Comprehensive reviews of the interfascial plane of the retroperitoneum: normal anatomy and pathologic entities

Navigating the labyrinth of peritoneal and extraperitoneal anatomy: abdominal spread made easy with a case based review

Essential to understanding disease spread in abdomen is to separate the peritoneum from the extraperitoneum. These areas have distinct anatomy with well-define separate pathways. The peritoneum is comprised of connected recesses that are potential spaces, normally not imaged except when containing excess fluid or air. Peritoneal recesses are formed by the opposing peritoneal surfaces and subdivided by the attachments of the ligaments and mesenteries to the parietal peritoneum. Disease flows within the recesses by changes in abdominal pressure. This forms a distinct spread pattern. The extraperitoneum is traditionally stratified by the renal fascia into the anterior and posterior pararenal spaces and the perirenal space. The fascia contains and directs spread from the contained organs with the compartments. Each space has a unique spread pattern defined by the containing fascia. The extraperitoneum is connected to the mesenteries and ligaments forming the subperitoneal space. This space interconnects the extraperitoneum with the mesenteries allowing for the normal continuum of blood vessels, lymphatics, and nerves but also forms the pathways for bidirectional spread of disease.

Management of retroperitoneal appendiceal perforation: a case report

Retroperitoneal appendiceal perforation presents unique challenges in surgical management due to the complex nature of the retroperitoneal space. We present a case of a 57-year-old male with retroperitoneal appendiceal perforation, characterized by the presence of a large amount of gas in the retroperitoneal space. Emergent laparoscopic surgery was performed to address the retroperitoneal involvement. In retroperitoneal appendiceal perforation, surgical intervention and postoperative drainage are of great significance to prevent septic shock. The interconnectedness of the retroperitoneal space with other body regions is highlighted, underscoring the potential for severe complications. This case emphasizes the need for a tailored approach to managing retroperitoneal appendiceal perforation, preventing potential complications associated with this condition.

Acute pancreatitis associated with pleural effusion: MDCT manifestations and anatomical basis

BACKGROUND

Acute pancreatitis (AP) is a severe condition with complications that can impact multiple organ systems throughout the body. Specifically, the diffusion of peripancreatic effusion to the pleural cavity is a significant phenomenon in AP. However, its pathways and implications for disease severity are not fully understood.

OBJECTIVE

This study aims to investigate the anatomical routes of peripancreatic effusion diffusion into the pleural cavity in patients with AP and to analyze the correlation between the severity of pleural effusion (PE) and the computed tomography severity index (CTSI) and acute physiology and chronic health evaluation II (APACHE II) scoring system.

METHODS

119 patients with AP admitted to our institution were enrolled in this study (mean age 50 years, 74 male and 45 female). Abdominal CT was performed, and the CTSI and APACHE II index were used to evaluate the severity of the AP, Meanwhile, the prevalence and semiquantitative of PE were also mentioned. The anatomical pathways of peripancreatic effusion draining to pleural were analyzed. Finally, the correlation relationship between the severity of AP and the PE was analyzed.

RESULTS

In 119 patients with AP, 74.8% of patients had PE on CT. The anatomic pathways of peripancreatic effusion draining to pleural included esophageal hiatus in 33.7% of patients, aortic hiatus in 6.7% of patients and inferior vena cava hiatus in 3.37% of patients. The rating of PE on CT was correlated with CTSI scores (r= 0.449, P= 0.000) and was slightly correlated with the APACHE II scores (r= 0.197, P= 0.016).

CONCLUSION

PE is a common complication of AP, which can be caused by anatomic pathways such as diaphragmatic hiatus. Due to its correlation with the CTSI score, the PE may be a supplementary indicator in determining the severity of AP.

Retroperitoneal anatomy with the aid of pathologic fluid: An imaging pictorial review

The retroperitoneum, a complex anatomical space within the abdominopelvic region, encompasses various vital abdominal organs. It is compartmentalized by fascial planes and contains potential spaces critical in multiple disease processes, including inflammatory effusions, hematomas, and neoplastic conditions. A comprehensive understanding of the retroperitoneum and its potential spaces is essential for radiologists in identifying and accurately describing the extent of abdominopelvic disease. This pictorial review aims to describe the anatomy of the retroperitoneum while discussing commonly encountered pathologies within this region. Through a collection of illustrative images, this review will provide radiologists with valuable insights into the retroperitoneum, facilitating their diagnostic proficiency to aid in appropriate patient clinical management.

