Medial Extent of the Anterior Gerota's Fascia

大 M放射훌훌횡슐誌第 25 卷第 2 ’!)! pp. 314 - 319, 1989 Journal 01 Korean Radiol앵 i c al Society, 25121 314 - 319, 1989

Medial Extent of the Anterior Gerota’s Fascia: An Anatomic Study Using Cadaver and CT

Jae Hoon Lim, M.D., Kyung Nam Ryu, M.D., Ho Kyun Kim, M.D., Yup Yoon, M.D., Sun Wha Lee, M.D., Young Tae Ko, M.D., Woo Suk Choi, M.D., and Dong Ho Lee, M.D.

Department of Diagnostic Radiology, Ky ung Hee Un iversity Hospital

〈 국문초록 〉

前 Gerota 體의 解홉”

慶熙、大學校醫科大學放射線科學敎室

f-f在勳·柳京南·金昊均 ·尹煙·李善和高永泰·崔祐碩·李東鎬

賢周圍 Ge r ota陳의 정확한 解곰U 를 알기 위하여 2 예으l 死體와 50예의 복부선산화단층촬영에서의 Gerota體中前體의 範圍를 관찰하였 마. 賢門下方에 서 는 左右뼈 IJ 前陳이 中心線으로 와서 복부대 동 액 과 下空靜版앞으로 융합하며 賢門上部에 서 는 前體이 弱하며 後 8쳤模이 나인성 장기 와 융합하는 것으로 추측된다. 따라서 좌우측 뽑房홈은 적어도 賢門下方에서는 양측이 서로 통하여測賢房뾰의 l7J(나 出血둥으1 Il옷體가 반대쪽의 賢房뽑으로 펴질 수도 있음을 강조한다.

- Abstract-

To stud y the anatomy of the perirenal space, authors dissected two cadavers and reviewed 50 computed tomographic (CT) scans, laying special emphasis on th e medial extent of the anterior layer

。 f Gerota’s fascia. It is conclud ed that, below the renal hilus level, anterior layers of the right and left Gerota’s fascia fus e each other across the midline anterior to the aorta and inferior vena cava Above the hilus level, anterior layers are very weak and seem to fuse wi th th e parietal peritoneu m or adjacent organs. Therefore, the right and left perirenal spaces may communicate across the midline, anterior to the lower aorta and ve na cava. T hus, at least in some subjects, the perirenal fluid or blood

。 f the right or left perirenal space may extend to the opposite perirenal space through the narrow midline extension of each perirenal spaces anterior to the vertebral body

이 논운은 1989 년도 1 월 24 일 정수하여 1 989 년 2 월 27 일에 채택되었음 . Recieved ] an. 24, Accepted Feb. 27, 1989

- 314- - Jae Hoon Lim , et al.: Medial Extent 01 the Anterior Gerota ’s Fascia: An Anatomi c stud y using cadaver and CT -

patients using 10 mm collimation and 9 sec scan Introduction times, and a GE c1/f 8800 scanner in seven pat ients using 10 mm collimation and 10 sec scan tim There has been extensive studies on the anato es. Consecutive CT scans through the upper abd my of Gerota’s fascia as well as perirenal and omen were performed during deep inspiration, pararenal spaces 1- 8). It is generally accepted that with the patient supine, at intervals of 10 to 15 the inferior aspect of the perirenal space (apex of rnm. Oral and intravenous contrast media were 8 the renal cone) is open inferiorli- ). It is also adrninistered in the majority. Intravenous antisp generally agreed that the anterior and posterior asmodics was administered to inhibit bowel per layers of Gerota’s fascia fuse laterally to form the istalsis. Z 8 lateroconal fascia - ). However, the superior and rnedial extent of the anterior and posterior layers Results. of Gerota’s fascia has been a subject of controve- rs/ - 8) and thus assumptions and explanations of Review of anatomic dissections of the Gerota’s extension of some pathologic processes described fascia revealed that, below the hilus of the kidney, in some textbooks and published papers are con- right and left anterior layers extended mediaIly 5 siderably discordant ,6,9 - 1l). towards the midline anterior to the aorta and in- To investigate this apparant discrepancy, we ferior vena cava (Fig. 1) , and fused with the op- undertook an anatomic study by cadaver dis- posite layer across the midline. Mesenteric root sections and analysis of the CT appearances of was not cIearly separated from the anterior Ger- Gerota’s fascia in normal and pathology, and he- ota’s fascia. Around the upper pole of the kidney, rein, we describe our understanding of the ret- the anterior layer fused with the posterior parietal roperitoneal fascial anatomy and discuss its cI inical peritoneum below the pancreas, or partly with the significance. pancreas. Computed tomography depicted variable medial Materials and Methods extent of Gerota’s fascia in terms of the level of the kidney. The fascia was normaIly less than 2 Two cadavers were dissected concentrating par mm thick, but more extensive and thickened in ticular importance on the medial extent of the patients with local malignancy, pancreatitis, retro anterior layer of Gerota’s fascia . The posterior peritoneal hemorrhage or edema. Gerota’s fascia parietal peritoneum and small bowel mesentery was visible over a greater extent in these patients were reflected anteriorly and anterior layer of Around the hilus level of the kidneys, the ante Gerota’s fascia was exposed. rior layer was visualized in some half of the cases, A total of 50 CT scans, in which Gerota’s fascia slightly more frequently visualized in the left side was cIearly visualized over at least 6 cm in cran (Table 1). MediaIly from the lateroconal fascia, iocaudal extent, were reviewed and the medial the anterior layer extended towards the midline, extent of the anterior layer of Gerota’s fascia was ended in the paramedian plane lateral to the inf recorded. Gerota’s fascia was less than 2 mm in erior vena cava and aorta in 26 % (right 13 cases, thickness in 25 cases, but was thickened by mal left 13 cases)of the time (Fig. 2a) . In some 20 % ignancy, pancreatitis, hemorrhage or edema in 25 of the cases (right 7 cases, left 13 cases), the fascia cases. Computed tomographic scans were per ended at the midline anterior to the great vessels, formed with a Toshiba TCT -80A scanner in 43 but did not cross the midline (Fig. 3). In 6 %(3

