Medial border of the perirenal space: CT and anatomic correlation.

PURPOSE: To explore the mode of spread of disease between the perirenal space and the perivascular central retroperitoneum and to determine the anatomy along the medial border of the perirenal space. MATERIALS AND METHODS: Anatomic dissection, injection of latex, and observation of cross sections of the abdomen were performed in nine cadavers. Attention was paid to the juncture of the central prevertebral, perivascular, and extraperitoneal regions, and the perirenal space. Anatomic findings were correlated with observations made at computed tomography (CT) in 82 patients with retroperitoneal hemorrhage (n = 24), inflammation (n = 37), and neoplasia (n = 21) involving the perirenal spaces or the central retroperitoneum. RESULTS: Along most of the length of each kidney, no apparent fascia separates the perirenal space from the central retroperitoneum. At this location, septa between fat lobules form a fenestrated multitier barrier. These septa were imperceptible on CT scans obtained in healthy individuals. After injection of latex in cadavers, this potential barrier was seen. In the clinical study, spread of disease was allowed in only 38 (30%) of 128 instances of potential spread. Spread was facilitated along the renal vessels and the interlobular septa. CONCLUSION: Beyond the kidneys, the renal fascia is closed, forming a cone superiorly and an inverted cone inferiorly. A network of interlobular septa acted as a barrier or pathway to the free spread of disease from the perirenal space to the central retroperitoneum or from the central retroperitoneum to the perirenal space.

Variability of the obturator vessels.

The obturator artery and vein are usually described as branches or tributaries of the internal iliac vessels although variations with connections to the external iliac or inferior epigastric vessels have been reported. Because these anomalous vessels are at risk in groin or pelvic surgeries that require dissection or suturing along the pelvic rim, we measured the frequency of these variations in 105 pelvic walls (45 in the United States and 60 in China). Our data show that 70-82% of pelvic halves and 83-90% of whole pelves had an artery, vein, or both in the variant position. Arteries were most often found in the normal position only but normal and anomalous veins were most frequently found together. These data show that it is far more common to find a vessel coursing over the pelvic rim at this site than not and have implications for both pelvic surgeons and anatomists.

Why perirenal disease does not extend into the pelvis: the importance of closure of the cone of the renal fasciae.

OBJECTIVE: The prevailing concept is that lack of fusion of the anterior and posterior renal fasciae caudally (an open cone) allows free communication between the perirenal space and the extraperitoneal portion of the pelvis. However, perirenal disease rarely extends into the pelvis and an open cone has not been observed on CT scans. Accordingly, we determined the anatomy of the caudal extent of the cone of the renal fasciae in cadavers and on CT scans. MATERIALS AND METHODS: Anatomic dissections of the lower portion of the retroperitoneum and the extraperitoneal portion of the pelvis were made in eight cadavers. Two cadavers were intact, two had colored latex injected into the perirenal space before dissections, and the abdomens and pelves of four were sectioned transversely in 3- to 5-cm-thick slices. The renal fasciae were traced on transparent films placed on the cross sections, and computer-generated three-dimensional representations of the tracings were made. These anatomic findings were correlated with observations made on CT scans of 59 consecutive patients with diseases involving the lower part of the retroperitoneum and the extraperitoneal portion of the pelvis (32 patients with hemorrhage, 16 with inflammatory processes, and 11 with neoplastic conditions). RESULTS: The anatomic study showed that the anterior and posterior renal fasciae merge to form a single multilaminar fascia in the iliac fossa. Anteriorly, this common fascia is loosely connected to the parietal peritoneum. Posteriorly lies the caudal continuation of the posterior pararenal compartment. This joins with the laterocaudal continuation of the central part of the retroperitoneum, which contains the iliac vessels. The distal part of the ureter lies within the caudal continuation of the single multilayered renal fascia. The CT studies done in patients showed that extension of the perirenal processes to the pelvis and vice versa was both restrained and uncommon: no direct extension of any abnormalities was observed in either direction, and laminar thickening of the fasciae was seen in one fifth of the patients. Similarly, no inferior communication of the perirenal space with the anterior or posterior pararenal spaces was seen. CONCLUSION: There is an anatomic barrier between the inferior perirenal space and the extraperitoneal pelvis formed by the fusion of the leaves of the renal fasciae into a single multilaminar fascia that acts as a barrier of disease extension. The multilaminar nature of this fascia, however, may also act as a filter, allowing some permeability between its layers. This potential interlaminar pathway is rare and is manifested as fascial thickening on CT scans. This laminar filter-barrier observation explains the lack of extension of perirenal diseases into the pelvis.

Peritoneal reflections of left perihepatic region: radiologic-anatomic study.

To clarify the anatomy of the peritoneal reflections of the left perihepatic region, the authors examined 95 cadavers. Thirty-eight were studied radiographically, 37 with sagittal dissection, and 20 with transverse dissection. In over 80% of the cadavers, the left triangular ligament of the liver separated the left suprahepatic space into anterior and posterior sections. The lesser omentum extended to the diaphragm, where its anterior layer reflected and continued as the posterior layer of the left triangular ligament. Thus, the posterior left suprahepatic space and the lesser sac were clearly separated by the lesser omentum and the stomach and over-lapped each other in three dimensions. The posterior left suprahepatic space was located anterosuperior to the lesser sac and in turn was continuous with the gastrohepatic space inferiorly. Carefully researched diagrams of both the midline sagittal and left parasagittal perihepatic spaces were developed. This information has clinical value when the radiologist is called on to drain a left perihepatic abscess.