Contrast-enhanced ultrasound findings in testicular torsion and non-testicular torsion.

PURPOSE: Testicular torsion requires emergency surgery; thus, prompt and correct diagnosis is very important. Ultrasound with color Doppler is usually the first-choice modality for diagnosis; however, skill and experience are required for confident diagnosis. Recently, contrast-enhanced ultrasound for the diagnosis of testicular torsion has been reported, but there have been only a few reports. This study aimed to compare contrast-enhanced ultrasound findings in cases of testicular torsion and non-testicular torsion. METHODS: Patients who underwent contrast-enhanced ultrasound for acute scrotum at our institution between April 2010 and January 2023 were divided into testicular torsion (n = 17) and non-testicular torsion (n = 16) groups. The respective contrast-enhanced ultrasound findings were retrospectively examined and compared. RESULTS: In 16 out of 17 cases of testicular torsion, the parenchyma of the affected testis was not enhanced. In the remaining case, reduced contrast enhancement was observed; however, it was still notably less than that observed on the unaffected testis. On the other hand, in all cases of non-testicular torsion (n = 16), the parenchyma of the affected testis was notably enhanced. CONCLUSION: Contrast-enhanced ultrasound is considered an easy and accurate method for diagnosing testicular torsion.

Contrast-enhanced ultrasonographic findings in torsion of the appendix testis or epididymis in children: a case series.

PURPOSE: Torsion of the appendix testis or epididymis is a cause of acute scrotum in children. Ultrasonography with color Doppler is the first-choice modality for diagnosis. However, this method requires skill and experience to make a diagnosis with confidence. Recently, contrast-enhanced ultrasonography for diagnosis in various fields has been reported. However, to our knowledge, there has been no report of this method being used to diagnose torsion of the appendix testis or epididymis. The purpose of this study was to retrospectively examine contrast-enhanced ultrasonographic findings in torsion of the appendix testis or epididymis. METHODS: Patients who underwent contrast-enhanced ultrasonography for torsion of the appendix testis or epididymis at our institution between April 2010 and April 2023 were enrolled in this study (n = 12). Contrast-enhanced ultrasonography findings of the affected appendage and the testis parenchyma were examined retrospectively. RESULTS: The parenchyma of the testes was notably enhanced in all the cases. However, 9 of the 12 cases showed that the appendage with torsion was not enhanced at all. In the remaining three cases, only slight enhancement was seen. Nevertheless, it was notably less than that of the parenchyma of the testis. CONCLUSION: Our findings indicated that contrast-enhanced ultrasonography may be an easy and reliable method for diagnosing torsion of the appendix testis or epididymis.

Infantile type I pleuropulmonary blastoma presenting with dyspnea due to compression by pneumothorax and an occupying tumor: a case report.

BACKGROUND: Pleuropulmonary blastoma (PPB) is an extremely rare and malignant pediatric lung tumor. Purely cystic PPB has a more favorable prognosis than solid PPB, but may be difficult to distinguish from a certain type of "benign" congenital pulmonary airway malformation before and during surgery. The influence of tumor rupture on long life prognosis has not been clarified in detail. CASE PRESENTATION: A 5-month-old boy underwent emergency transfer from another hospital due to a left thoracic cystic lesion and left pneumothorax detected on chest radiography performed for persistent wheeze and cough. Contrast-enhanced computed tomography of the chest revealed marked deviation of the mediastinum to the right due to a giant cystic lesion and pneumothorax. Thoracotomy was performed on hospital day 2. A cystic lesion had developed from the distal alveolar region of lower lobe of the left lung and the tumor showed a tiny adhesion to the left diaphragm and a tiny rupture near the adhesion. Partial lung excision including the cyst and scraping of the adhesion were performed. Histopathological investigations revealed immature blast cell-like mesenchymal cells and differentiated striated muscle cells in a dense cambium layer were found under the epithelium of the cystic lesion. Type I PPB was diagnosed. CONCLUSIONS: Surgery should be performed with the possibility of type I PPB in mind when an extrapulmonary cystic lung lesion is found. Since issues such as the pathogenesis and long-term prognosis of ruptured cases remain unclear, continued careful follow-up of this case will be required.

Challenging management of a baby with congenital multiple intestinal atresia, trisomy 18 and extremely low birth weight: a case report.

