Comparative assessment of the capability of machine learning-based radiomic models for predicting omental metastasis in locally advanced gastric cancer.

The study aims to investigate the predictive capability of machine learning algorithms for omental metastasis in locally advanced gastric cancer (LAGC) and to compare the performance metrics of various machine learning predictive models. A retrospective collection of 478 pathologically confirmed LAGC patients was undertaken, encompassing both clinical features and arterial phase computed tomography images. Radiomic features were extracted using 3D Slicer software. Clinical and radiomic features were further filtered through lasso regression. Selected clinical and radiomic features were used to construct omental metastasis predictive models using support vector machine (SVM), decision tree (DT), random forest (RF), K-nearest neighbors (KNN), and logistic regression (LR). The models' performance metrics included accuracy, area under the curve (AUC) of the receiver operating characteristic curve, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). In the training cohort, the RF predictive model surpassed LR, SVM, DT, and KNN in terms of accuracy, AUC, sensitivity, specificity, PPV, and NPV. Compared to the other four predictive models, the RF model significantly improved PPV. In the test cohort, all five machine learning predictive models exhibited lower PPVs. The DT model demonstrated the most significant variation in performance metrics relative to the other models, with a sensitivity of 0.231 and specificity of 0.990. The LR-based predictive model had the lowest PPV at 0.210, compared to the other four models. In the external validation cohort, the performance metrics of the predictive models were generally consistent with those in the test cohort. The LR-based model for predicting omental metastasis exhibited a lower PPV. Among the machine learning algorithms, the RF predictive model demonstrated higher accuracy and improved PPV relative to LR, SVM, KNN, and DT models.

[Successful Closure of Postpneumonectomy Bronchopleural Fistula with Inserting Technique of Omental Pedicle Flap into the Right Main Bronchus:Report of a Case].

A 67-year-old male was admitted to our hospital for the treatment of pyothorax due to bronchopleural fistula at right main bronchus after pneumonectomy for lung cancer( squamous cell carcinoma, pathological stageⅢB). After tube drainage and fenestration, we performed operation to close large diameter fistula, that was almost fully opened stump of the right main bronchus. Omental flap was sutured roughly to the fistula with four stiches and inserted into the bronchus lumen, and covered with latissimus dorsi muscle flap to fix omental pedicle flap and additionally performed thoracoplasty to close the residual space of the pleural cavity. Fistula at the stump became airtight after operation and pyothorax was cured, so our method was thought to be available to close large diameter bronchopleural fistula with omental pedicle flap.

Microbiota alert: Proteobacteria consume arginine to dampen omental antitumor immunity.

The microbiota can impact antitumor immunity, but whether the microbiota regulates omental antitumor immunity remains elusive. In this issue of Cell Host & Microbe, Meza-Perez et al. demonstrated that Proteobacteria consume arginine to increase Treg cell suppressive capacity and inhibit antitumor immune responses, promoting tumor growth in the omentum.

Cystic lymphangioma of the lesser omentum in an adult patient.

INTRODUCTION: Lymphangiomas belong to the group of benign vascular tumors that originate in the lymphatic tissue. Up to 90% of cases manifest in children before the second year of life. In adults, their presence is very rare. In most cases, they are located in the head, neck and axilla. Intra-abdominal lymphangiomas are very rare and represent less than 1% of all cases. CASE REPORT: The authors present the case of a 64-year-old female patient diagnosed with an intra-abdominal cystic lesion following a routine examination. A CT scan of the abdomen confirmed a cystic lesion located in the lesser omentum between the left lobe of the liver and the lesser curvature of the stomach. The patient was scheduled for laparoscopic exstirpation of the lesion. Histological examination confirmed the clinical diagnosis of cystic lymphangioma of the lesser omentum. CONCLUSION: The etiopathogenesis of lymphangiomas remains unclear. Despite the fact that they are benign tumors, lymphangiomas tend to have an infiltrative pattern of growth, invading surrounding structures. The majority of cases are asymptomatic and the diagnosis is incidental. The gold standard in treatment remains complete surgical extirpation with microscopically negative margins.

Eureka: objective assessment of the empty pelvis syndrome to measure volumetric changes in pelvic dead space following pelvic exenteration.

