Early onset neonatal thrombocytopenia is associated with severe intraventricular hemorrhage in very preterm infants: A retrospective cohort study

Abstract

BACKGROUND:

The role of platelet function in the development of intraventricular hemorrhage is still a subject of debate. In this study, we aimed to determine whether there is an association between platelet indices in the first week of life and severity of intraventricular hemorrhage in very preterm infants.

MATERIALS AND METHODS:

Preterm infants born < 30 weeks of gestation in our hospital were retrospectively evaluated. Platelet parameters, including platelet counts, mean platelet volume, platelet distribution width, and platelet mass were retrieved at two different time points: the initial value on the first day of life and the value closest to the end of the first week of life. The infants were categorized according to the findings of cranial ultrasonography as; no intraventricular hemorrhage, mild or severe intraventricular hemorrhage.

RESULTS:

Totally, 1051 infants were evaluated. The mean gestational age and birth weight for the entire cohort were 27.9±1.6 weeks and 1058±247 g, respectively. Infants in the severe intraventricular hemorrhage group had significantly lower gestational age (p < 0.001) and birthweight (p < 0.001) compared to other two groups. Furthermore, there were significant differences in platelet count and platelet mass between the groups at two time intervals. However, logistic regression analysis revealed that only platelet count of < 100×10⁹/L on the first postnatal day was independently associated with the severity of intraventricular hemorrhage.

CONCLUSION:

There is an association between platelet count of < 100×10⁹/L on the first postnatal day and severe intraventricular hemorrhage in very preterm infants.

Keywords

Mean platelet volume neonatal thrombocytopenia platelet mass preterm

1 Introduction

Intraventricular hemorrhage (IVH) remains a major cause of neonatal morbidity and mortality, particularly in the most immature infants [1]. Despite recent advances in preterm care, of interest the incidence of IVH has remained constant over the past two decades, with an overall incidence of 25 % for all grades of IVH and an incidence of the severest types of IVH (grades III and IV) at around 5% [2, 3]. Given the infants with IVH, particularly those with higher grades, are susceptible to significant cognitive and motor neurodevelopmental impairments later in life, recent studies have primarily focused on early prediction and identification of all prognostic factors that contribute to the development of IVH [4 –6]. Prematurity is the most important risk factor for IVH as the incidence and severity increase dramatically with decreasing gestational age and birth weight [7]. Additionally, combination of factors related mainly to regulation of blood flow, pressure, and volume in the vulnerable vascular bed of the germinal matrix of premature infants was revealed to play a significant role [8 –10].

Nonetheless, it is unclear whether abnormalities in platelet function also independently contribute to the multifaceted pathophysiology of IVH. As the gestational age decreases, the prevalence of thrombocytopenia also increases dramatically, and one study demonstrated that up to 75% of newborns born with a birth weight under 1000 g are affected by thrombocytopenia [11, 12]. The elevated incidence of thrombocytopenia has prompted researchers to investigate the potential role of platelet count and other platelet parameters in the pathogenesis of IVH in premature infants.

However, the literature has yielded mixed results regarding the relationship between abnormal platelet indices and the severity of IVH [12 –14]. While some studies, such as Von Lindern et al. have posited that the presence of thrombocytopenia, regardless of severity, can increase the incidence of IVH, others, like Rastogi et al., have not observed an association between stable thrombocytopenia and increased incidence of IVH in premature infants [15, 16]. In more recent studies, lower platelet mass has been linked to the presence of IVH in premature newborns, rather than platelet count [17]. Further research is necessary to ascertain the potential utility of platelet markers in predicting IVH and establish safe thresholds for platelet transfusions, as well as to develop more efficacious neuroprotective strategies.

Thus, the objective of this study was to investigate the platelet indices of preterm infants admitted to a neonatal intensive care unit (NICU) to evaluate whether severe IVH was independently associated with platelet counts and other platelet indices including mean platelet volume (MPV), platelet distribution width (PDW), and platelet mass.

2 Materials and Methods

In this retrospective cohort study, we evaluated medical records of preterm infants between January 2010 and April 2018 who were born < 30 weeks gestation and hospitalized in the first 24 hours of life at our tertiary NICU, Ankara, Turkey. This study was approved by the ethics review board of our institution in accordance with established ethical guidelines.