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cases), the right and left layers fused with the contralateral layer, anterior to the inferior vena cava and aorta(Fig. 4,5). In the remaining half(rig ht 27 cases, left 21 cases), the anterior layer of Gerota’s fascia was not visualized At the lower part than the hilus of the kidney, the fascia continued downwards with variable ex tent, some of them appeared continuous across the midline in front of great vessels (Fig. 2b). Around the uppεr p이 e of the kidney, however, in no case

Fig. 1. Cadaveric dissection of the left perirenal area The anterior layer of Gerota’s fascia (glis tening membrane covering the left kidn ey)stretched medially anterior to the aorta and inferior mesenteric artery (l arge arrowhea ds)seen through the Gerota’s fascia. The small bowel mesenteric root (long arrow)is not clear ly separated from the anterior Gerota’s fascia Cranially the anterior layer fused with the parietal peritoneum (short arrows)and partly with the pancreas tail (retracted upwards by forceps). Note the tom anterior Gerota’s fasc ia(small arrowheads)and kidney (K)within. P= Pancreas tail, K=Top of the left kidney Fig. 2. CT scans of a patient with stomach cancer (Reprinted, with th e permission of Clinical Radiology, from the reference 8) Table 1. Medial extent of anterior layer of Gero (a) CT scan through the hilus of kidneys ta’s fascia at the level of the hilus of showing thickened anterior and posterior the kidneys. (N =50) layers of Gerota’s fascia (arrowheads) Posterior layers fuse with the quadratus Extent Right Left lumborum (Q)at their lateral margins (curv ed arrows) Fusion with contralateral layer 3 3 (b) CT scan below the lower poles of kidneys Midline 7 13 shows continued downward extension of Paramedian 13 13 the right anterior Gerota’s fascia (arrowhe ads)anterior to the right ureter (U)and inf Not clearly visualized 27 21 enor vena cava

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showed unequivocal communication of the peri renal spaces across the midline, behind the cont inuous anterior Gerota’s fascia by fusion of each 9 side, at the lower lumbar leveI ). In this study, anterior layer of Gerota fascia extended towards the midline (Fig. 2,3) and even tually fused with contralateral layer in some cases (Fig. 2,4,5) Medial extension or fusion of both side anterior Gerota’s fascia was best demonst rated at renal hilus level and more or less extend ed inferiorly below the hilus level (Fig. 2a, b). This observation coincide with the result of Kne Fig. 3. Spontaneous perirenal hernorrhage in a patient eIand et al., studied by CT and cadaver dissect with hypernephrorna. Non-enh anced scan. CT 9 scan through the renal hilus level showing rig ion ). Above this level, the anterior layer was no ht anterior layer (arrow heads)extending to the longer seen. Probably it may blend with the post lateral rnargin of the inferi or vena cava (V). K 8 erior parietal peritoneum ) or with adjacent organ = Kidney parenchyma, H = Hernatorna, TR = lO Transve rsalis abdorninis s, such as the duodenum or pancreas ) as in our cadaver dissection(Fig. 1) . was the anterior layer clearly visualized. Clinical significance of the midline crossing of the anterior Gerota’sfascia has been discussed. Discussion Contralateral extension of urine and blood after