[Multi-Detector CT Findings of Typical and Atypical Appendicitis: A Pictorial Essay]

Multi-detector CT (MDCT) is a highly accurate diagnostic tool that is commonly used to evaluate appendicitis and its complications. The diagnosis of appendicitis based on MDCT findings can be difficult and challenging when the observed findings are inconsistent with the typical features. Atypical appendicitis includes a wide spectrum of features, such as variable positions of the appendix and cecum, complications, and unusual pathological findings of secondary appendicitis that mimic or induce appendicitis. Our pictorial essay describes the diverse spectrum of atypical appendicitis and appendicitis-like conditions in terms of location abnormalities, complications, and uncommon pathologies, including related tumors, reactive appendicitis, appendiceal diverticulitis, and IgG4-related disease. Through this essay, the readers can become more familiar with MDCT findings of atypical appendicitis.

Evaluation of the contour of the pancreas: types and frequencies

PURPOSE

Pancreas contour variations can sometimes be misdiagnosed as mass lesions. This study aimed to evaluate normal pancreatic contour morphology, variations, frequency and the development of the uncinate process.

METHODS

Out of 1183 consecutive computed tomography images taken in our hospital for various reasons (e.g. malignity, donor), 899 suitable images were included in the study. The following variations were identified: globular, elongated or globular-elongated contours of the pancreas head, protrusions of the body-tail surfaces and globular, lobular, globular-lobular, tapered and bifid contours of the tail. Hypoplasia and aplasia of the uncinate process were identified. All images were evaluated retrospectively by two radiologists.

RESULTS

Of the 899 patients, 504 (56.1%) were males. The mean age of the patients was 53.9 ± 14.7 (range 18-89). Hypoplasia of the uncinate process was found in 72 (8%) patients; aplasia was seen in 11 (1.2%) patients. Thirty-one (3.5%) of the pancreatic head variations were globular, 49 (5.4%) elongated and three (0.3%) elongated-globular. In patients with pancreatic uncinate process developmental anomaly, contour variations were also detected in the head of the pancreas. The pancreatic body-tail showed protrusions anteriorly in 76 (8%) patients and posteriorly in 11 (1.2%) patients. Seventy-two (8%) of the pancreatic tail variations were globular, 39 (4.4%) were globular-lobular, 18 (2%) were tapered and 17 (1.8%) were bifid.

CONCLUSION

Patients with pancreatic uncinate process developmental anomaly also have contour variations in the head of the pancreas. Pancreatic uncinate process developmental anomaly was seen in 9.2%. Pancreatic tail contour variation was 16.2%. The pancreatic body-tail showed protrusion in 9.2% of patients.

Experience of a tertiary-level urology center in the clinical urological events of rare and very rare incidence. IV. Urological surprises: 2. Clinically visible giant hydronephrosis in adults: Is there a significant function?

Background

Giant hydronephrosis is rare with a controversy about the complete loss of renal functions. Our objective is to present our center’s experience with the management of cases of clinically visible giant hydronephrosis considering the potential residual functions. Our study is a retrospective case series of clinically visible giant hydronephrosis which was managed during the period July 2001–June 2016. Demographic and clinical variables were studied with specific considerations to the potential residual functions.

Results

Of more than 82,000 urological interventions, only 47 cases (0.057%) were operated upon for clinically visible giant hydronephrosis. Group 1 included 21 patients (mean age = 50.43 ± 13.71 years) who were treated initially by nephrostomy tube, and group 2 included 26 patients (mean age = 42.96 ± 15.16 years) who were treated primarily by nephrectomy. The main clinical presentation was abdominal distention (61.7%), while 13 patients (27.7%) were unaware of the swellings. The commonest underlying causes of hydronephrosis were urolithiasis (68.1%) and bilharzial ureteral strictures (23.4%). The contralateral kidney was diseased in 22 cases (46.8%) including the bilateral clinically visible hydronephrosis in 7 cases (15%). Indications of placement of a nephrostomy tube included uremia, infections, and evaluation of renal functions, where 5 cases of group 1 regained significant split function ranged 14–33%.

Conclusions

Clinically visible giant hydronephrosis is an extreme form of renal dilatation with different etiologies such as urolithiasis and bilharziasis. Initial placement of a nephrostomy tube may save significant residual functions in these kidneys.

Experience of a tertiary-level urology center in the clinical urological events of rare and very rare incidence. IV. Urological surprises: 2. Clinically visible giant hydronephrosis in adults: Is there a significant function?