Infant characteristics including gestational age, birth weight, gender, antenatal steroid use, the 5th minute APGAR score, small for gestational age, number of twin gestations, respiratory distress syndrome (RDS), patent ductus arteriosus (PDA), early onset neonatal sepsis (EOS) (proven sepsis in the postnatal first 3 days), and requirement for mechanical ventilation were documented from medical records. In addition, maternal history of pregnancy-induced hypertension, prolonged rupture of membranes (PROM) (>18 h), and evidence of chorioamnionitis were also obtained from the obstetrical chart. The diagnosis of IVH was established through a cranial ultrasonographic (US) examination conducted by a pediatric radiologist. Our unit follows a routine protocol of performing cranial examinations at least twice within the first week after birth: initially on the first postnatal day and/or within the initial 72 hours of life, followed by another examination between postnatal days 5 and 7. Subsequent cranial US scans were performed once or twice a week until the infant reached the postmenstrual 34th week and finally at discharge, with the frequency adjusted based on the severity of cranial pathology. The IVH was graded from I to IV using the Papile et al. method modified for use with ultrasound scanning [18]. Grade 1-2 was considered mild, and grade 3-4 was considered severe IVH. Following the initial transfontanel US examination, an increase in IVH stage was seen in certain patients. The IVH of the highest grade was chosen in this circumstance.

Infants who underwent a cranial ultrasonography and had at least one complete blood count on their first day of life (DOL) and DOL 5–7 were included in this study. Infants with major congenital abnormalities and genetic conditions were excluded. The infants were further categorized according to the findings of cranial ultrasonography as; no IVH, mild IVH, or severe IVH.

Blood samples were drawn from the umbilical or peripheral veins and collected in tubes containing ethylene diamine tetraacetic acid. Platelet indices (count, MPV, and PDW) were determined using the Coulter Counter model LH (Coulter Electronics, Hialeah, FL, USA) and recorded. Platelet mass was recorded as the value obtained from the multiplication of platelet count by MPV: (PMI = [PC]×[MPV] /10³) fL.nL^-1 [19]. If patients had multiple platelet values on day 1, we had accepted the higher value. Nadir platelet value was selected for infants with more than one platelet count on DOL 5–7. Thrombocytopenia was defined as a platelet count below 150×10⁹/L and classified as mild (platelet count 100–149×10⁹/L), moderate (platelet count 50–99×10⁹/L) and severe (platelet count < 50×10⁹/L). Blood samples that were obtained prior to the subsequent cranial US evaluation were included in the analysis at both time intervals.

The primary outcome was an association between platelet counts and the severity of IVH in very preterm infants. The secondary outcome was to determine whether an association exists between MPV, PDW, or platelet mass and the severity of IVH.

2.1 Statistical analysis

Descriptive analysis was performed for demographic and clinical characteristics of the infants. Independent samples t-test or Mann Whitney U test was used for the comparison of continuous variables (normally or abnormally distributed) between two groups. Whereas difference among more than two groups was examined by ANOVA and Kruskal–Wallis test for normally and abnormally distributed variables, respectively. Chi-square test was used for comparison of ratios between the groups. Birth weight, gender, gestational age, PDA, presence of respiratory distress syndrome, mechanical ventilation, maternal factors including early membrane rupture, preeclampsia and antenatal steroid use, platelet count, platelet mass, MPV, PDW and thrombocytopenia were included in univariate analysis. Backward stepwise logistic regression analysis was performed to determine independent effects of variables on severe IVH. Entry into the multivariate model was conditional on a p value of 0.2 in univariate analysis. As we found that mild thrombocytopenia (platelet count 100–149×10⁹/L) appear to have no significance in terms of hemorrhage, only moderate and severe thrombocytopenia was included in the final analysis. All the statistical tests used were two-tailed. Statistical analysis was performed with SPSS software version 22.0 and statistical significance was set at p < 0.05.

