Micromethod for Bleeding Time in the Newborn
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Arch Dis Child: first published as 10.1136/adc.60.1.51 on 1 January 1985. Downloaded from Archives of Disease in Childhood, 1985, 60, 51-53 Micromethod for bleeding time in the newborn J M RENNIE, T GIBSON, AND R W I COOKE Regional Neonatal Intensive Care Unit, University of Liverpool, Liverpool Maternity Hospital SUMMARY A new method of measuring bleeding time using an Autolet device is described. Normal ranges of bleeding time and volume of blood used in the test have been defined in a population including preterm babies. Abnormal values have been shown in newborns with a variety of problems, and an abnormality of bleeding time has been found to precede intraventricular haemorrhage. Bleeding time has long been recognised as a useful Table 1 Distribution ofobservations by gestational age in vivo test of platelet-capillary function, but its measurement has been performed infrequently on Gestational age No neonates. Techniques for measurement have been 26-30 16 varied: Duke's original earlobe stab did not include 31-32 16 33-34 10 venostasis but recognised the importance of the 35-term 8 platelet in cessation of bleeding;' venostasis was Total 52 later added by Ivy to improve the sensitivity of the technique.2 Further developments have been in the use of templates,3 but the smallest template de- committee. Venous occlusion of the forearm was signed for the newborn requires the infliction of a 5 obtained by inflating a disposable plastic cuff mm by 0-5 mm deep incision on the forearm.4 In the (EME) with a mercury sphygmomanometer. Press- tiniest infants this is a substantial wound with a risk ures used were appropriate to the baby's weight4- of scarring and is therefore unsuitable for repeated 20 mm Hg for those less than 1000 g; 25 mm Hg 1000 observations. In view of the clinical need for an in to 2000 g; and 30 mm Hg greater than 2000 g-and vivo test of capillary-platelet interaction in situations produced visible venous distension. A standardised http://adc.bmj.com/ such as sepsis, intraventricular haemorrhage, and incision was produced on the cleaned skin of the administration of drugs known to have effects on the thumb using an Autolet device (Owen Mumford). prostaglandin pathway, a less traumatic method has Blood was absorbed from the incision every few been devised. Previous work has suggested that the seconds with filter paper until the flow ceased; time Autolet device reduces emotional sweating associ- to cessation of bleeding being recorded with a ated with capillary blood sampling5 and we there- stopwatch. fore used this in a standardised way to measure The filter paper was eluted in a measured volume bleeding time in the newborn. of Isoton (physiological saline with preservatives to on October 1, 2021 by guest. Protected copyright. prevent bacterial overgrowth). The haemoglobin Population and methods was converted to cyanmethaemoglobin, and the haemoglobin of the solution measured by col- Observations were made on 104 babies admitted to orimetry. From the baby's haemoglobin measure- the Liverpool Regional Neonatal Intensive Care ment the same day the volume of blood eluted could Unit over a nine month period. Fifty two of the be calculated. Volume estimations were made on a infants were clinically stable and receiving no drugs total of 82 estimations. Platelet counts and haemo- known to interfere with bleeding time; observations globin estimations were made as part of routine on these babies served to define the normal range. care. Distribution of the babies' gestational ages is shown in Table 1. Gestational ages ranged from 24 weeks Results to term, and birthweight from 834 g to 3500 g. Most observations were made in the first three days of Normal range. In the well babies there was no life, although the range was from three hours to 17 correlation between bleeding time and gestational days. The study was approved by the local ethical age, age at estimation, or birthweight. In 3 7 an 51 Arch Dis Child: first published as 10.1136/adc.60.1.51 on 1 January 1985. Downloaded from 52 Rennie, Gibson, and Cooke Clinical problems included severe respiratory dis- 15 tress syndrome, exchange transfusion, sepsis, liver failure, and birth asphyxia. Many of these babies had a low platelet count but in seven the bleeding time was long when the platelet count was normal, 10 suggesting an abnormality of function rather than number. These 7 infants had a median gestational age of 27 weeks and were all receiving respiratory support for hyaline membrane disease. All 7 de- veloped ultrasound scan evidence of periventricular haemorrhage, and two subsequently died. The relation between platelet count and bleeding 1-1 1.4 