Glossary of Terms
This glossary provides definitions of medical terms that can be related to necrotizing enterocolitis (NEC) to help parents and caregivers better understand the language and care their baby may encounter in the NICU.
Teddy
This page includes medical terms and definitions that may be used in connection with necrotizing enterocolitis (NEC) and neonatal intensive care. Some of the following words and terms may be difficult to read or emotionally triggering. We deeply understand how overwhelming the NICU can be, and how frightening it is to experience an NEC diagnosis.
Please know that this glossary is meant to help you better understand the medical language you may hear—it does not mean that your baby will experience all or any of the conditions or complications described.
Every baby’s journey is unique. If you are experiencing a NEC diagnosis and are looking for additional resources, please view our Resources for Families Recently Diagnosed and talk with your care team.
General NICU
NICU Levels
Level I (Well Care): Regular nursery care for all babies. Also known as a well-baby nursery.
Levl II (Special Care): Babies cared for in this level are ≥ 32 weeks of gestation at birth and typically have conditions that are expected to resolve quickly. Babies who receive Level II care often progress well with appropriate monitoring and treatment and require a short-term stay.
Level III (Neonatal Intensive Care): Comprehensive care for more seriously ill newborns of all gestational ages. Babies needing Level III care may have mild to complex critical conditions or medical problems that require breathing support, close monitoring, and long-term treatment.
Level IV (Advanced Neonatal Intensive Care): The highest level of neonatal care. Level IV units include the capabilities of Level III plus pediatric medical and surgical specialists available 24 hours a day. Babies may need major surgery, surgical repair for congenital conditions, life-threatening disease/conditions, and intensive ventilation.
Common Terminology
Preterm Infant: A baby born before 34 weeks of pregnancy
Late Preterm Infant: A baby born between 34 weeks and 36 weeks + 6 days of pregnancy. Late preterm babies may look similar in size to full-term babies, but their organs, including the brain, lungs, and digestive system, are still developing.
Term: In the NICU, 37 weeks of pregnancy is considered term.
Full Term Infant: A baby born at 39 weeks through 40 weeks + 6 days of pregnancy.
Very Low Birth Weight (VLBW): When a baby weighs less than 1500 g (3 pounds, 5 ounces) at birth.
Extremely Low Birth Weight (ELBW): When a baby weighs less than 1000 g (2 pounds, 3 ounces) at birth.
Broad-Spectrum Antibiotics: Medicines designed to kill or stop the spread of a wide variety of bacteria. They are used to treat NEC because it is associated with a variety of gut bacteria.
Central Line (PICC Line): In the NICU, a Peripherally Inserted Central Catheter (PICC) is a long, thin catheter inserted into a vein to reach the large vein that enters your baby’s heart to give nutrition or medicine, especially for critically ill and low birth weight infants.
Immunocompromised: Possessing a weaker immune system that can’t fight infections well. Premature and sick babies are more vulnerable to infections, including NEC.
Intrauterine growth restriction (IUGR): A condition where a fetus doesn’t grow to its expected size during pregnancy. Babies with IUGR are often born weighing less than 90% of other babies at the same gestational age. IUGR can lead to compromised gut function and blood flow, making the intestines more vulnerable to NEC.
Ischemia: A lack of blood flow to a part of the body, which can prevent tissues from getting the oxygen and nutrients they need. Ischemia in the intestines can lead to tissue damage and may play a key role in the development of NEC.
NEC Terms and Definitions
Necrotizing Enterocolitis (NEC)
Necrotizing enterocolitis (NEC): Necrotizing enterocolitis (NEC) is a devastating neonatal intestinal disease that can affect infants in their first weeks and months of life. “Necrotizing” means the process of tissue death, and “enterocolitis” means inflammation of the small intestine or colon. Babies who are born prematurely or with a medical condition, like a congenital heart defect, are most at risk of NEC, but sometimes full-term babies also develop NEC.
Bell’s Staging (Stage I-III): A method of clinical staging for infants describing how severe NEC is, from mild (Stage I) to severe (Stage III).
- Stage 1: Suspected NEC – Infant shows signs of feeding problems and illness.
- Stage 2: Definite NEC – Tests like X-rays or ultrasounds show gas in the walls of the intestines.
- Stage 3: Advanced NEC – Infant shows signs of severe illness and may need surgery on their intestines.
Recurrent NEC: A recurrence of NEC after a baby has initially recovered from the disease.
Cardiac NEC: A form of NEC that occurs in babies with heart conditions, especially congenital heart defects (CHD), and can occur even when they are born at term. Babies’ heart conditions can affect how blood flows to the intestines, leading to an increased risk of developing NEC. Learn more about cardiac NEC.
Feeding and Nutrition
Bolus Feeding: Nutrition is delivered in larger volumes at specific intervals, often 4-6 times a day, using a syringe or feeding pump.
Colostrum: Colostrum is the first form of breastmilk that is released by the mammary glands after giving birth. It is rich in antibodies and nutrients, thicker and more yellow than traditional breast milk. This early milk can protect the gut and may reduce the risk of NEC in premature infants.