3 Results

Of the 1422 infants born < 30 weeks gestation during the study period, 1051 (73.%) were available for evaluation (Fig. 1). The mean gestational age and birthweight of the study groups were 27.9±1.6 weeks and 1058±247 g, respectively. Infants were divided into three groups based on the degree of IVH: no IVH, mild IVH, and severe IVH. Of the infants, 93 (9%) were diagnosed with severe IVH. Table 1 represents the neonatal and maternal characteristics of the infants with respect to the severity of IVH. The group of infants with severe IVH had a statistically significantly lower median gestational age (p < 0.001) and birth weight (p < 0.001) compared to the groups with no or mild IVH. In addition, mechanical ventilation was required more frequently in the severe IVH group compared to the other groups. Infants with severe IVH also had the highest incidence of RDS, SGA, EOS and PDA as indicated in Table 1.

Fig. 1

Flow-chart of inclusion of study cohort.

Table 1

Infant characteristics of study groups

	No IVH n = 305	Mild IVH n = 653	Severe IVH n = 93	p
Neonatal characteristics
Gestational age,wk.	29 (27–29)	28 (26–29)	27 (26–28)	<0.001
Birthweight,g	1140 (940–1300)	980 (850–1170)	930 (770–1035)	<0.001
Male (%)	146 (47.8)	313 (47.9)	60 (64.5)	0.012
Antenatal steroid use (%)	208 (64)	405 (62)	61 (65.5)	0.08
Apgar, 5. Min(<5), n (%)	21 (6.9)	59 (9)	15 (16.1)	0.18
SGA, n (%)	26 (8.5)	78 (11.9)	20 (21.5)	0.02
Twin gestation, n (%)	68 (22.2)	30 (19.9)	24 (25.8)	0.32
EOS, n (%)	28 (9.2)	104 (15.9)	24 (25.8)	0.03
Mechanical ventilation,n (%)	106 (34.8)	362 (55.4)	78 (84)	<0.001
RDS,n (%)	169 (55.4)	424 (64.9)	79 (85)	<0.001
PDA,n (%)	86 (28.2)	239 (36.6)	55 (59.1)	<0.001
Maternal characteristics
PPROM (%)	51 (16.7)	124 (19)	12 (13)	0.19
Preeclampsia (%)	52 (17)	105 (16)	8 (8.5)	0.13

Continues variables represented as median(inter quartile range). IVH, intraventricular hemorrhage; PDA, patent ductus arteriosus; PPROM, premature preterm rupture of membranes; RDS, respiratory distress syndrom; EOS, early onset sepsis;SGA, small for gestational age.

On the first DOL; median platelet count and platelet mass were both lower in the severe IVH group compared to no IVH group. Twenty-six percent of infants had thrombocytopenia in severe IVH group while this ratio was 19.5% in mild IVH and 11.5% in no IVH groups (p < 0.001). On DOL 5–7, median platelet count was significantly lower in severe IVH group compared to other groups (p < 0.001). Platelet mass was significantly lower in severe IVH group (p < 0.001) while MPV and PDW values were similar between the groups at two time points (Table 2).

Table 2

Platelet indices of study groups

Platelet variables	No IVH n = 305	Mild IVH n = 653	Severe IVH n = 93	P
First DOL
Thrombocytopenia (%)	35 (11.5)	127 (19.4)	24 (25.8)	<0.001
Platelet count (×10⁹/L)	230 (180–285)	206 (164–258)	198 (146–257)	<0.001
MPV, fL	7.8 (7.2–8.4)	7.7 (7.2–8.4)	7.9 (7.3–8.5)	0.75
PDW	13 (11–14)	13 (11–16)	12.9 (11–15)	0.18
Platelet mass, fL/nL	1779 (1445–2210)	1606 (1269–2046)	1581 (1274–2147)	<0.001
5–7 DOL
Thrombocytopenia (%)	49 (16)	130 (19.9)	36 (38.7)	<0.001
Platelet count (×10⁹/L)	271 (179–384)	237 (159–341)	179 (112–273)	<0.001
MPV, fL	8.8 (8.1–9.7)	8.7 (7.8–9.5)	8.8 (8.2–9.8)	0.077
PDW	14.2 (12.5–16.4)	14.6 (11.6–16.9)	14.7 (12.3–16.9)	0.89
Platelet mass, fL/nL	2433 (1542–3405)	2055 (1350–2992)	1514 (1009–2488)	<0.001

Continues variables represented as median (inter quartile range). DOL, day of life; IVH, intraventricular hemorrhage; MPV, mean platelet volume; PDW, platelet distribution width.

