Neonates with suspected microangiopathic disorders: performance of standard manual schistocyte enumeration vs. the automated fragmented red cell count

Neonatal Thrombocytopenia: Factors Associated With the Platelet Count Increment Following Platelet Transfusion

OBJECTIVE

To understand better those factors relevant to the increment of rise in platelet count following a platelet transfusion among thrombocytopenic neonates.

STUDY DESIGN

We reviewed all platelet transfusions over 6 years in our multi-neonatal intensive care unit system. For every platelet transfusion in 8 neonatal centers we recorded: (1) platelet count before and after transfusion; (2) time between completing the transfusion and follow-up count; (3) transfusion volume (mL/kg); (4) platelet storage time; (5) sex and age of platelet donor; (6) gestational age at birth and postnatal age at transfusion; and magnitude of rise as related to (7) pre-transfusion platelet count, (8) method of enhancing transfusion safety (irradiation vs pathogen reduction), (9) cause of thrombocytopenia, and (10) donor/recipient ABO group.

RESULTS

We evaluated 1797 platelet transfusions administered to 605 neonates (median one/recipient, mean 3, and range 1-52). The increment was not associated with gestational age at birth, postnatal age at transfusion, or donor sex or age. The rise was marginally lower: (1) with consumptive vs hypoproductive thrombocytopenia (P < .001); (2) after pathogen reduction (P < .01); (3) after transfusing platelets with a longer storage time (P < .001); and (4) among group O neonates receiving platelets from non-group O donors (P < .001). Eighty-seven neonates had severe thrombocytopenia (<20 000/μL). Among these infants, poor increments and death were associated with the cause of the thrombocytopenia.

CONCLUSION

The magnitude of post-transfusion rise was unaffected by most variables we studied. However, the increment was lower in neonates with consumptive thrombocytopenia, after pathogen reduction, with longer platelet storage times, and when not ABO matched.

A "Gold Standard" Test for Diagnosing and Quantifying Hemolysis in Neonates and Infants

Identifying "gold standard" diagnostic tests can promote evidence-based neonatology practice. Hemolysis is a pathological shortening of the erythrocyte lifespan, differing from erythrocyte senescence in responsible mechanisms and clinical implications. Diagnosing hemolysis goes beyond a binary (yes vs. no) determination. It is characterized according to magnitude, and as acute vs. chronic, and genetically based vs. not. For neonates with significant hyperbilirubinemia or anemia, detecting hemolysis and quantifying its magnitude provides diagnostic clarity. The 2022 American Academy of Pediatrics (AAP) Clinical Practice Guideline on management of hyperbilirubinemia in the newborn states that hemolysis is a risk factor for developing significant hyperbilirubinemia and neurotoxicity. The guideline recommends identifying hemolysis from any cause, but specific guidance is not provided. A spectrum of laboratory tests has been endorsed as diagnostic methods for hemolysis. Herein we examine these laboratory tests and recommend one as the "gold standard" for diagnosing and quantifying hemolysis in neonates and infants.

Traversing Their Path to the Peripheral Smear: The Journey of Traumatized Red Blood Cells

Background  Thrombotic microangiopathy encompasses a wide range of conditions, of which thrombotic thrombocytopenic purpura being a medical emergency requires prompt intervention, with schistocytes being a reliable morphological indicator of microvascular injury. However, there are conditions other than thrombotic microangiopathic anemia where schistocytes can be seen in large numbers. These nonthrombotic microangiopathic conditions are broadly grouped under cytoskeletal abnormalities, mechanical damage, and thermal injuries. Automated methods in schistocyte evaluation have shown varied reproducibility requiring manual identification. International Council for Standardization in Hematology (ICSH) recommends standardized morphological criteria and quantitative assessment as a percentage after counting at least 1,000 red blood cells in optimal areas of smear to reduce interobserver variability. Objectives  The aim of this study was to evaluate and quantitate schistocytes in thrombotic microangiopathic and nonthrombotic microangiopathic groups using ICSH guidelines and to evaluate interobserver reproducibility of manual schistocyte count. Materials and Methods  Overall, 157 peripheral blood smears showing schistocytes were studied by two independent observers using ICSH recommendations on light microscopy. The hematological findings were correlated with clinical diagnosis and other relevant investigations. Results  Schistocytes were observed in five cases of thrombotic microangiopathic anemia and 152 cases of nonthrombotic microangiopathic anemia. Schistocyte count in thrombotic microangiopathic anemia and nonthrombotic microangiopathic anemia groups with mean (±standard deviation) value was 2.28 ± 2.65% and 0.76 ± 0.67%, respectively ( p  < 0.001). The correlation coefficient between the two observers was 0.59 (confidence interval = 0.966-1.346) showing an excellent agreement on the reproducibility of schistocytes by application of ICSH guidelines. Conclusion  Percentage of schistocytes more than 1% is a robust morphological indicator for diagnosis of thrombotic microangiopathic anemia in adults. Strict application of ICSH guidelines reduces interobserver bias.

