Spleen stiffness by 2-D shear wave elastography is the most accurate predictor of high-risk esophagogastric varices in children with biliary atresia.

AIM: Esophagogastric variceal hemorrhage is a cause of poor prognosis in patients with biliary atresia (BA). To prevent variceal hemorrhage, simple and reliable screening methods for high-risk esophagogastric varices (HR-EGV) are needed. We evaluated the efficacy of liver stiffness (LS) and spleen stiffness (SS) as measured by 2-D shear wave elastography (2D-SWE), which was reported to be more accurate than transient elastography, for detecting HR-EGV in children with BA. METHODS: Thirty-four children with BA were enrolled. Both LS and SS were measured by 2D-SWE. The presence of large esophageal varices or esophageal varices of any size with red wale marking and/or the presence of gastric varices along the cardia were defined as HR-EGV. Clinical data were collected and previously reported prediction indices for varices were calculated. RESULTS: Liver stiffness and SS were obtained from all patients. Fourteen patients showed HR-EGV. Significantly different variables between patients with and without HR-EGV were as follows: spleen diameter (116 mm vs. 95 mm), clinical prediction rule (104.7 vs. 124.7), King's variceal prediction score (78.8 vs. 99.4), aspartic aminotransferase-to-platelet ratio index (2.03 vs. 0.98), LS (2.63 m/s vs. 1.87 m/s), and SS (4.44 m/s vs. 3.69 m/s). The highest area under the receiver operating characteristic curve for detecting HR-EGV was that for SS (0.900), and the cut-off SS of 4.12 m/s yielded 92.9% sensitivity and 90% specificity. The intraclass correlation coefficient for intra-observer reproducibility was 0.828. CONCLUSIONS: Spleen stiffness from 2D-SWE offered the most accurate predictor of HR-EGV in BA children.

Efficacy of and prognosis after steroid pulse therapy in patients with poor reduction of jaundice after laparoscopic Kasai portoenterostomy.

PURPOSE: High-dose postoperative steroid therapy after Kasai portoenterostomy is reported to improve jaundice clearance and a strong anti-inflammatory activity might prevent fibrous tissue formation which is often observed at the porta hepatis in revision surgery. We started steroid pulse therapy for the patients with cessation of decrease in jaundice and aimed to evaluate the efficacy in this study. METHODS: The demographics and outcomes of patients who underwent laparoscopic Kasai portoenterostomy and received steroid pulse therapy within 2 months postoperatively between September 2014 and December 2018 were retrospectively reviewed; the therapy was determined successful when the serum total bilirubin level decreased to or below two-thirds of the pre-therapy level after 2 weeks. Patient data in the successful group were compared with those in the unsuccessful group. RESULTS: Steroid pulse therapy was successful in seven of 16 patients (43.8%). The percentage of patients whose serum total bilirubin level decreased to normal was significantly higher in the successful group at 3 months (85.7% vs. 11.1%, P = 0.0028) and after all (100% vs. 33.3%, P = 0.011). CONCLUSIONS: Steroid pulse therapy was effective for some patients. Unsuccessful cases may have little chances of jaundice clearance; revision Kasai portoenterostomy would be a good option.

Usefulness of fetal magnetic resonance imaging for postnatal management of congenital lung cysts: prediction of probability for emergency surgery.

BACKGROUND: Emergency rescue lung resection is rarely performed to treat congenital lung cysts (CLCs) in neonates. Many reports have described fetal CLC treatment; however, prenatal predictors for postnatal respiratory failure have not been characterized. We hypothesized that fetal imaging findings are useful predictors of emergency surgery. METHODS: We retrospectively studied patients with CLC who underwent lung surgery during the neonatal period in our hospital between January 2001 and December 2015. The demographic data, fetal imaging findings, and intra- and postoperative courses of patients who underwent emergency surgery (Em group) were compared with those of patients who received elective surgery, i.e., non-emergency surgery (Ne group). RESULTS: The Em group and Ne group included 7 and 11 patients, respectively. No significant difference was noted in gestational age, time at prenatal diagnosis, birth weight, and body weight at surgery. The volumes of contralateral lung per thoracic volume were significantly smaller in the Em group than in the Ne group (p = 0.0188). Mediastinal compression was more common in the Em group (7/7) than in the Ne group (4/11) (p = 0.0128). CONCLUSIONS: This is the report describing neonatal emergency lobectomy in patients with CLC evaluated by fetal MRI using the lung volume ratio and mediastinal shift. In patients with CLC, mediastinal shift and significant decreases in contralateral lung volumes during the fetal stages are good prenatal predictors of postnatal emergency lung resection.