Background

Giant hydronephrosis is rare with a controversy about the complete loss of renal functions. Our objective is to present our center’s experience with the management of cases of clinically visible giant hydronephrosis considering the potential residual functions. Our study is a retrospective case series of clinically visible giant hydronephrosis which was managed during the period July 2001–June 2016. Demographic and clinical variables were studied with specific considerations to the potential residual functions.

Results

Of more than 82,000 urological interventions, only 47 cases (0.057%) were operated upon for clinically visible giant hydronephrosis. Group 1 included 21 patients (mean age = 50.43 ± 13.71 years) who were treated initially by nephrostomy tube, and group 2 included 26 patients (mean age = 42.96 ± 15.16 years) who were treated primarily by nephrectomy. The main clinical presentation was abdominal distention (61.7%), while 13 patients (27.7%) were unaware of the swellings. The commonest underlying causes of hydronephrosis were urolithiasis (68.1%) and bilharzial ureteral strictures (23.4%). The contralateral kidney was diseased in 22 cases (46.8%) including the bilateral clinically visible hydronephrosis in 7 cases (15%). Indications of placement of a nephrostomy tube included uremia, infections, and evaluation of renal functions, where 5 cases of group 1 regained significant split function ranged 14–33%.

Conclusions

Clinically visible giant hydronephrosis is an extreme form of renal dilatation with different etiologies such as urolithiasis and bilharziasis. Initial placement of a nephrostomy tube may save significant residual functions in these kidneys.

Experience of a tertiary-level urology center in the clinical urological events of rare and very rare incidence. IV. Urological surprises: 2. Clinically visible giant hydronephrosis in adults: Is there a significant function?

Background

Giant hydronephrosis is rare with a controversy about the complete loss of renal functions. Our objective is to present our center’s experience with the management of cases of clinically visible giant hydronephrosis considering the potential residual functions. Our study is a retrospective case series of clinically visible giant hydronephrosis which was managed during the period July 2001–June 2016. Demographic and clinical variables were studied with specific considerations to the potential residual functions.

Results

Of more than 82,000 urological interventions, only 47 cases (0.057%) were operated upon for clinically visible giant hydronephrosis. Group 1 included 21 patients (mean age = 50.43 ± 13.71 years) who were treated initially by nephrostomy tube, and group 2 included 26 patients (mean age = 42.96 ± 15.16 years) who were treated primarily by nephrectomy. The main clinical presentation was abdominal distention (61.7%), while 13 patients (27.7%) were unaware of the swellings. The commonest underlying causes of hydronephrosis were urolithiasis (68.1%) and bilharzial ureteral strictures (23.4%). The contralateral kidney was diseased in 22 cases (46.8%) including the bilateral clinically visible hydronephrosis in 7 cases (15%). Indications of placement of a nephrostomy tube included uremia, infections, and evaluation of renal functions, where 5 cases of group 1 regained significant split function ranged 14–33%.

Conclusions

Clinically visible giant hydronephrosis is an extreme form of renal dilatation with different etiologies such as urolithiasis and bilharziasis. Initial placement of a nephrostomy tube may save significant residual functions in these kidneys.

Imaging of infracolic and pelvic compartment by linear EUS

The peritoneal cavity is subdivided into supracolic and infracolic compartments by transverse mesocolon, which attaches the colon to the posterior abdominal wall. Infracolic compartment is subdivided into right and left compartment by small bowel mesentery. Left infracolic space freely communicates with pelvic compartment. The infracolic compartment contains the coils of small bowel which is separated from paracolic gutter on either side by ascending and descending colon. Pelvic compartment mainly contains bladder, rectum and genital organ (prostate, seminal vesicle in male and uterus in female). The evaluation of different compartments of peritoneum is gaining importance in multimodality imaging. It has become essential that clinicians and endosonographers thoroughly understand the peritoneal spaces and the ligaments and mesenteries that form their boundaries in order to localize disease to a particular peritoneal/subperitoneal space and formulate a differential diagnosis on the basis of that location. In this article we describe the applied EUS anatomy of peritoneal ligaments, infracolic and pelvic compartments of peritoneum and there technique of imaging from stomach, duodenum, sigmoid colon and rectum. Imaging from stomach images the infracolic compartment through transverse mesocolon, imaging from duodenum images the infracolic compartment through the mesentery and imaging from rectum and sigmoid images the infracolic and pelvic compartments through the sigmoid mesocolon and pelvic peritoneum.

