| 释义 |
necrotizing enterocolitis
Thesaurus| Noun | 1. | necrotizing enterocolitis - an acute inflammatory disease occurring in the intestines of premature infants; necrosis of intestinal tissue may followNECinflammatory disease - a disease characterized by inflammation |
necrotizing enterocolitis
Necrotizing Enterocolitis DefinitionNecrotizing enterocolitis is a serious bacterial infection in the intestine, primarily of sick or premature newborn infants. It can cause the death (necrosis) of intestinal tissue and progress to blood poisoning (septicemia).DescriptionNecrotizing enterocolitis develops in approximately 10% of newborns weighing less than 800 g (under 2 lbs). It is a serious infection that can produce complications in the intestine itself—such as ulcers, perforations (holes) in the intestinal wall, and tissue necrosis—as well as progress to life-threatening septicemia. Necrotizing enterocolitis most commonly affects the lower portion of the small intestine (ileum). It is less common in the colon and upper small bowel.Causes and symptomsThe cause of necrotizing enterocolitis is not clear. It is believed that the infection usually develops after the bowel wall has already been weakened or damaged by a lack of oxygen, predisposing it to bacterial invasion. Bacteria proliferate in the bowel and cause a deep infection that can kill bowel tissue and spread to the bloodstream.Necrotizing enterocolitis almost always occurs in the first month of life. Infants who require tube feedings may have an increased risk for the disorder. A number of other conditions also make newborns susceptible, including respiratory distress syndrome, congenital heart problems, and episodes of apnea (cessation of breathing). The primary risk factor, however, is prematurity. Not only is the immature digestive tract less able to protect itself, but premature infants are subjected to many stresses on the body in their attempt to survive.Early symptoms of necrotizing enterocolitis include an intolerance to formula, distended and tender abdomen, vomiting, and blood (visible or not) in the stool. One of the earliest signs may also be the need for mechanical support of the infant's breathing. If the infection spreads to the bloodstream, infants may develop lethargy, fluctuations in body temperature, and periodically stop breathing.DiagnosisThe key to reducing the complications of this disease is early suspicion by the physician. A series of x rays of the bowel often reveals the progressive condition, and blood tests confirm infection.TreatmentOver two-thirds of infants can be treated without surgery. Aggressive medical therapy is begun as soon as the condition is diagnosed or even suspected. Tube feedings into the gastrointestinal tract (enteral nutrition) are discontinued, and tube feedings into the veins (parenteral nutrition) are used instead until the condition has resolved. Intravenous fluids are given for several weeks while the bowel heals.Some infants are placed on a ventilator to help them breathe, and some receive transfusions of platelets, which help the blood clot when there is internal bleeding. Antibiotics are usually given intravenously for at least 10 days. These infants require frequent evaluations by the physician, who may order multiple abdominal x rays and blood tests to monitor their condition during the illness.Sometimes, necrotizing enterocolitis must be treated with surgery. This is often the case when an infant's condition does not improve with medical therapy or there are signs of worsening infection.The surgical treatment depends on the individual patient's condition. Patients with infection that has caused serious damage to the bowel may have portions of the bowel removed. It is sometimes necessary to create a substitute bowel by making an opening (ostomy) into the abdomen through the skin, from which waste products are discharged temporarily. But many physicians are avoiding this and operating to remove diseased bowel and repair the defect at the same time.Postoperative complications are common, including wound infections and lack of healing, persistent sepsis and bowel necrosis, and a serious internal bleeding disorder known as disseminated intravascular coagulation.PrognosisNecrotizing enterocolitis is the most common cause of death in newborns undergoing surgery. The average mortality is 30-40%, even higher in severe cases.Early identification and treatment are critical to improving the outcome for these infants. Aggressive nonsurgical support and careful timing of surgical intervention have improved overall survival; however, this condition can be fatal in about one-third of cases. With the resolution of the infection, the bowel may begin functioning within weeks or months. But infants need to be carefully monitored by a physician for years because of possible future complications.About 10-35% of all survivors will eventually develop a stricture, or narrowing, of the intestine that occurs with healing. This can create an intestinal obstruction that will require surgery. Infants may also be more susceptible to future bacterial infections in the gastrointestinal tract and to a delay in growth. Infants with severe cases may also suffer neurological impairment.The most serious long-term gastrointestinal complication associated with necrotizing enterocolitis is short-bowel, or short-gut, syndrome. This refers to a condition that can develop when a large amount of bowel must be removed, making the intestines less able to absorb certain nutrients and enzymes. These infants gradually evolve from tube feedings to oral feedings, and medications are used to control the malabsorption, diarrhea, and other consequences of this condition.PreventionIn very small or sick premature infants, the risk for necrotizing enterocolitis may be diminished by beginning parenteral nutrition and delaying enteral feedings for several days to weeks.Some have suggested that breast milk provides substances that may be protective, but there is no evidence that this reduces the risk of infection. A large multicenter trial showed that steroid drugs given to women in preterm labor may protect their offspring from necrotizing enterocolitis.Key termsEnteral nutrition — Liquid nutrition provided through tubes that enter the gastrointestinal tract, usually through the mouth or nose.Necrosis — The death of cells, a portion of tissue, or a portion of an organ due to permanent damage of some sort, such as a lack of oxygen supply to the tissues.Parenteral nutrition — Liquid nutrition provided through tubes that are placed in the veins.Sepsis — The presence of pus-forming or other disease-causing organisms in the blood or tissues. Septicemia, commonly known as blood poisoning, is a common type of sepsis.Sometimes necrotizing enterocolitis occurs in clusters, or outbreaks, in hospital newborn (neonatal) units. Because there is an infectious element to the disorder, infants with necrotizing enterocolitis may be isolated to avoid infecting other infants. Persons caring for these infants must also employ strict measures to prevent spreading the infection.ResourcesOtherNeonatology on the Web. http://www.neonatology.org.enterocolitis [en″ter-o-ko-li´tis] inflammation of the small intestine and colon.antibiotic-associated enterocolitis that in which treatment with antibiotics alters the bowel flora and results in diarrhea or enterocolitis" >pseudomembranous enterocolitis. See also colitis" >antibiotic-associated colitis.hemorrhagic enterocolitis enterocolitis characterized by hemorrhagic breakdown of the intestinal mucosa, with inflammatory cell infiltration.necrotizing enterocolitis the development of necrotic patches in the intestine that interfere with digestion and absorption; see also necrotizing enterocolitis.pseudomembranous enterocolitis an acute inflammation of the bowel mucosa, with the formation of pseudomembranous plaques, usually associated with antimicrobial therapy. See also colitis" >pseudomembranous colitis.
