Kleihauer–Betke test: Difference between revisions
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==Semi-quantification== | ==Semi-quantification== | ||
This is done for '''Rh- | This is done for '''Rh-positive''' mothers to estimate the severity of a suspected feto-maternal hemorrhage, which can be suspected by various clinical findings (including neonatal anemia, stillbirth, intrauterine growth restriction, hydrops fetalis, decreased or absent fetal movements, non-reassuring fetal heart rate tracing, sinusoidal fetal tracing, and fetal tachyarrythmias, placenta previa with bleeding, and placental abruption)<ref> {{cite journal| author=Solomonia N, Playforth K, Reynolds EW| title=Fetal-maternal hemorrhage: a case and literature review. | journal=AJP Rep | year= 2012 | volume= 2 | issue= 1 | pages= 7-14 | pmid=23946896 | doi=10.1055/s-0031-1296028 | pmc=3653511 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23946896 }} </ref>. | ||
10HPFs (in 40x) are scanned, and fetal RBCs are counted (cells per 10 HPFs, not average per HPF), and classified as: | 10HPFs (in 40x) are scanned, and fetal RBCs are counted (cells per 10 HPFs, not average per HPF), and classified as: | ||
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| 12 || 12 | | 12 || 12 | ||
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:*Calculate how much the count for the second and third areas deviated from 100, and take the average thereof, which will be used as standard deviation.<ref group= | :*Calculate how much the count for the second and third areas deviated from 100, and take the average thereof, which will be used as standard deviation.<ref group=note name=sd>Technically, the standard deviation would be calculated as the average deviation from the mean of all areas, but the simplified calculation used in this resource can be regarded to be close enough for practical purposes.</ref> If the standard deviation is higher than 12, count a total of 2000 cells regardless of areas and calculate as per formula above, and the rest of the steps can be skipped. | ||
:*Use the table at right to estimate how many areas in total you need to count in order to have a mean number of cells per area with an acceptable confidence interval. | :*Use the table at right to estimate how many areas in total you need to count in order to have a mean number of cells per area with an acceptable confidence interval. | ||
4. After having counted the needed number of areas, calculate the average of the number of cells per area (or per x number of squares), and assume that number for the rest of the counting.<br> | 4. After having counted the needed number of areas, calculate the average of the number of cells per area (or per x number of squares), and assume that number for the rest of the counting.<br> | ||
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File:KB stain area calculation for 100 cells.jpg|100 cells are counted, and their area is marked with a rectangle. | File:KB stain area calculation for 100 cells.jpg|100 cells are counted, and their area is marked with a rectangle. | ||
File:KB stain - calculation of same area 1.jpg|A new location is randomly chosen, and inside the same rectangular area, 94 cells are counted. This is a deviation 6 cells compared to the first count. | File:KB stain - calculation of same area 1.jpg|A new location is randomly chosen, and inside the same rectangular area, 94 cells are counted. This is a deviation 6 cells compared to the first count. | ||
File:KB stain - calculation of same area 2.jpg|thumb|A third area of the same size yields a count of 108 cells, deviating 8 from 100. The standard deviation used<ref group= | File:KB stain - calculation of same area 2.jpg|thumb|A third area of the same size yields a count of 108 cells, deviating 8 from 100. The standard deviation used<ref group=note name=sd/> is therefore the mean of 6 and 8, which is 7. As per the table, one more area needs to be counted. | ||
File:KB stain - calculation of same area 3.jpg|The third area yields 110 cells. The average number of cells per area is now calculated as the mean of 100, 94, 108 and 110, which is 103. | File:KB stain - calculation of same area 3.jpg|The third area yields 110 cells. The average number of cells per area is now calculated as the mean of 100, 94, 108 and 110, which is 103. | ||
File:KB stain -calculation of additional areas.jpg|With an average of 103 cells per area, the number of areas needed to presumably include at least 2000 cells in our case is another 16. | File:KB stain -calculation of additional areas.jpg|With an average of 103 cells per area, the number of areas needed to presumably include at least 2000 cells in our case is another 16. | ||