BACKGROUND: Large tissue defects following pelvic exenteration (PE) fill with fluid and small bowel, leading to the empty pelvis syndrome (EPS). EPS causes a constellation of complications including pelvic sepsis and reduced quality of life. EPS remains poorly defined and cannot be objectively measured. Pathophysiology of EPS is multifactorial, with increased pelvic dead space potentially important. This study aims to describe methodology to objectively measure volumetric changes relating to EPS. METHODS: The true pelvis is defined by the pelvic inlet and outlet. Within the true pelvis there is physiological pelvic dead space (PDS) between the peritoneal reflection and the inlet. This dead space is increased following PE and is defined as the exenteration pelvic dead space (EPD). EPD may be reduced with pelvic filling and the volume of filling is defined as the pelvic filling volume (PFV). PDS, EPD, and PFV were measured intraoperatively using a bladder syringe, and Archimedes' water displacement principle. RESULTS: A patient undergoing total infralevator PE had a PDS of 50 ml. A rectus flap rendered the pelvic outlet watertight. EPD was then measured as 540 ml. Therefore there was a 10.8-fold increase in true pelvis dead space. An omentoplasty was placed into the EPD, displacing 130 ml; therefore, PFV as a percentage of EPD was 24.1%. CONCLUSIONS: This is the first reported quantitative assessment of pathophysiological volumetric changes of pelvic dead space; these measurements may correlate to severity of EPS. PDS, EPD, and PFV should be amendable to assessment based on perioperative cross-sectional imaging, allowing for potential prediction of EPS-related outcomes.

Adipocyte pyroptosis occurs in omental tumor microenvironment and is associated with chemoresistance of ovarian cancer.

BACKGROUND: Ovarian carcinoma (OC) is a fatal malignancy, with most patients experiencing recurrence and resistance to chemotherapy. In contrast to hematogenous metastasizing tumors, ovarian cancer cells disseminate within the peritoneal cavity, especially the omentum. Previously, we reported omental crown-like structure (CLS) number is associated with poor prognosis of advanced-stage OC. CLS that have pathologic features of a dead or dying adipocyte was surrounded by several macrophages is well known a histologic hallmark for inflammatory adipose tissue. In this study, we attempted to clarify the interaction between metastatic ovarian cancer cells and omental CLS, and to formulate a therapeutic strategy for advanced-stage ovarian cancer. METHODS: A three-cell (including OC cells, adipocytes and macrophages) coculture model was established to mimic the omental tumor microenvironment (TME) of ovarian cancer. Caspase-1 activity, ATP and free fatty acids (FFA) levels were detected by commercial kits. An adipocyte organoid model was established to assess macrophages migration and infiltration. In vitro and in vivo experiments were performed for functional assays and therapeutic effect evaluations. Clinical OC tissue samples were collected for immunochemistry stain and statistics analysis. RESULTS: In three-cell coculture model, OC cells-derived IL-6 and IL-8 could induce the occurrence of pyroptosis in omental adipocytes. The pyroptotic adipocytes release ATP to increase macrophage infiltration, release FFA into TME, uptake by OC cells to increase chemoresistance. From OC tumor samples study, we demonstrated patients with high gasdermin D (GSDMD) expression in omental adipocytes is highly correlated with chemoresistance and poor outcome in advanced-stage OC. In animal model, by pyroptosis inhibitor, DSF, effectively retarded tumor growth and prolonged mice survival. CONCLUSIONS: Omental adipocyte pyroptosis may contribute the chemoresistance in advanced stage OC. Omental adipocytes could release FFA and ATP through the GSDMD-mediate pyroptosis to induce chemoresistance and macrophages infiltration resulting the poor prognosis in advanced-stage OC. Inhibition of adipocyte pyroptosis may be a potential therapeutic modality in advanced-stage OC with omentum metastasis.

Omental metastases in patients with pseudomyxoma peritonei or colorectal peritoneal metastases - is routine omentectomy justified?

