Retinopathy of prematurity: Recommendations for screening

Retinopathy of prematurity (ROP) is a disorder of the developing retinal blood vessels of the preterm infant. New recommendations for screening and treatment of ROP have been published in the past few years. Current evidence suggests that screening infants with gestational ages of 30 6/7 weeks or less (regardless of birth weight) and birth weights of 1250 g or less is a strategy with a very small likelihood that an unscreened baby would have treatable ROP. Individual centres may choose to extend birth weight screening criteria to 1500 g. Initial screening should be performed at 31 weeks' postmenstrual age in infants with gestational ages of 26 6/7 weeks or less at birth, and at four weeks' chronological age in infants with gestational ages of 27 weeks or more at birth by an ophthalmologist skilled in the detection of ROP. Follow-up examinations are conducted according to the ophthalmologist's recommendation. Infants with high-risk prethreshold ROP and threshold ROP are referred for retinal ablative therapy. Developing processes for ROP screening, documenting results and communicating results to parents as well as health professionals involved in the infant's care are important responsibilities for all nurseries providing care for preterm infants.     

Management outcome in prethreshold retinopathy of prematurity

PURPOSE: To evaluate the success of and timing for intervention in retinopathy of prematurity (ROP). PATIENTS AND METHODS: Eighty-two eyes of 50 children with stage 3 ROP were divided into two groups based on severity. Cryotherapy or laser therapy was performed soon after the detection of threshold stage in the first group of 40 eyes and at a prethreshold stage in the second group of 42 eyes. The patients were observed from 4 months to 2 years and regression or progression was noted. Unfavorable outcomes including macular and disc drag and the progression of ROP to stages 4 and 5 were correlated with birth weight, gestational age, age at threshold, and age at intervention. RESULTS: Regression of ROP occurred in 75 (91.46%) of the eyes. An overall unfavorable outcome occurred in 14 (17.07%) of the eyes, 11 of which reached threshold during the critical period of 37 to 39 postconceptional weeks of age. Of the cases (n = 14) with an unfavorable outcome, 9 eyes (22.5%) were in the group treated in the threshold stage (n = 40) and 5 eyes (11.9%) were in the group treated at a prethreshold stage (n = 42). The mean birth weight, gestational age, age at threshold, and age at intervention in the favorable and unfavorable outcome groups were 953.2 +/- 2.19 g and 1,059.57 +/- 2.62 g, 28.63 +/- 2.03 weeks and 28.36 +/- 1.98 weeks, 38.04 +/- 2.13 weeks and 37.71 +/- 1.13 weeks, and 38.32 +/- 2.34 weeks and 38.25 +/- 1.05 weeks, respectively. CONCLUSION: Early intervention at a prethreshold stage of ROP or at a younger postconceptional age (ie, younger than 37 weeks) may decrease the incidence of an unfavorable outcome.     

中国大陆早产儿视网膜病变临床特点和眼底病变的多中心调查

目的通过多中心筛查反映中国大陆早产儿视网膜病变(ROP)的发生率及相关流行病学特征。方法 2010年6月1日至2012年6月1日ROP调查协作组在中国大陆7个行政区域首先邀请有能力行ROP筛查的医院,从新生儿生后第4周或纠正胎龄32周行初次眼底检查,使用统一型号的间接眼底镜和电子眼底镜,依据ROP分期决定随访方案,经复旦大学附属眼耳鼻喉科医院培训、考核认证的ROP筛查医生,参照ROP国际分类法诊断和分期。结果中国7个行政区共22家医院6 091例出生体重2 000 g或胎龄34周的早产儿或因重大疾病进行了氧疗(≥5 d)的新生儿中,ROP924例,发生率为15.2%。轻度ROP(1和2期)92.3%(853/924),重度ROP(3期及以上)7.7%(71/924),急进型ROP患儿7例。行激光或手术治疗69例,均为ROP 3期以上病例。924例ROP患儿胎龄28~36+5(30.2±2.2)周,出生体重624~3 400(1 364±344)g。呈现出生体重越低和出生胎龄越小ROP发生率逐渐增高趋势,出生体重越低和出生胎龄越小轻度ROP的发生率未见逐渐增高的趋势。ROP 4~5期仅出现在出生胎龄30周和出生体重1 250 g的新生儿。妇幼保健院较儿童专科医院和综合性医院儿科ROP发生率低,但重度ROP发生率高。结论中国大陆ROP发生率为15.2%,出生胎龄30周ROP发生率为46.9%,出生体重1 500 g ROP发生率为30.6%。     

