Anemia is one of the most important causes of morbidity and mortality in developing countries, especially among pregnant women 1. The world prevalence of anemia in pregnant women and non-pregnant women is 41.8% and 30.2% respectively 2. Pregnant Sudanese women are susceptible to anemia regardless to their age and parity and anemia is one of the leading causes of maternal and perinatal morbidity and mortality 345.

Assessment of hemoglobin is one of the most reliable indicators for anemia, and is widely used to screen for anemic individuals, and to evaluate responses to interventions 6. Hemoglobin concentration is routinely measured using automated hematology analyzers. Although, these are very accurate and reliable, they are expensive and problems of samples transport to the laboratory may delay treatment resulting in preventable deaths 7. In poor resources where automated hematology analyzer is not available other methods of low price and that require less skill are highly needed. Although Cyanmethemoglobin method is cheaper and often used, it takes more time. The semi-quantitative gravimetric copper sulfate method which is used in blood donation is very easy and inexpensive; it does not provide an acceptable degree of accuracy.

The HemoCue^® hemoglobin photometer has been widely used for as a point-of-care device for hemoglobin estimation in mobile blood donations and critical care areas in health facilities 8. Previous studies showed contradictory results regarding the accuracy of HemoCue^®; some of research reported a high accuracy of HemoCue^® compared with standard laboratory methods 910. However, others did not recommend this device in general practice 111213. Few published data exist on the accuracy of HemoCue^® in the measurement of hemoglobin during pregnancy 1415. The aim of this study was to compare the accuracy of HemoCue^® using venous and capillary samples with that of the automated hematology analyzer in the measurement of hemoglobin among pregnant Sudanese women at Khartoum Hospital.

This was a cross sectional study carried- out among pregnant women at Khartoum hospital in Sudan during the period of October through December 2011. Convenient sampling method was used in the study in which all available subjects who fulfilled the inclusion criteria at the Khartoum hospital antenatal care clinic were recruited in the study every day until total number of sample size was achieved. Sample size of 108 subjects was calculated based on a 2-sided hypothesis tests using Epiinfo with 80% power and confidence interval of 95%. After signing an informed consent venous and capillary blood samples were taken from each woman to be measured by HemoCue^® (venous and capillary) and the automated analyzer.

Capillary blood samples were collected by finger prick in the middle finger of left hand, after cleaning and massaging the finger to facilitate blood flow. Venous blood samples were collected into vacutainer tubes and were analyzed immediately by HemoCue^® and the tubes were sent to the medical laboratory of the hospital for the analyses by automated analyzer.

A total number of 108 pregnant women were recruited in this study. Their mean (SD) of the age and gestational age were 27.6 (6.8) years and 24.9 (10.2) weeks.

The mean (SD) hemoglobin level was 12.70 (1.77), 12.87 (2.04) and 11.53 (1.63) g/dl using HemoCue^® venous sample, HemoCue^® capillary sample and automated hematology analyzer, respectively (Table 1).

Recently HemoCue^® portable hemoglobin photometer using venous or capillary blood samples has been widely used for quick assessment of hemoglobin concentrations; especially in poor settings where skills and resources are limited.

The accuracy of HemoCue^® for measuring hemoglobin in clinical settings is still a matter of controversy. The results of this study have shown that the hemoglobin concentration of HemoCue^® using either venous or capillary blood samples have lower level of precision and was not comparable with that of automated hematology analyzer; the limits of agreement were larger than the predefined clinically acceptable limits of ±1 g/dl. This is goes with the previous findings of the studies conducted among pregnant women at high altitude 14 and adult patients hospitalized in surgical intensive care unit 21. The difference between the readings has been explained by the use of only one microcuvette with HemoCue^® especially when using capillary blood samples and laboratory values, and advised loading multiple microcuvettes and averaging the hemoglobin values obtained has been proposed 22.

However, other studies showed that the results obtained by using HemoCue^® for hemoglobin assessment among pregnant women were comparable to that of automated hematology analyzer as a standard 9. Bernard et al., found that the results of hemoglobin concentration among pregnant and non-pregnant populations using HemoCue^® were comparable to that of automated hematology analyzer and Cyanmethemoglobin methods 23. Other studies which were conducted in different settings and populations such as patients with gastrointestinal bleeding, surgical patients repeated measurement of one sample, urban general practice, neonates, patients undergoing aortic surgery in the theatre and blood donors recommended HemoCue^® for the hemoglobin estimation 82425262728293031. Paiva et al. found that HemoCue^® was more appropriate for capillary compared to venous blood samples 32. However, there was within-subject variability of capillary blood hemoglobin values that might explain the unreliability of the method, and it has been shown that two capillary samples taken from different fingers of the same subjects had hemoglobin concentrations differing by/ more than two g/dL using the HemoCue^® 6.

In spite of the non-acceptable agreement of HemoCue^® with automated hematology analyzer in this study, the HemoCue^® is however simple to use, need minimum training, cheap, and gives an immediate result. Furthermore, it is useful in clinical and epidemiological settings where finger puncture allows capillary blood sampling as an easy technique which is less resource-intensive than vein puncture, and is more acceptable to patients and the community.

Hemoglobin concentration assessment by HemoCue^® using either venous or capillary blood samples does not have an acceptable agreement with automated hematology analyzer. Therefore this study does not recommend this device for hemoglobin concentration assessment among pregnant women.

The authors declare that they have no competing interests.

IA and MIY designed the study and participated in the statistical analyses, SA and MH conducted the clinical work. MH conducted the lab work. All the authors approved the draft and the final paper.