Introduction of resection of intrahepatic bile duct stenosis-causing membrane or septum into laparoscopic choledochal cyst excision.

PURPOSE: We previously showed that meticulous probing and resection of the intrahepatic bile duct stenosis (IHBDS)-causing membrane or septum was effective in preventing hepatolithiasis after choledochal cyst excisions in open surgeries. Then, we introduced this maneuver into laparoscopic choledochal cyst excisions in 2014 and performed routine resections since then. The aim of this study was to show the feasibility of this method in laparoscopic surgery. METHODS: We retrospectively reviewed the demographics and outcomes of patients who underwent laparoscopic choledochal cyst excisions at our hospital between January 2014 and December 2017. The patients who underwent surgical treatment for IHBDS-causing membrane or septum were compared with those who did not undergo the procedure. The outcomes of the patients with IHBDS were also compared between patients who were ≥ 3 years of age and those < 3 years at operation. RESULTS: Seventeen of 35 patients underwent laparoscopic resection of IHBDS-causing membrane or septum. There were no complications related to the procedure although the operative time and intraoperative bleeding amount increased in the patients with IHBDS who were ≥ 3 years of age. CONCLUSIONS: Meticulous probing and excision of the IHBDS-causing membrane or septum is safe and feasible during laparoscopic choledochal cyst excision.

Long-term outcomes and complications after laparoscopic-assisted anorectoplasty vs. posterior sagittal anorectoplasty for high- and intermediate-type anorectal malformation.

PURPOSE: Laparoscopic-assisted anorectoplasty (LAARP) is a minimally invasive procedure in which the levator ani muscle is left to potentially improve postoperative fecal continence. This study aimed to retrospectively evaluate postoperative complications and long-term outcomes of fecal continence after LAARP and compare them to those after posterior sagittal anorectoplasty (PSARP). METHODS: Forty-five male patients with high and intermediate anorectal malformation (aged ≥ 4 years) who underwent LAARP or PSARP (LAARP 29, PSARP 16) from 1999 to 2013 were included. Postoperative complications and postoperative fecal continence were retrospectively evaluated and compared. Postoperative complications were also compared before and after introducing a urethroscope during fistula resection. RESULTS: Complications after LAARP and PSARP were seen in 12 vs. 2 cases (p = 0.09) of mucosal prolapse and in 9 vs. 1 case (p = 0.07) of posterior urethral diverticulum (PUD), respectively. The incidence of PUD decreased after introduction of a urethroscopy from 40% in 8/20 cases to 11% in 1/9 cases. No significant difference was found in terms of fecal continence in both groups. CONCLUSION: Through our study, greater improvement of postoperative fecal continence after LAARP has not been shown. LAARP was at higher risk for mucosal prolapse and PUD. However, precise dissection of the urethral fistula could be performed after the introduction of urethroscopy.

Investigation of the feasibility and safety of single-stage anorectoplasty in neonates with anovestibular fistula.

PURPOSE: Anovestibular fistula (AVF) is the most common type of anorectal malformation in females. Delayed anorectoplasty with fistula dilatation is commonly performed during infancy; however, we have been actively performing anorectoplasty in neonates. We report the surgical complications and postoperative defecation function associated with single-stage anorectoplasty performed in neonates. METHODS: Patients who underwent surgery for AVF between 2007 and 2017 at two institutions were retrospectively studied. The operation time, amount of bleeding, time to start oral intake, perioperative complications, and Kelly's score were compared among patients who underwent surgery as neonates and those who underwent surgery as infants. RESULTS: Eighteen neonates and 17 infants underwent anterior sagittal anorectoplasty. The median operation time and time to start oral intake were significantly shorter in the neonatal group (72 min; 3 days, respectively) than in the infant group (110 min, p = 0.0002; 5 days, p = 0.0024, respectively). Postoperative wound disruption was significantly more frequent in the infant group. Of the ten patients each in the neonatal and infant groups, there was no significant difference in Kelly's score at age ≥ 4 years. CONCLUSION: Single-stage anorectoplasty in neonates with AVF can be feasibly performed and does not impair postoperative defecation function. LEVELS OF EVIDENCE: III.

Single-stage laparoscopic transanal pull-through modified Swenson procedure without leaving a muscular cuff for short- and long-type Hirschsprung disease: a comparative study.