BACKGROUND: The greater omentum is routinely resected during cytoreductive surgery (CRS), but few studies have analyzed the rationale behind this. This study aimed to assess the prevalence of omental metastases (OM) and the correlation between macroscopically suspected and microscopically confirmed OM, in patients with pseudomyxoma peritonei (PMP) or colorectal peritoneal metastases (PM). METHOD: All patients without previous omentectomy, treated with initial CRS and hyperthermic intraperitoneal chemotherapy for PMP or colorectal PM, at Uppsala University Hospital in 2013-2021, were included. Macroscopic OM in surgical reports was compared with histopathological analyses. RESULTS: In all, 276 patients were included. In those with PMP, 112 (98%) underwent omentectomy and 67 (59%) had macroscopic suspicion of OM. In 5 (4%) patients, the surgeon was uncertain. Histopathology confirmed OM in 81 (72%). In patients with macroscopic suspicion, 96% had confirmed OM (positive predictive value, PPV). In patients with no suspicion, 24% had occult OM (negative predictive value, NPV = 76%). In patients with colorectal PM, 156 (96%) underwent omentectomy and 97 (60%) had macroscopic suspicion. For 5 (3%) patients, the surgeon was uncertain. OM was microscopically confirmed in 90 (58%). PPV was 85% and NPV was 89%. The presence of OM was a univariate risk factor for death in PMP (HR 3.62, 95%CI 1.08-12.1) and colorectal PM (HR 1.67, 95%CI 1.07-2.60), but not in multivariate analyses. CONCLUSION: OM was common and there was a high risk of missing occult OM in both PMP and colorectal PM. These results support the practice of routine omentectomy during CRS.

Establishing an animal model for peritoneal catheter malfunction caused by omental wrapping using negative pressure suction: in vitro and in vivo exploration.

BACKGROUND: This study aims to establish a simplified and effective animal model of catheter malfunction caused by omental wrapped using negative pressure suction. METHOD: The peritoneal dialysis catheter outlet was linked to a negative-pressure (0-75mmHg) suction pump to intensify the negative pressure. Different negative pressures were tested for model construction in vitro. In vivo, a model of peritoneal catheter malfunction caused by omental wrapped was constructed in five beagles after catheter placement. Catheter drainage conditions and related complications were monitored before and after the model establishment. RESULTS: In the vitro experiment, the overall success rate of constructed models was 90% (36/40). The total malfunction rate was higher in 62.5 mmHg (10/10) and 75 mmHg (10/10) than in 12.5 mmHg (8/10) and 37.5 mmHg (8/10). The outflow velocity of dialysate at 62.5 mmHg was significantly lower than that at 12.5 mmHg and 37.5 mmHg, without a statistically significant difference compared to 75 mmHg. In the in vivo experiment, catheter outflow velocity increased, and residual fluid volume decreased after omental wrapped (99.6 ± 6.7 ml/min vs. 32.6 ± 4.6 ml/min at initial five minutes, p < 0.0001; 69.2 ± 16.3 ml vs. 581.0 ± 109.4 ml, p < 0.001). And the outflow velocity was finally below 2 ml/min. No severe related complications (such as infection, organ damage, or bleeding) were observed through laparoscopic examination and dialysate tests seven days post-operation. CONCLUSION: Utilizing negative pressure suction to increase negative pressure around catheter tip is a simple, safe, and effective method for establishing an animal model of omental wrapped leading to catheter malfunction.

Evidence That Peripheral Leptin Resistance in Omental Adipose Tissue and Liver Correlates with MASLD in Humans.

Leptin regulates lipid metabolism, maximizing insulin sensitivity; however, peripheral leptin resistance is not fully understood, and its contribution to metabolic dysfunction-associated steatotic liver disease (MASLD) is unclear. This study evaluated the contribution of the leptin axis to MASLD in humans. Forty-three participants, mostly female (86.04%), who underwent cholecystectomy were biopsied. Of the participants, 24 were healthy controls, 8 had MASLD, and 11 had metabolic dysfunction-associated steatohepatitis (MASH). Clinical and biochemical data and the gene expression of leptin, leptin receptor (LEPR), suppressor of cytokine signaling 3 (SOCS3), sterol regulatory element-binding transcription factor 1 (SREBF1), stearoyl-CoA desaturase-1 (SCD1), and patatin-like phospholipase domain-containing protein 2 (PNPLA2), were determined from liver and adipose tissue. Higher serum leptin and LEPR levels in the omental adipose tissue (OAT) and liver with MASH were found. In the liver, LEPR was positively correlated with leptin expression in adipose tissue, and SOCS3 was correlated with SREBF1-SCD1. In OAT, SOCS3 was correlated with insulin resistance and transaminase enzymes (p < 0.05 for all. In conclusion, we evidenced the correlation between the peripheral leptin resistance axis in OAT-liver crosstalk and the complications of MASLD in humans.

