Application of 3-Dimensional Printing in Pediatric Living Donor Liver Transplantation: A Single-Center Experience.

Three-dimensional (3D) printing has been used to support organ transplantations. However, whether it helps remains unclear. This study aimed to present and assess the application of 3D-printed liver models in pediatric living donor liver transplantation (LDLT). The 3D images were printed to touchable liver models with transparent liver parenchyma, specifically colored hepatic vessels, and biliary structures. A total of 30 consecutive recipients were enrolled in the study: 10 were operated on with the support of 3D printing (3D-printing group) and 20 (control group) were operated on without it. Detailed photographs and data of the cases in the 3D-printing group were presented. One patient underwent auxiliary partial orthotopic liver transplantation using the left lobe graft, in which the abdominal cavity model was also printed to test whether the planned graft fit the recipient's abdominal cavity. The 3D-printed models facilitated surgical planning and procedures, particularly in the management of hepatic veins and in the prevention of large-for-size syndrome. The operative time of donors in the 3D-printing group was significantly shorter compared with the control group (2.3 ± 0.4 versus 3.0 ± 0.4 hours; P < 0.001). Inpatient costs for donors in the 3D-printing group were 17.1% lower than those in the control group (34.6 ± 6.6 versus 41.7 ± 10.4 thousand ¥; P = 0.03). In conclusion, in small infants and complicated pediatric LDLT patients, 3D-printed models can help minimize the risk of large-for-size syndrome and graft reduction. The 3D-printed models may be conducive to liver graft procurement and intraoperative assistance in pediatric LDLT.

Comparative Anatomy of the Ovine and Female Pelvis.

BACKGROUND: Pelvic organ prolapse affects half of vaginally parous women. Several animal models are used to study its pathophysiology and treatment. Sheep are interesting because they develop spontaneously prolapse with similar risk factors as women and can be used for vaginal surgery. This study describes ovine pelvis anatomy and compares it to women's pelvis to provide anatomical tools for translational researchers. METHODS: MRI, pelvic dissections, and histology were used for detailed macro- and microscopic analysis of relevant anatomical structures in 6 nulliparous ewes. RESULTS: Although sheep are quadrupeds, the gross and microscopic anatomies are similar to the female pelvis. Principal differences are the shape and its orientation, the absence of the sacrospinous ligament and the internal obturator. The levator ani (except for the puborectalis) and the coccygeus muscle are present, yet the latter is more developed - coinciding with the tail. The dimensions and morphology of the ovine vagina is comparable. The retropubic and the rectovaginal space are accessible transvaginally. There is a wide expression of estrogen receptors with low or absent immunoreactivity in the urethral epithelium, bladder, anus and internal anal sphincter. CONCLUSION: The ovine pelvic floor has many anatomical and ultrastructural similarities to the female pelvic floor.

Normal computed tomographic features and reference values for the coelomic cavity in pet parrots.

BACKGROUND: The increasing popularity gained by pet birds over recent decades has highlighted the role of avian medicine and surgery in the global veterinary scenario; such a need for speciality avian medical practice reflects the rising expectation for high-standard diagnostic imaging procedures. The aim of this study is to provide an atlas of matched anatomical cross-sections and contrast-enhanced CT images of the coelomic cavity in three highly diffused psittacine species. RESULTS: Contrast-enhanced computed tomographic studies of the coelomic cavity were performed in 5 blue-and-gold macaws, 4 African grey parrots and 6 monk parakeets by means of a 4-multidetector-row CT scanner. Both pre- and post-contrast scans were acquired. Anatomical reference cross-sections were obtained from 5 blue-and-gold macaw, 7 African grey parrot, and 9 monk parakeet cadavers. The specimens were stored in a -20 °C freezer until completely frozen and then sliced at 5-mm intervals by means of a band saw. All the slices were photographed on both sides. Individual anatomical structures were identified by means of the available literature. Pre- and post-contrast attenuation reference values for the main coelomic organs are reported in Hounsfield units (HU). CONCLUSIONS: The results provide an atlas of matched anatomical cross-sections and contrast-enhanced CT images of the coelomic cavity in three highly diffused psittacine species.