PURPOSE: The Soave procedure (SO) is performed most commonly for Hirschsprung disease. SO reduces the risk of injury to the pelvic structures; however, a residual aganglionic muscle cuff could interfere with bowel movement and lead to obstructive enterocolitis. The Swenson procedure is considered ideal in terms of peristalsis. Currently, laparoscopic surgery provides better visualization and facilitates precise dissection, possibly leading to feasible performance of the laparoscopic modified Swenson procedure (SW). We present our operative technique and the efficacy of the SW compared with that of SO. METHODS: We retrospectively reviewed the records of 16 and 27 patients who underwent SW and SO, respectively, between 2012 and 2017. RESULTS: Operative time, blood loss, length of stay, and frequency of bowel movements showed no significant difference between the two groups. In the SW group, temporary dysuria occurred in one patient, postoperative enterocolitis in two, wound infection in one, and severe perianal excoriation in four, whereas in the SO group, obstructive symptoms occurred in three patients, small-bowel obstruction in one, and severe perianal excoriation in three. The complications and outcomes were comparable between both groups. CONCLUSION: Laparoscopic SW was safe and feasible for the short-term follow-up outcomes.

Oral administration of eicosapentaenoic acid suppresses liver fibrosis in postoperative patients with biliary atresia.

PURPOSE: Biliary atresia (BA) is characterized by progressive inflammation of the biliary system. This inflammation persists and causes liver fibrosis, although jaundice disappears after Kasai portoenterostomy (KP). We aimed to confirm whether the oral administration of eicosapentaenoic acid (EPA) suppresses liver fibrosis in postoperative patients with BA. METHODS: We reviewed patients who underwent laparoscopic KP (lapKP) between January 2014 and September 2017. From December 2016, 30 mg/kg/day of EPA was orally administered to patients who opted to take medicine (EPA group). Patients who did not receive EPA were assigned to the non-EPA group. Mac-2 binding protein sugar chain modified isomer (M2BPGi) and hyaluronic acid (HA) levels were compared between the two groups in patients showing disappearance of jaundice at 6 months after the first lapKP. RESULTS: Seventeen patients in the non-EPA group and 11 in the EPA group were enrolled. At 6 months after the first lapKP, 10 patients in the non-EPA group and six in the EPA group were without jaundice. M2BPGi and HA levels were significantly lower in the EPA group. CONCLUSIONS: Liver fibrosis was suppressed in patients without jaundice 6 months after lapKP, who were administered EPA. We believe that periductular inflammation was alleviated by EPA supplementation.

Independent Risk Factors and 2-Year Outcomes of Acute Kidney Injury after Surgery for Congenital Heart Disease.

BACKGROUND: Data are limited regarding risk factors for acute kidney injury (AKI) following cardiac surgery in children with congenital heart disease (CHD). This observational study was performed to examine temporal trends in AKI incidence according to the Pediatric Risk, Injury, Failure, Loss, End-Stage Renal Disease (pRIFLE) criteria, identify independent risk factors for AKI after cardiac surgery, and examine associations between AKI and long-term mortality. METHODS: We retrospectively evaluated 418 patients (259 males, 159 females; median age, 5 months) who underwent cardiac surgery for CHD between April 2007 and August 2013. Patients were followed up for 2 years. AKI was defined according to the pRIFLE criteria as ≥25% decrease in estimated creatinine clearance. RESULTS: AKI developed postoperatively in 104 cases (24.9%). Approximately 80% belonged to the "Risk" category according to the pRIFLE criteria, and only 21 cases (5%) required renal replacement therapy (peritoneal dialysis in all cases). Multivariate analysis revealed 3 independent risk factors for onset of AKI: young age (<1 year), surgery in Risk Adjustment in Congenital Heart Surgery (RACHS-1) category ≥4, and long cardiopulmonary bypass (CPB) time (≥90 min). Twenty-three patients (22%) with AKI died during the 2-year follow-up. In multivariate cox hazard regression analysis, the most significant contributor to risk of mortality was AKI. CONCLUSIONS: Postoperative AKI was strongly associated with young age, high RACHS-1 category, and prolonged CPB time. In addition, mortality rate was higher in patients who survived after recovery from AKI than in those without AKI, even among the lower pRIFLE categories.

Laparoscopic resection of neuroblastomas in low- to high-risk patients without image-defined risk factors is safe and feasible.