Conditions that promote transcellular neutrophil migration in vivo.

Circulating leukocytes enter tissue either through endothelial junctions (paracellular) or via a pore through the body of endothelial cells (transcellular). We have previously shown that genetically replacing VE-cadherin with a VE-cadherin-α-catenin (VEC-αC) fusion construct-which binds constitutively to actin-obstructs junctions, and blocks leukocyte extravasation in lung, skin and postcapillary venules of cremaster muscle. However, neutrophil recruitment into the inflamed peritoneal cavity was unimpaired. Investigating reasons for this, here, we visualized neutrophil diapedesis by 3D intravital video microscopy in the cremaster muscle and omentum, the major site of neutrophil recruitment into the peritoneal cavity. We found that 80% of neutrophil-extravasation occurred through HEVs in the omentum, which was unimpaired by VEC-αC. In addition, in larger venules (60-85 µm) of both tissues, less than 15% of neutrophils extravasated transcellularly in WT mice. However, in VEC-α-C mice, transcellular diapedesis increased severalfold in the omentum, but not in the cremaster. In line with this, omental venules expressed higher levels of ICAM-1 and atypical chemokine receptor 1. Furthermore, only in the omentum, VEC-αC expression caused reduced elongation of venular endothelium in flow-direction, suggesting different biomechanical properties. Collectively, VEC-αC does not inhibit paracellular transmigration in all types of venules and can modulate the diapedesis route.

Omental Flap Technique in Pancreaticojejunostomy: Does it Prevent Pancreatic Fistula Development after Pancreaticoduodenectomy?

AIM: The aim of our study was to investigate the clinical results of omental flap application during pancreaticojejunostomy (PJ) anastomosis in pancreatoduodenectomy (PD) surgeries. METHODS: The data of patients who underwent pancreaticoduodenectomy in our hospital were evaluated retrospectively. The patients were divided into two groups; patients with an omental flap (Group 1) and those without an omental flap (Group 2). The demographic and other characteristics of the groups and the incidence of postoperative pancreatic fistula (POPF) development were compared. RESULTS: One hundred patients were included (39 females, 61 males) Group 1 consisted of 20 patients with omental flaps and Group 2 consisted of 80 patients without omental flaps. While no clinically significant (Grade B and C) leaks were observed in Group 1, both biochemical and clinically significant leak rates were lower in Group 1 compared to 4 patients (5%) in Group 2. There was no statistically significant difference compared with Group 2 (p > 0.05). CONCLUSIONS: Although not statistically significant in this study, postoperative complication rates and the incidence of POPF tended to decrease in patients who underwent omental flaps.

Proteobacteria impair anti-tumor immunity in the omentum by consuming arginine.

Gut microbiota influence anti-tumor immunity, often by producing immune-modulating metabolites. However, microbes consume a variety of metabolites that may also impact host immune responses. We show that tumors grow unchecked in the omenta of microbe-replete mice due to immunosuppressive Tregs. By contrast, omental tumors in germ-free, neomycin-treated mice or mice colonized with altered Schaedler's flora (ASF) are spontaneously eliminated by CD8+ T cells. These mice lack Proteobacteria capable of arginine catabolism, causing increases in serum arginine that activate the mammalian target of the rapamycin (mTOR) pathway in Tregs to reduce their suppressive capacity. Transfer of the Proteobacteria, Escherichia coli (E. coli), but not a mutant unable to catabolize arginine, to ASF mice reduces arginine levels, restores Treg suppression, and prevents tumor clearance. Supplementary arginine similarly decreases Treg suppressive capacity, increases CD8+ T cell effectiveness, and reduces tumor burden. Thus, microbial consumption of arginine alters anti-tumor immunity, offering potential therapeutic strategies for tumors in visceral adipose tissue.