Computer vision quantitation of erythrocyte shape abnormalities provides diagnostic, prognostic, and mechanistic insight

Examination of red blood cell (RBC) morphology in peripheral blood smears can help diagnose hematologic diseases, even in resource-limited settings, but this analysis remains subjective and semiquantitative with low throughput. Prior attempts to develop automated tools have been hampered by their poor reproducibility and limited clinical validation. Here, we present a novel, open-source machine-learning approach (denoted as RBC-diff) to quantify abnormal RBCs in peripheral smear images and generate an RBC morphology differential. RBC-diff cell counts showed high accuracy for single-cell classification (mean AUC, 0.93) and quantitation across smears (mean R2, 0.76 compared with experts, interexperts R2, 0.75). RBC-diff counts were concordant with the clinical morphology grading for 300 000+ images and recovered the expected pathophysiologic signals in diverse clinical cohorts. Criteria using RBC-diff counts distinguished thrombotic thrombocytopenic purpura and hemolytic uremic syndrome from other thrombotic microangiopathies, providing greater specificity than clinical morphology grading (72% vs 41%; P < .001) while maintaining high sensitivity (94% to 100%). Elevated RBC-diff schistocyte counts were associated with increased 6-month all-cause mortality in a cohort of 58 950 inpatients (9.5% mortality for schist. >1%, vs 4.7% for schist; <0.5%; P < .001) after controlling for comorbidities, demographics, clinical morphology grading, and blood count indices. RBC-diff also enabled the estimation of single-cell volume-morphology distributions, providing insight into the influence of morphology on routine blood count measures. Our codebase and expert-annotated images are included here to spur further advancement. These results illustrate that computer vision can enable rapid and accurate quantitation of RBC morphology, which may provide value in both clinical and research contexts.

Severe Anemia at Birth-Incidence and Implications

OBJECTIVE

To identify neonates with severe anemia at birth, defined by a hemoglobin or hematocrit value within the first 6 hours after birth that plotted below the 1st percentile according to gestational age. For each patient, we retrospectively determined whether caregivers recognized the anemia within the first 24 hours after birth and the probable cause and outcome of anemia.

STUDY DESIGN

This was a retrospective cohort analysis of Intermountain Healthcare population-based data from neonates born between January 2011 and December 2020 who had a hemoglobin or hematocrit value measured within the first 6 hours after birth below the 1st percentile lower reference interval (hematocrit ∼35% in near-term/term neonates).

RESULT

Among 299 927 live births, we identified 344 neonates with severe anemia at birth. In 191 of these neonates (55.5%), the anemia was recognized by caregivers during the first 24 hours. Anemia was more likely to be recorded as a problem (85%) if the hemoglobin was ≥2 g/dL below the 1st percentile (P < .001). The lowest hemoglobin values occurred in those in whom hemorrhage was the probable cause (P < .013 vs hemolysis and P < .001 vs hypoproduction, mixed cause, or indeterminant.) Treatment was provided to 39.5%. A retrospective review suggested that mixed mechanisms, particularly hemorrhagic plus hemolytic, occurred more commonly than was recognized at the time of occurrence.

CONCLUSIONS

Severe anemia at birth often went unrecognized on the first day of life. Algorithm-directed retrospective reviews commonly identified causes that were not listed in the medical record. We postulate that earlier recognition and more accurate diagnoses would be facilitated by an electronic medical record-associated hemoglobin/hematocrit gestational age nomogram.

Neonatal Reference Intervals for the Complete Blood Count Parameters MicroR and HYPO-He: Sensitivity Beyond the Red Cell Indices for Identifying Microcytic and Hypochromic Disorders

OBJECTIVE

To create neonatal reference intervals for the MicroR and HYPO-He complete blood count (CBC) parameters and to test whether these parameters are sensitive early markers of disease at early stages of microcytic/hypochromic disorders while the CBC indices are still normal.

