Pediatrics and Neonatology (2011) 52, 155e160
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ORIGINAL ARTICLE
Complete Blood Count Reference Values of Cord Blood in Taiwan and the Influence of Gender and Delivery Route on Them Yu-Hsun Chang a,b, Shang-Hsien Yang a, Tso-Fu Wang c, Teng-Yi Lin d, Kuo-Liang Yang e, Shu-Huey Chen a,e,f,* a
Department of Pediatrics, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan Institute of Medical Sciences, Buddhist Tzu-Chi University, Hualien, Taiwan c Department of Hematology and Oncology, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan d Department of Laboratory Medicine, Buddhist Tzu-Chi General Hospital, Hualien, Taiwan e Buddhist Tzu-Chi Stem Cells Center, Hualien, Taiwan f Department of Medicine, College of Medicine, Tzu-Chi University, Hualien, Taiwan b
Received Apr 30, 2010; received in revised form Jul 5, 2010; accepted Aug 14, 2010
Key Words complete blood count; cord blood; differential count; reference values
Background: Cord blood banking has become more popular in recent years. Checking cord blood complete blood count (CBC) and white blood cell (WBC) differential counts (DCs) is essential before cryopreserving the cord blood units. Therefore, establishing the normal reference values of cord blood CBC and WBC DC is important in clinical practice and research. Objectives: To obtain a large-scale population-based normal CBC and WBC DC reference values of healthy neonates’ cord blood from a public cord blood bank and to investigate the influence of the gender and delivery route. Methods: From September 2001 to November 2006, the cord blood of healthy Taiwanese neonates with gestational age 36 weeks and more were collected by Tzu Chi Cord Blood Bank with written informed consents. All cord blood samples were analyzed by Sysmex XE2100 automated hematology analyzer (Sysmex Corporation, Kobe, Japan) to obtain the CBC. The WBC DC was calculated by manual method. We used Student’s t test and Mann-Whitney U test for investigating the influences of gender and delivery route on the CBC and WBC DC reference values. The results were presented by mean standard deviation or 2.5e97.5th percentiles. Results: In the study period, totally 5602 cord blood samples were collected eligibly for analysis. The cord blood CBC and WBC DC normal reference values were calculated. The female neonates had significantly higher mean corpuscular volume, platelet count, and WBC count, but lower red
* Corresponding author. Department of Pediatrics, Buddhist Tzu-Chi General Hospital, 707, Section 3, Chung-Yang Road, Hualien 970, Taiwan. E-mail address:
[email protected] (S.-H. Chen). 1875-9572/$36 Copyright ª 2011, Taiwan Pediatric Association. Published by Elsevier Taiwan LLC. All rights reserved. doi:10.1016/j.pedneo.2011.03.007
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Y.-H. Chang et al blood cell (RBC) count, hemoglobin (Hb), hematocrit, and mean corpuscular Hb concentration values (p < 0.001). Newborns through vaginal delivery had significantly higher RBC count, Hb, hematocrit, platelet count, and WBC count (p < 0.001). The percentages of some different types WBC were significantly influenced by gender and delivery routes. Male babies had higher lymphocyte, monocyte, eosinophil, basophil, and nucleated RBC ratios than the female neonates. Newborns through cesarean section had significantly lower neutrophil, monocyte, and nucleated RBC ratios, but higher lymphocyte and eosinophil ratios, than newborns through vaginal delivery. Conclusion: We successfully obtained the normal CBC and WBC DC reference values of the cord blood in Taiwan. Gender and delivery routes were important confounding factors that influenced the cord blood CBC and WBC DC values. Copyright ª 2011, Taiwan Pediatric Association. Published by Elsevier Taiwan LLC. All rights reserved.
