Comparison Of Abdominal Radiographs And Sonography In Prognostic Prediction Of Infants With Necrotizing Enterocolitis

Background and objectiveNecrotizing enterocolitis(NEC)is one of the most common diseases that seriously threatens the lives of newborns.In recent years,with the improvement of rescue techniques for premature infants,the morbidity of NEC has increased significantly.According to statistics,among preterm infants with a birth weight of less than 1500 g,the morbidity of NEC is as high as 5%to 10%,and the mortality rate can reach 20%to 30%.More than 30%to 50%NEC children need surgery.NEC treatment is divided into non-surgical conservative treatment and surgical treatment.Non-surgical treatment is suitable for children with early mild disease,and timely regular treatment can avoid a part of the surgical probability.However,once the indications for surgery are not grasped,delaying the operation can lead to serious consequences.NEC can be divided into localized and generalized types.For children with generalized NEC,once full-thickness necrosis occurs,there are often disastrous consequences such as death or short bowel syndrome.Therefore,it is very important to grasp surgical indications.There is no doubt that the absolute surgical indication of NEC is recognized as the digestive tract perforation which is often traditionally determined by relying on abdominal X-ray findings of free peritoneal gas.However,due to the influence on the interference of gas volume,wrapping,adhesion and other factors,in most cases,the digestive tract perforation of many children patients can not be shown in abdominal X-ray examinations.The timing of surgery can be judged more accurately when combining with the results of ultrasound,physical examination and abdominocentesis.If the systemic symptoms are heavy in children with the generalized type NEC,undergoing surgeries after blindly waiting for the occurrence of digestive tract perforation will delay the condition of the patient and even lose the opportunity for treatment.The following non-absolute indications need to be considered comprehensively and combined with the experience of clinicians:1.Clinical symptoms such as abdominal distention and hemafecia continue to aggravate after regular conservative treatment;2.Peritoneal irritation sign occurs and aggravates;3.Intestinal loop fixation or severe pneumatosis intestinalis and portal venous gas are found in X-ray images;4.Laboratory examination found the blood culture was positive within 96h of NEC onset,hyponatremia(<130 mmol/L)occurs within 24h,durative severe acidosis(pH<7.25),thrombocytopenia(blood platelet count<50000/mm3),neutropenia(neutrophil absolute value<2 000/mm3)and C-reactive protein(CRP)increases.At present,the most common and popular auxiliary examination method is abdominal X-ray examination.Most experts’ consensus and guidelines for diagnosis and treatment are based on X-ray findings.The Dukes DAAS 10 sub-scale was used to standardize the images reading.The higher the score,the higher the diagnosis rate of necrotizing enterocolitis and the worse the condition.In recent years,ultrasound has been used ever more than before in the management and treatment of NEC patients.Many experts believe that ultrasound can not only show portal venous gas,pneumatosis intestinalis,pneumoperitoneum and other symptoms,but also dynamically display the conditions of intestinal wall thickness,peristalsis,and intestinal wall blood perfusion.Compared with X-ray,it is more in line with the apostasis of NEC and more conducive to guiding the therapy.However,the results of ultrasound examination are greatly affected by the level of the physician.At present,there is no sub-scale similar to Dukes DAAS 10 to standardize and quantify its diagnosis.The purpose of writing this article is to explore the factors that may have implications for the prognosis of NEC in children patients with ultrasonography and X-ray findings,comparing them with each other,and to a certain extent,guiding the NEC disease management and the grasping of surgical indications.MethodsWe retrospectively study conducted 86 neonates were analyzed in this study.Inclusion criteria:neonates born between 1st,Jun,2010 and 30th,Dec,2016 and hospitalized in the NICU of Qilu children’s hospital;clinical symptoms suggestive of NEC,as defined by the presence of abdominal distension,increased gastric residuals(>20%of enteral feeding volume),or blood in the stool(macroscopically or microscopically);confirmation of the NEC episode using abdominal imaging examinations,including one abdominal radiograph and ultrasonography,performed as soon as NEC was suspected.Exclusion criteria:absence of abdominal radiographic or ultrasonographic images for the NEC episode.Two groups were defined based on the outcome:a group for infants who have survived without surgery,and a group for infants who have needed surgery or have died.The US and radiographic findings were reviewed by two board-certified radiologists(a pediatric radiology fellow and a pediatric radiologist with morethan 15 years of experience).Both were blinded to the clinical outcome and to the findings