AUTHOR AND EDITOR INFORMATION

Section 1 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Background

Polycythemia, defined as a central venous hematocrit (Hct) of greater than 65%, is a relatively common disorder. The primary concern with polycythemia is related to hyperviscosity and its associated complications. Blood viscosity increases exponentially as the Hct rises above 42%. This associated hyperviscosity is thought to contribute to the symptom complex observed in approximately one half of infants with polycythemia. However, only 47% of infants with polycythemia have hyperviscosity, and only 24% of infants with hyperviscosity have a diagnosis of polycythemia.

Pathophysiology

As the central Hct increases, viscosity increases. The arterial oxygen content also increases.  Changes in blood flow are observed in some organs; this is due to changes in viscosity or changes in arterial oxygen content. The change in blood flow may influence oxygenation and may influence the delivery of substances to organs that are dependent on plasma flow, such as glucose. 

Many factors determine blood viscosity. The primary factor in the newborn is the Hct. As such, viscosity increases as Hct rises. Other factors that uniquely contribute to blood viscosity in the neonate include increased RBC volume and decreased deformability of the fetal erythrocyte.  Plasma proteins, platelets, WBCs and endothelial factors also contribute to viscosity; however, they are not clinically significant in the newborn.

Frequency

United States

Polycythemia occurs in 0.4-12% of neonates. It is more common in infants who are small for their gestational age (SGA) and in infants who are large for their gestational age (LGA). However, most infants with polycythemia are of appropriate size or weight for their gestational age (AGA). Infants of mothers with diabetes have an incidence of more than 40%, and those born to mothers with gestational diabetes have an incidence of more than 30%. Polycythemia is also common in infants who have experienced delayed clamping of the umbilical cord. Hyperviscosity occurs in 6.7% of infants.

Mortality/Morbidity

• The central nervous, cardiopulmonary, gastrointestinal, and renal systems are at risk.
• Metabolic derangements are common.
• Coagulation also can be affected.

Age

• The Hct peaks 6-12 hours after birth and then declines until the infant is aged 24 hours, at which time it equals the Hct in cord blood.
• Fewer than 40% of infants with a Hct greater than 64% at 2 hours still have a high value at 12 hours or later.

CLINICAL

Section 3 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

History

Neonates with polycythemia may have the following findings:

• Lethargy
• Irritability
• Jitteriness
• Tremors
• Seizures
• Cerebrovascular accidents
• Respiratory distress
• Cyanosis
• Apnea

Physical

• General
• • The most obvious finding is plethora or ruddiness.
  • Priapism may be observed in male patients.
• CNS
• • CNS manifestations are the most common problems observed with polycythemia and hyperviscosity.
  • Symptoms include lethargy, irritability, jitteriness, tremors, seizures, and cerebrovascular accidents.
• Cardiopulmonary: Manifestations include respiratory distress, tachypnea, cyanosis, apnea, and congestive heart failure. Increases in Hct are associated with a decrease in pulmonary blood flow in all newborns. In those with a Hct of 65% or more, the decrease in pulmonary blood flow may be associated with respiratory distress and cyanosis.
• Gastrointestinal
• • Poor feeding is reported in more than one half of all infants with polycythemia and hyperviscosity.
  • Necrotizing enterocolitis (NEC) is a rare but devastating complication of polycythemia or hyperviscosity. Historically, about 44% of term infants with NEC have polycythemia. More recent data suggest that polycythemia may not have a large role in the development of NEC in the term infant but may be related to partial exchange transfusion with colloid to reduce the Hct.
• Renal: Manifestations include decreased glomerular filtration rates, oliguria, hematuria, proteinuria, and renal vein thrombosis.
• Metabolic
• • Hypoglycemia is the most common metabolic derangement and is observed in 12-40% of infants with polycythemia.
  • Hypocalcemia is the next most common metabolic derangement and is found in 1-11% of neonates with polycythemia.
• Coagulation
• • Coagulation can be affected.
  • Thrombocytopenia
  • Disseminated intravascular coagulation (DIC) is rare.

