Lifespan's A - Z Health Information Library

Hyperviscosity is the slowing and blockage of blood flow caused by too many red blood cells in an infant's blood.

Hyperviscosity occurs when the percentage of red blood cells (RBCs) in the infant's blood is greater than 65%. This may result from various conditions that develop before birth, such as hypoxia, inherited diseases, birth defects, or a delay in clamping the umbilical cord.

The excess RBCs block the flow of blood in the smallest blood vessels. This leads to tissue death from lack of oxygen. This blocked blood flow can affect all organs, such as the kidneys, lungs, and brain.

Infants with hyperviscosity may develop feeding problems, cyanosis, low blood sugar, jaundice, and other problems.

• Very ruddy red complexion
• Feeding problems
• Lethargy
• Seizures

• Bluish skin
• Low blood sugar
• Rapid breathing
• Respiratory distress
• Kidney failure
• Jaundice

• Hematocrit (RBCs/volume)
• Chem-20 to check blood sugar, BUN, creatinine
• Blood gases
• Urinalysis

Treatment may include:

• Raising the amount of body fluids
• Exchange transfusions

The outlook is good for infants with mild hyperviscosity and those who receive treatment for severe hyperviscosity.

Some children may have mild changes in neurological development. Parents who believe their child may show any signs of developmental delay should contact their health care provider.

• Seizures
• Kidney failure
• Necrotizing enterocolitis
• Decreased fine motor control
• Strokes

Routine blood tests performed after a baby is born include a hematocrit, which counts the number of red blood cells. This test allows for quick detection of the hyperviscosity.