Laparoscopically treated bowel obstruction secondary to a lesser omental hernia resulting from a previous laparoscopic total colectomy for ulcerative colitis: A report of two cases.

Lesser omental hernias are rare; however, they should be considered in symptomatic bowel obstruction subsequent to a subtotal or total colectomy. This report describes two cases of recurrent bowel obstruction secondary to lesser omental hernias after laparoscopic total colectomies for ulcerative colitis. Initially, these patients had been treated conservatively; however, due to symptom recurrence, surgical intervention was decided on. In both cases, laparoscopic surgery revealed lesser omental hernias. The small bowel, which had entered from the dorsal aspect of the stomach, was returned to the original position, and the lesser omentum was closed. The patients were discharged uneventfully, with no recurrent bowel obstruction during the follow-up period. These cases highlight the importance of including internal hernias in the differential diagnosis relative to recurrent bowel obstruction, in patient subpopulations with a prior history of a subtotal or total colectomy. Confirmation by computed tomography is preferable.

Phase-changing citrate macromolecule combats oxidative pancreatic islet damage, enables islet engraftment and function in the omentum.

Clinical outcomes for total-pancreatectomy followed by intraportal islet autotransplantation (TP-IAT) to treat chronic pancreatitis (CP) are suboptimal due to pancreas inflammation, oxidative stress during islet isolation, and harsh engraftment conditions in the liver's vasculature. We describe a thermoresponsive, antioxidant macromolecule poly(polyethylene glycol citrate-co-N-isopropylacrylamide) (PPCN) to protect islet redox status and function and to enable extrahepatic omentum islet engraftment. PPCN solution transitions from a liquid to a hydrogel at body temperature. Islets entrapped in PPCN and exposed to oxidative stress remain functional and support long-term euglycemia, in contrast to islets entrapped in a plasma-thrombin biologic scaffold. In the nonhuman primate (NHP) omentum, PPCN is well-tolerated and mostly resorbed without fibrosis at 3 months after implantation. In NHPs, autologous omentum islet transplantation using PPCN restores normoglycemia with minimal exogenous insulin requirements for >100 days. This preclinical study supports TP-IAT with PPCN in patients with CP and highlights antioxidant properties as a mechanism for islet function preservation.

Retromesenteric omental flap as arterial coverage in pancreaticoduodenectomy: A novel technique to prevent postpancreatectomy hemorrhage.

BACKGROUND: Clinically relevant postpancreatectomy hemorrhage occurs in 10% to 15% of patients after pancreaticoduodenectomy, mainly in association with clinically relevant postoperative pancreatic fistula. Prevention of postpancreatectomy hemorrhage by arterial coverage with a round ligament plasty or an omental flap is controversial. This study assessed the impact of arterial coverage with an original retromesenteric omental flap on postpancreatectomy hemorrhage after pancreaticoduodenectomy. METHODS: This single-center retrospective study included 812 open pancreaticoduodenectomies (2012-2021) and compared 146 procedures with arterial coverage using retromesenteric omental flap to 666 pancreaticoduodenectomies without arterial coverage. The Fistula Risk Score was calculated. The primary endpoint was a 90-day clinically relevant postpancreatectomy hemorrhage rate according to the International Study Group of Pancreatic Surgery classification. RESULTS: There were more patients with a Fistula Risk Score ≥7 in the arterial coverage-retromesenteric omental flap group: 18 (12%) versus 48 (7%) (P < .01). Clinically relevant postpancreatectomy hemorrhage was less frequent in the arterial coverage- retromesenteric omental flap group than in the no arterial coverage group: 5 (3%) versus 66 (10%), respectively (P = .01). Clinically relevant postoperative pancreatic fistula occurred in 28 (19%) patients in the arterial coverage- retromesenteric omental flap group compared with 165 (25%) in the no arterial coverage group (P = .001). There were fewer reoperations for postpancreatectomy hemorrhage or postoperative pancreatic fistula in the arterial coverage- retromesenteric omental flap group: 1 (0.7%) versus 32 (5%) in the no arterial coverage group (P = .023). In multivariate analysis, arterial coverage with retromesenteric omental flap was an independent protective factor of clinically relevant postpancreatectomy hemorrhage (odds ratio 0.33; 95% confidence interval [0.12-0.92], P = .034) whereas postoperative pancreatic fistula of any grade (odds ratio = 10.1; 95% confidence interval: 5.1-20.3, P < .001) was predictive of this complication. CONCLUSION: Arterial coverage with retromesenteric omental flap can reduce rates of clinically relevant postpancreatectomy hemorrhage after pancreaticoduodenectomy. This easy and costless technique should be prospectively evaluated to confirm these results.