Intraabdominal microdialysis - methodological challenges.

Microdialysis is used for in vivo sampling of extracellular molecules. The technique provides a continuous and dynamic view of concentrations of both endogenous released and exogenous administered substances. Microdialysis carries a low risk of complications and has proven to be a safe procedure in humans. The technique has been applied in several clinical areas, including gastrointestinal surgery. Microdialysis may be used for studies of tissue metabolism, and the technique is also a promising tool for pharmacological studies of drug penetration into abdominal organ tissue and the peritoneal cavity. The clinical significance of intraabdominal microdialysis in postoperative monitoring of surgical patients has yet to be proven. In this review, we introduce the microdialysis technique, and we present an overview of theoretical and practical considerations that should be taken into account when using microdialysis in intraabdominal clinical research.

Apparent Diffusion Coefficient of Normal Abdominal Organs and Bone Marrow From Whole-Body DWI at 1.5 T: The Effect of Sex and Age.

OBJECTIVE: The objectives of this study were to define the range of apparent diffusion coefficients (ADCs) from whole-body DWI in normal abdominal organs and bone marrow, to identify ADC differences between sexes and changes occurring with age, and to evaluate the effect of the fat fraction (FF) on the ADC of normal liver parenchyma and bone marrow. MATERIALS AND METHODS: Fifty-one healthy volunteers (mean age = 38 years; age range = 23-68 years) underwent whole-body DWI using single-shot echo-planar imaging (b = 0, 150, 400, 750, and 1000 s/mm(2)). A two-point Dixon technique was used to evaluate the FF. Perfusion-sensitive ADCs, which we refer to as "ADCALL," and perfusion-insensitive ADCs, which we refer to as "ADCHIGH," of the liver and renal parenchyma, spleen, pancreatic tail, and red and yellow bone marrow were calculated. The relationships between ADC and sex, age, and FF were examined. RESULTS: ADCALL and ADCHIGH were significantly higher in female volunteers for the pancreatic tail (p = 0.046 and 0.008, respectively), red bone marrow (p = 0.029 and 0.001), and yellow bone marrow (p < 0.001 for both) but with considerable overlap. There were significant negative correlations between ADCALL and ADCHIGH and age in the liver parenchyma (p = 0.008 and 0.01, respectively) and in the yellow bone marrow (p = 0.013 and 0.039) for all subjects. ADCALL and ADCHIGH were also negatively correlated with FF in the liver parenchyma (p = 0.006 and 0.008, respectively) and in yellow bone marrow (p < 0.001 and p = 0.001) in all subjects. CONCLUSION: The ADCs of normal liver parenchyma and bone marrow change significantly with age. The ADCs of bone marrow in women are significantly higher than those of men and correlate strongly with FF. These effects may have an impact on image interpretation when using whole-body DWI to assess disease burden and treatment response.

Optimising abdominal space with deep neuromuscular blockade in gynaecologic laparoscopy--a randomised, blinded crossover study.