Effect of retinopathy of prematurity on resolution acuity development in 1- to 3-year-old children

PURPOSE: To assess the pattern of visual development in children aged 1-3 years with stage 1-3 retinopathy of prematurity (ROP). METHODS: One hundred forty-four infants weighing <1500 g were divided into three groups according to ROP stage. Randomly chosen preterm infants were the controls. Ophthalmic examinations started 4-7 weeks after birth and were performed until the retina was fully vascularized or until any ROP that had developed resolved. Preferential looking acuity measurements were carried out at 12, 18, 24, and 36 months of age. RESULTS: Infants with stage 1-2 or no ROP showed evidence of improving acuity development after 12 months. Infants with stage 3 ROP had significantly lower acuity scores compared to infants with stage 1-2 or no ROP at the 18- and 24-month follow-up examinations (P<.001). At 36 months, the visual acuity of infants with stage 3 ROP showed evidence of improving development but still lagged behind infants with stage 1-2 or no ROP. CONCLUSION: Although mild ROP does not seem to have a considerable effect on the development of resolution acuity until age 3, severe forms of ROP may be associated with impaired visual development, which strongly suggests the necessity of periodic monitoring of early visual acuity in infants with ROP.     

Screening for retinopathy of prematurity in a tertiary care newborn unit in Turkey: frequency, outcomes, and risk factor analysis

PURPOSE: To report the frequency, risk factors, and outcomes of screening for retinopathy of prematurity (ROP). METHODS: Data of neonates with a gestational age of 34 weeks or less were analyzed and the predictors on the development of ROP were determined by using logistic regression analysis. RESULTS: Of the 318 neonates, the frequency of ROP was 37.1% for any stage and 7.2% for stage 3 or greater. Treatment was needed in 16.1% of neonates with ROP. No treatment was required in neonates with a gestational age of greater than 32 weeks. Oxygen therapy, sepsis, gestational age of 32 weeks or less, and birth weight of less than 1,250 g were determined as the independent risk factors. CONCLUSIONS: Although frequency of ROP in Turkey is similar to that in the United States, the rate of severe ROP necessitating treatment seems to be higher in Turkey. Neonates with a gestational age of 32 weeks or less, a birth weight of less than 1,250 g, sepsis, and oxygen therapy may have a greater risk of developing ROP and screening should be intensified in the presence of these risk factors.     

早产儿视网膜病的筛查及其高危因素分析

目的 分析早产儿视网膜病(ROP)的危险因素,为合理防治ROP提供理论依据.方法回顾分析2006年7月至2008年5月,我院NICU住院的胎龄≤36周、出生体重≤2500 g行ROP筛查的1675例早产儿临床资料.记录早产儿的性别、胎数、孕周、出生体重、用氧情况、患全身疾病情况及孕母情况.同时用单因素χ~2检验和多因素Logistic回归分析筛选和判定早产儿ROP发生的危险因素.结果 1675例早产儿中,发生ROP 195例,ROP患病率为11.6%.195例ROP患儿中,达到阈值前病变Ⅰ型或阈值病变者35例,占筛查早产儿的2.1%.ROP发生的相关因素分析发现,出生体重越低、胎龄越小、氧疗时间越长,ROP患病率越高.Logistic回归分析结果 表明,低出生体重、小胎龄、窒息、呼吸暂停、氧疗是ROP发生的高危因素(OR值分别为0.957、1.052、1.186、5.314、1.881).结论 低出生体重、小胎龄、窒息、呼吸暂停、氧疗是ROP发生的高危因素,建议对具有高危因素的所有早产儿均进行ROP筛查.     

Retinopathy of prematurity: review of a seven-year period in a Danish neonatal intensive care unit

Arrae M, Peitersen B. Retinopathy of prematurity: review of a seven-year period in a Danish neonatal intensive care unit. Acta Pædiatr 1994;83:501–5. Stockholm. ISSN 0803–5253
In the period 1985–1991, 21675 infants were born at the University Hospital of Copenhagen, Hvidovre Hospital, Denmark. Two hundred and twenty-four infants (10.3%) with birth weights 1500 g and gestational ages 32 completed weeks were transferred to the neonatal intensive care unit of the hospital. One hundred and eighty survived to at least 8 weeks of age and 170 had eye examinations. Forty-five of the 170 infants examined (26.5%) had retinopathy of prematurity (ROP) and 18 (40%) of these developed blindness or severely impaired vision, a higher incidence than reported in other studies. Significant differences were found between infants with and without ROP for: birth weight, gestational age, Apgar score at 1 min, resuscitation, ventilator treatment, duration of supplementary oxygen, severe complications in the neonatal period and sequels from the central nervous system. Statistical analyses, corrected for correlations, showed that the occurrence of ROP was related significantly to early intubation, hypotension, persistent ductus arteriosus and necrotizing enterocolitis.     

