Overview
Definition:
Neonatal polycythemia is defined as a venous hematocrit (Hct) of ≥ 65% in a term or preterm infant
it is also referred to as neonatal hyperviscosity syndrome when symptomatic
Partial exchange transfusion (PET) involves the removal of the infant's blood and simultaneous replacement with an equal volume of plasma or a crystalloid solution to reduce the hematocrit.
Epidemiology:
The incidence of symptomatic polycythemia varies widely, reported between 1-5% of neonates
Risk factors include maternal diabetes, intrauterine growth restriction, post-term gestation, chronic intrauterine hypoxia, and chromosomal abnormalities like Trisomy 21
Twin-to-twin transfusion syndrome can also predispose to polycythemia in the recipient twin.
Clinical Significance:
Untreated symptomatic polycythemia can lead to significant morbidity including neurologic deficits (seizures, hypotonia), renal abnormalities, gastrointestinal complications (necrotizing enterocolitis), and pulmonary hypertension
Prompt diagnosis and management, including PET when indicated, are crucial to prevent these severe outcomes and ensure long-term health.
Clinical Presentation
Symptoms:
Jitteriness or irritability
Poor feeding
Lethargy
Tachypnea
Vomiting
Tremors
Hypoglycemia
Seizures.
Signs:
Plethoric (ruddy) complexion
Cyanosis
Hepatomegaly
Splenomegaly
Tachypnea
Irregular respirations
Poor peripheral perfusion
High-pitched cry
Hypotonia.
Diagnostic Criteria:
The diagnosis is confirmed by a venous hematocrit ≥ 65% in asymptomatic infants, and ≥ 60% in symptomatic infants
Investigations should also aim to identify the underlying cause and rule out other conditions
Guidelines from AAP and other professional bodies are used.
Diagnostic Approach
History Taking:
Key history points include maternal medical conditions (diabetes, hypertension), pregnancy complications (intrauterine growth restriction, post-maturity, prolonged rupture of membranes), birth history (birth weight, Apgar scores, need for resuscitation, placental abnormalities), and family history of polycythemia or related conditions
Red flags include evidence of intrauterine hypoxia or delayed cord clamping in at-risk infants.
Physical Examination:
A systematic examination focusing on vital signs, assessment for plethora, cyanosis, signs of hyperviscosity affecting major organ systems (CNS, renal, GI, respiratory), and identification of any underlying anomalies
Auscultation for cardiac murmurs and assessment of peripheral pulses are important.
Investigations:
Venous hematocrit (Hct) is the primary diagnostic test
typically confirmed on cord blood or at birth
Complete blood count (CBC) with differential
Blood glucose levels
Serum calcium and bilirubin
Renal function tests (BUN, creatinine)
Blood gas analysis if respiratory distress is present
Urinalysis
Imaging may include abdominal ultrasound to assess renal and liver size, and cranial ultrasound if neurologic signs are present
Genetic testing may be considered in specific cases.
Differential Diagnosis:
Conditions that can mimic polycythemia include maternal-induced hyperglycemia (causing fluid shifts), dehydration (leading to hemoconcentration), and cyanotic heart disease
Other causes of neonatal distress such as sepsis, hypoglycemia, and respiratory distress syndrome must be ruled out.
Management
Initial Management:
For asymptomatic infants with Hct 60-65%, conservative management with increased fluid intake and close monitoring is often sufficient
For symptomatic infants with Hct ≥ 60% or asymptomatic infants with Hct > 65%, partial exchange transfusion is indicated
Ensure hemodynamic stability before initiating PET.
Partial Exchange Transfusion:
The goal is to reduce the Hct to 55-60%
Using an umbilical venous catheter (UVC) placed in the inferior vena cava (distal to the diaphragm), remove 5-10 mL of the infant's blood and simultaneously infuse an equal volume of fresh frozen plasma (FFP), normal saline, or 5% albumin
The volume to be exchanged (V) is calculated as: V = (Hct_initial - Hct_target) / Hct_initial * Blood Volume (approx
80-90 mL/kg)
Typically, a 10-20% reduction in Hct is achieved per exchange
The procedure should be performed slowly over 1-2 hours
Close monitoring of vital signs, fluid balance, and Hct levels is essential
An alternative is using the infant's own cryopreserved blood collected at birth, if available, for reinfusion.
Supportive Care:
Maintain adequate hydration and caloric intake
Monitor blood glucose levels closely
Treat hypoglycemia with IV dextrose
Manage any seizures aggressively
Provide respiratory support if needed
Monitor for signs of complications such as necrotizing enterocolitis or renal dysfunction
Adequate nursing care and observation are paramount throughout the management process.
Complications
Early Complications:
Complications of PET include coagulopathy (due to removal of clotting factors with FFP), thrombotic events, fluid overload or deficit, electrolyte imbalances, hypothermia, infection at the catheter site, and air embolism
Complications of untreated polycythemia include seizures, necrotizing enterocolitis, renal vein thrombosis, and pulmonary hypertension.
Late Complications:
Long-term sequelae can include neurologic impairment, developmental delays, and behavioral issues in children who experienced severe or symptomatic polycythemia and its complications
Neurodevelopmental follow-up is crucial.
Prevention Strategies:
Prevention strategies focus on identifying and managing risk factors during pregnancy (e.g., tight glycemic control in diabetic mothers) and optimizing neonatal care (e.g., avoiding routine delayed cord clamping in high-risk pregnancies if polycythemia is a concern, though delayed clamping has benefits)
Early identification of risk factors and prompt monitoring of Hct in at-risk neonates is key.
Prognosis
Factors Affecting Prognosis:
The prognosis is generally good with timely and appropriate management
Factors influencing prognosis include the severity of polycythemia, presence of symptoms, underlying etiology, development of complications, and promptness of intervention
Neonates with neurologic complications often have a poorer long-term outcome.
Outcomes:
With successful reduction of hematocrit and management of complications, most neonates with polycythemia can expect normal neurodevelopmental outcomes
Infants who experience significant neurologic events or organ damage may have residual deficits.
Follow Up:
Infants treated for polycythemia, especially those who were symptomatic or had complications, require developmental surveillance and follow-up
This includes regular pediatric visits, hearing and vision screening, and neurodevelopmental assessments as indicated to monitor for any long-term effects.
Key Points
Exam Focus:
Define polycythemia and hyperviscosity syndrome
Understand indications for partial exchange transfusion based on hematocrit levels and clinical status
Recall the formula for calculating volume of exchange
Identify common complications of PET and polycythemia
Recognize risk factors for neonatal polycythemia.
Clinical Pearls:
Always check Hct from a venous sample for diagnosis
Differentiate symptomatic from asymptomatic polycythemia for management decisions
Consider FFP as the replacement fluid in PET, but saline or albumin are alternatives if FFP is unavailable or contraindicated
Monitor infants closely for signs of hyperviscosity even if Hct is just above 60%.
Common Mistakes:
Over-reliance on cord blood Hct alone without considering venous Hct at a later time
Performing exchange transfusion in asymptomatic infants with Hct < 65%
Inadequate monitoring of Hct levels and vital signs during or after the procedure
Not considering other causes of neonatal distress that can mimic polycythemia.