BACKGROUND: Insufflation of the abdomen during laparoscopy improves surgical space, but may cause post-operative shoulder pain. The incidence of shoulder pain is reduced using a lower insufflation pressure, but this may, however, compromise the surgical space. We aimed at investigating whether deep neuromuscular blockade (NMB) would enlarge surgical space, measured as the distance from the sacral promontory to the trocar in patients undergoing gynaecologic laparoscopy. METHODS: Fourteen patients were randomised in an assessor-blinded crossover design. The distance from the sacral promontory to the trocar was measured during deep NMB and without NMB at pneumoperitoneum 8 and 12 mmHg both. Additionally, we assessed surgical conditions while suturing the abdominal fascia using a 4-point subjective rating scale. Deep NMB was established with rocuronium and reversed with sugammadex. RESULTS: At 12 mmHg pneumoperitoneum, deep NMB improved surgical space with a mean of 0.33 cm (95% confidence interval 0.07-0.59) (P=0.01, paired t-test) compared with no NMB. At 8 mmHg pneumoperitoneum deep NMB improved surgical space with a mean of 0.3 cm (95% confidence interval, 0.06-0.54) (P=0.005) compared with no NMB. Deep NMB resulted in significantly better ratings of surgical conditions during suturing of the fascia (P=0.03, Mann-Whitney U-test). CONCLUSION: Deep NMB enlarged surgical space measured as the distance from the sacral promontory to the trocar. The enlargement, however, was minor and the clinical significance is unknown. Moreover, deep NMB improved surgical conditions when suturing the abdominal fascia.

The subperitoneal space and peritoneal cavity: basic concepts.

The subperitoneal space and peritoneal cavity are two mutually exclusive spaces that are separated by the peritoneum. Each is a single continuous space with interconnected regions. Disease can spread either within the subperitoneal space or within the peritoneal cavity to distant sites in the abdomen and pelvis via these interconnecting pathways. Disease can also cross the peritoneum to spread from the subperitoneal space to the peritoneal cavity or vice versa.

Subperitoneal extension of disease processes between the chest, abdomen, and the pelvis.

The subserous space is a large, anatomically continuous potential space that interconnects the chest, abdomen, and pelvis. The subserous space is formed from areolar and adipose tissue, and contains branches of the vascular, lymphatic, and nervous systems. As such, it provides one large continuous space in which many disease processes can spread between the chest, abdomen, and the pelvis.

Laparoscopic surgery for colon cancer: a review of the fascial composition of the abdominal cavity.

Laparoscopic surgery has generally been performed for digestive diseases. Many patients with colon cancer undergo laparoscopic procedures. The outcomes of laparoscopic colectomy and open colectomy are the same in terms of the long-time survival. It is important to dissect the embryological plane to harvest the lymph nodes and to avoid bleeding during colon cancer surgery. To date, descriptions of the anatomy of the fascial composition have mainly involved observations unrelated to fundamental embryological concepts, causing confusion regarding the explanations of the surgical procedures, with various vocabularies used without definitions. We therefore examined the fascia of the abdominal space using a fascia concept based on clinical anatomy and embryology. Mobilization of the bilateral sides of the colon involves dissection between the fusion fascia of Toldt and the deep subperitoneal fascia. It is important to understand that the right fusion fascia of Toldt is divided into the posterior pancreatic fascia of Treitz dorsally and the anterior pancreatic fascia ventrally at the second portion of the duodenum. A comprehensive understanding of fascia composition between the stomach and transverse colon is necessary for dissecting the splenic flexure of the colon. As a result of these considerations of the fascia, more accurate surgical procedures can be performed for the excision of colon cancer.

Mitigating the squash effect: sloths breathe easily upside down.

Sloths are mammals renowned for spending a large proportion of time hanging inverted. In this position, the weight of the abdominal contents is expected to act on the lungs and increase the energetic costs of inspiration. Here, we show that three-fingered sloths Bradypus variegatus possess unique fibrinous adhesions that anchor the abdominal organs, particularly the liver and glandular stomach, to the lower ribs. The key locations of these adhesions, close to the diaphragm, prevent the weight of the abdominal contents from acting on the lungs when the sloth is inverted. Using ventilation rate and body orientation data collected from captive and wild sloths, we use an energetics-based model to estimate that these small adhesions could reduce the energy expenditure of a sloth at any time it is fully inverted by almost 13%. Given body angle preferences for individual sloths in our study over time, this equates to mean energy saving of 0.8-1.5% across individuals (with individual values ranging between 0.01 and 8.6%) per day. Given the sloth's reduced metabolic rate compared with other mammals and extremely low energy diet, these seemingly innocuous adhesions are likely to be important in the animal's energy budget and survival.

