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 anteri or and posterior renal fasciae caudally (an open cone) allows free com munication between the perirenal space and the extraperitoneal portion of the pelvis, However, perirenal disease rarely extends into the pel vis and an open cone has not been observed on CT scans, Accordingly, w e 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 extrap eritoneal portion of the pelvis were made in eight cadavers, Two cadav ers were intact, two had colored latex injected into the perirenal spa ce before dissections, and the abdomens and pelves of four were sectio ned transversely in 3- to 5-cm-thick slices, The renal fasciae were tr aced on transparent films placed on the cross sections, and computer-g enerated three-dimensional representations of the tracings were made, These anatomic findings were correlated with observations made on CT s cans 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 w ith neoplastic conditions). RESULTS, The anatomic study showed that th e anterior and posterior renal fasciae merge to form a single multilam inar fascia in the iliac fossa, Anteriorly, this common fascia is loos ely connected to the parietal peritoneum. Posteriorly lies the caudal continuation of the posterior pararenal compartment. This joins with t he laterocaudal continuation of the central part of the retroperitoneu m, which contains the iliac vessels, The distal part of the ureter lie s within the caudal continuation of the single multilayered renal fasc ia, The CT studies done in patients showed that extension of the perir enal processes to the pelvis and vice versa was both restrained and un common: no direct extension of any abnormalities was observed in eithe r direction, and laminar thickening of the fasciae was seen in one fif th of the patients. Similarly, no inferior communication of the perire nal space with the anterior or posterior pararenal spaces was seen, CO NCLUSION, There is an anatomic barrier between the inferior perirenal space and the extraperitoneal pelvis formed by the fusion of the leave s 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 betwee n its layers, This potential interlaminar pathway is rare and is manif ested as fascial thickening on CT scans, This laminar filter-barrier o bservation explains the lack of extension of perirenal diseases into t he pelvis.