STUDY DESIGN

We retrospectively collected the CBC parameters MicroR and HYPO-He, along with the standard CBC parameters, from infants aged 0-90 days at Intermountain Healthcare hospitals using Sysmex hematology analyzers. We created reference intervals for these parameters by excluding values from neonates with proven microcytic disorders (ie, iron deficiency or alpha thalassemia) from the dataset.

RESULT

From >11 000 CBCs analyzed, we created reference intervals for MicroR and HYPO-He in neonates aged 0-90 days. The upper intervals are considerably higher in neonates than in adults, validating increased anisocytosis and polychromasia among neonates. Overall, 52% of neonates with iron deficiency (defined by reticulocyte hemoglobin equivalent <25 pg) had a MicroR >90% upper interval (relative risk, 4.14; 95% CI, 3.80-4.53; P < .001), and 68% had an HYPO-He >90% upper interval (relative risk, 6.64; 95% CI, 6.03-7.32; P < .001). These 2 new parameters were more sensitive than the red blood cell (RBC) indices (P < .001) in identifying 24 neonates with iron deficiency at birth.

CONCLUSIONS

We created neonatal reference intervals for MicroR and HYPO-He. Although Sysmex currently designates these as research use only in the US, they can be measured as part of a neonate's CBC with no additional phlebotomy volume or run time and can identify microcytic and hypochromic disorders even when the RBC indices are normal.

2021 update of the 2012 ICSH Recommendations for identification, diagnostic value, and quantitation of schistocytes: Impact and revisions

In 2012, the International Council for Standardization in Hematology (ICSH) published recommendations for the identification, quantitation, and diagnostic value of schistocytes. In the present review, the impact of these recommendations is evaluated. This work is based on citations in peer-reviewed papers published since 2012. The first 2012 ICSH Recommendations have also been revised to incorporate newly published data in the literature and current best laboratory practice. Recommended reference ranges have been proposed for healthy adults and full-term neonates of 1% or less schistocytes. More than 1% of morphologically identified schistocytes on the blood film are considered suspicious for thrombotic microangiopathy. For preterm infants, a normal level of 5% or less is recommended. The fragment red cell count (FRC) generated by some automated hematological analyzers provides a valuable screening tool for the presence of schistocytes. Specifically, the absence of FRCs can be used as a valuable parameter to exclude the presence of schistocytes on the blood film. The validity and usefulness of microscope schistocytes and automated FRCs, respectively, are discussed in the context of the laboratory diagnostic tests used for thrombotic microangiopathies.

Usefulness of automated fragmented red blood cell percentage in the diagnosis of paediatric haemolytic uraemic syndrome

INTRODUCTION

Presence of schistocytes in peripheral blood smear supporting haemolysis is important for diagnosis and decision-making in paediatric haemolytic uraemic syndrome (HUS). High observer dependency and requirement of expertise for peripheral smear evaluation propels us to think of other modalities to overcome these issues. We envisage that newer techniques like automated fragmented red blood cell percentage (FRC %), whose role has been described in transplant associated HUS and thrombotic thrombocytopenic purpura, can serve the purpose.

METHODS

Twenty-eight children with HUS after excluding secondary causes were enrolled in this study. Blood samples were analysed for FRC% at admission, using SYSMEX XN-1000 (Japan) haematology analyser, and simultaneously, schistocytes in peripheral smear were reported by a single expert haematopathologist.

RESULTS

Median age was 56 months ranging from 2 to 140 months. FRC% was elevated in 85.8% (n-24/28) with a mean of 4.56 ± 3.1%. FRC% had a sensitivity of 95.4% (C.I: 77.16% to 99.88%) in children who had FRC% >1.49% with an accuracy of 85.71% (C.I: 67.33% to 95.97%). However, specificity was only 50% (C.I: 11.81% to 88.19%) with a positive likelihood ratio of 1.91. Receiver-operator curve showed an AUC value of 0.841.

CONCLUSION

We suggest automated FRC% as a rapid and highly sensitive index for screening of paediatric HUS; however, a peripheral blood film examination is a must in cases with count >2% to avoid false positives as the index has low specificity.