Gastrointestinal tract involvement in acute pancreatitis: initial findings and follow-up by magnetic resonance imaging

BACKGROUND

To study the initial and follow up patterns of gastrointestinal tract involvement in acute pancreatitis (AP) using magnetic resonance imaging (MRI).

METHODS

A total of 209 patients with AP undergoing abdominal MRI on 1.5 T MRI were compared to 100 control patients selected from our daily clinical caseload who underwent MRI over the same recruitment period and had no other disease which can cause abnormality of gastrointestinal tract. Initial and follow up MRI examinations of gastrointestinal tract abnormalities were noted for AP patients. The severity of AP was graded by the MRSI and APACHE II. Spearman correlation of gastrointestinal tract involvement with MRSI and APACHE II was analyzed.

RESULTS

In 209 patients with AP, 63% of the AP patients on their initial MRI exams and 5% of control subjects had at least one gastrointestinal tract abnormality (P<0.05). In the control group, thirty-seven patients were normal on MRI, 24 patients with renal cysts, eighteen patients with liver cysts, eleven patients with liver hemangiomas, and ten patients with splenomegaly. The abnormalities of gastrointestinal tract observed in AP patients included thickened stomach wall (20%), thickened duodenum wall (27%), thickened ascending colon wall (11%), thickened transverse colon wall (15%), and thickened descending colon wall (26%), among others. Gastrointestinal tract abnormalities were correlated with the MRSI score (r=0.46, P<0.05) and APACHE II score (r=0.19, P<0.05). Among 62 patients who had follow up examinations, 26% of patients had gastrointestinal tract abnormality, which was significantly lower than that in the initial exams (P<0.05). Resolution of gastrointestinal tract abnormal MRI findings coincided with symptom alleviation in AP patients.

CONCLUSIONS

Gastrointestinal tract abnormalities on MRI are common in AP and they are positively correlated with the severity of AP. It may add value for determining the severity of AP.

Mortality risk factor analysis in colonic perforation: would retroperitoneal contamination increase mortality in colonic perforation?

Purpose

Colonic perforation is a lethal condition presenting high morbidity and mortality in spite of urgent surgical treatment. This study investigated the surgical outcome of patients with colonic perforation associated with retroperitoneal contamination.

Methods

Retrospective analysis was performed for 30 patients diagnosed with colonic perforation caused by either inflammation or ischemia who underwent urgent surgical treatment in our facility from January 2005 to December 2014. Patient characteristics were analyzed to find risk factors correlated with increased postoperative mortality. Using the Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity (POSSUM) audit system, the mortality and morbidity rates were estimated to verify the surgical outcomes. Patients with retroperitoneal contamination, defined by the presence of retroperitoneal air in the preoperative abdominopelvic CT, were compared to those without retroperitoneal contamination.

Results

Eight out of 30 patients (26.7%) with colonic perforation had died after urgent surgical treatment. Factors associated with mortality included age, American Society of Anesthesiologists (ASA) physical status classification, and the ischemic cause of colonic perforation. Three out of 6 patients (50%) who presented retroperitoneal contamination were deceased. Although the patients with retroperitoneal contamination did not show significant increase in the mortality rate, they showed significantly higher ASA physical status classification than those without retroperitoneal contamination. The mortality rate predicted from Portsmouth POSSUM was higher in the patients with retroperitoneal contamination.

Conclusion

Patients presenting colonic perforation along with retroperitoneal contamination demonstrated severe comorbidity. However, retroperitoneal contamination was not found to be correlated with the mortality rate.

Short-Term Changes in Algometry, Inclinometry, Stabilometry, and Urinary pH Analysis After a Thoracolumbar Junction Manipulation in Patients with Kidney Stones

OBJECTIVES

To determine the efficacy of a high-velocity low-amplitude manipulation of the thoracolumbar junction in different urologic and musculoskeletal parameters in subjects suffering from renal lithiasis.

DESIGN

Randomized, controlled blinded clinical study.

SETTINGS/LOCATION

The Nephrology departments of two hospitals and one private consultancy of physiotherapy in Valencia (Spain).

SUBJECTS

Forty-six patients suffering from renal lithiasis.

INTERVENTIONS

The experimental group (EG, n = 23) received a spinal manipulation of the thoracolumbar junction, and the control group (CG, n = 23) received a sham procedure.