1-7 20 2-3 2-6 2-9 3-2 3-5 3-8 time is shown in Fig. 2. Ten of the babies with a Bleeding tknes (minutes) prolonged bleeding time subsequently died, reflect- Fig. 1 Distribution ofnormal bleeding times. ing the severity of the associated illness. During the five month period from October 1983 to February observation was made on a single occasion, and in 1984 a total of 33 babies who subsequently de- the remainder serial observations were made on veloped intraventricular haemorrhage had bleeding successive days. Thus a total of 82 observations form times measured before the bleed occurred. Fifteen the histogram for definition of normal bleeding time of these measurements were abnormal, confirming (Fig. 1); 97% of these observations fall below 3-5 the association between intraventricular haemor- minutes, which is therefore taken as the upper limit rhage and prolonged bleeding time noted by Setzer of normal. et al,6 and also showing that the disturbance of platelet-capillary interaction seen with in- Reproducibility. Duplicate observations were per- traventricular haemorrhage is not always a secon- formed in the same baby at the same time on 30 dary phenomenon as has been suggested.7 It is of occasions. Variation, expressed as the difference note that all the babies whose initial bleed was between the two results as a percentage of the larger parenchymal were in this group. result, varied from 0% to 32%, with mean variation 9%. On 25 of the occasions the variation was less Discussion than 10%. Measurement of bleeding time by this method is The reproducibility of the method is, therefore, http://adc.bmj.com/ acceptable, and to minimise trauma the punctures simple and rapid to perform with sterile disposable were single at a given time thereafter. equipment and causes minimal disturbance to the infant, who remains in his own incubator. In several Volume estimations. The volume of blood eluted infants on transcutaneous monitoring no alteration from babies with a normal bleeding time was always in TcPo2 could be seen. The device is cheap and less than 0-15 ml: the volume of blood eluted from easily obtainable. Use of the thumb as the chosen babies with a prolonged bleeding time was much site for puncture avoids problems associated with greater, the mean being 0-27 ml. Student's t-test laceration of superficial forearm veins,8 and it is on October 1, 2021 by guest. Protected copyright. applied to the means clearly shows two populations (Table 2). 400- Abnormal bleeding time. seven of the babies L Twenty 300_ 0 studied who were ill were identified with a prolonga- x. tion of bleeding time, often on several occasions. * * - gO 41 .2 0 0 Table 2 Means of volumes of blood (ml) eluted from a. babies with normal and abnormal bleeding times * 0 0 0 100- *0 *0- No Mean (SD) .0 . Normal bleeding time (<3-5 minutes) 52 0-10 ()10 1 2 Abnormal bleeding time 1 2 3 4 5I5 6 >7 (> 3-5 minutes) 26 0-27 0-22 Bleeding time (ffnutes) Students t test on means, P=0 001 Fig. 2 Scatterplot of platelet count against bleeding time. Arch Dis Child: first published as 10.1136/adc.60.1.51 on 1 January 1985. Downloaded from Micromethod for bleeding time in the newborn 53 easier to maintain an even pressure while activating study of abnormalities induced by agents such as the device. indomethacin and phototherapy. The normal range The method gives a bleeding time which is slightly established may also help to confirm suspected shorter than previous work.9 Large numbers of coagulation defects in infants in whom venepuncture observations have not been made on preterm babies is difficult and laboratory studies, therefore, unreli- in the past, and previous workers mainly used able or unobtainable. template methods, which tend to give longer bleed- ing times than stab incisions (Table 3). The addition References of volume estimations by an observer unaware of Duke WW. The relationship of blood platelets to haemorrhagic the bleeding time has served to confirm the reliabil- disease. JAMA 1910-60:1185-92. 2 Ivy AG, Nelson D. Bucher G. The standardisation of certain ity of the method, and the abnormal results. Few factors in the cutaneous venostasis bleeding time technique. previous attempts, and none in neonates, have been J Lab Clin Med 1941;26:1812-22. made to measure the volume of blood used in the 3 Harker LA, Slichter SJ. The bleeding time as a screening test test and these gave widely differing figures, from for evaluation of platelet function. N Engl J Med 1972;287: 1 155-9. 0005 ml to 13 ml.10 4 Feusner JHi. Normal and abnormal bleeding times in neonates Neonatal platelets are known to be normal in and young children utilising a fully standardised templatc number but to have impaired function, with abnor- technique. Ain J Clint Pathol 1980;74:73-7.