The Retroperitoneal Spaces: Anatomy and Pathology Related to theUrinary Tract
Mindy M. Horrow, MD, FACR, FAIUM
Director of Body Imaging
Albert Einstein Medical Center
Associate Professor of Radiology
Thomas Jefferson University School of Medicine
All photos retain the copyrights of their original owners
© Mindy Horrow, MD
Anterior and Posterior RenalFasciae
ARF = Gerota fascia - thinner
PRF = Zuckerkandle fascia -thicker, formed of 2 layers 2apposition of ARF and lateralconal fascia creating potentialspace
Normal Retroperitoneal Anatomy
Anterior Renal Fascia Posterior Renal Fascia
Anterior Pararenal Space
Boundaries
–Anteriorly: post parietal peritoneum
–Posteriorly: ARF
Contents: Ascending and descending colon,duodenum, pancreas
Continuous across midline, with root of smallbowel mesentery and inferiorly with perirenal,posterior pararenal and prevesical spaces
Posterior Pararenal Space
Boundaries
–Anteriorly: PRF and lateral conal fascia
–Posteriorly: transverse fascia
–Limited by and parallels psoas m.
–Open laterally to flank and inferiorally to pelvis
Contents: Fat (no visceral organs)
Continuous (potentially) with each other viaproperitoneal fat of anterior abdominal wall
Interfascial RetroperitonealPlanes
Retromesenteric - between anterior pararenal andperinephric spaces contiguous across midline andlaterally with retrorenal and lateral conal space
Retrorenal - between perinephric and posteriorpararenal spaces
Lateral conal
*Combined fascial plane continues into pelvisanterolateral to psoas m. allowing pathway to pelvis
*Trifurcation of 3 planes - anterioposterior location isvariable
The Perirenal Space
Anterior and post renal fasciae
Extent: Superior, medial, lateral,inferior
Contents
Extent of Perirenal Space
Superior - open to bare area of liver andcontiguous with mediastinum
Medial - above renal hila perirenal spacesare separate, beginning at level of hilathere is communication
Lateral - ARF, PRF fuse to form lateralconal fascia
Inferior - ARF & PRF converge blend about8 cm below kidney
Contents of Perirenal Space
Kidney, proximal collecting system,renal septa, adrenal gland
Renal vasculature and perirenal vessels
Lymphatics
Bridging septa
Newborn renal sonogram
Herniation of left kidney and adrenal gland
through Foramen of Bochdalek into posterior mediastinum
Bridging Renal Septa
Fibrous lamellae
3 types:
I -connect renal capsule with renalfascia
II-only connected to capsule,circumscribing kidney
III-connect ARF to PRF
Spread viaPerinephric Bridging Septa
Thickened septa - nonspecific but may beearly sign of renal/perinephric disease
May preclude complete percutaneousdrainage of perinephric fluid collections
Serve as conduit for spread of fluid,inflammation, neoplasm
Involvement of septae depends uponrapidity of process
CRF: Prominent bridging septae
and small amount of perinephric fluid
Kidney “sweat sign”
Fluid in perirenal space corresponding tothickened septae and fluid on CT scan
Echogenic kidneys in patient with CRF
Renal Capsule
Composed of fibrous tissue and smoothmuscle
Forms a firm, smooth investment for thekidney
Will be sharply deflected over margin of asubcapsular collection/mass withflattening and compression of the kidney
Pathways of Spread of Diseasein the Retroperitoneum
Slowly accumulating, non-aggressiveprocesses confined to 3 main spaces
Rapidly developing collectionsaccumulate and spread within fascialplanes, along bridging septae, andlymphatics
Acute Pancreatitis
Inflammatory process spares perinephricspaces
Acute hemorrhage in anterior pararenal spaceinvolves perinephric space via septae
Lymphatic Spread of Diseasefrom Perinephric Space
Small perirenal lymph nodes
Nodes in renal hilum
Periaortic/pericaval nodes
Lymphatic Spread of Diseaseto Perinephric Space
Transpleural and transdiaphragmaticlymphatics from lung and mediastinum
to perinephric space
Extension ofRetroperitoneal Fluid into Pelvis