Body frame variation and adiposity in development, a mixed-longitudinal study of "Cape Coloured" children.

OBJECTIVES: The obesity epidemic is impacting both developed and undeveloped countries worldwide. It has only been recently that wide scale public campaigning has focused on prevention rather than intervention. Individual variations in food metabolism and energy expenditure may be responsible for much of the adiposity present amongst individuals. This article studies individual variation in relationship between lean trunk size and adiposity. METHODS: A mixed longitudinal growth study was conducted between 1986 and 1995 among urban and rural "Cape Coloured" schoolchildren from the Western Cape Province of South Africa. The sample consists of 127 females and 130 males between the ages of 6 and 20 years measured 6-9 times each. Correlations between age-standardized triceps, subscapular and abdominal skinfold thicknesses and quotient indices obtained by expressing trunk length, lower limb, and upper limb lengths and bi-acromial and bi-iliocristal diameters as percentages of body height were explored for each year of growth. RESULTS: Significant correlation coefficients (P < 0.05) between 0.087 and 0.511 were found in both males and females, between bi-acromial and bi-iliocristal indices and three skinfold thicknesses, but not between trunk and limb lengths and skinfolds. CONCLUSIONS: Skeletal frame width and amount of adiposity are correlated. The correlation persists longitudinally throughout childhood and adolescence in individuals living in very poor, as well as, in good environmental conditions.

[In vivo anatomical study of inferior attachment of renal fascia in adult with acute pancreatitis as shown on multidetector computed tomography].

This study aims to explore the inferior adhesion of the renal fascia (RF), and the inferior connectivity of the perirenal spaces (PS) with multidetector computed tomography (MDCT), and to investigate the diagnostic value of CT for showing this anatomy. From May to July 2012, eighty-two patients with acute pancreatitis presented in our hospital were enrolled into this study and underwent contrast-enhanced CT scans. All the image data were used to perform three dimensional reconstruction to show the inferior attachment of RF and the inferior connectivity of PS. The fusion of anterior renal fascia (ARF) and posterior renal fascia (PRF) next to the plane of iliac fossa were found on the left in 71.95% (59/82) cases, and on the right in 75.61% (62/82). In these cases, bilateral perirenal spaces, and anterior and posterior pararenal spaces were not found to be connected with each other. No fusion of ARF and PRF below the level of bilateral kidneys occurred on the left side in 28.05% (23/82) cases and on the right side in 24.39% (20/82). In these patients, the PS extended to the extraperitoneal space of the pelvic cavity and further to the inguinal region, and bilateral anterior and posterior pararenal spaces were not found to be connected with each other. Three-dimensional reconstruction on contrast-enhanced MDCT could be a valuable procedure for depicting inferior attachment of RF, and the inferior connectivity of PS.

Novel threadlike structures on the surfaces of mammalian abdominal organs are loose bundles of fibrous stroma with microchannels embedded with fibroblasts and inflammatory cells.

Novel threadlike structures (NTSs) on the surfaces of mammalian abdominal organs have recently attracted interests regarding their ability to transport fluid, enable cell migration, and possibly facilitate cancer metastasis. Nevertheless, histological studies of NTSs have been sporadic and often have inconsistent interpretations of the NTS internal structure. In this article, we provide a synthetic and consistent view of the NTS internal structure: the NTS is a loose bundle of fibrous stroma that forms interstitial channels and microsinusoids infiltrated with inflammatory cells. The fibroblasts are embedded in the stroma and mostly aligned along the major axis of the NTS. The sinusoids, which are in inconsecutive cross sections, have boundaries more or less delineated by extracellular fibers, partly surrounded by endothelial-like cells, or both. We compare these morphological features to other well-known connective tissues (i.e., trabecular meshwork and lymphatic capillary) and discuss the biomechanical and biological functions of NTSs based on their structural characteristics.