OUTCOME MEASURES

Pressure pain thresholds (PPTs) of both quadratus lumborum and spinous processes from T10 to L1, lumbar flexion range of motion, stabilometry, and urinary pH were measured before and immediately after the intervention. A comparison between pre- and postintervention phases was performed and an analysis of variance for repeated measures using time (pre- and postintervention) as intrasubject variable and group (CG or EG) as intersubject variable.

RESULTS

Intragroup comparison showed a significant improvement for the EG in the lumbar flexion range of motion (p < 0.001) and in all the PPT (p < 0.001 in all cases). Between-group comparison showed significant changes in PPT in quadratus lumborum (p < 0.001), as well as in the spinous processes of all of the evaluated levels (p < 0.05). No changes in urinary pH were observed (p = 0.419).

CONCLUSION

Spinal manipulation of the thoracolumbar junction seems to be effective in short term to improve pain sensitivity, as well as to increase the lumbar spine flexion.

Scary gas: pathways in the axial body for soft tissue gas dissection (part I)

Gas is often encountered in abnormal locations in the torso, including within soft tissue compartments, vessels, and bones. The clinical significance of this gas ranges from incidental, benign, and self-limited to aggressive infection requiring immediate surgery. As a result of fascial interconnectivity and pressure differences between compartments, gas can dissect distant from its source. Gas can easily dissect between spaces of the extrapleural thorax, subperitoneal abdomen, deep cervical spaces, and subcutaneous tissues. The pleural and peritoneal cavities are normally isolated but may communicate with the other spaces in select situations. Dissection of gas may cause confusion as to its origin, potentially delaying treatment or prompting unnecessary and/or distracting workup and therapies. The radiologist might be the first to suggest and identify a remote source of dissecting gas when the clinical manifestation alone might be misleading. The purpose of this paper, the first in a three-part series on soft tissue gas, is to explore the various pathways by which gas dissects through the superficial and deep compartments of the torso.

Endoscopic ultrasound of peritoneal spaces

The peritoneal cavity is subdivided into supracolic and infracolic compartments by transverse colon and its mesocolon. The supracolic compartment contains the liver, spleen, stomach, and lesser omentum. The infracolic compartment contains the coils of small bowel surrounded by ascending, transverse, and descending colon and the paracolic gutters. The imaging of different compartments is possible by various methods such as ultrasound (US) and computerized tomography. The treating physicians should be familiar with the relevant radiological anatomy of different compartments and spaces as accurate localization of fluid collection/lymph node in peritoneal cavity greatly aids in selection of a treatment strategy. The role of endoscopic US (EUS) is emerging for detail evaluation of all parts of peritoneal cavity as it provides an easy access for fine-needle aspiration from different compartments of peritoneal cavity. In this review, we describe the techniques of evaluation of different parts of supracolic compartments of peritoneum by EUS.

Chronic, nonspecific, postinfectious, retroperitoneal fibrosis and ureteral obstruction

INTRODUCTION

Two cases of severe ureteral obstruction following nonspecific, postinfectious, chronic retroperitoneal fibrosis are described, which both originated by a primitive intestinal pathology.

PATIENTS

This complication was observed in two women: first, 65 years old, submitted for ulcerative colitis to a total proctocolectomy, with ileo-pouch-anal anastomosis, complicated by an anastomotic fistula; and second, 66 years old, operated with an extended left hemicolectomy, for an adenocarcinoma of the recto-sigmoid colon complicated with a vaginal fistula. In these cases, computerized tomography demonstrated a unilateral hydronephrosis, secondary to a complete obstruction of the ureter; a subsequent nephro-ureterectomy became necessary. Histology demonstrated nonspecific inflammatory lesions.

DISCUSSIONS

Postinfectious, chronic inflammation of the retroperitoneum acts on the ureteral and peri-ureteral tissues, inducing an inflammatory and then a fibrotic process.

CONCLUSIONS

We underline the opportunity of a precocious and radical treatment of every retroperitoneal infection.

Single-port endoscopic mesocolic and mesorectal excision using an extraperitoneal approach

BACKGROUND

The extraperitoneal rectal dissection via a transanal approach facilitates the mesorectal dissection. The retroperitoneal approach for mesocolic excision may also offer some similar advantages. To complete the lymphadenectomy of extraperitoneal mesorectal resection, we developed an innovative approach for upper rectal and mesocolic excision via an exclusive retroperitoneal dissection using a single-port access at the site of the future stomy.

METHODS

This study was a prospective pilot study and was conducted between 2013 and 2015 at two oncologic centers. Five consecutive patients, with ano-rectal cancer requiring permanent stoma, underwent this procedure.