necrotizing [nek´ro-tīz″ing] causing necrosis.necrotizing enterocolitis (NEC) the development of necrotic patches in the intestine that interfere with digestion and absorption and can lead to a paralytic ileus, perforation, and peritonitis. The entire bowel may be affected, or the ischemic necrosis may be localized.
NEC is a serious condition that occurs most often in preterm and very immature neonates; it develops in about 5 per cent of all neonates in neonatal intensive care units. The exact cause of the condition is not known, but it is related to ischemia or poor perfusion of blood vessels in sections of the bowel. The ischemia is thought to occur when an earlier oxygen depletion in the heart and brain, as in anoxia or shock, causes blood to be shunted away from less vital organs such as the intestine.
Since the incidence of NEC is low in neonates who are breast-fed, it is likely that the necrotizing process is initiated by a response to the protein in cow's milk and the profuse multiplication of bacteria that thrive more readily in cow's milk than in breast milk. The gas-forming bacteria invade the damaged intestinal cells, causing them to rupture and producing pneumatosis intestinalis, that is, the presence of air in the submucosal or subserosal surfaces of the colon.
Abdominal x-rays will show a characteristic invasion of air in the intestinal wall. If perforation has occurred, the x-ray will reveal free air in the abdominal cavity. Nonspecific symptoms of NEC usually appear in the first week of life and may be overlooked when caregivers are preoccupied with more obvious life-threatening problems. Typically, the neonate exhibits lethargy, vomiting, distended abdomen, signs of intestinal bleeding, and absence of bowel sounds.
Once the condition is diagnosed, all oral feedings are stopped to rest the intestinal tract. Feeding must then be accomplished intravenously. Gastrointestinal decompression via nasogastric suction may be instituted to relieve distention, and antibiotics administered to limit secondary bacterial infection. Progressive deterioration or evidence of perforation are indications for surgery to remove the diseased portion of the bowel. If damage is extensive an ileostomy or colostomy may be necessary.nec·ro·tiz·ing en·ter·o·co·li·tisextensive ulceration and necrosis of the ileum and colon in premature infants in the neonatal period; possibly due to perinatal intestinal ischemia and bacterial invasion.necrotizing enterocolitis Neonatology A disease of premature infants, affecting the terminal ileum 3-10 days after birth, representing 2% of neonatal ICU admissions and 10% of admissions of premature infant, or low birth weight neonates, causing significant M&M Clinical Banal to fulminant with abdominal distension, vomiting, hematochezia, intestinal gangrene, perforation, sepsis, shock; survival 80%; NEC is rare in breast-fed children, who may be protected by IgA in maternal milk; oral IgA-IgG solution in LBW infants may be protective. Cf Pigbel. nec·ro·tiz·ing en·te·ro·co·li·tis (nek'rō-tīz-ing en'tĕr-ō-kŏ-lī'tis) Extensive ulceration and necrosis of the ileum and colon in premature infants. necrotizing enterocolitis A dangerous disorder featuring patches or diffuse area of tissue death (necrosis) in the small or large intestine especially in premature infants but also sometimes in full-term babies. It is most likely to affect babies that are unwell, especially those with congenital heart disease or respiratory distress syndrome. A severe infection with the organism CLOSTRIDIUM DIFFICILE is often present. Aetiology remains unclear, diagnosis is difficult and treatment often proves inadequate. Some cases have been ascribed to interference with the oxygen free radicals used by phagocytes to perform their immunological function by overdosage with the antioxidant vitamin E.LegalSeenecSee NEC
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Related to necrotizing enterocolitis: necrotizing fasciitisSynonyms for necrotizing enterocolitisnoun an acute inflammatory disease occurring in the intestines of premature infantsSynonymsRelated Words |