BACKGROUND: Several studies have reported that minimally invasive surgery (MIS) might be considered for resecting neuroblastomas without image-defined risk factors (IDRFs); however, there are no studies comparing the outcomes of laparotomy and laparoscopy in IDRF-negative patients. Thus, we investigated the feasibility of laparoscopic surgery and compared the two abovementioned approaches. METHODS: To compare the effects of laparotomy with those of laparoscopy in patients with neuroblastomas without IDRFs, the following items were retrospectively compared: largest tumor dimension, volume of blood loss, time required to initiate postoperative feeding, locoregional recurrence rate, survival, etc. RESULTS: Nine patients without IDRFs (three at low-to-medium risk and six at high risk) underwent laparotomy, and seven patients without IDRFs (two at low-to-medium risk and five at high risk) underwent laparoscopy. Median duration of surgery was 221 (130-304) and 172 (122-253) min in the laparotomy and laparoscopy groups, respectively, showing no significant difference. Median postoperative time required for resuming meal consumption was significantly longer in the laparotomy (4 days; 2-5) group than that in the laparoscopy group (3 days; 2-3; p = 0.023). Median blood loss was significantly higher in the laparotomy group (5 ml/Kg;2.6-16) than that in the laparoscopy group (2.1 ml/Kg;0.1-4.0; P = 0.037). Median follow-up period was 81 (52-94) and 21 (17-28) months, locoregional recurrence rates were 22 and 0% at 1 year, 1-year progression-free survival rates were 78 and 100%, and overall survival rates were 67 and 100% in the laparotomy and laparoscopy groups, respectively, with no significant differences. CONCLUSIONS: MIS for the treatment of neuroblastomas without IDRFs in low- to high-risk patients is safe and feasible and does not compromise the treatment outcome.

Oral alendronate in pediatric chronic recurrent multifocal osteomyelitis.

Chronic recurrent multifocal osteomyelitis (CRMO) primarily affects children and adolescents, and is characterized by episodic sterile osteomyelitis over several years. No definitive treatment is available. Non-steroidal anti-inflammatory drugs (NSAID) are common first-line agents, but provide limited improvement in bone pain and do not affect disease duration. Several agents are utilized in the case of non-response to NSAID, including corticosteroids, methotrexate, and tumor necrosis factor-blocking agents. Bisphosphonates are increasingly being used. Most case series involve cyclic i.v. pamidronate, but this restricts the social lives of children and their families. Although oral medication has advantages over cyclic i.v. infusion because it does not require repeated hospital admissions, there have been no reports on treatment with oral bisphosphonates, such as alendronate, in pediatric CRMO patients. This case report describes the use of oral bisphosphonate as an alternative treatment in CRMO patients in whom standard therapy has failed.

Affinity Labeling with 4-Azidophthalimide (AzPI): Relation between Labeling Rate and Fluorescence Intensity.

We recently developed 4-azidophthalimide (AzPI) as a compact fluorogenic photoreactive tag that can be attached to ligands to achieve selective fluorescence labeling of target proteins even in the presence of a large excess of non-target proteins. To further establish the utility of the AzPI tag, we focused here on streptavidin labeling with biotin-AzPI conjugates, and evaluated the relation between the amount of covalently labeled streptavidin (labeling rate) and fluorescence intensity. The labeling rate was proportional to the fluorescence intensity under standardized photo-irradiation conditions. Prolongation of the photo-irradiation time led to a marked increase in the labeling rate, but this was accompanied by a gradual decrease in the fluorescence intensity, which appeared to be due at least in part to photo-induced degradation of the target streptavidin. These findings should be helpful for achieving sensitive fluorescence detection of target proteins by using the AzPI tag.

Comparison of outcomes of thoracoscopic primary repair of gross type C esophageal atresia performed by qualified and non-qualified surgeons.

PURPOSE: Although thoracoscopic repair of esophageal atresia has become widespread, most studies are based on operations performed by expert surgeons. Therefore, the outcomes of operations performed by non-expert surgeons are not well known. The aim of this study was to compare outcomes based on operator skill level. METHODS: We retrospectively reviewed the demographics and outcomes of patients with Gross type C esophageal atresia, who underwent primary thoracoscopic repair at our hospital between January 2014 and August 2016. Outcomes of surgeries performed by qualified surgeons, as determined by the Japanese Society for Endoscopic Surgery were compared with those of non-qualified surgeons. All operations were performed by or under the supervision of one qualified surgeon. RESULTS: Nine operations were performed by qualified surgeons and six operations by non-qualified surgeons with >10 years of experience in surgery. None of the patients developed anastomotic leakage or recurrent tracheoesophageal fistula. However, the operative time and rate of stricture formation at the beginning of the weaning period were significantly higher in the latter group (P = 0.008 and 0.044). CONCLUSIONS: Although supervision of experts would improve results in thoracoscopic repair of esophageal atresia, the results indicate that good skill is necessary to avoid anastomotic stricture.