Malignant Extrarenal Rhabdoid tumor derived from the greater omentum: A case report and literature review.

BACKGROUND: Malignant extrarenal rhabdoid tumor (MERT) is a rare and highly metastatic tumor, which is more than 75% of patients dying within 6 months of initial diagnosis, and it often leads to misdiagnosis and delayed treatment. CASE: This paper reports a 16-year-old girl who presented with the chief complaint of acute abdominal pain. She underwent laparoscopic exploration and excisional biopsy, then pathological examination and immunohistochemistry revealed "extrarenal malignant rhabdomyoma." One month after operation, she died of intra-abdominal hemorrhage and multiple organ dysfunction. CONCLUSION: MERT were often misdiagnosed and had a poor prognosis. The surgery and chemotherapy are usually beneficial to prolong the survival time of patients with MERT.

Mediastinal transposition of the greater omentum for treatment of infected prostheses of the ascending aorta and aortic arch.

OBJECTIVES: The aim of this study was to evaluate the outcomes of transposition of the omentum into the mediastinum to support the replacement of infected aortic grafts or to cover infected aortic grafts that are not amenable for surgical replacement. METHODS: All patients with thoracic aortic graft infections who underwent mediastinal transposition of the omentum at our institution between 2005 and 2023 were included in this study. Mediastinal transposition of the omentum was performed either after replacement of the infected graft ('curative concept') or solely as bailout procedure by wrapping the infected graft ('palliative concept'). The diagnosis, including computed tomography scans during follow-up, was made according to the criteria of the Management of Aortic Graft Infection Collaboration. RESULTS: The patient cohort consisted of 31 patients. Both in-hospital and 1-year mortality were 0% (n = 0) for the curative concept (n = 9) compared to 23% (n = 5) and 41% (n = 9) for the palliative concept (n = 22), respectively. There was no graft infection-associated death or recurrence of infection after 3 years in the curative group. Survival was 52% at 3 years in the palliative group, with freedom of infection in 59% of the patients (n = 13). CONCLUSIONS: Transposition of the omentum and wrapping of the infected aortic prosthetic graft is a useful bailout strategy for patients who are ineligible for replacement of an infected aortic graft. However, mortality stays high. For radical treatment of aortic graft infections, it may prove an effective supportive therapy and represents an important tool in the armamentarium of cardiac surgeons.

A human omentum-specific mesothelial-like stromal population inhibits adipogenesis through IGFBP2 secretion.

Adipose tissue plasticity is orchestrated by molecularly and functionally diverse cells within the stromal vascular fraction (SVF). Although several mouse and human adipose SVF cellular subpopulations have by now been identified, we still lack an understanding of the cellular and functional variability of adipose stem and progenitor cell (ASPC) populations across human fat depots. To address this, we performed single-cell and bulk RNA sequencing (RNA-seq) analyses of >30 SVF/Lin- samples across four human adipose depots, revealing two ubiquitous human ASPC (hASPC) subpopulations with distinct proliferative and adipogenic properties but also depot- and BMI-dependent proportions. Furthermore, we identified an omental-specific, high IGFBP2-expressing stromal population that transitions between mesothelial and mesenchymal cell states and inhibits hASPC adipogenesis through IGFBP2 secretion. Our analyses highlight the molecular and cellular uniqueness of different adipose niches, while our discovery of an anti-adipogenic IGFBP2+ omental-specific population provides a new rationale for the biomedically relevant, limited adipogenic capacity of omental hASPCs.

