and common in laboratories. Multiple studies have called into question the necessity of this practice, with most studies concluding it is unnecessary for accurate result reporting. Some reports have shown limited utility of repeat testing in specific instances, such as when the results fall outside the analytic measurement range [5]. But the laboratories must confirm the receipt of CV result by the intended recipient and read back is required and noted.

Aims and Objective:

1. To analyze the critical value (CV) data in hematology section of the laboratory.

2. To compare the monthly frequencies of critical values for different parameters.

3. To suggest measures for improving the effectiveness and operational efficiency of the critical value notification (CVN) process as a part of quality improvement of the lab.

The present study was a retrospective observational study conducted in the hematology section of laboratory at The Oxford Medical College Hospital and Research Centre, Bangalore. The lab received blood samples from out-patient departments (OPDs), in-patient departments [Intensive care units (ICUs), wards and operation theatres (OTs)] and emergencies. A total of 259 critical values were reported by the lab. A maximum of 160(61.7%) critical values were recorded from the emergency department followed by IPD 82 (31.5%) and OPD 17(6.5%) departments.

A total of 51286 tests were performed in the lab over a period of six months (October 2024 to March 2025). The parameters which were selected by the laboratory for CVN were platelets, hemoglobin, WBC and INR from hematology section. 

Total critical values reported was 259 out of total 51286 tests done.

 Rate = Total critical values reported / Total number of tests

             259/51286 x100 = 0.5

The critical value limit ranges of different parameters are shown in Table 2.

A maximum of 160(61.7%) critical values were recorded from the emergency department followed by IPD [Intensive care units (ICUs), wards and operation theatres (OTs)] 82 (31.6%) and OPD 17(6.5%) departments (Table 3).

Critical values in these parameters constituted 259 (0.51%) of the total test of 51286 reported by the lab. Monthly data collected showed the most commonly notified for critical value were Platelet110(42.4%) followed by Hemoglobin 108(40.9%), WBC 28 (10.8%) and INR 15 (5.7%) as shown in Table 4. Critical value notifications were maximum in the morning shifts (162, 62.5%) and minimum in the night shifts (15, 5.7%), Fig 1.

We implemented the following measures in our laboratory for improving the effectiveness and operational efficiency of the critical value notification process: Telephonic communication and short messages with the run data were sent to the concerned clinical caregiver as and when any abnormally critically high or low value was noted in the test. We also checked the difficulties faced by Laboratory staff in the procedure of call back and found that most of the delays were due to busy phone lines of wards & ICU. Most of the time patients or their attendants were not aware of correct patient’s diagnosis, requested investigations details and registration identification. Despite all these hurdles our Laboratory staffs were successful in maintaining notification time to patient or treating physician/ clinical care provider ranging from 10 to 30 minute. (Table 5)

Table 1: Regulatory considerations for implementation of a CV system

Table 2: List of critical value limit ranges of different parameters in hematology section.

Table3: Distribution of the critical values by clinical care areas

Table 4: Monthly Distribution of critical values for different parameters tested

Fig 1: Critical value data distribution in each shift

Table 5: Time taken in notification of critical alerts to respective department.

6. Table showing comparison of our study with other studies:

Critical result and urgent sample results notification is very important for critical treatment decision. Appropriate and timely management of patients largely depends on the clinical communication. A large number of reports have proven the ability of information technology to speed up the process of critical value reporting. In our lab the in-house Laboratory Information System (LIS) software was developed but still lacks the automatic flags of the test results requiring CVN and sends short message service (SMS) to the concerned caregivers. Training the laboratory staff for the policy of laboratory critical value identification and notification process and documenting the same in the log sheets has helped in reducing the timeline for the CVN. In a study conducted by Lynn TJet al., in order to improve communication between clinical providers and the laboratory, the secure text messaging (STM) for CVN was implemented [6].

Agarwal et al reported that there is a poor awareness among nursing and lab staff regarding urgent sample and critical value reporting [7].

In the present study, other reasons for delay in CVN include shifting patients to other location in the hospital for example from in patient ward to ICU and phone call not attended by caregivers. But this was reduced by sending an SMS alert to the closed group system among the staffs and clinical caregivers. Moreover, the practice of repeating critical values has been shown to add little value in regard to hematology and coagulation and is not necessary for accurate reporting when the shifting has been done. Evaluation of the impact of the repeat practice was performed and reduced as repeating critical hematology and coagulation results was found to be an unnecessary process that leads to wasting of laboratory resources and lengthened turnaround time, delaying clinical intervention [8].

In the OPD cases, one of the major challenges faced in CVN process was that unlike inpatients, there was no fixed patient location to which the CV can be telephonically notified.

Another observation was that CVNs were highest in the morning shifts (162, 62.5%) and minimum in the night shifts (15, 5.7%). This may be attributed to the increased test volume during the peak working hours in mornings and active communication process due to increased number of technical staffs in the morning shifts. Similar findings were observed in a study by Desai KN et al. [9]

A study by Hawkins on ‘laboratory turnaround time’ also noted that training of laboratory staff to expedite handling of laboratory samples, improves services [10].

The key goal for our study was to train the technical staffs on how to identify critical values on automated instruments and how to notify within the time frame enlisted as turnaround time in the lab for critical value notification which is 30 mins to 1 hour for our lab. In a national survey, 11% of patients stated that they had experienced delays in receiving abnormal test results.[11] Poor awareness among nursing and lab staff regarding critical value reporting was the main reason for the delays in the patient management intervention. After intervention we have found an improvement in reporting and recording of critical value samples in separate register log data sheet.

Fernandes et al reported that the time taken to convey specimens to the laboratory can be shortened by using a pneumatic tube system. [12]

One of the strategies to strengthen the CVN process could be to have a robust Laboratory Information System (LIS) that could automatically detect critical value and raise alarm which automatically send out short messages or emails to the treating physician directly.13] Help from the hospital management and the IT department in this regard would really improve in communication process. Similar finding was also stated by T Mukhopadhyay et al. [14]

Unexpected system technical issues or malfunctions, and human errors  due to high workload, distractions, fatigue, or failure to recognize the critical nature of certain values were some of the reasons for delays in notification which was also found in similar study done by Vallalkani KN et al. [15]

The limitation of the study is that evaluation could not be done on the morbidity and mortality of the patients who were reported of critical values. Further studies can be planned in that perspective.

Laboratory has an essential responsibility of efficient and timely communication of critical test results. Quality indicator in lab has become a mandatory policy for the improvement in Quality standard for accredited laboratories. A written policy for implementing critical value notification with a well-coordinated communication between laboratory personnel and the clinical care provider are fundamental to improve patient care. Information technology (IT) plays an essential component of medical laboratories and also for the immediate communication with the clinicians. The critical value notification was highest for platelets (118, 45.5%) and maximum notification was done in the EMD (160, 61.7%) in our study. The importance of both verbal and non-verbal communication processes for notification of CVs has been established and the significance of employing innovative measures to improve the CVN process has been highlighted.

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