Left thoracoscopic two-stage repair of tracheoesophageal fistula with a right aortic arch and a vascular ring.

A right aortic arch (RAA) is found in 5% of neonates with tracheoesophageal fistulae (TEF) and may be associated with vascular rings. Oesophageal repairs for TEF with an RAA via the right chest often pose surgical difficulties. We report for the first time in the world a successful two-stage repair by left-sided thoracoscope for TEF with an RAA and a vascular ring. We switched from right to left thoracoscopy after finding an RAA. A proximal oesophageal pouch was hemmed into the vascular ring; therefore, we selected a two-stage repair. The TEF was resected and simple internal traction was placed into the oesophagus at the first stage. Detailed examination showed the patent ductus arteriosus (PDA) completing a vascular ring. The subsequent primary oesophago-oesophagostomy and dissection of PDA was performed by left-sided thoracoscope. Therefore, left thoracoscopic repair is safe and feasible for treating TEF with an RAA and a vascular ring.

Comparing surgical outcomes of complete thoracoscopic lobectomy for congenital cystic lung disease between neonatal and infantile patients.

Thoracoscopic lobectomy has recently become a widely used surgical treatment for congenital cystic lung disease, but significant issues can arise in some cases, such as a limited working space in neonates, a limited view in cases involving large cystic lesions. We reviewed the treatment outcomes of neonates that underwent complete thoracoscopic lobectomy or segmentectomy and evaluated the operative difficulties. From January 2008 to October 2015, 38 patients under the age of 1 year underwent complete thoracoscopic lobectomy or segmentectomy for cystic lung disease at our institution. We compared the intra- and postoperative data of the neonate group (N group) with those of the infant group (I group). Fourteen and 24 patients underwent thoracoscopic lobectomy or segmentectomy in the N group and I group, respectively. The operative time and amount of intraoperative blood loss did not differ significantly between the two groups (p=0.694 and p=0.878, respectively), but the duration of the postoperative hospitalization period was significantly longer (p<0.01) in the N group. The frequencies of postoperative complications did not differ significantly between the two groups. The operative time of thoracoscopic lobectomy was significantly longer in cases involving incomplete lobar fissures than in those involving normal lobar fissures. Surgical outcomes of complete thoracoscopic lobectomy for neonatal cases are almost equivalent compared with infantile cases, and thoracoscopic lobectomy takes longer in cases involving incomplete lobar fissures.

Dichloromaleimide (diCMI): A Small and Fluorogenic Reactive Group for Use in Affinity Labeling.

Chemical probes comprising a ligand moiety, a reactive group (e.g. epoxide, haloacetyl or photoreactive group) and a tag unit (e.g. fluorophore or radioisotope) are widely used in affinity labeling to identify the target proteins of bioactive molecules. However, design and synthesis of highly functionalized chemical probes are often time-consuming. In this paper, we propose a simple design strategy for chemical probes bearing a small 2,3-dichloromaleimide (diCMI) unit, which serves as a combined reactive group and tag unit by reacting with a nucleophilic lysine residue near the ligand-binding site of the target protein to generate the 2-amino-3-chloromaleimide fluorophore. Model ligand-protein experiments confirmed that the diCMI unit has suitable reactivity and fluorogenic capability for efficient affinity labeling.

Steroid pulse therapy prevents restenosis following balloon dilatation for esophageal stricture.

PURPOSE: This study aimed to evaluate the effectiveness of intravenous steroid pulse therapy following balloon dilatation for esophageal stenosis and stricture in children. METHODS: The study enrolled six children, including three with congenital esophageal stenosis and three with anastomotic strictures after surgery for esophageal atresia, all of whom were treated by balloon dilatation combined with high-dose intravenous methylprednisolone pulse therapy. Methylprednisolone was injected intravenously at a dose of 20 mg/kg/day for 2 days, starting from the day of dilatation, followed by 10 mg/kg/day for 2 days, for a total of 4 days. RESULTS: Esophageal stricture recurred in all three patients with congenital esophageal stenosis despite repeated balloon dilatation without methylprednisolone. However, the symptoms of dysphagia improved and did not recur after systemic steroid pulse therapy following balloon dilatation. Symptoms also resolved in all three patients with anastomotic strictures following balloon dilatation with systemic steroid pulse therapy. All six patients remained asymptomatic after 6-21 months follow-up, with no complications. CONCLUSION: Intravenous methylprednisolone pulse therapy following balloon dilatation is safe and effective for the treatment of esophageal stenosis and strictures in children.