Laparoscopic peritoneal dialysis catheter insertion with omentopexy-sparing the omentum in children.

INTRODUCTION: Continuous ambulatory peritoneal dialysis is an important modality of renal replacement therapy in children. Catheter dysfunction (commonly obstruction) is a major cause of morbidity and is a significant concern that hampers renal replacement therapy. As omentum is a significant cause of obstruction, some recommend routine omentectomy during insertion of the peritoneal dialysis catheter. Omentopexy rather than omentectomy has been described in adults to spare the omentum as it may be needed as a spare part in many conditions. Laparoscopic approach is commonly preferred as it provides global evaluation of the peritoneal space, proper location of the catheteral end in the pelvis and lesser morbidity due to inherent minimally invasive nature. AIM: The aim of this study is to present the technique of laparoscopic peritoneal dialysis catheter placement in children with concurrent omentopexy. METHODS: We retrospectively evaluated our patients who underwent laparoscopic placement of peritoneal dialysis catheter with concomitant omentopexy or omentectomy. RESULTS: A total of 30 patients were enrolled who received either omentectomy (n = 18) or omentopexy (n = 12). Four catheters were lost in the omentopexy group (33%) and 3 in the omentectomy group (17%), but none were related to omental obstruction. Three out of 4 patients in the omentopexy group and 2 out of 3 patients in the omentectomy group had a previous abdominal operation as a potential cause of catheter loss. Previous history of abdominal surgery was present in 6 patients (50%) in the omentopexy group and 3 patients (17%) in the omentectomy group. CONCLUSIONS: As omentum was associated with catheter failure, omentectomy is commonly recommended. Alternatively, omentopexy can be preferred in children to spare an organ that may potentially be necessary for many surgical reconstructive procedures in the future. Laparoscopic peritoneal dialysis catheter placement with concomitant omentopexy appears as a feasable and reproducible technique. Although the catheter loss seems to be higher in the omentopexy group, none was related with the omentopexy procedure and may be related to the higher rate of history of previous abdominal operations in this group.

Primary segmental omental torsion, mimicking acute appendicitis.

Primary segmental omental torsion (PSOT) is a very rare cause of acute abdominal pain, and it may often imitate the clinical picture of acute appendicitis. In instances of acute abdominal pain without anorexia, nausea, and vomiting, omental torsion should be included in the differential diagnosis. Any misdiagnosis may lead to major complications such as intraabdominal abscesses and adhesions. A 63-year-old overweight man with a body mass index (BMI) of 41 Kg/m2 presented to the emergency department on a remote island with acute abdominal pain. His medical history included type 2 diabetes mellitus managed with insulin, essential hypertension, osteoarthritis, and no previous abdominal operations. He reported a sharp pain originating in the epigastrium and the right hypochondrium that started five days prior. Physical examination revealed rebound tenderness and guarding across the abdomen with a positive McBurney sign. However, the patient did not report vomiting and was not nauseous. Vital signs were as follows: blood pressure 116/56 mmHg, heart rate 98 beats/min, respiratory rate 19 breaths/min, and a temperature of 38.2 0C. Laboratory results showed a white blood cell count of 10.6, neutrophils of 8.11, C-reactive protein (CRP) 74 mg/l, haemoglobin11.6 g/dl, and hematocrit 36.9%. Due to the absence of a radiographer at the hospital during that period, no imaging investigations were conducted. Diagnostic laparoscopy demonstrated diffused hemoperitoneum and necrotic mass at the site of the hepatic flexure. Initially suspected to be an advanced colon cancer, the decision was made to proceed with open surgery. The necrotic segment of the omentum was found at the right superior point of attachment of the omentum to the hepatic flexure. Consequently, the necrotic segment of the omentum was resected. A thorough investigation of the abdominal cavity did not detect any other abnormalities or pathologies. The patient recovered uneventfully and was transferred to the surgical ward. Torsion of the omentum is a very rare cause of acute abdominal pain. This case highlights the necessity of considering PSOT in the differential diagnosis of acute abdominal pain, especially in cases where symptoms are suggestive of appendicitis but diagnostic findings are negative.