Key Definitions & Abbreviations Every NICU Nurse Should Know

Teach Me Tuesday: Little Bits to Grow Your Knowledge

September is NICU Awareness Month, and what better way to celebrate than by going back to the basics—the common definitions and abbreviations we use every day in the NICU. Whether you’re brand new or years into your NICU career, knowing this “language” is foundational to giving safe care, anticipating needs, and communicating clearly with your team.

Why Abbreviations Matter

The NICU can feel like an alphabet soup: NEC, IVH, TPN, HFOV, ROP… the list goes on. These abbreviations aren’t just shorthand—they carry weight. Each one represents a condition, treatment, or piece of equipment that can completely change how we care for a baby.

Clear communication is safety in the NICU. Misunderstanding an abbreviation could mean missing a diagnosis, misinterpreting a treatment plan, or not knowing what to monitor closely.

Key NICU Definitions & Abbreviations

Labor & Birth History

• SGA – Small for Gestational Age: Baby born <10th percentile for weight. At risk for hypoglycemia, temperature instability, and feeding difficulties.

• AGA – Appropriate for Gestational Age: Baby’s weight falls in the expected range for gestational age.

• LGA – Large for Gestational Age: >90th percentile. Often linked to maternal diabetes and risk for hypoglycemia.

• EOS – Early Onset Sepsis: Infection presenting in the first 72 hours of life.

• LOS – Late Onset Sepsis: Infection presenting after 72 hours.

• REDF – Reversed End Diastolic Flow: Doppler finding in pregnancy suggesting poor placental function and risk for growth restriction.

Nutrition & Lines

• TPN – Total Parenteral Nutrition: IV nutrition providing glucose, amino acids, electrolytes, and sometimes lipids. Used until feeds are established.

• HMF – Human Milk Fortifier: Added to breast milk to increase calories and protein for preterm infants. Typically introduced once feeds reach a certain volume while weaning TPN.

• OG/NG Tube – Orogastric/Nasogastric Tube: Used to deliver feeds when baby can’t yet coordinate suck-swallow-breathe.

• PICC Line – Peripherally Inserted Central Catheter: For longer-term IV nutrition or medications.

Respiratory Support

• CPAP – Continuous Positive Airway Pressure: Helps keep alveoli open, used for babies with mild to moderate respiratory distress.

• HFNC – High-Flow Nasal Cannula: Provides blended oxygen and some positive pressure.

• HFOV – High-Frequency Oscillatory Ventilation: Advanced ventilation strategy for severe lung disease.

• iNO – Inhaled Nitric Oxide: Pulmonary vasodilator used for PPHN (Persistent Pulmonary Hypertension of the Newborn).

Major Diagnoses

• IVH – Intraventricular Hemorrhage: Bleeding in the brain’s ventricles.

  • Grade I: Bleeding confined to germinal matrix

  • Grade II: Bleeding extends into ventricles, no dilation

  • Grade III: Bleeding with ventricular dilation

  • Grade IV: Bleeding extends into brain tissue (parenchymal involvement)

• NEC – Necrotizing Enterocolitis: Intestinal inflammation and necrosis, primarily in preterm infants. Early signs may be subtle but can progress quickly.

• ROP – Retinopathy of Prematurity: Abnormal retinal blood vessel growth in preterm infants. Screening is based on gestational age and birth weight (commonly <32 weeks or <1500 g).

How to Use This Knowledge in Practice

When you receive report, these abbreviations should act as red flags that frame how you think about your patient:

• A baby on TPN + HMF tells you they’re transitioning on the feeding protocol—anticipate fluid changes and monitor tolerance.

• A diagnosis of IVH means you’ll pay closer attention to neuro checks, head circumference, and position handling.

• A baby awaiting ROP screening reminds you of their prematurity, fragility, and long-term monitoring needs.

Abbreviations aren’t just letters—they’re clues to the bigger picture of each baby’s story.

Takeaway

NICU care is complex, but starting with a solid understanding of the language helps everything else fall into place. The next time you hear NEC, IVH, or TPN in report, pause and ask yourself: What does this mean for my patient right now?

Mastering the basics is how we grow into confident, prepared NICU nurses.