Logistic regression analysis revealed that severe IVH was independently associated with gestational age (adjusted OR = 0.72, 95% CI 0.62–0.85; p < 0.001), mechanical ventilation (adjusted OR = 4.49, 95% CI 2.28–8.82; p < 0.001) and a platelet count < 100×10⁹/L in the first DOL (OR = 2.75, 95% CI 1.05–6.2; p = 0.039) (Table 3). However, our analysis revealed no statistically significant association between IVH and other platelet indices.

Table 3

Independent risk factors for severe intraventricular hemorrhage

	OR (95% CI)	p
Gestational age	0.72 (0.616–0.851)	<0.001
Mechanical ventilation	4.49 (2.28–8.82)	<0.001
Platelet count < 100×10⁹/L on DOL-1	2.75 (1.05–7.20)	0.039

CI, confidence interval; DOL, day of life; OR, Odds ratio.

4 Discussion

Prior studies have revealed a link between severe IVH and a low platelet count, and the present study based on the first DOL platelet count confirms this association [13 –15]. Our study further indicates that a platelet count < 100×10⁹/L on the first DOL remains an independent risk factor for severe IVH. Additionally, our findings support previous observations that lower birth weight and gestational age are associated with an increased likelihood of severe IVH [9]. However, no correlation was found between IVH and platelet count after the first DOL or other platelet indices at either time.

IVH continues to be a major risk factor for adverse long-term neurological sequelae in preterm infants. To our knowledge, the present study includes one of the largest cohorts to date investigating the potential relationship between platelet indices and severe IVH in this vulnerable population. Kahn et al. reported that infants who had thrombocytopenia during the first three postnatal day exhibit higher incidence and more severe IVH compared to non-thrombocytopenic infants [20]. Similarly, a meta-analysis concluded that neonates with platelet counts < 100×10⁹/L during the first week of life had an increased incidence of IVH [21]. This is further supported by retrospective cohort of infants born at less than 30 weeks gestation, in addition to cardiopulmonary resuscitation and/or intubation in the delivery room, thrombocytopenia, regardless of degree and occurrence time found to be independently associated with IVH [22]. Nonetheless, despite these supporting findings, the role of thrombocytopenia in the pathogenesis of IVH remains a subject of controversy. In a report by Von Lindern et al., it was observed that although severe IVH occurs more frequently in neonates with thrombocytopenia, approximately one-third of thrombocytopenic infants developed IVH before thrombocytopenia in the cohort [15]. This observation raises the possibility that a consumptive process resultant from severe IVH may be the cause of the drop in platelet count rather than its effect. Nevertheless, in this particular cohort, initial complete blood samples were collected immediately following birth prior to the first ultrasonography assesment to confirm the presence of thrombocytopenia before IVH.

The timing of thrombocytopenia is a crucial factor to consider, as the platelet count typically reaches its nadir after the first day of life, with a nadir on days 4 to 5 and recovery by 7 to 10 days [23]. Mitsiakos et al. found that the platelet count on the first day of life could predict all forms of IVH in extremely premature infants, but no discernible difference in platelet indices was observed when the presence of IVH was restricted to severe cases (24). Furthermore, when infants were subgrouped for the presence of severe IVH during the first day of life, platelet count did not differ among groups, contrary to our study. However, this series had a notably smaller sample size than ours. Another study investigated thrombocytopenia on the first and second day of life in relation to the risk of developing IVH in preterm infants [25]. The authors found a lower platelet count at 24–48 hours of life in infants with severe IVH, but no difference was observed in platelet counts within the first 24 hours. This is contrary to our findings that the only platelet count in the first postnatal day is associated with severe IVH.

Our study has demonstrated an incidence of severe IVH of 9% in very preterm infants, which is comparable to the incidence reported in previous studies [9 –11]. Previous studies have shown that the incidence of IVH in preterm infants is amplified in the presence of various clinical factors, including mechanical ventilation, respiratory distress, pulmonary hemorrhage, pneumothorax, chorioamnionitis, asphyxia, sepsis, and patent ductus arteriosus [9, 10]. Nevertheless, in our study, only the presence of mechanical ventilation was found to be an independent risk factor for severe IVH. A few studies suggested that hemostatic efficacy of platelet plug formation may be influenced more by the platelet mass than the platelet count and elevated MPV values have been associated with IVH in preterm infants [26, 27]. However, our results have not confirmed this hypothesis. Neither MPV nor platelet mass has not been associated with the grading of IVH in our larger series.