[MDCT features and anatomic-pathological basis of the diseases in central thoracic-abdominal junctional region].

This paper is to determine relationship between MDCT features and anatomic-pathology of the diseases in central thoracic-abdominal junctional region. 3 cadavers were cut transversely and another 3 vertically to observe the anatomy of thoracic-abdominal junctional zone. 93 patients with diseases in central thoracic-abdominal junctional zone were scanned with MDCT. The correlation between MDCT features of the diseases in central thoracic-abdominal junctional region and the anatomic-pathology of the diseases in this region was evaluated. On cadaver sections, central thoracic-abdominal junctional region was an area between anterior chest wall and dorsal spine in vertical direction. The region was separated into upper and lower sections by diaphragm. The upper section mainly contains heart and pericardium, while the lower contains broad ligament and left lobe of liver. The hiatus of diaphragm are vena caval foramen, esophageal foramen and aortic foramen in anterior-posterior turn. In the present study, 23 patients had portal hypertension, 18 had dissection of aorta, 8 got diseases in inferior vena cava, 9 had lymphoma, 12 got diseases in multiple vertebrae, 7 had lower thoracic esophageal carcinoma accompanied with metastasis in upper abdominal lymph nodes, 9 had carcinoma of abdominal esophagus and/or gastric cardia, 4 had esophageal hiatal hernia and 3 patients had neurogenic tumor in posterior mediastinum and/or superior spatium retroperitoneale. The MDCT features and distribution of the diseases in central thoracic-abdominal junctional region influence the anatomic-pathology characteristics in this region.

The impact of the intra-abdominal space on liver regeneration after a partial hepatectomy in rats.

BACKGROUND: Little is known about the relationship between intra-abdominal space and liver regeneration. The present study was experimentally designed to investigate the influence of the "occupied space" or the "loss of occupied space" on a regenerating liver. METHODS: Experiment 1: Rats were randomly assigned to two groups: SO (space occupied) rats (n = 40); occupancy of intra-abdominal space followed by a two-thirds partial hepatectomy (PH) and control rats (n = 40); A PH alone. The rats in both groups were euthanized at 24, 48, 96, and 168 h after the operation. Computed tomography (CT) images were analyzed to evaluate the regenerating-direction and the shape of the regenerated remnant liver. The liver to body weight ratio and the proliferating cell nuclear antigen (PCNA) labeling index were measured at each time point. Experiment 2: A second laparotomy was performed at 168 h after the PH in both groups; occupier-removal for the SO rats and a sham operation for the control rats. The rats in both groups were euthanized at 24 and 168 h after the second operation. The liver to body weight ratio and PCNA labeling index were measured at each time point. RESULTS: Experiment 1: The remnant liver of the SO rats enlarged toward the dorsal and caudal side because liver regeneration toward the ventral side in the SO rats was inhibited with the occupier in the abdominal space at 96 h, and later, after the PH. CT images showed a statistically significant difference in the shape of the regenerated remnant liver between the control group and the SO group. The liver/body weight ratio was significantly decreased in the SO rats at 96 and 168 h after PH (P < 0.05). There was no significant difference between the groups in the PCNA labeling index. The SO rats showed a significant increase of the PCNA labeling of the inferior right lobe (10.6%) in comparison with the index of the superior right lobe (7.8%), which came in direct contact with the occupier, at 96 h after the operation (P < 0.05). The cell density of superior right lobe of the SO rats group was significantly higher than that of the control group at 168 h after operation (P < 0.05). Experiment 2: There was no statistically significant difference in the liver/body weight ratio at 168 hrs after the second operation between the groups. However, there was a statistically significant increase of the PCNA labeling index 24 h after the second operation in the occupier-removal rats in comparison with the control rats (P < 0.05). CONCLUSION: The occupied intra-abdominal space was therefore found to suppress liver regeneration after a partial hepatectomy, while the removal of such an occupied space stimulated the regeneration of the liver.