RESULTS

The bowel was never touched or mobilized to perform the lymphadenectomy, and no Trendelenburg was required. The median operative duration was 300 min (range 205-310). The quality of the surgical plane was classified as good (mesorectal) in the five patients. The median circumferential and distal margins were, respectively, 5 mm (range 1-20) and 20 mm (range 5-25). The median number of harvested lymph nodes was 11 (range 5-18). No laparotomy or multiport laparoscopy was required. There was no death. Two patients had perineal wound dehiscence (one minor and one major).

CONCLUSIONS

The mesocolic excision via a retroperitoneal approach is feasible, completes naturally the transanal mesorectal excision and may confer several advantages including no morbidity of small bowel manipulation or Trendelenburg position. Further studies are required to analyze this approach.

Extraperitoneal ascending appendicitis: Usefulness of the split interfascial plane sign on MDCT

PURPOSE

To retrospectively evaluate the multidetector computed tomography (MDCT) findings of extraperitoneal ascending appendicitis.

MATERIALS AND METHODS

The MDCT examinations of 10 patients with extraperitoneal ascending appendicitis confirmed by laparoscopic surgery were retrospectively analyzed. Preoperative MDCT examinations were obtained after intravenous administration of iodinated contrast material in all patients. Transverse and coronal reformatted MDCT images were reviewed in consensus by two radiologists. The presence of the extraperitoneal triangle sign, the split interfascial plane sign, and the other classical findings of appendicitis were evaluated.

RESULTS

Luminal dilatation, wall enhancement of the inflamed appendix, and fat infiltration were present in 10/10 patients (100%). The perforation of the inflamed appendix with abscess formation was present in 4/10 patients (40%). The split interfascial plane sign was present in 7/10 patients (70%), and parts of inflamed appendix or periappendiceal abscess were located behind the right extraperitoneal triangle in 8/10 patients (80%).

CONCLUSION

The split interfascial plane sign and the presence of an appendiceal tip or periappendiceal abscess located in the right extraperitoneal triangle are highly suggestive of extraperitoneal ascending appendicitis on MDCT.

Important CT findings for prediction of severe appendicitis: involvement of retroperitoneal space

Background

Determination of the severity of appendicitis and differentiation between complicated and uncomplicated appendicitis are clinically important. Severe appendicitis frequently affects extraperitoneal spaces. We have investigated CT findings of retroperitoneal space (RPS) in patients with appendicitis to create a model for identification of complicated appendicitis.

Method

CT images of 223 patients with pathologically proven appendicitis were reviewed. The total number of the segments in RPS where inflammatory changes were located (RPS count) was obtained as well as appendiceal diameter, appendicolithiasis, WBC count, and CRP level. Data were analyzed to identify factors indicating complicated appendicitis. Univariate analysis was conducted to identify statistically significant variables. A multivariable logistic regression analysis was performed in order to find independent predictors of complicated appendicitis.

Results

Patients with complicated appendicitis were more likely to have higher RPS count (P < 0.001), appendicolithiasis (P = 0.002), higher CRP level (P < 0.001), and greater appendix diameter (P < 0.001) than patients with uncomplicated appendicitis. Statistical analysis showed RPS count was the most helpful predictor of complicated appendicitis.

Conclusion

Radiologists and surgeons should be aware of the importance of CT findings in RPS when treating patients with appendicitis. Complicated appendicitis can be predicted by RPS count, diameter of the appendix, appendicolithiasis, and CRP level.

The urogenital-hypogastric sheath: an anatomical observation on the relationship between the inferomedial extension of renal fascia and the hypogastric nerves

PURPOSE

The study aimed to perform an anatomical observation on the inferomedial extension of the renal fascia (RF) to the pelvis and explore its relationship with the hypogastric nerves (HGNs).

METHODS

Gross anatomy was performed on 12 formalin-fixed and 12 fresh cadavers. Sectional anatomy was performed on four formalin-fixed cadavers.

RESULTS

Different from the traditional concept, both the anterior and posterior RF included the outer and inner layer with different inferomedial extensions. The multiple layers of RF extended downward to form a sandwich-like and compound fascia sheath with potential and expandable spaces which was named as "the urogenital-hypogastric sheath." Below the level of the origin of the inferior mesenteric artery, the bilateral urogenital-hypogastric sheath communicated with the counterpart in front of the great vessels in the midline and the superior hypogastric plexus ran into the urogenital-hypogastric sheath which carried the HGNs, ureters, and genital vessels downward to their terminations in the pelvis. In the retrorectal space, the urogenital-hypogastric sheath surrounded the fascia propria of the rectum posterolaterally as a layer of coat containing HGNs.