中国多中心新生儿重症监护室胎龄小于34周早产儿出院前视网膜病变发生率的横断面调查

目的调查中国NICU胎龄34周早产儿视网膜病变(ROP)发生率。方法数据来源于"基于证据的质量改进方法降低我国新生儿重症监护室院内感染发生率的整群随机对照试验"所建立的早产儿临床数据库,收集25家三级NICU 2015年5月1日至2018年4月30日住院期间接受积极治疗、转出NICU或死亡前至少完成1次ROP筛查的胎龄34周早产儿的临床资料,分析不同胎龄及出生体重早产儿的ROP发生率、分期及治疗方式,并比较各单位间的差异。结果14 015例34周的早产儿在出院前或死亡前至少进行了1次ROP筛查,筛查阳性2 304例(16.4%),其中ROP1期1 092例(7.8%),ROP2期1 004例(7.2%),ROP 3～5期208例(1.5%)。胎龄28周早产儿ROP发生率为56.5%(578/1 023),3～5期ROP发生率为9.6%(98/1 023)。出生体重1 000 g和1 000～1 499 g早产儿ROP发生率分别为54.2%(465/858)和22.1%(1 411/6 381),3～5期ROP发生率分别为9.6%(82/858)和1.5%(95/6 381)。2 304例ROP早产儿在出院前188例(8.2%)接受治疗,其中眼内药物注射117例。各单位间ROP发生率存在显著差异。结论胎龄34周的早产儿的ROP发生率为16.4%,8.2%的ROP患儿接受治疗,其中62%采用玻璃体内注药,不同单位间ROP发生率差异显著。     

Retinopathy of prematurity in infants weighing 1000-1499 g at birth

Objectives: To review the incidence and severity of retinopathy of prematurity (ROP) in infants with birthweights 1000-1249 g and 1250-1499 g, to establish whether the upper weight limit for routine ophthalmological examination might safely be lowered. Methodology Prospective cohort study of infants born between 1 January 1977 and 31 December 1992 cared for in the neonatal nurseries at the Royal Women's Hospital, Melbourne. Data were retrieved on 1373 infants who survived their initial hospitalization. They comprised 657 with birthweights 1000-1249g (group 1) and 716 with birthweights 1250-1499g (group 2). There were 76 outborn infants in group 1 and 97 in group 2; the remaining infants were all born at the Royal Women's Hospital. Ocular examinations commenced at 2 weeks of age, when possible, and at 2-weekly intervals after that. Results In group 1, ROP was detected in 14.6% (96/657) and severe ROP (bilateral stage 3-5) in 5.0% (33/657). Five (0.8%) children required surgical intervention (reaching threshold disease); following surgery, one was legally blind, one had severely impaired vision, and the other three had near-normal vision. Another child was blind; he was born at 28 weeks gestational age with a birthweight of 1170g, and was transferred to a Level II hospital at 9 weeks chronological age with no detectable retinopathy. He returned 1 year later totally blind with detached retinae (grade 5 ROP). The prevalence of bilateral blindness in this group was 0.3% (2/657). In group 2, ROP was detected in 6.4% (46/716) and severe ROP in 0.8% (6/716). No children required surgery; three were found to be myopic at follow up but the corrected visual acuity was normal. No children in group 2 were blind. No significant difference was found between the rates of ROP in inborn and outborn infants. Conclusion In neonatal units with similar rates of ROP and visual outcome, routine ophthalmological examination in the neonatal nursery of infants weighing more than 1249g at birth is probably unnecessary.     