Causes

• Increased fetal erythropoiesis secondary to fetal hypoxia. Underlying causes include the following:
• • Placental insufficiency can be secondary to preeclampsia, primary renovascular disease, chronic or recurrent abruptio placenta, maternal cyanotic congenital heart disease, postdate pregnancy, and maternal smoking. Most of these maternal conditions may also be associated with intrauterine growth restriction (IUGR).
  • Endocrine abnormalities associated with increased fetal oxygen consumption resulting in fetal hypoxia include congenital thyrotoxicosis and Beckwith-Wiedemann syndrome or infants of a diabetic mother (IDM) with poor glycemic control.
  • Genetics disorders (eg, trisomy 13, trisomy 18, trisomy 21) are also underlying causes.
• Hypertransfusion
• • Delayed cord clamping allows for an increased blood volume to be delivered to the infant. When cord clamping is delayed more than 3 minutes after birth, blood volume increases 30%.
  • Gravity also may be a factor because of the position of the delivered infant in relation to the maternal introitus before cord clamping.
  • In the event of delayed cord clamping, blood flow to the infant is enhanced by oxytocin.
  • Twin-to-twin transfusion syndrome due to a vascular communication occurs in approximately 10% of monozygotic twin pregnancies.
  • In intrapartum asphyxia, blood volume is shifted from the placenta to the fetus.

DIFFERENTIALS

Section 4 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Method of blood draw: Capillary Hct measurements depend on regional blood flow and can widely vary from central venous measurements, generally overestimating the central or true Hct.

Iatrogenic problems: These may be related to transfusion.

WORKUP

Section 5 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Lab Studies

• The central venous Hct measurement is used as a surrogate for diagnosing hyperviscosity because it is a readily available. Most clinical laboratories are not able to measure blood viscosity.
• Other laboratory tests include measurements of the following:
• • Serum glucose and calcium levels: Measure these to determine if the patient has decreased levels that require treatment.
  • Bilirubin level: Measure this level in the infant with jaundice and polycythemia because the increased RBC mass leads to an increased load of bilirubin precursors that can result in hyperbilirubinemia.
  • Arterial blood gases (ABG): Consider measuring ABG values to assess oxygenation in the symptomatic infant with respiratory distress and cyanosis.
  • Platelet count: This count may demonstrate thrombocytopenia if thrombosis or DIC are present.

TREATMENT

Section 6 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Medical Care

Therapy is based on both the measured central venous Hct and the presence or absence of symptoms.

Treatment of polycythemia with partial exchange transfusion remains controversial. Regarding treatment with partial exchange, the Committee of the Fetus and Newborn of the American Academy of Pediatrics states, "The accepted treatment of polycythemia is partial exchange transfusion (PET). However there is no evidence that exchange transfusion affects the long term outcome."

• Treatment for asymptomatic patients
• • Hct 65-75%: Perform cardiorespiratory monitoring and monitoring of Hct and glucose levels every 6 hours and observe the patient for symptoms.
  • Hct more than 75% on repeated measurements: Consider partial exchange transfusion. 
• Treatment for symptomatic patients
• • Hct 60-65%: Consider alternative explanations for the symptoms. Although polycythemia and hyperviscosity may be the etiology of the symptoms, other causes for the symptoms must be excluded.
  • Hct more than 65% with symptoms attributable to polycythemia and hyperviscosity: Perform partial exchange transfusion.
• Partial exchange transfusion
• • Perform a partial exchange transfusion by using an umbilical venous catheter to reduce the central Hct to 50-55%.
  • The total blood volume to be exchanged is determined as follows: [blood volume(patient's Hct – desired Hct)]/(patient's Hct), where blood volume = the patient's weight in kilograms multiplied by 90 mL/kg.
  • Normal saline is the replacement fluid of choice for exchange transfusions because it is effective and inexpensive. As alternatives, Plasmanate, 5% albumin, or fresh frozen plasma can be used. However, none of these is more effective than normal saline. In addition, both 5% albumin and fresh frozen plasma are blood products, and certain religious beliefs prohibit their use. Lastly, these colloid products have been associated with complications such as NEC.
  • Sterile technique is required.
  • An exchange transfusion can be performed in 3 ways, depending on the type of vascular access that is available. Regardless of the method used, aliquots should not exceed approximately 5 mL/kg delivered or removed over 2-3 minutes.
    • If only a single umbilical venous catheter is in place, use a push-pull technique. With this technique, the withdrawal of blood is alternated with the administration of replacement fluid through the single catheter. Do not remove more than 5 mL/kg in any single withdrawal.
    • If both umbilical venous and arterial catheters are in place, withdraw blood from the arterial catheter while administering the replacement fluid through the venous catheter.
    • If a venous or arterial umbilical catheter and a peripheral venous catheter are in place, the former can be used for blood withdrawal, while the latter is used to simultaneously and continuously infuse the replacement fluid.