Accurate clinical judgment regarding platelet transfusions in premature infants necessitates a comprehensive evaluation of the potential benefits and risks. In the most recent randomized clinical trial comparing platelet transfusion thresholds in preterm infants, implementation of a higher threshold of 50×/10⁹ L was linked with unfavorable consequences, leading to a higher rate of death or significant neurodevelopmental impairment at a corrected age of 2 years [28]. Nonetheless, it is important to note that low platelet counts might also present potential risks, as highlighted by our study’s finding that platelet count<100×10⁹/L in the first day of life constitutes a risk factor for severe IVH. Our findings indicates that clinical approach for prophylactic platelet transfusion thresholds should be evaluated in the presence of other associated risk factors in very preterm infants.

This study is subject to certain inherent limitations attributable to its retrospective design. The platelet counts were only assessed at two specific time points, with values between these time points not included. Given the transient nature of thrombocytopenia in some patients, this may limited the accurary of the data concerning actual incidence and severity of thrombocytopenia in the population. Furthermore, it can also be discussed that obtaining blood samples from this vulnerable population can be challenging, potentially resulting in poor quality samples and platelet clumping, which may have led to an overestimation of the true incidence of thrombocytopenia. Lastly, although our unit had standard protocols regarding prophylactic platelet transfusion threshold in very preterm infants, no data on platelet transfusions were included.

In conclusion, further research appear to be needed to identify the clinical approaches that will reduce the rate of severe IVH and its contribution to worse outcomes in the long term follow-up of very preterm infants in cases of thrombocytopenia in the first postnatal day.

Funding

None declared.

Author contributions

All authors have accepted responsibility for the entire content of this manuscript and approved its submission.

Conflict of interest

Authors state no conflict of interest.

Informed consent

Not applicable.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the Ankara Dr. Zekai Tahir Burak Women’s Health Education and Research Hospital (24/29.05.2018) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standard.

References

Schindler

, Koller-Smith

, Lui

, Bajuk

, Bolisetty

. New South Wales and Australian capital territory neonatal intensive care units’ data collection, Causes of death in very preterm infants cared for in neonatal intensive care units: A population-based retrospective cohort study. BMC Pediatr 2017;17(1):59.

Owens

. Intraventricular hemorrhage in the premature neonate, Neonatal Netw 2005;24:55–71.

Pinto-Martin

, Whitaker

, Feldman

, Van Rossem

, Paneth

. Relation of cranial ultrasound abnormalities in low-birthweight infants to motor or cognitive performance at ages 2, 6, and 9 years, Dev Med Child Neurol 1999;41(12):826–33.

Roze

, Van Braeckel

, van der Veere

, et al. Functional outcome at school age of preterm infants with periventricular hemorrhagic infarction, Pediatrics 2009;123(6):1493–500.

Jain

, Kruse

, Demissie

, Khandelwal

. Impact of mode of delivery on neonatal complications: trends between and J Matern Fetal Neonatal Med 2009;22(6):491–500.

Horbar

JD:

: Vermont-Oxford Network 1997 database summary, Burlington, Vt, 1997, Vermont Oxford Network.

Synnes

, Macnab

, Qiu

, et al. Neonatal intensive care unit characteristics affect the incidence of severe intraventricular hemorrhage, Med Care 2006;44(8):754–9.

Alderliesten

, Lemmers

, Smarius

et al. Cerebral oxygenation, extraction, and autoregulation in very preterm infants who develop periintraventricular hemorrhage, J Pediatr 2013;162(4):698–704.e2.

Linder

, Haskin

, Levit

, et al. Risk factors for intraventricular hemorrhage in very low birth weight premature infants: a retrospective case-control study, Pediatrics.e 2003;111(5 Pt 1):590–5.

10.

Lee

, Kim

, Jung

, et al. Risk factors for periventricular-intraventricular hemorrhage in premature infants, J Korean Med Sci 2010;25(3):418–24.