[MDCT features and anatomic-pathology in right thoracic-abdominal junctional region diseases].

This paper was objected to determine the relationship between MDCT features and anatomic-pathology of diseases in right thoracic-abdominal junctional region. We cut 3 cadavers transversely and another 3 vertically to observe the anatomy of thoracic-abdominal junctional zone. We scanned 69 patients with diseases in right thoracic-abdominal junctional zone by MDCT. The correlation between MDCT features of right thoracic-abdominal junctional region and the anatomic-pathology in this region was evaluated. We found results as that in cadaver sections, the right pulmonary ligament, which was below inferior pulmonary vein, attached the inferior lobe of right lung to the esophagus, that the coronary ligament, which interiorly extended from falciform ligament and laterally formed into right triangular ligament, contained two layers, and that the bare area of liver, which positioned between the two layers of coronary ligament, was directly next to diaphragm with no peritoneum covered. There were 50 cases with both pleural and ascitic fluid, while the pleural fluid was divided into anterior and posterior compartments by the right pulmonary ligament, whereas the ascitic fluid was limited in perihepatic space in majority. Among the 50 cases, 5 patients had lung cancer with diaphragmatic pleura, diaphragm and upper abdomen involved. 5 patients had right hepatic lobe cancer with subdiaphragmatic peritoneum, crura diaphragmatis and lower thoracic cavity involved. 1 patient had right adrenal carcinoma with phrenic metastasis. 8 patients had inflammation in right lower thorax and/or right upper abdomen. The spreads of these diseases include mainly direct invasion, blood and lymphatic spread routs in the region. Conclusion could be drawn that the MDCT features and distribution of right thoracic-abdominal junctional region diseases correlate with the anatomical characteristics in this region.

Adaptation to herbivory and detritivory drives the convergent evolution of large abdominal cavities in a diverse freshwater fish radiation (Otophysi: Characiformes).

Convergent evolution is often interpreted as evidence of natural selection favoring an optimal phenotype during adaptation. Morphological convergence is frequently found among lineages that converge on diet, but most studies have focused on morphological traits that relate exclusively to food handling and processing. In vertebrates, there is a strong inverse relationship between intestine length and trophic level. However, little is known about whether adaptation to a low trophic level influences the evolution of abdominal cavities that can accommodate larger intestines. Here, I reconstruct the evolutionary history of trophic ecology and examine abdominal cavity shape across 157 species of the fish order Characiformes to determine whether adaptation to an herbivorous-detritivorous diet drives convergent evolution of large abdominal cavities. Herbivorous-detritivorous species evolved significantly larger abdominal cavities than other trophic groups and repeatedly converged on a similar abdominal cavity morphology. Other trophic groups evolved abdominal cavity morphologies either stochastically or by selective pressures from an untested ecological character. These findings demonstrate that the selective demands of a larger intestinal tract promote the repeated convergence of a large abdominal cavity within herbivorous-detritivorous characiform fishes, while allowing other lineages to evolve randomly or adapt in response to other selection pressures, contributing to the overall body shape diversity of the order.

Can Hernia Sac to Abdominal Cavity Volume Ratio Predict Fascial Closure Rate for Large Ventral Hernia? Reliability of the Tanaka Score.