CONCLUSION

The multiple layers of RF with different extensions are the anatomical basis of the formation of the urogenital-hypogastric sheath. As a special fascial structure in the retroperitoneal space and the pelvis, emphasis on its formation and morphology may be helpful for not only unifying the controversies about the relationship between the pelvic fascia and HGNs but also improving the intraoperative preservation of the HGNs by dissecting in the correct surgical plane.

Preliminary embryological study of the radiological concept of retroperitoneal interfascial planes: what are the interfascial planes?

PURPOSE

Recently, the radiological concept of retroperitoneal interfascial planes has been widely accepted to explain the extension of retroperitoneal pathologies. This study aimed to explore embryologically based corroborative evidence, which remains to be elucidated, for this concept.

METHODS

Using serial or semi-serial transverse sections from 29 human fetuses at the 5th-25th week of fetal age, we microscopically observed the development of the retroperitoneal fasciae and other structures in the retroperitoneal connective tissue. A hypothesis for the formation of the interfascial planes was generated from the developmental study and analysis of retroperitoneal fasciae in computed tomography images from 224 patients.

RESULTS

Whereas the loose connective tissue was uniformly distributed in the retroperitoneum by the 9th week, the primitive renal and transversalis fasciae appeared at the 10th-12th week, as previous research has noted. By the 23rd week, the renal fascia, transversalis fascia, and primitive adipose tissue of the flank pad emerged. In addition, the primitive lateroconal fascia, which runs parallel to and close to the posterior renal fascia, emerged between the renal fascia and the adipose tissue of the flank pad. Conversely, pre-existing loose connective tissue was sandwiched between the opposing fasciae and was compressed and narrowed by the developing organs and fatty tissues.

CONCLUSION

Through this developmental study, we provided the hypothesis that the compressed loose connective tissue and both opposed fasciae compose the interfascial planes. Analysis of the thickened retroperitoneal fasciae in computed tomography images supported this hypothesis. Further developmental or histological studies are required to verify our hypothesis.

The anatomical compartments and their connections as demonstrated by ectopic air

Air/gas outside the aero-digestive tract is abnormal; depending on its location, it is usually called emphysema, referring to trapped air/gas in tissues, or ectopic air/gas. It can be associated to a wide range of disorders, and although it usually is an innocuous condition, it should prompt a search for the underlying aetiology, since some of its causes impose an urgent treatment. In rare instances, it may itself represent a life-threatening condition, depending on the site involved and how quickly it evolves. Abnormal air/gas beyond viscera and serosal spaces, reaches its location following some anatomic boundaries, such as fascia, which may help search the source; however if the air pressure exceeds the strength of the tissues, or the time between the aggression and the imaging is too long, the air/gas is almost everywhere, which may hinder its cause. Good knowledge of the anatomic spaces and how they connect between them facilitates the quick detection of the cause.

Teaching points

• Ectopic air can be depicted on conventional radiographs; but CT is more sensitive and accurate

• Visceral and retropharyngeal spaces directly communicate with mediastinum

• Renal fascia is a single multilaminated structure, which contains potential space

A comprehensive review of the retroperitoneal anatomy, neoplasms, and pattern of disease spread

A clear understanding of the normal anatomy and pattern of disease spread is important in evaluating many retroperitoneal disorders. Primary retroperitoneal tumors are uncommon, accounting for 0.1%-0.2% of all malignancies in the body; 80%-90% of all primary retroperitoneal tumors are malignant. The primary retroperitoneal neoplasms can be divided into solid or cystic masses. The solid neoplasms can be classified according to their tissue of origin into 3 main categories: mesodermal tumors, neurogenic tumors, and extragonadal germ cell tumors. Computed tomography and magnetic resonance imaging play a vital role in the localization, characterization, evaluation of the extent of local invasion, assessment of metastases, and determination of treatment response for these tumors. The diagnosis of a primary retroperitoneal malignancy is often challenging owing to overlap of imaging findings. A definitive diagnosis can be established only at histopathologic analysis. However, knowledge of the important tumor characteristics, growth pattern, and vascularity can assist in narrowing the differential diagnosis.