FOLLOW-UP

Section 7 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• Carefully monitor vital signs and bilirubin, glucose, and electrolyte levels as needed.
• Feedings may cautiously be introduced a number of hours after completing the partial exchange transfusion.

Further Outpatient Care

• Perform routine newborn follow-up care.

Complications

• Apnea
• Arrhythmia
• Vasospasm
• Vessel perforation
• Air embolus
• Thrombosis
• Infarction
• Thrombocytopenia
• Hemolysis
• Electrolyte abnormalities
• Hypoglycemia
• Hypocalcemia
• Intrahepatic hematoma
• Necrotizing enterocolitis

Prognosis

• Infants are at increased risk for neurological deficits including speech abnormalities, fine-motor delays, and gross-motor delays.
• Partial exchange transfusion has not been shown to reduce these problems, and umbilical partial exchange continues to show increased risk for NEC. Recent data suggests that the cause of impaired long-term outcome is also the cause of the polycythemia; both conditions are associated with intrauterine fetal hypoxia.

MISCELLANEOUS

Section 8 of 9  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Use of a blood product (eg, albumin) in an exchange transfusion may result in the transmission of infection. Infections related to blood products can be avoided by using normal saline, which is sterile and which has been shown to be as effective as albumin.
• Informed consent must be obtained as exchange transfusions have multiple risks (see Partial exchange transfusion).
• Umbilical partial exchange transfusion increases risk of NEC especially if colloid is used.
• No improvement in neurologic outcomes has been reported with partial exchange transfusion. However, polycythemia and neurologic abnormalities have been linked. Because of this, a symptomatic infant who has not been treated with partial exchange transfusion and who subsequently develops neurologic abnormalities may be considered inadequately treated.

REFERENCES

Section 9 of 9

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Follow-up
• Miscellaneous
• References

• AAP. American Academy of Pediatrics Committee on Fetus and Newborn: routine evaluation of blood pressure, hematocrit, and glucose in newborns. Pediatrics. Sep 1993;92(3):474-6. [Medline].
• Awonusonu FO, Pauly TH, Hutchison AA. Maternal smoking and partial exchange transfusion for neonatal polycythemia. Am J Perinatol. Oct 2002;19(7):349-54. [Medline].
• Dempsey EM, Barrington K. Short and long term outcomes following partial exchange transfusion in the polycythaemic newborn: a systematic review. Arch Dis Child Fetal Neonatal Ed. Jan 2006;91(1):F2-6. [Medline].
• Drew JH, Guaran RL, Grauer S, Hobbs JB. Cord whole blood hyperviscosity: measurement, definition, incidence and clinical features. J Paediatr Child Health. Dec 1991;27(6):363-5. [Medline].
• Pappas A, Delaney-Black V. Differential diagnosis and management of polycythemia. Pediatr Clin North Am. Aug 2004;51(4):1063-86, x-xi. [Medline].
• Rosenkrantz TS. Polycythemia and hyperviscosity in the newborn. Semin Thromb Hemost. Oct 2003;29(5):515-27. [Medline].
• Schimmel MS, Bromiker R, Soll RF. Neonatal polycythemia: is partial exchange transfusion justified?. Clin Perinatol. Sep 2004;31(3):545-53, ix-x. [Medline].
• Shohat M, Reisner SH, Mimouni F, Merlob P. Neonatal polycythemia: II Definition related to time of sampling. Pediatrics. Jan 1984;73(1):11-3. [Medline].
• Werner EJ. Neonatal polycythemia and hyperviscosity. Clin Perinatol. Sep 1995;22(3):693-710. [Medline].
• Wirth FH, Goldberg KE, Lubchenco LO. Neonatal hyperviscosity: I. Incidence. Pediatrics. Jun 1979;63(6):833-6. [Medline].
• Wong W, Fok TF, Lee CH, et al. Randomised controlled trial: comparison of colloid or crystalloid for partial exchange transfusion for treatment of neonatal polycythaemia. Arch Dis Child Fetal Neonatal Ed. Sep 1997;77(2):F115-8. [Medline].

Article Last Updated: Sep 4, 2007