BACKGROUND: Extremely low birth weight (< 1000 g) still influences postsurgical prognosis in the neonatal and infantile periods. Additionally, the life expectancy of neonates with trisomy 18 is extremely poor owing to various comorbidities. Therefore, it takes courage to perform laparotomy for the purpose of treatment of congenital multiple intestinal atresia in a baby with an unpredictable life prognosis. CASE PRESENTATION: Fetal ultrasonography revealed cardiac malformation, intestinal dilation, and physical characteristics suggestive of a chromosomal abnormality in this case. The patient was diagnosed with trisomy 18 after birth, with an extremely low birth weight. An atrial septal defect, ventricular septal defect, dilated jejunum, and a very thin collapsed small intestine were found on ultrasonography. With a diagnosis of congenital small intestinal atresia, a challenging laparotomy was done at 3 days of age, with jejunal atresia and multiple distal small intestinal atresia were observed. The jejunal end and distal small intestinal stump were separated into stomas at the wound edge. Hypertrophic pyloric stenosis developed at the age of 3 months and resolved with medication. The patient gained weight (2 kg) by daily stool injection into anal side of the intestine and decompression against poor peritonitis of dilated jejunum using enteral feeding tube for the long period. Finally, we could perform intestinal reconstruction safely and successfully at the age of 9 months. Tracheotomy was performed due to difficulty in extubation associated with chronic lung disease. The patient was discharged at the age of 1 year and 3 months, and no major problems were noted at the age of 2 years. CONCLUSIONS: We treat congenital intestinal atresia in extremely low birth weight infants with severe chromosomal abnormalities and severe cardiac malformations as follows: Stoma creation is performed quickly to avoid deterioration of the patient's hemodynamics. After that, while continuing enteric management, palliative cardiovascular surgery is performed as necessary, and the patient's body weight and intestinal tract status are determined to allow safe intestinal reconstruction.

Neonatal necrotizing fasciitis with gas gangrene due to peripherally inserted central catheter-related infection.

BACKGROUND: Necrotizing fasciitis in neonates is a rare and life-threatening infection involving necrosis of the skin, subcutaneous tissues, deep fascia, and sometimes underlying muscles, with a fulminant course and high mortality rate. Necrotizing fasciitis with gas gangrene related to infection of a peripherally inserted central catheter is very rare. CASE PRESENTATION: The patient was a full-term female neonate born by vaginal delivery. Following diagnosis of patent ductus arteriosus, indomethacin was administered from a peripherally inserted central catheter for 3 days. Four days after the termination of medical treatment for the patent ductus arteriosus, the patient developed fever and a severely elevated inflammatory response was identified from blood testing. Around the right anterior chest wall, corresponding to the site of the catheter tip, redness was increased and gas crepitus was felt under the skin. Computed tomography revealed emphysema in the anterior chest, in subcutaneous areas and between muscles. Emergency surgical debridement was performed under a diagnosis of necrotizing fasciitis with gas gangrene. With antibiotic treatment, we started to fill the wound with a dialkyl carbamoyl chloride-coated dressing and povidone-iodine sugar ointment after washing with saline once a day. The patient survived and after 3 weeks of treatment with the dressing, the wound had successfully resolved without motor impairments. CONCLUSIONS: In addition to medical treatment and prompt surgical debridement, we used dialkyl carbamoyl chloride-coated dressing and povidone-iodine sugar ointment for antiseptic dressings and successfully treated neonatal necrotizing fasciitis with gas gangrene caused by peripherally inserted central catheter infection with Citrobacter koseri.

Axillary skin crease incision versus conventional posterolateral incision in open repair of patent ductus arteriosus for extremely low birth weight infants: a retrospective study.

BACKGROUND: Thoracotomy with posterolateral incision (PLI) is commonly used for surgical repair of patent ductus arteriosus (PDA) in extremely low birth weight (ELBW) infants. Some reports have described thoracotomy for PDA using an axillary skin crease incision (ASCI) in consideration of cosmetic problems such as surgical wounds and thoracic deformities, but the details remain unclear. METHODS: In this study, we performed clipping ligation by thoracotomy with ASCI for ELBW infants with PDA from 2011 to 2015 for the purpose of improving cosmetic results, and retrospectively compared the results with those for conventional PLI cases performed from 2016 to 2020. RESULTS: ASCI was found to be associated with serious surgical complications and showed a significant difference in outcome parameters only for surgery time, suggesting a safety problem for ASCI. Considering these results, PLI allows clipping of the nearby PDA from the thoracotomy wound while looking straight ahead, whereas the PDA in ASCI is positioned deep and oblique to the thoracotomy wound, so the clipping angle is limited and accurate completion of the procedure is difficult. CONCLUSIONS: Regarding PDA repair in ELBW infants, ASCI shows a high risk of serious surgical complications. Conventional PLI remains preferable for safe and accurate results.