Italian multicentre study on retinopathy of prematurity

The aim of this prospective multicentre study was to evaluate the influence of a number of perinatal factors on the development of ROP in high risk preterm infants with gestational age ≤30 weeks. All infants consecutively born in, or transferred to, one of the 14 participating centres from 1 January 1992 through 31 December 1993, who had a gestational age of 30 weeks or less and no congenital anomalies and survived to the age of 6 months, were included in the study. Of the 380 infants with mean ± SD gestational age of 28.4 ± 1.6 weeks (range 23–30 weeks) and birth weight of 1157 ± 335 g (range 485–2480 g) that were eligible for the study, 82 (21.5%) developed ROP stage 1 or 2 and 57 (15%) ROP stage 3 or 3+. Step-wise logistic regression analysis showed that the following factors had a significant predictive value for the development of ROP stage 3 or 3+: gestational age (Odds Ratio (OR)=0.6144 for each increment of 1 week of gestational age), birth weight (OR=0.843 for each increment of 100 g of birth weight), prenatal steroids (OR 4.044 for lacking or incomplete prophylaxis), RDS (OR 2.294), oxygen dependency at 60 days (OR 2.085), necrotising enterocolitis (OR 2.597). Conclusion This study confirms the role of prematurity, low birth weight and RDS in the pathogenesis of ROP, and emphasises the importance of prenatal steroid prophylaxis of RDS in very preterm infants. Furthermore, our data suggest that infants with oxygen dependency at 60 days or necrotising enterocolitis are at very high risk of developing ROP. Received: 29 September 1996 and in revised form: 28 January 1997 / Accepted: 1 April 1997     

早产儿视网膜病的高危因素分析

目的了解我院早产儿视网膜病（refinopathy of prematurity,ROP）的发病状况,并对其高危因素进行分析。方法对2010年1月至2012年12月在我院新生儿科住院的早产儿（胎龄≤36周,体重≤2．5kg）,于生后2周进行ROP筛查,并定期随访。将患儿全身状况及吸氧、母孕期吸氧、先兆子痫、胎盘早剥等因素进行分析。结果255例患儿全部完成了眼底筛查,在周边视网膜血管化或病变退化后终止随访,发现ROP16例（26只眼）,ROP患病率为6．3％（5．1％）,其中Ⅰ期12例,Ⅱ期3例,Ⅲ期1例。高危因素分析示胎龄、出生体重、吸氧时间,吸氧浓度、机械通气与ROP相关（P〈0．05）;母孕期吸氧、先兆子痫、胎盘早剥等因素与ROP发病无关。结论早产、吸氧浓度高、机械通气是ROP的主要危险因素。对早产儿适时进行ROP筛查,并对发现的ROP早期进行有效视网膜激光光凝术,可控制病变,降低早产儿的致盲率。     

Incidence of retinopathy of prematurity requiring treatment in infants born greater than 30 weeks' gestation and with a birthweight greater than 1250 g from 1998 to 2002: a regional study

AIM: To ascertain the prevalence of significant Retinopathy of Prematurity (ROP) and ROP requiring treatment in infants born greater than 30 weeks gestation and with a birthweight greater than 1250 g, utilising the Neonatal Intensive Care Units' (NICUS) data collection from 1998 to 2002. Second, to determine whether infants delivered at more than 30 weeks gestation or with a birthweight greater than 1250 g require ROP screening. METHODS: A review of the New South Wales and Australian Capital Territory NICUS data collection from 1998 to 2002 was performed. Infants of gestational age 31-33 weeks and with a birthweight greater than 1250 g were included. A review was performed of these infants to ascertain stage of ROP, threshold disease and treatment for ROP. RESULTS: 2292 infants were greater than 30 weeks and had a birthweight greater than 1250 g. Of these 1386 (60%) were not examined or died prior to eye examination. No ROP was noted in 888 of the 904 infants examined (98%), 13 infants had stage 1 (1.4%), five infants stage 2 (0.6%) and no infant had stage 3 ROP. No infant developed stage 3 ROP, required treatment for ROP or had threshold disease. CONCLUSION: In this regional study of infants greater than 30 weeks gestation and with a birthweight greater than 1250 g, the prevalence of any ROP was low (2.0%). This study supports evidence from other studies that screening for ROP could be restricted, at least within our referral network, to infants less than 30 completed weeks and a birthweight less than 1250 g.     