1. Introduction
2. Materials and Methods
Complete blood count (CBC) is one of the commonly used laboratory examinations for evaluating the clinical condition of diseased neonates. For newborn babies, it is sometimes difficult to obtain sufficient blood sample for CBC because of the difficulty of accessing the blood vessels. Repeat puncture of arteries or indwelling of the arterial lines cannot be avoided in this condition, especially for clinically ill newborn babies. However, it may bring unnecessary complications, such as thromboembolism and arterial spasm, which compromise distal circulation of extremities and induce gangrenous changes.1 Cord blood provides an alternative choice for just-born babies if blood sampling is necessary.2,3 In addition, cord blood is enriched with hematopoietic stem cells and progenitors, which is a good source for stem cell transplantation and regenerative medicine.4e6 More and more people have stored their babies’ cord blood units in public or private cord blood banks. Comparing with bone marrow and mobilized peripheral hematopoietic stem cells, the advantages of cord blood in hematopoietic stem cell transplantation include the easy and harmless collection procedure, immediate availability, lower risk of transmissible diseases, and acceptable partial HLA mismatches. However, the cord blood has some disadvantages, such as delayed neutrophil and platelet engraftment, immune reconstruction, and insufficient cell dose for larger recipients. Studies have shown that the cell dose is the most important factor for cord blood donor selection, and a minimum required cell dose is 3 107 nucleated cells/ recipient’s weight in kilogram. Checking CBC and white blood cell differential count (WBC DC) is essential before cryopreserving the cord blood units. Therefore, the normal reference values of CBC and WBC DC are important in clinical practice. Previous studies provided important information about the hematological features of cord blood.7e9 However, the sample size was relatively small. Establishing the cord blood CBC normal reference values from large-scale population is critical.10 The donated cord blood bank provides a chance of collecting the CBC and WBC DC information from healthy term neonates. Therefore, we established the normal CBC and WBC DC reference values of the cord blood obtained from Buddhist Tzu Chi Cord Blood Bank in Taiwan.
2.1. Cord blood collection From September 2001 to November 2006, the donated cord blood samples of healthy Taiwanese singleton term neonates born to married mothers were collected by Tzu Chi Cord Blood Bank with written informed consents before the procedure. The cord blood samples with net weight more than 90 g were included. All these samples that met the exclusion criteria listed in Table 1 were not included. The maternal, paternal, and family histories were collected for statistical analysis. All cord blood samples were collected by the standard procedures approved by Buddhist Tzu Chi Stem Cell Center. After delivery, the cord was sterilized by povidone, and a 16-gauge needle was inserted into the umbilical vein. The cord blood was collected by gravity into a collecting bag containing 28-mL anticoagulant phosphate-citrate-dextrose. After the blood flow stopped, the needle was removed. The bag was stored at 4e10 C and sent to the processing center within 24 hours.11 One to two milliliters aspirated cord blood from cord blood bag was infused in an EDTA-containing tube. Subsequently, the cord blood CBC and WBC DC were analyzed in the central laboratory of Hualien Buddhist Tzu Chi General Hospital by experienced technicians.
2.2. Analysis of cord blood CBC and WBC DC All cord blood samples were analyzed by Sysmex XE2100 automated hematology analyzer (Sysmex Corporation, Kobe, Japan) to obtain the CBC results, including the red blood cells (RBCs), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular Hb (MCH), mean corpuscular Hb concentration (MCHC), WBC, and platelets. According to the quality control chart and Westgard rules, 13S/22S/R4S, the analyzer, was calibrated twice daily by using the commercial assayed control cell.12 The WBC DC was calculated by manual calculation by experienced technicians. The WBC count analyzed by automated hematology analyzer was corrected according to the nRBC percentiles with the following formula: corrected WBC count Z (uncorrected WBC count 100)/ (number of nRBCs per 100 WBCs þ 100).9 Both uncorrected WBC and corrected WBC are shown in Table 3.