Median sternotomy approach for the repair of esophageal atresia: a case report.

BACKGROUND: Repair of esophageal atresia is usually performed through the right thoracic cavity. However, when the upper pouch of the esophagus and tracheoesophageal fistula (TEF) is located in the thoracic inlet and completely on the left side of trachea, it is difficult to dissect and anastomose the esophagus through the right thoracic cavity. We present a case of esophageal atresia, with the esophageal upper pouch located high and completely on the left side of trachea, successfully repaired via the median sternotomy approach. CASE PRESENTATION: A male neonate with a birth weight of 1766 g was prematurely delivered via cesarean section at 34 weeks of gestation. Contrast-enhanced computed tomography (CT) showed that the upper pouch of the esophagus was located at the thoracic inlet and completely on the left side of the trachea; hence, a diagnosis of esophageal atresia was made. Moreover, a TEF was connected to the trachea at the level of the lower end of the upper esophageal pouch. An aberrant right subclavian artery and persistent left superior vena cava were also detected. Esophageal dissection and anastomosis were determined to be very difficult if approached from the right thoracic cavity. Therefore, we performed median sternotomy one day after the neonate was born. The upper pouch of the esophagus and TEF were easily dissected via the median sternotomy approach. Anastomosis of the esophagus was performed, with a good visual field, to the left of the trachea. The postoperative course was uneventful. CONCLUSIONS: This is the first reported case of a median sternotomy approach for esophageal atresia. This technique may be useful when a right thoracic approach is difficult, especially if the esophageal upper pouch is located completely to the left of the trachea or if it is higher than the normal position.

Hemi-Clamshell Approach for Fetal Lung Interstitial Tumor Resection in a Neonate: A Case Report.

Fetal lung interstitial tumor (FLIT) is a rare primary lung mass in neonates. Classical incisions, such as posterolateral thoracotomy or median sternotomy, do not provide optimal exposure of the operative field for the resection of pediatric thoracic giant tumors. Herein, we report a rare case of a FLIT in a full-term male neonate, with complete resection achieved using a hemi-clamshell approach, which provided the required visualization of the operative field. The neonate was transferred to our hospital because of mild respiratory distress, which developed 18-hour after normal vaginal delivery. A mass in his right chest, without a midline shift, was observed on chest radiographs. Computed tomography showed a well-circumscribed solid anterior cervicothoracic mass, with a uniform density and no apparent cysts, diagnosed as a primary thoracic giant tumor. Once the patient was clinically stabilized, we proceeded with right upper lobectomy, using a hemi-clamshell approach, full sternotomy, and anterolateral thoracotomy, on postnatal day 22. Histopathologic examination revealed an 8.5 × 6.5 × 4.0 cm solid mass within the right upper lobe, which was diagnosed as a FLIT. His postoperative recovery was uneventful. The patient was followed up for 1 year, with no complaints or symptoms and no postoperative shoulder dysfunction. Gross total resection of primary thoracic giant tumors can be accomplished in neonates with optimal exposure of the chest cavity using a hemi-clamshell approach.

Epithelial and ganglionic distribution at the distal rectal end in anorectal malformations: could it play a role in anastomotic adaptation?

PURPOSE: In anorectal malformations (ARMs), the epithelium of the distal rectal end is not well described. We histomorphologically evaluated epithelial and ganglionic distribution in the distal rectal end of ARMs resected during anorectoplasty to assess similarities and differences with normal anal canal structure. METHODS: In this single-center retrospective study, specimens from 60 ARM patients (27 males, 33 females) treated between 2008 and 2019 were evaluated. RESULTS: Epithelium type and alignment sequence as well as ganglionic distribution were similar in the distal rectal end and in a normal anal canal. Stratified columnar epithelium (anal transitional zone, ATZ) was seen in 49/60 (81.7%) cases and in all ARM types, including the no-fistula type. Anal crypts were identified in the stratified columnar epithelium (ATZ) of 46/49 (93.9%) patients. Regarding distal rectal end-resecting anorectoplasty, in 90% of patients, resection was performed distal to the Herrmann line. Ganglion cell distribution was exclusively proximal to the Herrmann line. CONCLUSION: Epithelial and ganglionic distribution was similar in the distal rectal end of ARMs and in a normal anal canal. The ATZ is the epithelial boundary between the rectum and skin in a normal anal canal. ATZ preservation could reproduce anal canal structure in ARM reconstruction.