Continuous Feeding: Nutrition is delivered continuously by a feeding pump over a 24-hour period at a constant rate.
Oral Care with Colostrum: Gently swabbing a baby’s mouth with colostrum to deliver antibodies. This helps protect babies from infection, even before they’re ready to feed. Oral care with colostrum is not considered feeding by mouth.
Elemental Formula: A special formula where proteins are broken down into their simplest form (amino acids). Sometimes used when infants cannot tolerate regular or even partially hydrolyzed formulas. Also known as amino-acid-based formula (AAF).
Enteral Feeding (Tube Feeding): A way to provide nutrition directly into the digestive system when a baby cannot receive nutrition by mouth. It is often placed in the first 24-72 hours after birth.
NG (naso gastric) Tube: a feeding tube inserted in the nose (naso) that ends in the stomach (gastric) for feedings.
OG (oral gastric) Tube: a feeding tube inserted into the mouth (oral), extending into the stomach (gastric).
Exclusive Human Milk Diet (EHMD): A feeding plan where a baby receives only human milk (mother’s own milk or donor milk) along with human milk–based fortifiers if needed. No animal-based fortifiers are used.
Feeding Intolerance (FI): The inability to tolerate enteral feedings. Symptoms may include abdominal distention, vomiting, or changes in stool. Feeding intolerance can be an early sign of NEC.
Human Milk Fortifier (HMF): powdered or liquid supplement added to human milk (MOM or PDHM) to increase its calories, protein, and nutrients. Premature babies often need extra nutrition to grow. Human Milk Fortifier can can be made from bovine (cow’s) milk or human milk, depending on what is available in your NICU.
Mother’s Own Milk (MOM): Breast milk produced by a baby’s parent. Mother’s own milk can help protect babies from NEC and is easier for the intestines to digest. When it is expressed by hand or pumped it is called Expressed Breast Milk (EBM).
NPO (nil per os, or nothing by mouth): A medical instruction meaning the baby cannot have anything to eat or drink by mouth. Babies with NEC are often placed on NPO so their intestines can rest and heal.
Pasteurized Donor Human Milk (PHDM): Donor milk provided in the NICU is pasteurized (heat-treated) to destroy bacteria and viruses while preserving many of the milk’s beneficial properties.
Partially Hydrolyzed Formula: Infant formula in which cow’s milk proteins are broken down into smaller pieces to make them easier to digest. In preterm infants, partially hydrolyzed formula may be used to promote feeding tolerance.
Refeeding Syndrome: When feeding resumes after a long break, it can cause an electrolyte imbalance. Babies recovering from NEC may be at risk when feeds are restarted.
Total Parenteral Nutrition (TPN): Essential nutrients are provided through IV when a baby’s gut is unable to tolerate enteral feedings, allowing the bowel to rest and heal.
Gastrointestinal Related Terms
Ascites: An abnormal buildup of fluid in the abdomen between the lining of the abdomen and the abdominal organs. In the context of NEC, it often indicates a more severe stage of the disease.
Bacterial Translocation: The process where bacteria normally found in the intestines migrate to normally sterile areas, like the bloodstream or lymph nodes. In NEC, this translocation contributes to sepsis and other complications.
Bowel Sounds: Noises made by the intestines when they move gas or food. Doctors listen for these sounds; if they’re very quiet or absent, it may mean the intestines are not working properly. With NEC, decreased or absent bowel sounds are a significant clinical finding, often indicating a worsening of the condition.
Dysbiosis: An unhealthy imbalance of gut bacteria. Dysbiosis is believed to increase NEC risk in preterm infants.
Gastroschisis: A birth defect where a baby’s intestines are outside the body. Babies with this condition are more vulnerable to intestinal damage and may have a higher NEC risk.
Gut Microbiome: The community of bacteria that lives in the intestines.
Ileus: A condition where the intestines temporarily stop moving. It can cause bloating and feeding problems and can occur with NEC.
Intestinal Perforation: Also known as perforated bowel. A life-threatening complication where a hole forms in the wall of the small or large intestine.
Meconium: A baby’s first poop, usually dark green and sticky. Delayed or absent meconium can signal a bowel problem, which may relate to NEC.
Mucosal Injury: Damage to the inner lining of the intestines. This could be an early sign of NEC that compromises the gut barrier, allowing bacteria to pass through the weakened abdominal wall.
Necrosis: Tissue death. In NEC, parts of the intestinal tissue can die and may need to be removed by surgery.
Peritonitis: A severe complication of NEC described as inflammation and infection of the abdominal lining that occurs when a hole develops in the intestine (perforation), allowing bacteria and bowel contents to leak into the abdomen, causing infection and inflammation of the abdominal cavity.
Pneumatosis Intestinalis: A rare form of air leak into the stomach and intestinal wall. It is often used as a radiological finding in preterm infants to diagnose NEC.
Pneumoperitoneum: Air trapped in the belly outside the intestines, seen on an X-ray. This usually means there’s a hole in the intestine (perforation), which is a serious emergency with NEC.