Development of 8-17 XNAzymes that are functional in cells.

DNA enzymes (DNAzymes), which cleave target RNA with high specificity, have been widely investigated as potential oligonucleotide-based therapeutics. Recently, xeno-nucleic acid (XNA)-modified DNAzymes (XNAzymes), exhibiting cleavage activity in cultured cells, have been developed. However, a versatile approach to modify XNAzymes that function in cells has not yet been established. Here, we report an X-ray crystal structure-based approach to modify 8-17 DNAzymes; this approach enables us to effectively locate suitable XNAs to modify. Our approach, combined with a modification strategy used in designing antisense oligonucleotides, rationally designed 8-17 XNAzyme ("X8-17") that achieved high potency in terms of RNA cleavage and biostability against nucleases. X8-17, modified with 2'-O-methyl RNA, locked nucleic acid and phosphorothioate, successfully induced endogenous MALAT-1 and SRB1 RNA knockdown in cells. This approach may help in developing XNAzyme-based novel therapeutic agents.

Effect of Side Chain Functional Groups on the DPPH Radical Scavenging Activity of Bisabolane-Type Phenols.

Methods for improving the antioxidant activity of phenolic compounds have been widely investigated; however, most studies have focused on the structure⁻activity correlations of substituents on the aromatic rings of catechols or flavonoids. We investigated the influence of side chain functional groups on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of xanthorrhizol and curcuphenol analogues. These compounds were synthesised by the side chain functional group conversion of curcumene, followed by direct oxidation of the aromatic ring. We determined the DPPH radical scavenging activity from the half-maximal effective concentration (EC50) obtained from a DPPH assay in methanol. The positional relationships of the side chain with the aromatic ring and phenolic OH group were determined using density functional theory calculations, and the stability of different conformations was compared. Electron transfer-proton transfer was determined to be the dominant mechanism in the DPPH reaction with xanthorrhizol analogues, based on the correlation between the EC50 and ionisation potential. The radical cation was greatly stabilised in the structure where the side chain functional group was close to the aromatic ring. Stabilisation also depended on the phenolic OH group position. In future antioxidant design, aromatic ring substituent conversion and the use of functional groups far from the OH group or ring should be explored.

A Novel Laparoscopic Surgery Model with a Device to Expand the Abdominal Working Space in Rats: The Influence of Pneumoperitoneum and Skin Incision Length on Postoperative Inflammatory Cytokines.

PURPOSE: Experimental models of laparoscopic surgery generally use large animals owing to a sufficient abdominal working space. We developed a novel laparoscopic surgery model in rats. We performed intestinal anastomosis to demonstrate the feasibility and reliability of this model. MATERIALS AND METHODS: We designed a device for rats that expanded the abdominal working space and allowed us to manipulate the intraperitoneal organs by hand under direct vision with pneumoperitoneum. We performed small bowel resection and intestinal anastomosis in rats using this model. To elucidate the effects of pneumoperitoneum and skin incision length, rats were randomly divided into four groups with differing surgical techniques: small incision group, large incision group, small incision + pneumoperitoneum group, and large incision + pneumoperitoneum group. Intraoperative abdominal pressure and postoperative cytokines were measured. RESULTS: One experimenter completed small bowel resection and hand-sewn anastomosis under direct vision without any difficulties or assistance. Carbon dioxide pneumoperitoneum was maintained at 8-10 mmHg during surgery in both pneumoperitoneum groups. Necropsies revealed no evidence of anastomotic leakage at 24 h after surgery. The interleukin-6 and C-reactive protein concentrations were significantly greater in large incision group than in small incision group, but were not significantly different between small incision + pneumoperitoneum group and small incision group. These cytokines concentrations were the greatest in large incision + pneumoperitoneum group. CONCLUSIONS: Our laparoscopic surgery model in rats is a simple and reliable experimental model. The length of skin incision might be a more influential determinant of surgical invasiveness than pneumoperitoneum.