Histological features of complete tracheal rings in congenital tracheal stenosis.

PURPOSE: Congenital tracheal stenosis is a disease in which complete tracheal cartilage rings (CTCR) cause airway narrowing. Although tracheal cartilage malformation has been suggested as a cause of CTCR, no histological studies have been performed. Here, we report a comparison of the tissues from CTCR and normal tracheal cartilage. METHODS: Thirty-one infants who underwent slide tracheoplasty at our institution from May 2016 to August 2019 were included. Tissues from ten autopsy cases without tracheal lesions were used as controls. The survey items were tracheal cartilage cell density, cartilage thickness, and chondrocyte findings. RESULTS: The median cartilage cell density from cases was 23/125 × 125 µm2 and from controls was 23.5/125 × 125 µm2 (p = 0.90). The median cartilage thickness from cases was 689 µm and from controls was 840 µm (p = 0.11). Comparing the ventral and dorsal sides of the CTCR tissues, the cell density was significantly different (median ventral 23/125 × 125 µm2; median dorsal 19.5/125 × 125 µm2; p = 0.034). There were no significant findings in the chondrocytes of the CTCR tissues. CONCLUSION: CTCR tissues did not differ in cartilage density and thickness from normal tracheal cartilage.

AFP-L3 as a Prognostic Predictor of Recurrence in Hepatoblastoma: A Pilot Study.

The α-fetoprotein (AFP) level is a sensitive biomarker of active hepatoblastoma (HB). This study aimed to clarify whether the Lens culinaris agglutinin A-reactive fraction of AFP (AFP-L3) after complete resection is a prognostic predictor of HB recurrence. Fourteen HB patients who underwent complete resection of HB were divided into the recurrence group (RG, n=4) and the non-recurrence group (NRG, n=10). The AFP level and AFP-L3 before and after radical surgery were compared between the 2 groups. There was no significant difference in AFP levels in the early postoperative period between the 2 groups (P=0.54), and AFP was not an early prognostic factor for HB recurrence. At 2 months after surgery, the AFP-L3 fell below the detection limit only in the NRG (7/10 cases) (NRG=70.0% vs. RG=0%, P=0.03). In addition, there were some cases of recurrence in those whose AFP level decreased to the normal range, but none in those whose AFP-L3 fell below the detection limit. In conclusion, the AFP-L3 decreased earlier than did the AFP level; thus, the AFP-L3 after complete resection may be a predictor for HB recurrence.

Correction to: Two infant cases of intraperitoneal arterial hemorrhage due to a duplication cyst: a case report.

An amendment to this paper has been published and can be accessed via the original article.

Mechanism of pancreatic juice reflux in pancreaticobiliary maljunction: A fluid dynamics model experiment.

BACKGROUND: Pancreatic juice reflux to the common bile duct and gallbladder is observed in the pancreaticobiliary maljunction (PBM), and various pathological conditions occur in the biliary tract. However, the mechanism of pancreatic juice reflux has not been discussed yet. This study aimed to investigate the mechanism of this phenomenon from the perspective of the fluid dynamics theory. METHODS: A fluid dynamics model of PBM without biliary dilatation having gallbladder function and of the pressure of sphincter of Oddi was developed. Water (as bile juice and pancreatic juice) was flowed to these models with a flow rate similar to that in humans. Pancreatic and bile juice flow and bile duct pressure were observed in three phases of gallbladder function. Moreover, the same experiment was performed in the PBM without biliary dilatation model without gallbladder. RESULTS: Pancreatic juice reflux could be observed when the gallbladder was passively expanded with the pressure in the bile duct lower than that in the sphincter of Oddi. However, pancreatic juice reflux was not observed in the model without gallbladder. CONCLUSIONS: Gallbladder function may be strongly involved in pancreatic juice reflux in PBM without biliary dilatation. Cholecystectomy may be able to stop the reflux of pancreatic juice.

Risk factors for the recurrence of perineal canal.

