Background and purpose: Some patients need to repeat certain tests. However, despite a peripheral vein catheter in the patients usually phlebotomy is done. This study examined the biochemical and hematological test results of the two methods of usual blood sampling and blood sampling through peripheral vein catheter.

Materials and methods: A case-control study was carried out in 96 patients admitted to the intensive care unit in Sari Imam Khomeini Hospital, 2014. Each patient was considered as a control group. Blood samples were taken in the usual way (control) and peripheral venous catheter (case). To obtain a blood sample, peripheral venous catheters were washed by 2cc of normal saline. After 5 minutes, 0.5 CC blood was discarded and sampling was performed again. In all samples the levels of hemoglobin, hematocrit, sodium, potassium, BUN, Cr and FBS were investigated. Results were analyzed using Chi-square test, t-test, Wilcoxon, and Fisher’s exact test in SPSS V.18.

Results: The patients were 56.2% male (n= 54). Mean age of the participants was 47.58±17.83 years. The results showed no significant difference in the values of hemoglobin (P=0.452), hematocrit (P=0.718), potassium (P=0.282), BUN (P=0.239), Cr (P=0.247) and FBS (P=0.074) between the two methods. But a significant difference was found between the values determined for sodium levels (P= 0.034).

Conclusion: Blood sampling through peripheral venous catheter while the patient is receiving liquid, is a reliable method for the analysis of hematocrit, hemoglobin, BUN and Cr.