Method, analysis system, analyzer, and computer program for analyzing cause of prolonging coagulation time

An analysis system configured to analyze a blood sample obtained from a single patient and determine a suspected cause of prolongation of time to form coagulation in the blood sample, wherein the suspected cause relates to possible presence of lupus anticoagulant (LA) in the blood sample, possible presence of heparin in the blood sample or suspicion of another cause other than the presence of LA and heparin, the analysis system comprising:

• a sample preparator including
• a sample dispenser including a first arm and a first pipette attached to the first arm, the sample dispenser configured to dispense the blood sample in each of a first cuvette and a second cuvette, and
• a reagent dispenser including a second arm and a second pipette attached to the second arm, the reagent dispenser configured to dispense an activated partial thromboplastin time (APTT) measurement reagent and a calcium solution in each of the first cuvette and the second cuvette;
• a light applicator configured to apply light to the first cuvette and the second cuvette;
• a detector configured to detect the light through the first cuvette and the second cuvette;
• and
• a controller operably connected with the sample preparator, the light applicator, and the detector, wherein
• the controller is programmed to:
• control the sample preparator to
• dispense the blood sample from the single patient and the APTT measurement reagent in the first cuvette, and dispense the calcium solution in the first cuvette a first waiting time after dispensing the blood sample and the APTT measurement reagent in the first cuvette, and
• dispense the blood sample from the single patient and the APTT measurement reagent in the second cuvette, and dispense the calcium solution in the second cuvette a second waiting time after dispensing the blood sample and the APTT measurement reagent in the second cuvette, wherein the second waiting time is set to longer than the first waiting time, and neither the first cuvette nor the second cuvette contains other blood sample than the blood sample from the single patient,
• control the light applicator to apply light to the first cuvette and the second cuvette that each contain the blood sample, the APTT measurement reagent, and the calcium solution,
• obtain from the detector a first set of coagulation data representing a first light-absorbance profile of the light detected through the first cuvette,
• obtain from the detector a second set of coagulation data representing a second light-absorbance profile of the light detected through the second cuvette,
• obtain at least one pair of parameters selected from two pairs of parameters defined below:
• (i) a pair of parameters A1 and A2, wherein the parameter A1 relates to a first coagulation time determined from the first light-absorbance profile, and the parameter A2 relates to a second coagulation time determined from the second light-absorbance profile;
• and
• (ii) a pair of parameters B1 and B2, wherein the parameter B1 relates a first maximum coagulation speed determined from a first order differentiation of the first light-absorbance profile, and the parameter B2 relates to a second maximum coagulation speed determined from a first order differentiation of the second light-absorbance profile,
• calculate an arithmetic relationship between the parameters in the selected at least one pair, wherein the calculated arithmetic relationship relates to either a difference between the selected at least one pair of parameters or a ratio between the selected at least one pair of parameters, and
• analyze the calculated arithmetic relationship relative to at least one predetermined value to determine the suspected cause of prolongation of coagulation time.