Blood loss due to diagnostic testing in extremely preterm infants in 22 European countries: a prospective observational study.

BACKGROUND

Extremely preterm infants often develop anemia of prematurity, partly caused by blood losses for laboratory diagnostic tests during their stay in the neonatal intensive care unit (NICU). However, international quantitative data on diagnostic blood loss in extremely preterm infants are limited.

METHODS

We performed an international, prospective, observational study across 64 NICUs across 22 European countries (ISRCTN17267090) to describe diagnostic blood losses during the first 28 days after birth in extremely preterm infants born below 28 weeks. Data collected between September 1st, 2022 and August 31st, 2023 (6-weeks per center).

FINDINGS: We included 320 extremely preterm infants (46% female; median gestational age at birth 26 + 1 weeks; median birthweight 800 g). Median estimated cumulative diagnostic blood loss at day 28 in infants born at 24, 25, 26, 27 weeks' gestation was 49.6%, 25.9%, 19.7%, 11.5% of calculated initial blood volume (assuming 70 mL/kg birthweight), respectively. Median number of laboratory tests ranged from 6.5 to 25 per center after birth (postnatal day 1-2), and median associated diagnostic blood loss on day 1 and 2 combined ranged from 1.6 to 26.7 mL/kg. There was considerable variation between centers in minimum blood volumes required for laboratory testing. Infants admitted to centers with small-volume analyzers experienced half the cumulative diagnostic blood loss by day 28 (8.2 mL/kg), compared to those admitted to centers with medium- and large-volume analyzers (17.3 and 19.9 mL/kg, respectively).

INTERPRETATION: In this cohort study of extremely preterm infants, we found significant diagnostic blood losses, particularly in the first week, resulting in an estimated cumulative loss of half of the initial blood volume in infants born at 24 weeks. Our findings highlight considerable variations between European centers, underlining the need to understand these differences and minimize diagnostic blood losses whenever possible in this vulnerable patient population.

FUNDING: Sanquin, ESPR, EBA.