PURPOSE: The aim of this study was to investigate risk factors for recurrence in the perineal canal (PC). METHODS: Patients with PC who underwent operations were enrolled in this study and were divided into recurrence and non-recurrence groups. Preoperative infection, the age at the operation, the presence of colostomy and the treatment procedure for fistula were retrospectively investigated. Regarding the treatment procedure for fistula, either closure of the rectal wall with stitches or ligation of fistula in the rectum was performed. These factors were compared between the two groups. RESULTS: Six of 17 patients with PC who underwent surgical treatment had recurrence. There were no significant differences in the incidence of preoperative infection, age at operation or presence of colostomy (p = 0.60, 0.38, 1.00, respectively). In the recurrence group, all patients were treated by closure of the rectal wall. In the non-recurrence group, five were treated by the closure of the rectal wall with stitches and six by ligation of the fistula. There was a significant association between recurrence and the treatment procedure for fistula (p = 0.04). CONCLUSION: Closure of the rectal wall with stitches is a risk factor for the recurrence of PC.

Repair of type IV laryngotracheoesophageal cleft (LTEC) on ECMO.

PURPOSE: A type IV laryngotracheoesophageal cleft (LTEC) is a very rare congenital malformation. Type IV LTEC that extends to the carina have poor prognosis and are difficult to manage. We present our experience with surgical repair in such a case using extracorporeal membranous oxygenation (ECMO). METHODS: A male infant, who was diagnosed with Goldenhar syndrome, showed severe dyspnea and dysphagia. Laryngoscopy indicated the presence of LTEC. The patient was transferred to our institute for radical operation 26 days after birth. Prior to surgery, a balloon catheter was inserted in the cardiac region of stomach through the lower esophagus to block air leakage, to maintain positive pressure ventilation. We also performed observations with a rigid bronchoscope to assess extent of the cleft, and diagnosed the patient with type IV LTEC. After bronchoscopy, we could intubate the tracheal tube just above the carina. Under ECMO, repair of the cleft was performed by an anterior approach via median sternotomy. RESULTS: The patient was intubated via nasotracheal tube and paralysis was maintained for 2 weeks, using a muscle relaxant for the first 3 days. Two weeks after surgery, rigid bronchoscopy showed that the repair had been completed, and the tracheal tube was successfully extubated without tracheotomy. CONCLUSIONS: Although insertion of a balloon catheter is a very simple method, it can separate the respiratory and digestive tracts. This method allowed for positive pressure ventilation and prevented displacement of the endotracheal tube until ECMO was established. As a result, we safely performed the operation and the post-operative course was excellent.

Dilatation of the common channel in pediatric congenital biliary dilatation remaining after radical operation.

BACKGROUND: In congenital biliary dilatation, the protein plug is likely impacted, especially in a dilated common channel. However, nobody has discussed whether this dilatation of common channel remains after radical operation. The aim of this study was to investigate the situation of the dilated common channel after radical operation. METHODS: The status of the common channel was investigated at radical operation and follow-up. We then evaluated whether dilation of the common channel remained postoperatively. Moreover, the association between status of the common channel and postoperative pancreatic complication was evaluated. RESULTS: Postoperative condition of the common channel was able to be evaluated ultrasonographically in 42 patients. The common channel was dilated at the time of operation in 18 patients and remained dilated postoperatively in 11 of these 18 patients. Dilatation of the common channel was not identified in any patients without dilatation at the time of operation. No patients in this series showed any postoperative pancreatic complications, even if a dilated common channel remained. CONCLUSIONS: Dilatation of the common channel can remain postoperatively in congenital biliary dilatation, but does not appear to be associated with postoperative pancreatic complications.

Clinical features and risk factors of bile duct perforation associated with pediatric congenital biliary dilatation.

PURPOSE: This study aimed to investigate the clinical features and risk factors of bile duct perforation in pediatric congenital biliary dilatation (CBD) patients. METHODS: CBD patients, whose initial symptom was abdominal pain, were enrolled in this study and were divided into perforated and non-perforated groups. The clinical features of the perforated group were investigated. Moreover, the age at operation, sex, and morphologic features of the extrahepatic bile duct were compared between the groups. RESULTS: Fifteen cases of bile duct perforation (10.4%) were identified among the 144 CBD patients who had abdominal pain. Majority of bile duct perforation occurred in patients aged < 4 years. The median duration from onset of abdominal pain to bile duct perforation was 6 (4-14) days. Age at onset [< 4 years old; P = 0.02, OR 13.9, (1.663, 115.3)], shape of extrahepatic bile duct [non-cystic type; P = 0.009, OR 8.36, (1.683, 41.5)], and dilatation of the common channel [P = 0.02, OR 13.6, (1.651, 111.5)] were risk factors of bile duct perforation. CONCLUSIONS: Emergent bile duct drainage might be planned to prevent bile duct perforation if CBD patients have the abovementioned risk factors and experience persistent abdominal pain lasting for a few days from onset.