Anatomic connections of the diaphragm: influence of respiration on the body system

The article explains the scientific reasons for the diaphragm muscle being an important crossroads for information involving the entire body. The diaphragm muscle extends from the trigeminal system to the pelvic floor, passing from the thoracic diaphragm to the floor of the mouth. Like many structures in the human body, the diaphragm muscle has more than one function, and has links throughout the body, and provides the network necessary for breathing. To assess and treat this muscle effectively, it is necessary to be aware of its anatomic, fascial, and neurologic complexity in the control of breathing. The patient is never a symptom localized, but a system that adapts to a corporeal dysfunction.

Anatomic pathways of peripancreatic fluid draining to mediastinum in recurrent acute pancreatitis: visible human project and CT study

Background

In past reports, researchers have seldom attached importance to achievements in transforming digital anatomy to radiological diagnosis. However, investigators have been able to illustrate communication relationships in the retroperitoneal space by drawing potential routes in computerized tomography (CT) images or a virtual anatomical atlas. We established a new imaging anatomy research method for comparisons of the communication relationships of the retroperitoneal space in combination with the Visible Human Project and CT images. Specifically, the anatomic pathways of peripancreatic fluid extension to the mediastinum that may potentially transform into fistulas were studied.

Methods

We explored potential pathways to the mediastinum based on American and Chinese Visible Human Project datasets. These drainage pathways to the mediastinum were confirmed or corrected in CT images of 51 patients with recurrent acute pancreatitis in 2011. We also investigated whether additional routes to the mediastinum were displayed in CT images that were not in Visible Human Project images.

Principal Findings

All hypothesized routes to the mediastinum displayed in Visible Human Project images, except for routes from the retromesenteric plane to the bilateral retrorenal plane across the bilateral fascial trifurcation and further to the retrocrural space via the aortic hiatus, were confirmed in CT images. In addition, route 13 via the narrow space between the left costal and crural diaphragm into the retrocrural space was demonstrated for the first time in CT images.

Conclusion

This type of exploration model related to imaging anatomy may be used to support research on the communication relationships of abdominal spaces, mediastinal spaces, cervical fascial spaces and other areas of the body.

Asymptomatic isolated partial hiatal herniation of the pancreas: MDCT evaluation and anatomical explanation: case report and review of literature

Isolated herniation of the pancreas through a gastroesophageal hiatus is an extremely rare condition, and only one case has been reported in the world literature. We describe a MDCT diagnosis of isolated partial hiatal hernia containing the body of a normal pancreas in an asymptomatic patient, give an anatomical explanation and review the corresponding literature.

Acute conditions affecting the perinephric space: imaging anatomy, pathways of disease spread, and differential diagnosis

The perinephric space is an important, central compartment of the retroperitoneum which may host various acute conditions. Imaging evaluation of the perinephric space requires an understanding of its anatomy and the pathways of disease spread to and from other retroperitoneal compartments. Numerous acute conditions can affect the perinephric space and may occur in isolation, extend from nearby retroperitoneal structures, or be part of a systemic condition. Familiarity with the key imaging findings of acute conditions affecting the perinephric space is imperative to facilitate diagnosis and guide treatment. The purpose of this article is to review and illustrate the relevant anatomy, pathways of disease spread, and acute pathology encountered during cross-sectional imaging evaluation of the perinephric space.

Imaging of the retroperitoneum

The retroperitoneum is the compartmentalized space bounded anteriorly by the posterior parietal peritoneum and posteriorly by the transversalis fascia. It extends from the diaphragm superiorly to the pelvic brim inferiorly. This article discusses clinically relevant anatomy of the abdominal retroperitoneal spaces, their cross-sectional imaging evaluation with computed tomography and magnetic resonance imaging, and the imaging features of common retroperitoneal pathologic processes.

Extraluminal colonic carcinoma invading into kidney: a case report and review of the literature

Renal metastasis from primary colon cancer is very rare, comprising less than 3% of secondary renal neoplasms. There are just 11 cases reported in the medical literature of colonic adenocarcinoma metastatic to the kidney. Of these cases, none occurred via direct invasion. We report a unique case of a 51-year-old female with extraluminal colonic adenocarcinoma which directly invaded into the kidney. Additionally, we investigate the causal relationship between the site of invasion and a previous stab injury by reviewing the role of the peritoneum and Gerota's fascia in preventing the spread of metastatic cancer into the perirenal space. Due to the rarity of this event, we present this case including a review of the existing literature relative to the diagnosis and treatment.