Guideline 10.2 — Anemia, Polycythemia & Thrombocytopenia

BEDSIDE ACTION BOX

Acute anaemia with shock (pallor, tachycardia, poor perfusion, e.g., after abruption/feto-maternal or acute blood loss) → resuscitate and give emergency O-negative red cells; don't wait for a formal crossmatch if life-threatening.
For non-acute anaemia, transfuse to a threshold matched to gestation, postnatal age, and respiratory support (use your unit's restrictive threshold table), not to a fixed number.
Symptomatic polycythaemia (venous Hct >65% with symptoms — jitteriness, lethargy, poor feeding, hypoglycaemia, respiratory distress) → hydrate, treat hypoglycaemia, and consider partial exchange transfusion (dilutional, using normal saline).
Confirm true polycythaemia on a venous (not capillary) sample; capillary Hct overestimates.
Severe thrombocytopenia or bleeding → assess for NAIT/sepsis/DIC, apply restrictive platelet thresholds (PlaNeT-2), and see guideline 10.4. Well infant <7 days with platelets <50 = NAIT until proven otherwise.

1. Overview

Overview

This guideline covers three common neonatal haematological problems: anaemia (from blood loss, haemolysis, or reduced production — including anaemia of prematurity), polycythaemia (raised haematocrit causing hyperviscosity), and an approach to thrombocytopenia. The unifying principle is to treat the infant, not the number — using restrictive, evidence-based thresholds and always seeking the underlying cause.

Why This Topic Matters

Both over- and under-transfusion cause harm. Restrictive red-cell and platelet strategies (e.g., PlaNeT-2 for platelets) are as safe as — or safer than — liberal ones, and unnecessary partial exchange for asymptomatic polycythaemia exposes infants to procedural risk (including NEC) without benefit.

2. Who This Guideline Applies To

Scope

Neonates with anaemia (acute loss, haemolysis, anaemia of prematurity), polycythaemia, or thrombocytopenia.
Infants being considered for red-cell/platelet transfusion or partial exchange transfusion.
Cross-references: hyperbilirubinaemia (10.1), the bleeding neonate (10.3), platelet disorders/NAIT (10.4), and sepsis (8.1/8.2).

3. Key Definitions

Term	Definition
Anaemia of prematurity	Normocytic, normochromic anaemia of preterm infants from low erythropoietin, short RBC lifespan, and phlebotomy losses (typically weeks 4–8).
Polycythaemia	Venous haematocrit >65% (or Hb >~22 g/dL); risk of hyperviscosity.
Hyperviscosity	Impaired microcirculation from raised Hct — the mechanism of polycythaemia symptoms.
Partial exchange transfusion (PET)	Removing blood and replacing with normal saline to lower Hct while maintaining volume.
Thrombocytopenia	Platelet count <150 ×10⁹/L; severe <50; very severe <25.
NAIT	Neonatal alloimmune thrombocytopenia — severe isolated thrombocytopenia in a well infant; see 10.4.

4. Anaemia — Causes

Mechanistic Framework

Classify by mechanism — this guides investigation and treatment.

Mechanism	Examples	Clues
Blood loss	Feto-maternal/twin-twin transfusion, abruption/cord accident, iatrogenic phlebotomy, internal haemorrhage (IVH, subgaleal, hepatic/splenic).	Acute: shock with normal initial Hb; chronic: pallor without distress; Kleihauer for FMH.
Haemolysis	Rh/ABO incompatibility, G6PD, spherocytosis, sepsis.	Jaundice, high reticulocytes, positive DAT, abnormal film.
Reduced production	Anaemia of prematurity, congenital (Diamond-Blackfan), infection (parvovirus B19).	Low reticulocytes; timing (weeks 4–8 in preterm).

Work-up

FBC, film, reticulocytes, blood group + DAT, bilirubin; maternal Kleihauer if feto-maternal haemorrhage suspected; G6PD and further tests as indicated. Minimise iatrogenic phlebotomy and use delayed cord clamping to reduce anaemia of prematurity; ensure iron supplementation for preterm infants.

5. Red-Cell Transfusion

Restrictive, State-Based Thresholds

Use your unit's restrictive Hb/Hct threshold table, which rises with respiratory support and falls with postnatal age; large trials (e.g., ETTNO, TOP) show restrictive thresholds are safe.
Typical top-up volume ~15–20 mL/kg of packed red cells over ~3–4 hours (verify locally); use irradiated/CMV-safe products where indicated.
Acute major loss with instability: resuscitate and give emergency group O RhD-negative red cells; treat the source of bleeding.
Reduce need: delayed cord clamping, minimal sampling, and iron/nutrition; erythropoietin is used selectively per unit policy.