Cord blood CBC and influence factors Table 1
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Exclusion criteria of donated cord blood samples
1. Consanguinity 2. Smoking during pregnancy 3. Unfavorable past history before pregnancy (1) Hepatitis B, hepatitis C, HIV, HTLV-1, syphilis infections (2) Malignancies; chronic diseases, such as insulin-dependent diabetes mellitus, autoimmune disease, psychological diseases, and others. (3) Returned from overseas less than 3 wk, returned from malaria endemic area less than 1 yr, and patients got malaria infection within 3 yr (4) Stillbirth or intrauterine fetal demise 4. Unfavorable pregnancy history (1) Multifetal pregnancy (2) Pregnancy-related complications (3) Abnormal amniotic fluid sampling results, or 34-yr-old or older without amniotic fluid sampling examinations 5. Second-degree relatives of the babies got malignancies with hereditary tendency or infectious hematological diseases 6. Third-degree relatives of the babies got congenital red cell diseases, immunodeficiencies, thrombopathies, and metabolic diseases, etc. 7. Unfavorable perinatal history (1)Gestational age less than 36 wk (2)Premature rupture of membrane more than 24 hr (3)Maternal fever more than 38 C (4)Maternal perinatal complications (5)Babies with fetal distress, respiratory distress, meconium stain, fever, or congenital anomalies (6)Abnormal placenta, placenta abruption, chorioamnionitis (7)Thin umbilical cord or length less than 10 cm
2.3. Statistical analysis
We performed Student’s t test to evaluate the mean differences of the variances of cord blood CBC by gender (male vs. female) and delivery route [vaginal delivery vs. cesarean section (C/S)]. Normal reference values of CBC were defined as mean SD. Because the data of DC were not in normal distributions, we used a nonparametric test, Mann-Whitney U test, to evaluate the differences of the variances of WBC DC
The database of cord blood CBC and WBC DC analyzed in this study was delinked from any identifiable personal information, such as IDs, names, telephone numbers, and addresses. For evaluating the demographic data, we obtained the sample size (n), mean standard deviation (SD), and range.
Table 2
Demographic data of cord blood donors Total (n Z 5602)
Maternal age (yr) Gestational age (wk) Birth body weight (g) Cord blood weight (g)
Male (n Z 2910, 52%)
Female (n Z 2683, 48%)
Mean SD
Range
Mean SD
Range
Mean SD
Range
29.9 3.9 38.9 1.1 3254.0 354.6 140.5 22.3
16e44 36e42 2130e5000 93.6e246.3
29.8 3.8 38.8 1.1 3301.8 351.0 140.7 22.0
16e44 36e42 2130e4840 93.6e243.5
29.9 3.9 38.9 1.1 3202.6 351.6 140.4 22.7
18e44 36e42 2156e5000 95.6e246.3
Total (n Z 5602)
Male (n Z 2910, 52%)
Female (n Z 2683, 48%)
n
%
n
%
n
%
Gestational age Preterm Term Post-term
97 5489 16
1.7 98.0 0.3
58 2846 6
2.0 97.8 0.2
39 2634 10
1.5 98.2 0.4
Delivery route Vaginal Cesarean section Missing
2692 1004 1906
72.8 27.2
1386 525
72.5 27.5
1305 479
73.2 26.8
n Z sample size; SD Z standard deviation. Preterm: gestational age less than 37 weeks. Term: gestational age between 37 and 41 weeks. Post-term: gestation age 42 weeks and greater.
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Table 3 The cord blood complete blood count normal reference values (mean standard deviation) and the impact of gender and delivery route Total RBC (106/mL) Hb (g/dL) Hct (%) MCV (mm3) MCH (pg/cell) MCHC (% Hb/cell) Platelets (103/mL) Uncorrected WBC (103/mL) Corrected WBC* (103/mL) nRBC (/100 WBC)
3.22 0.44 11.2 1.5 36.9 4.6 115.0 6.8 34.9 1.9 30.3 1.2 217 45 9.8 2.9 9.5 2.7 3.4 5.5
Gender
p
Male
Female
3.25 0.44 11.3 1.5 37.1 4.6 114.4 6.5 34.8 1.8 30.5 1.2 213 45 9.5 2.7 9.2 2.5 3.5 5.7
3.18 0.44 11.1 1.5 36.6 4.5 115.6 7.1 34.9 1.9 30.2 1.2 221 46 10.2 3.1 9.9 2.9 3.1 5.4