A case of biliary atresia with pancreaticobiliary maljunction.

BACKGROUND: The pathogenesis of biliary atresia (BA) is still unknown. There are several reports on the etiology of BA, including pancreaticobiliary maljunction (PBM). We experienced a case of Kasai type IIIa BA with PBM, in which we found elevation of pancreatic enzymes in the gallbladder. We evaluated whether PBM is related to the pathogenesis of BA based on our findings. CASE PRESENTATION: The patient was born at 40 weeks of gestation. His body weight at birth was 2850 g. At the age of 4 days, he had an acholic stool and was referred to our hospital. Abdominal ultrasonography showed that triangular cord sign was negative. The gallbladder was isolated with a diameter of 19 mm, and it contracted in response to oral feeding. His ultrasonographic findings were atypical for BA, but his jaundice did not improve. Therefore, we performed an operation at the age of 56 days. Intraoperative cholangiography showed a common bile duct and pancreatic duct and a common channel patent, while the common hepatic duct or intrahepatic duct was not visualized. Bile in the gallbladder contained colorless fluid, which showed elevated lipase level (34,100 IU/L). We performed Kasai portoenterostomy under the diagnosis of Kasai type IIIa BA with PBM. The patient's postoperative course was uneventful, and he was discharged on day 30 after the operation. Histopathological evaluation showed that the lumens of the common bile duct and cystic duct were patent. However, the common hepatic duct was closed, and only bile ductules with diameters of less than 50 µm were isolated. Infiltration of lymphocytes was detected in the porta hepatis. No apparent inflammation was observed around the cystic duct, which was constantly exposed to pancreatic juice because of reflux through PBM. CONCLUSIONS: Reflux of pancreatic juice through PBM might not be an etiological factor for BA, but might be associated with patency of the common and cystic bile ducts in Kasai type IIIa BA.

Classification of pancreaticobiliary maljunction and clinical features in children.

BACKGROUND: In 2015, the Committee on Diagnostic Criteria of the Japanese Study Group on Pancreaticobiliary Maljunction (PBM) proposed a classification of PBM into four types: (A) stenotic type, (B) non-stenotic type, (C) dilated channel type, and (D) complex type. To validate this classification and clarify the clinical features of the four types of PBM, a retrospective multicenter study was conducted. METHODS: The study group of 317 children with PBM was divided into the four types of PBM. Clinical features, preoperative complications, operations, and postoperative pancreatic complications were evaluated. RESULTS: All patients underwent excision of the extrahepatic bile duct. In type A, the age was younger and there was a higher incidence of cystic dilatation. Non-dilatation of the common bile duct was frequently seen in type B. Abdominal pain with hyperamylasemia was frequently seen in types B and C. In particular, the incidence of protein plugs and biliary perforation was high in type C (56.1% and 14.3%, respectively). The overall incidence of acute pancreatitis was 7.3%. Pancreatitis after excisional surgery was rare in the children in this study. Two patients with type D (0.6%) developed chronic pancreatitis postoperatively. CONCLUSIONS: This proposed classification is simple and correlates well with clinical features.

Predictive factor for intraoperative tumor rupture of Wilms tumor.

PURPOSE: For Wilms tumor, intraoperative tumor rupture with wide tumor spillage during surgical manipulation raises the classification to stage 3. Then, postoperative chemotherapy must be more intensive, and abdominal radiotherapy is added. Therefore, intraoperative tumor rupture should be avoided if possible. However, predictive factors for intraoperative tumor rupture have not been sufficiently described. Here we examined the risk factors for intraoperative tumor rupture. METHODS: Patients with Wilms tumor who underwent treatment according to the National Wilms Tumor Study or the Japanese Wilms Tumor Study protocol at our institution were reviewed retrospectively. Collected cases were categorized into two groups: the ruptured group and the non-ruptured group. Risk factors for intraoperative tumor rupture, including the ratio of the tumor area to the abdominal area in a preoperative single horizontal computed tomography slice (T/A ratio), were investigated in both groups. RESULTS: The two groups were not different in age, body weight, tumor laterality, sex, or histological distribution. The T/A ratio in the ruptured group was significantly higher than that in the non-ruptured group. Receiver operating characteristic curve analysis identified a discriminative value for a T/A ratio >0.5. CONCLUSION: The T/A ratio can be a predictive factor for intraoperative tumor rupture of Wilms tumor.