早产儿视网膜病发病情况及危险因素分析

目的探讨早产儿视网膜病(ROP)发病情况及影响ROP患病的危险因素。方法对2004-03—2005-12在北京大学第一医院新生儿监护室住院的胎龄≤34周和(或)出生体重≤2000g的早产儿在生后4~6周或校正胎龄至32周时进行眼底检查,并对相关危险因素进行分析。结果203例早产儿中有25例发生ROP,发生率为12.31%,7例出现阈值或阈值前病变需要治疗,占3.44%,Logistic回归分析表明小胎龄、低出生体重、母亲合并妊娠期糖尿病是发生ROP的危险因素,ROP组与正常眼底组在这三方面差异均有统计学意义(P<0.05)。结论小胎龄、低出生体重、母亲合并妊娠期糖尿病是发生ROP的危险因素。     

Macular pigmentary changes as a sequelae of retinal hemorrhages in premature infants with retinopathy of prematurity

PURPOSE: We assess the incidence of macular changes in ROP patients with retinal hemorrhages. PATIENTS AND METHODS: The premature group consisted of 360 children born 32 weeks gestation and/or with weight below 1,500 g. We used the RetCam-120 Digital Retinal Camera to document retinal changes. RESULTS: Of the 360 premature infants 241 (67%) had no ROP, and 119 (33%) had ROP. Of the preterm infants with ROP retinal hemorrhages were found in 46 (38%) children. Of the newborns with ROP and with retinal hemorrhages, macular pigmentary changes were found in 3 (6%) patients. Of these 3 patients, the first had pre-threshold ROP, the second threshold ROP and had underwent diode laser photocoagulation, and the third patient had stage 2 ROP. In the patients with pre-threshold and threshold ROP retinal hemorrhages appeared 6 weeks after birth and macular pigmentary changes were found 6 months after birth. In the patient with stage 2 ROP hemorrhages appeared 7-8 weeks after birth and macular pigmentary changes were detected 12 months after birth. CONCLUSIONS: Although macular hemorrhages almost always resorb without complications, our study allows the assumption that retinal hemorrhages may cause macular pigmentary changes in the macula, and thus may lead to deprivation amblyopia. Our results may suggest that the presence of the macular pigmentary changes may be related to the hemorrhage and not to the specific therapy or to the disease.     

Incidence and risk factors for retinopathy of prematurity in the West Black Sea region, Turkey

The objective of this study was to determine the incidence, risk factors and severity of retinopathy of prematurity (ROP) and to establish screening criteria for our region. Data on 330 infants with gestational age at birth < or = 34 weeks were analyzed retrospectively for a ROP diagnosis and risk factors. Infants with type 1 ROP were treated with argon laser photocoagulation. ROP was detected in 106 of 330 infants; 18 infants had type 1 ROP and were treated. Two infants with ROP that progressed to stage 4 disease required surgery. No treatment was needed in infants born after 32 weeks of gestation. Respiratory distress syndrome and low gestational age were the most important risk factors for type 1 ROP. In the West Black Sea region of Turkey, screening all premature infants with a gestational age < or = 32 weeks or a birth weight < or = 1900 g appears to be appropriate.     

RetCam数字视网膜照像机检测早产儿视网膜病

目的探讨早产儿视网膜病变（ROP）的早期诊断方法。方法对2006年10～12月本院NICU126例住院的早产儿共252眼,在生后4周或矫正胎龄达32～34周时,采用RetCam数字视网膜照像机进行眼底数字照像。结果7眼出现ROP改变,发生率为2.7%;其中1期病变4眼,2期病变1眼,3期附加病变（＋plus病变）2眼,未发现4期和5期病变,无1例发生并发症。结论RetCam数字视网膜照像机可早期、快速、安全有效的诊断ROP,对ROP的早期诊断具有重要价值。     