⚠ Verify

Exact Hb/Hct transfusion thresholds and volumes must come from your local transfusion policy — flagged for expert review.

6. Polycythaemia

Recognition & Management

Definition: venous Hct >65%. Confirm on a venous sample — capillary/heel-prick overestimates. Warmed samples improve accuracy.
Causes: delayed cord clamping/cord stripping, twin-twin transfusion (recipient), IUGR/placental insufficiency, maternal diabetes, and some chromosomal/endocrine conditions.
Symptoms (hyperviscosity): plethora, jitteriness, lethargy, poor feeding, hypoglycaemia, respiratory distress, hypocalcaemia, thrombocytopenia; rarely NEC, renal vein thrombosis, seizures.
Management: asymptomatic and Hct 65–70% → hydrate and recheck. Symptomatic (or very high Hct per local policy) → partial exchange transfusion with normal saline to reduce Hct to ~55%, alongside treating hypoglycaemia and ensuring hydration.
Partial-exchange volume is calculated from blood volume and the target/observed Hct — follow the unit formula; be alert to NEC risk after the procedure.

7. Thrombocytopenia — Approach

Classify by Timing & Clinical State

Early (<72 h): often placental insufficiency/IUGR (mild, self-limiting), perinatal asphyxia, or congenital infection; if severe in a well infant → suspect NAIT (see 10.4).
Late (>72 h): think sepsis, NEC, and DIC (usually a sick infant).
Severity: <50 severe, <25 very severe; assess for bleeding and cause.

Restrictive Platelet Transfusion (PlaNeT-2)

Use restrictive thresholds: a threshold of 25 ×10⁹/L (rather than 50) was as safe or safer than a higher threshold in preterm infants without major bleeding.
Higher thresholds apply for active major bleeding or before invasive procedures per local policy.
For NAIT: use HPA-compatible/washed maternal or random-donor platelets and IVIG per the NAIT pathway — see 10.4.

8. Management Algorithm

Anaemia — stable or shocked?

Shocked/acute loss → resuscitate + emergency O-neg red cells + stop the bleeding. Stable → investigate mechanism and use restrictive thresholds.

Confirm the diagnosis

FBC, film, reticulocytes, DAT, bilirubin; Kleihauer if FMH suspected; venous Hct to confirm polycythaemia; assess platelet count, timing, and clinical state.

Polycythaemia — symptomatic?

Asymptomatic (Hct 65–70%) → hydrate, recheck. Symptomatic → partial exchange with saline to Hct ~55%; treat hypoglycaemia.

Thrombocytopenia — well or sick?

Well infant, severe, <7 days → suspect NAIT (10.4). Sick/late → sepsis/NEC/DIC work-up. Apply restrictive platelet thresholds.

Transfuse to threshold, not to a number

Use local restrictive Hb/platelet thresholds; give the correct, appropriately modified product (irradiated/CMV-safe as indicated).

⚠ Do-not-miss

Occult major haemorrhage (subgaleal, IVH, intra-abdominal); NAIT in a well thrombocytopenic baby (intracranial-haemorrhage risk); NEC after partial exchange; and haemolysis driving both anaemia and jaundice.

9. Blood Products & Safety

Product	Typical use	Notes
Packed red cells	~15–20 mL/kg (verify) for anaemia at threshold	Irradiated/CMV-safe where indicated; emergency O RhD-negative for acute loss.
Normal saline	Replacement fluid for partial exchange (polycythaemia)	Dilutional; avoids donor exposure.
Platelets	Severe thrombocytopenia/bleeding at threshold	Restrictive (PlaNeT-2); special products for NAIT (see 10.4).
FFP / cryoprecipitate	Coagulopathy/DIC (see 10.3)	Guided by coagulation results and bleeding.

10. Monitoring

Parameter	When	Action
Hb / Hct	Post-transfusion / post-PET, and per trend	Confirm target; investigate ongoing losses.
Glucose / calcium	Polycythaemia and post-PET	Treat hypoglycaemia/hypocalcaemia.
Platelet count	After transfusion / per cause	Reassess threshold; investigate persistent low counts.
Abdominal signs	After partial exchange	Watch for NEC (feeding intolerance, distension).
Bilirubin	If haemolysis	Manage per 10.1.