Short Bowel Syndrome (SBS): A condition where there isn’t enough intestine to absorb nutrients properly. Babies who had large sections of bowel removed due to NEC may develop SBS.
Strictures: Narrowed areas in the intestine caused by scar tissue. These can develop after NEC, after healing has occurred.
Lab and Blood Tests
Anemia of Prematurity (AOP): A condition where a preterm baby does not have enough red blood cells or hemoglobin to carry oxygen. This is common in premature infants and may increase the risk of developing NEC.
C-reactive protein (CRP): A substance produced by the liver in response to inflammation. CRP levels can be elevated in both stage II and stage III NEC. Persistently elevated CRP levels, especially after the initiation of medical management, may indicate complications that require surgical intervention.
Metabolic Acidosis: A condition where the body has too much acid in the blood. This can happen in NEC and may be a sign that the baby’s body is under stress.
Neonatal Hypoglycemia: Low blood sugar in a newborn baby.
Pro-inflammatory Cytokines: Proteins made by the body that cause inflammation. These may play a role in how NEC develops and progresses.
Physical Signs and Symptoms
Abdominal Distension: Swelling or bloating of the abdomen. This can be caused by a buildup of gas or fluid in the intestines and can be an early sign of NEC or other intestinal problems.
Abdominal Wall Erythema: Redness on the skin of a baby’s belly. This may be a sign of infection or inflammation in the belly and could suggest NEC.
Hematochezia: The passage of fresh blood in a baby’s stool. This is often an early symptom of NEC.
Skin Mottling: Patchy or blotchy skin that can look purplish or pale. This may be a sign of poor circulation or sepsis (infection).
Respiratory Terms
Apnea of Prematurity: Where premature infants experience pauses in breathing for 20 seconds or longer, or shorter pauses accompanied by bradycardia or low blood oxygen saturation levels.
Hypoxia: A condition where not enough oxygen reaches the body’s tissues. In babies, hypoxia usually happens during or immediately after birth and can reduce the oxygen supply to vital organs like the brain and intestines. Low oxygen in the gut may increase the risk of NEC.
Oxygen Saturation (SpO₂): A measure of how much oxygen is in the blood.
Respiratory Distress: When your baby has trouble breathing, including fast breathing, grunting, or chest retractions. This can happen for a variety of reasons but can also be an early sign of NEC. NEC can cause or worsen breathing problems if infection spreads.
Surgical Terms
Bowel Resection: The surgical removal of sections of the intestine that are damaged or necrotic due to the disease. Often used when treatments like antibiotics and bowel rest fail to control the infection and tissue damage.
Laparotomy: A surgical procedure that involves making an incision in the abdominal wall.
Ostomy: A procedure creating a small opening (stoma) in your baby’s belly. A part of the intestine is pulled through to the outside, letting your baby pass stool into a special bag while the bowel rests and heals.
Peritoneal Drain: A tube placed into your baby’s belly to remove infected fluid. This is sometimes used to stabilize babies with NEC before full surgery but babies may or may not need surgery after peritoneal drain placement.
Tests and Procedures
Abdominal X-ray: An imaging test that shows what’s going on inside a baby’s belly. Doctors use X-rays to look for signs of NEC, such as air in the bowel wall or a hole in the intestine.
Doppler Ultrasound or Bowel Ultrasound: Can be a valuable tool in the diagnosis and management of NEC in newborns, particularly preterm infants. It helps assess blood flow to the intestines, which can be compromised in NEC, and can aid in differentiating NEC from other conditions.
Echogenicity: A term used to describe how much sound is bounced back by tissues. In the context of NEC, echogenicity refers to findings on an ultrasound, where there are increased ultrasound waves off of the bowel wall.
Transfusion: A procedure in which donated blood/blood components are given through an intravenous line (IV) to replace blood/blood components that may be low. There are 2 types of transfusions that are typically done in the NICU: red blood cells and platelets.
Other Medical Conditions
Multisystem Organ Failure: When multiple organs (like the lungs, heart, and kidneys) begin to stop working. This can happen in very severe NEC and is life-threatening.
Systemic Inflammatory Response Syndrome (SIRS): A serious whole-body reaction to infection or inflammation. NEC can lead to SIRS, which may cause sepsis or organ failure.
Patent Ductus Arteriosus (PDA): A heart condition where a blood vessel doesn’t close after birth. Babies with PDA may have lower gut blood flow, increasing NEC risk.
Spontaneous Intestinal Perforation (SIP): A condition where a tear occurs in the intestine of a newborn, typically an extremely premature infant, without a clear underlying cause and without the inflammation seen in NEC. This is clinically different from NEC.
Sepsis: A life-threatening condition that arises when the body’s response to an infection goes into overdrive, damaging its own tissues and organs. When NEC progresses, it can cause intestinal perforation, allowing bacteria from the intestine to enter the bloodstream. This triggers a systemic inflammatory response, leading to sepsis.
Resources for Families Recently Diagnosed
Learning about NEC can help you advocate for your baby and make informed decisions. There is not a single cause of this disease, and it is not your fault if your baby develops NEC. We have developed this page of resources to support families who are facing a NEC diagnosis.