BACKGROUND: The hernia sac to abdominal cavity volume ratio (VR) on abdominal CT was described previously as a way to predict which hernias would be less likely to achieve fascial closure. The aim of this study was to test the reliability of the previously described cutoff ratio in predicting fascial closure in a cohort of patients with large ventral hernias. METHODS: Patients who underwent elective, open incisional hernia repair of 18 cm or larger width at a single center were identified. The primary end point of interest was fascial closure for all patients. Secondary outcomes included operative details and abdominal wall-specific quality-of-life metrics. We used VR as a comparison variable and calculated the test characteristics (ie, sensitivity, specificity, and positive and negative predictive values). RESULTS: A total of 438 patients were included, of which 337 (77%) had complete fascial closure and 101 (23%) had incomplete fascial closure. The VR cutoff of 25% had a sensitivity of 76% (95% CI, 71% to 80%), specificity of 64% (95% CI, 54% to 74%), positive predictive value of 88% (95% CI, 83% to 91%), and negative predictive value of 45% (95% CI, 36% to 53%). The incomplete fascial closure group had significantly lower quality of life scores at 1 year (83.3 vs 52.5; p = 0.001), 2 years (85 vs 33.3; p = 0.003), and 3 years (86.7 vs 63.3; p = 0.049). CONCLUSIONS: In our study, the VR cutoff of 25% was sensitive for predicting complete fascial closure for patients with ratios below this threshold. Although there is a higher likelihood of incomplete fascial closure when VR is ≥ 25%, this end point cannot be predicted reliably. Additional studies should be done to study this ratio in conjunction with other hernia-related variables to better predict this important surgical end point.

Radiologic and anatomic study of the extraperitoneal space associated with the rectum.

OBJECTIVE: The objective of our study was to clarify the anatomic and radiologic features of the extraperitoneal fasciae and fascial spaces associated with the rectum. MATERIALS AND METHODS: Fourteen embalmed cadavers were studied: two for gross anatomy; six for sectional anatomy, of which two underwent histologic study; and six for space perfusion study. These examinations were followed by CT and cross dissection to observe the pelvic extraperitoneal fasciae and the role of the fasciae in the anatomic subdivision and communication of the fascial spaces. Eighty healthy subjects underwent CT or MRI to identify the imaging characteristics of the pelvic fasciae. RESULTS: Cadaver dissection and histologic study revealed a distinct sheath consisting of dense connective tissue encasing the rectum and surrounding adipose tissue like a sleeve that divided the rectal extraperitoneal space into the perirectal space and pararectal space. Perfusion studies showed communication between the pararectal spaces and the vesical extraperitoneal space anteriorly and the anterior pararenal space superiorly, but not with the perirectal space. In healthy subjects, both CT (95.0%) and MRI (97.5%) showed a circular or linear structure representing the rectal fascia outside the rectum encasing the rectum and its surrounding adipose tissue. CONCLUSION: The extraperitoneal segment of the rectum and its surrounding adipose tissue are encased by a fascia, like a sleeve, that can be seen on CT and MRI in healthy populations. The fascia divides the rectal extraperitoneal space into the perirectal space and pararectal space, and it may prevent lesions of the rectum from spreading to other pelvic extraperitoneal spaces.

Influence of anatomic landmarks in the virtual environment on simulated angled laparoscope navigation.

BACKGROUND: The aim of this study is to investigate the influence of the presence of anatomic landmarks on the performance of angled laparoscope navigation on the SimSurgery SEP simulator. METHODS: Twenty-eight experienced laparoscopic surgeons (familiar with 30° angled laparoscope, >100 basic laparoscopic procedures, >5 advanced laparoscopic procedures) and 23 novices (no laparoscopy experience) performed the Camera Navigation task in an abstract virtual environment (CN-box) and in a virtual representation of the lower abdomen (CN-abdomen). They also rated the realism and added value of the virtual environments on seven-point scales. RESULTS: Within both groups, the CN-box task was accomplished in less time and with shorter tip trajectory than the CN-abdomen task (Wilcoxon test, p < 0.05). No significant differences were found between the performances of the experienced participants and the novices on the CN tasks (Mann-Whitney U test, p > 0.05). In both groups, the CN tasks were perceived as hard work and more challenging than anticipated. CONCLUSIONS: Performance of the angled laparoscope navigation task is influenced by the virtual environment surrounding the exercise. The task was performed better in an abstract environment than in a virtual environment with anatomic landmarks. More insight is required into the influence and function of different types of intrinsic and extrinsic feedback on the effectiveness of preclinical simulator training.