早产儿视网膜血管发育成熟度的研究

目的 研究早产儿出生时视网膜血管的发育及其影响因素,与早产儿视网膜病(ROP)发生之间的关系.方法 2006年10至12月,在北京军区总医院新生儿监护病区住院的不同胎龄和出生体重的84例新生儿,于生后1周内,扩瞳后用Retcam Ⅱ数码照相机拍摄眼底照片,评价视网膜血管化的程度,分析母亲和婴儿因素对视网膜血管化的影响.并追踪观察视网膜血管化程度与ROP发生的关系.计数资料用四格表X2检验,计量资料以x±s表示,两样本均数行t检验.结果在本组84例中,视网膜血管化达到Ⅰ区和Ⅱ区在胎龄<30周早产儿组中为91.7%(11/12),在胎龄31～33周组为46.2%(12/26),在胎龄34～36周组为3.84%(1/26),在胎龄37～40周组为0(0/20);在出生体重<1500 g组为80%(12/15),1500 g<出生体重<1700 g组为57.1%(8/14),1700 g<出生体重<2000 g组为36.4%(4/11),在2000 g组为0(0/44).单变量分析显示胎龄(F=31.9193,P=0.000)、出生体重(F=32.4532,P=0.000)、产前使用糖皮质激素(F=36.9391,P=0.000)、表面活性物质(F=24.000,P=0.0000)、母亲营养状态(F=4.184,P=0.041)、RDS(F=17.6191,P=0.000)、生产方式(F=10.972,P=0.0022)和需氧超过48 h(F=22.076,P=0.0000)等和视网膜的不成熟有关.多变量分析显示视网膜血管化主要受胎龄(95%CI=1.57～261.728,P=0.021)影响.追踪观察视网膜不成熟的24例早产儿,最终发现有15例发生ROP,占62.5%(X2=45.1087,P=0.000).结论在胎龄31～34周的早产儿视网膜血管化存在较大的变异性.母亲和胎儿因素可能影响出生时视网膜的血管范围.胎龄是影响视网膜成熟度的主要因素.不成熟的视网膜是发生ROP的根本原因.     

Laser treatment of zone I prethreshold and stage 3 threshold retinopathy of prematurity

PURPOSE: To analyze the structural outcomes of zone I prethreshold and stage 3 threshold retinopathy of prematurity following laser ablation. PATIENTS AND METHODS: This nonrandomized observational case series evaluated 71 eyes of 36 infants who weighed less than 1,250 g at birth. Infants were treated at either prethreshold or threshold severity. The structural outcomes were compared using Fisher's exact test. RESULTS: The structural outcome was favorable in 96% and 80% of the prethreshold and threshold groups, respectively (P = .069). When an unfavorable outcome was defined as dragging of the temporal vessels, the difference was significant (P = .0257). CONCLUSION: Early treatment of zone I disease may result in a better structural outcome.     

Evidence for changing guidelines for routine screening for retinopathy of prematurity

CONTEXT: Existing guidelines recommended by the Canadian Pediatric Society (CPS) and American Academy of Pediatrics (AAP) for routine screening for retinopathy of prematurity (ROP) remain controversial. OBJECTIVE: To determine whether current guidelines for routine screening for ROP should be changed. DESIGN: We examined data that were collected as part of a larger study of 14 neonatal intensive care units (NICUs) in Canada. We examined the effect of strategies using different birth weight (BW) and gestational age (GA) criteria for routine ROP screening, and performed a cost-effectiveness analysis. SETTING: The 14 NICUs (except one) are regional tertiary level referral centres serving geographic regions of Canada, and include approximately 60% of all tertiary-level NICU beds in Canada. PATIENTS: This large cohort included all 16 424 infants admitted to 14 Canadian NICUs from January 8, 1996, to October 31, 1997. INTERVENTIONS: None. MAIN OUTCOME MEASURE: Treatment for ROP. RESULTS: The most cost-effective strategy was to routinely screen only infants having a BW of 1200 g or less. This included all infants treated for ROP (except 1 outlier at 32 weeks GA and 1785 g BW), at a marginal cost per additional person with improved vision of $513 081 for screening patients between 28 weeks GA and 1200 g BW, compared with $1 800 039 and $2 075 874 for using the current AAP and CPS guidelines, respectively (cryotherapy outcomes). Results for laser therapy were similar, but costs were slightly lower. This strategy reduced the number of infants screened under the current CPS guidelines by 46%. CONCLUSION: Screening only infants having a BW of 1200 g or less is the most cost-effective strategy for routine ROP screening.     

Outcome of neonatal necrotising enterocolitis: results of the BAPM/CDSC surveillance study, 1981-84.

Neonatologists in 100 special care baby units in the United Kingdom and Ireland collaborated in a four year surveillance study of neonatal necrotising enterocolitis. The average overall annual reporting rate of necrotising enterocolitis for infants in England and Wales was 0.3/1000 live births, but ranged from 9.5/1000 live births in infants weighing less than 1000 g at birth to 0.2/1000 live births in infants weighing 2500 g or more. There were more deaths among girls, infants who weighed less than 1500 g at birth, those whose bleeding was abnormal or who had low peripheral platelet counts, infants with Gram negative bacteraemia, and very low birthweight infants who developed it during the first few days of life. In both boys and girls, and in all birthweight groups, operation was associated with increased mortality.