of other imaging modalities.Decisions were reached by consensus.Plain abdominal radiographs were performed according to the following protocol:at the bedside,single anteroposterior view,patient in supine position,Radiographs were evaluated for the intestinal gas pattern and the presence or the absence of intramural gas,portal venous gas,and free peritoneal gas.The intestinal gas pattern on the abdominal radiograph was considered normal if the intestinal gas was evenly distributed throughout the abdomen without separation of intestinal loops.The intestinal gas pattern was then categorized into four types:(1)decreased intestinal gas or gasless intestine;(2)normal intestinal gas;(3)dilatation;and(4)dilatation and elongation.Sonographic examination wasGray scale images were used to assess bowel wall for thickening(2.5 mm)and thinning(1.1 mm),PI,PVG,and intraabdominal fluid.Indications for surgery included lack of improvement or clinical deterioration despite optimal medical treatment,as well as pneumoperitoneum(with instability or severe alteration in clinical status).The independent sonographic factors found to be significantly related to diagnosis of NEC at multivariable logistic analysis in all patients entered into the logistic model.The sum of the odds rate which impact the regressional function was used in the logistic model to predict the diagnosis of preterm neonates with NEC.Continuous variables were expressed as mean ± SD(standard deviation)and compared using a two-tailed unpaired Student’s test;categorical variables were compared using x2 or Fisher analysis.The cutoffs of bowel wall were defined by Youden’s index shown in receiver-operating characteristic(ROC)curve analysis and by other published reports.The diagnostic performance of the thick bowel wall(more than 2.5 mm),intramural gas(pneumatosis intestinalis),portal venous gas,and reduced peristalsis was measured using the area under ROC curve(AUC).AUCs were also used to compare the logistic with other single sonographic parameter for diagnosing NEC using the Hanley and McNeil method The predictions of all models were expressed in sensitivity,specificity,positive,and negative predictive values at aparticular cut-off value.A value of p<0.05 was considered significant in all the analyses.Statistical analysis of continuous and categorical variables and ROC curve analysis was computed using MedCalcV.11.0.3.0(MedCalc software,Mariakerke,Belgium).ResultsAmong these patients,39 infants(45.3%)required surgical treatment.In the surgery and no surgery groups,respectively.Overall,25 patients(29.1%)exhibited intramural gas on abdominal radiographs,with 4 patients(4.7%)displaying no pneumatosis on sonography.Conversely,61 neonates(70.9%)exhibited no intramural gas on abdominal radiographs,with 8(9.3%)displaying pneumatosis on sonography.AUS revealed free peritoneal gas(n = 12/10),abdominal fluid(n = 11/8),thick bowel wall(more than 2.5 mm)(n = 15/5),thin bowel wall(less than 1.1 mm)(n ＝6/7),intramural gas(pneumatosis intestinalis)(n = 17/10),portal venous gas(n = 8/2),focal fluid collections(n = 11/12),and reduced peristalsis(n = 12/5)in patient with/without surgery While AR revealed free peritoneal gas(n = 12/5),Intramural gas(n = 18/7),portal venous gas(n = 7/2),decreased intestinal gas or gasless intestine(n=11/14),normal intestinal gas(n = 8/7)and dilatation and elongation(n = 15/7)in patient with/without surgery.Prognostic value of abdominal radiographs and sonography A multivariable logistic regression analysis was further performed to assess these radiographic and sonographic factors that demonstrated significant effects in univariate analysis for prognosis of NEC.After adjusting for competing sonographic factors,we identified that thick bowel wall(more than 2.5 mm),intramural gas(pneumatosis intestinalis),portal venous gas,and reduced peristalsis were independent prognostic factors associated with surgical NEC.After adjusting for competing radiographic factors,we identified that free peritoneal gas,portal venous gas,and dilatation and elongation were independent prognostic factors associated with surgical NEC.Comparison of AR and AUS in prognostic prediction of patients with NEC We found that the AUROC for AR logistic model was 0.745(95%CIO.629-0.812),which was significant lower than the AUS logistic model(AUROC:0.857,95%CI 0.802-0.946)for predicting prognosis of NEC(p = 0.014).ConclusionAmong signs provided by AUS:thick bowel wall(more than 2.5 mm),intramural gas(pneumatosis intestinalis),portal venous gas,and reduced peristalsis are closely related to the poor prognosis of NEC,suggesting that surgery may be required or the death of patient.Among signs offered by abdominal X-ray findings:free peritoneal gas,portal venous gas,and dilatation and elongation are closely related to the poor prognosis of NEC.Compared with that of the X-ray,the ultrasonographic signs are more accurate in indicating the prognosis of NEC.Abdominal ultrasonography plays an important role in disease management,prognosis evaluation and surgical indication of NEC.During the clinical work,we should pay attention to the information provided by it.