11.

Oren

, et al. Assessment of clinical impact and predisposing factors for neonatal thrombocytopenia, Indian J Pediatr 1994;61(5):551–8.

12.

Christensen

, Henry

, Wiedmeier

, Stoddard

, Sola-Visner

, Lambert

, et al. Thrombocytopenia among extremely low birth weight neonates: data from a multihospital healthcare system, J Perinatol 2006;26(6):348–53.

13.

Lupton

, Hill

, Whitfield

, Carter

, Wadsworth

, Roland

. Reduced platelet count as a risk factor for intraventricular hemorrhage, Am J Dis Child 1988;142(11):1222–4.

14.

Baer

, Lambert

, Henry

, Christensen

. Severe Thrombocytopenia in the NICU, Pediatrics 2009;124(6):e1095–100.

15.

von Lindern

, van den Bruele

, Lopriore

, Walther

. Thrombocytopenia in neonates and the risk of intraventricular hemorrhage: a retrospective cohort study, BMC Pediatr 2011;11:16.

16.

Rastogi

, Olmez

, Bhutada

, Rastogi

. Drop in platelet counts in extremely preterm neonates and its association with clinical outcomes, J Pediatr Hematol Oncol 2011;33(8):580–4.

17.

Zisk

, Mackley

, Christensen

, Paul

. Is a small platelet mass associated with intraventricular hemorrhage in very low-birth-weight infants? J Perinatol 2011;31(12):776–9.

18.

Papile

, Burstein

, Koffler

. Incidence and evolution of subependymal and intraventricular hemorrhage: a study of infants with birth weights less than 1,500 gm, J Pediatr 1978;92(4):529–34.

19.

Kasap

, Takcı

, Erdogan Irak

, Gümüser

, Sönmezgöz

, Gül

, et al. Neonatal thrombocytopenia and the role of the platelet mass index in platelet transfusion in the neonatal intensive care unit, Balkan Med J 2020;37(3):150–6.

20.

Kahn

, Richardson

, Billett

. Association of thrombocytopenia and delivery method with intraventricular hemorrhage among very-low-birth-weight infants, Am J Obstet Gynecol 2002;186:109–16.

21.

Grevsen

, Hviid

CVB

, Hansen

, Hvas

. The role of platelets in premature neonates with intraventricular hemorrhage: A systematic review and meta-analysis, Semin Thromb Hemost 2020;46(3):366–78.

22.

Roberts

, Javed

, Hocker

, Wang

, Tarantino

. Risk factors associated with intraventricular hemorrhage in extremely premature neonates, Blood Coagul Fibrinolysis 2018;29(1):25–9.

23.

Murray

, Roberts

. Circulating megakaryocytes and their progenitors in early thrombocytopenia in preterm neonates, Pediatr Res 1996;40:112–9.

24.

Mitsiakos

, Papathanasiou

, Kyriakidis

, Karagianni

, Tsepis

, Tzimou

, Lazaridou

, Chatziioannidis

. Intraventricular Hemorrhage and Platelet Indices in Extremely Premature Neonates. J Pediatr Hematol Oncol. 2016;38(7):533–8.

25.

Dani

, Poggi

, Barp

, Berti

, Fontanelli

. Mean platelet volume and risk of bronchopulmonary dysplasia and intraventricular hemorrhage in extremely preterm infants, Am J Perinatol 2011;28(7):551–6.

26.

Eldor

, Avitzour

, Or

, Hanna

, Penchas

. Prediction of haemorrhagic diathesis in thrombocytopenia by mean platelet volume, Br Med J (Clin Res Ed) 1982;285(6339):397–400.

27.

Cekmez

, Tanju

, Canpolat

, Aydinoz

, Aydemir

, Karademir

, Sarici

. Mean platelet volume in very preterm infants: a predictor of morbidities? Eur Rev Med Pharmacol Sci 2013;17(1):134–7.

28.

Moore

, D’Amore

, Fustolo-Gunnink

, Hudson

, Newton

, Santamaria

, et al. PlaNeT2 MATISSE Two-year outcomes following a randomised platelet transfusion trial in preterm infants, Arch Dis Child Fetal Neonatal Ed 2023;108(5):452–7.