11. Contraindications & Precautions

Safety Cautions

Do not perform partial exchange for asymptomatic polycythaemia at modestly raised Hct — procedural risk (NEC) without proven benefit.
Confirm polycythaemia on a venous sample; do not act on capillary Hct alone.
Use restrictive transfusion thresholds; avoid liberal, number-driven transfusion.
Use correctly modified products (irradiated/CMV-safe) per indication; observe transfusion-reaction monitoring.
Never delay resuscitation/emergency red cells in acute haemorrhagic shock.
Treat NAIT-suspected severe thrombocytopenia urgently (ICH risk) — see 10.4.

12. Escalation & Parent Counselling

Escalate When…

Haemorrhagic shock or occult major bleeding — senior/NICU, transfusion lab, surgery as needed.
Symptomatic polycythaemia needing partial exchange, or complications (NEC, thrombosis).
Severe/very severe or NAIT-suspected thrombocytopenia — haematology and the NAIT pathway (10.4).

Parent Counselling Points

"Premature babies often become mildly anaemic; we transfuse only when needed, using careful thresholds, and reduce blood tests to a minimum."
"If the blood is too thick (high haematocrit) and your baby has symptoms, we can gently thin it with a fluid exchange."
"Low platelets have several causes; we investigate the reason and only give platelets when the level or bleeding makes it necessary."

13. Key Pearls

High-Value Clinical Pearls

Classify anaemia by mechanism: loss, haemolysis, or reduced production (reticulocytes + DAT + film).
Acute loss can have a normal initial Hb — treat the clinical picture (shock), not the first number.
Use restrictive red-cell thresholds (ETTNO/TOP); reduce need with delayed cord clamping and minimal sampling.
Confirm polycythaemia on a venous Hct; treat only symptomatic infants with partial exchange (saline) to Hct ~55%.
Restrictive platelet threshold ~25 ×10⁹/L in stable preterm infants (PlaNeT-2).
Well infant + severe isolated thrombocytopenia = NAIT until proven otherwise (10.4).

14. Common Mistakes to Avoid

Mistake	Why it harms	Better practice
Diagnosing polycythaemia on capillary Hct.	Over-diagnosis, unnecessary PET.	Confirm on a venous sample.
Partial exchange for asymptomatic polycythaemia.	NEC risk without benefit.	Hydrate and recheck if asymptomatic.
Liberal, number-driven transfusion.	Donor exposure, no benefit.	Restrictive, state-based thresholds.
Reassurance from a normal Hb in acute bleed.	Delayed resuscitation.	Treat shock; give emergency O-neg cells.
Missing NAIT in a well thrombocytopenic baby.	ICH risk.	Urgent NAIT pathway (10.4).
Not seeking the cause of thrombocytopenia.	Misses sepsis/NEC/DIC.	Classify by timing/clinical state.

15. Board-Style High-Yield Summary

Key Takeaways

Anaemia: classify as loss / haemolysis / reduced production; acute loss may show a normal early Hb.
Transfuse red cells on restrictive, respiratory-support- and age-based thresholds (ETTNO/TOP); ~15–20 mL/kg (verify locally).
Polycythaemia = venous Hct >65%; treat symptomatic infants with saline partial exchange to Hct ~55%.
Thrombocytopenia: early = placental/asphyxia/NAIT (if well+severe); late = sepsis/NEC/DIC.
Restrictive platelet threshold ~25 ×10⁹/L in stable preterm infants (PlaNeT-2); higher for major bleeding/procedures.
Reduce anaemia of prematurity: delayed cord clamping, minimal phlebotomy, iron.

16. References

1.Bedside Clinical Guidelines Partnership / West Midlands Neonatal ODN. Anaemia; Polycythaemia; Thrombocytopenia; Blood Product Transfusion. Neonatal Guidelines 2025–28.
2.Curley A, et al. (PlaNeT-2/MATISSE). Randomized trial of platelet-transfusion thresholds in neonates. N Engl J Med. 2019.
3.Franz AR, et al. (ETTNO). Effects of liberal vs restrictive transfusion thresholds on neurodevelopment (preterm). JAMA. 2020.
4.Kirpalani H, et al. (TOP). Higher or lower haemoglobin transfusion thresholds for preterm infants. N Engl J Med. 2020.
5.New HV, et al. British Society for Haematology guidelines on transfusion for fetuses, neonates and older children. Br J Haematol. 2016.

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Chapter 10.2 — Anemia, Polycythemia & Thrombocytopenia