Major route - via fused interfascial planes withdorsal extension, medial to iliac vessels(perinephric collections)
Minor route - dorsal extension lateral to iliacvessels in contact with iliopsoas muscle
Minor route - medially into prevesical space(anterior parerenal collections)
Inflammatory Processesand Fluid Collections
Infections
Urinomas
Hematomas
Pseudocysts
Infections
Most originate from kidney
May spread through all spaces and viabare area to peritoneum and thorax
Xanthogranulomatous pyelonephritis
Subcapsular
Abscess
Chronic Perinephric Abscess
Pyelonephritis in Ectopic Kidneys
Adrenal Level Renal Level
Patient with fever
after left
hemicolectomy
Xanthogranulomatous
Pyelonephritis
Obstructed upper pole Extension to post pararenal
space and post abd wall
Pancreatic Trauma with Pseudocyst
Pancreatitis in Anterior Pararenal Space
Phlegmon, 4/11 Pseudocyst, 6/25
Collections related toureteroscopy
Subcapsular
Perinephric
Pararenal
Subcapsular collection
Perinephric Collection
Posterior PararenalRegion- withinretrorenal space
Hematomas
Traumatic- MVA, iatrogenic
Spontaneous- tumor, vascular (AAA,AVM, arteritis), hematologic disorders,endstage kidney
Spread of hepatic or splenic hematomasto perinephric space without renalinjury
Leaking aortic aneurysm
Spontaneous
Hemorrhage in
End-stage Kidney
Subcapsular to perinephric to anteriorpararenal hematoma secondary torenal artery stent placement
ATN with vicariousgallbladder excretion
Renal Cell Carcinoma
with spontaneous
hemorrhage
Bilateral Adrenal
Hemorrhages
extending to
perinephric spaces
TraumaticAvulsion Renal
Artery
with
perinephrichematoma
RRA
Fractured Kidney with large
retroperitoneal mixed
hematoma-urinoma
Initial image
Delayed Image
Acute ureteral calculi
Secondary findings include:
1. Thickening of Gerota’s fascia
2. Perinephric fluid
3. Renal enlargement
4. Renal hypodensity
Distal rightureteralcalculus
Distal leftureteralcalculus
Solid Processes
RCC-invasion of perirenal fat, thickening of renalfascia
Lymphoma-multiple renal masses, contiguousretroperitoneal masses, perirenal masses, singlerenal mass
Metastasis-to perirenal lymphatics - melanoma,RCC, lung (via pleura/mediastinal connections)
Fibrosis-AO, IVC, ureters, perinephric space
Amyloidosis-perirenal soft tissue collections
Renal Cell Carcinoma with
Spread to Gerota’s Fascia
Retroperitoneal Lymphoma
Lymphadenopathy- can directly invadekidney or encase ureter
Perirenal involvement- transcapsular,direct spread from lymph nodes,isolated disease (least common)
Lymphoma- Direct invasion of Kidneys
Perirenal Lymphoma
9-9
11-6
Bilateral Perirenal Lymphoma
Lymphoma involving the small bowel mesentery,anterior pararenal space,
perinephric space and kidneys
Metastatic
Lung Cancer
Perinephric
Metastasis
Adrenal
Metastasis
Retroperitoneal Fibrosis
Most commonly idiopathic
Other causes: aortic hemorrhage, aortitis,methysergide toxicity, prior surgery orXRT, collagen vascular disease (Riedel’sthyroiditis, sclerosing mediastinitis)
Clinical: 40-60 yrs, males>females
Hydronephrosis, ureteral narrowing, slightmedial ureteral displacement
Retroperitoneal Fibrosis
Retroperitoneal Fibrosis extending
into perinephric and postpararenal
spaces
References
Aikawa, et al. Pelvic Extension of Retroperitoneal Fluid: Analysis inVivo. AJR 1998;671-677
Aizenstein, et al. Interfascial and Perinephric Pathways in theSpread of Retroperitoneal Disease: Refined Concepts Based on CTobservations. AJR 1997;168:639-643
Bechtold, et al. The Perirenal Space: Relationship of PathologicProcesses to Normal Retroperitoneal Anatomy. Radiographics1996;16:841-854
Molmenti, et al. Anatomy of the Retroperitoneum: Observations ofthe Distribution of Pathologic Fluid Collections. Radiology1996;200:95-103
Rastopoulous, et al. Medial Border of the Perirenal Space: CT andAnatomic Correlation. Radiology 1997;205:777-784
Thornton, et al. Helical CT Evaluation of the Perirenal Space and ItsBoundaries: A Cadaveric Study. Radiology 2001;659-663
The End