Retroperitoneal fascial anatomy has been stud ied extensively by the earlier anatomists 1- 4). Gerota described direct continuity of the right and left anterior fascia across the midline in front of 1 the vena cava and aorta ) . Congdon and Edson, and Tobin described occasional continuity of the 2 both side anterior layer across the midline ,4). However, Mitchel denied the continuity3). He con cluded that anterior layer of Gerota fascia merged with the connective tissue surrounding the abd ominal great vessels. Later, Meyers described pe rirenal space had no continuity across the midline as the anterior layer of Gerota’s fascia blended into the dense mass of connective tissue surroun Fig. 4. CT scan of a patient with lyrnph orna showing fu sion of th e thi ckened right and left Gero ta’s 5 ding the great vessels ). RecentIy, some authors fascia (arrows) across the rn idline anterior t 。 studied the extent of Gerota’s fascia with CT scans. th e inferior vena cava (V)and aorta (A). Note fu sio n of th e right posterior laye r (a rrowhead) Feldberg found occasional continuity of the wi th the lateral rn arg in (curved arrow) of th e anterior Gerota’s fascia across the midline at and quadratus lumborurn (Q). RK=Right kidn ey 7 infilt rated by lyrnph orna, LK=Left kidney. P below the left renal vein ). Kneeland et al. , with =Psoas muscle in fil lrated by lyrnph orna, PH the CT scans of cadaver and patients in vivo , = Pancreas head - 317- - 大韓放射線훌훌學會註 : 第 25 卷第 2 號 1989 -

of both perirenal fascia across the midline through a narrow channel around the great vessels behind 9 the anterior renal fascia ) . Midline continuity of anterior Gerota’s fascia confines the pancreatic in flammatory process within the anterior parare nal space by thickening of the fascia (Fig. 5) though enzymatic disruption of the fascia occurs and in flammation can be extended into the perirenal space Although CT is a powerf비 tool for the study of anatomy, especially in vivo study, the visibility of G~rota ’ s fascia on CT scanning is influenced by various factor7,8). The fascia, though it is present, may be too thin to be demonstrated or may be averaged by adjacent perirenal fat. Craniocaudal orientation of the fascia is an important factor: the more perpendicular to the plane of the slice it is , the clearer it will be demonstrated. This is why the fascia near the upper and lower poles of the kid 8 ney is diffiωlt to see on CT scans ). When the fas미 a comes in contact with the adjacent organs, such as the pancreas or duodenum, the fascia Fig. 5. Phlegmonous pancreatitis showing med ial ext. blends with these organs and thus the fascia is not ent 01 the anterior and posterior laye rs 01 Gerota’s lascia visualized on CT (Fig. 5). (a) CT scan thro ugh the upper part 01 the Other factors, such as resolution of the scanner, kidneys. P osterior layer 01 right Ge rota’s lascia (arrowhead)luses (curved arrow)wi th blurring caused by long scan time, or lack of peri- the diaphragm lar lateral to th e quadratus lumborum (QL). Right anterior lascia is partly visualized. Left anterior lascia is obliterated \open arrows)by the swollen pancreas and cons id ered to play a ro le as a barrier to inflammatory extension into the perirenal space (b) CT scan through th e renal hilus level. Lelt anterior layer (arrows)extends towards the midline, anterior to the aorta, blends with the pos terior wall 01 the 3rd portion 01 the du ode num (D3). P osteri or layers (arrow. heads)luse with the lateral margin 01 the qu adratus lumborum (QL) traumatic rupture of a kidney (Fig. 6) or bilateral perirenal hemorrhage by rupture of abdominal Fig. 6. CT scan of a patient with left renal trauma aortic aneurysm can be explained by the presence Co ntrast media leaks into the anteromedial part of the left perirenal space (arrows) and of the anterior Gerota’s fascia crossing the midl extends towards the midline (open arrow) ll ine ,12) , Kneeland et aL , discussed communication anterior to the aorta (A). U=Ureter - 318- - Jae Hoon Lim . et a1.: Medial Extent 01 th e Anterior Gerota’s Fascia: An Anatomic study using cadaver and CT -

renal or pararenal fat , play a role in the visibility of the fascia. These factors explain the low rate of REFERENCES visualization of the anterior layer in spite of the fact that the anterior layers do exist and fuse each l. Gerota D. Beiträge zur Kenntnis des Befestigun other in the midline. gsapparates der Niere. Archives für Anatomie und Another factor to be borne in mind as well is Entwickelungsgeschichte. Anat Abteil 19.'265-285, individual variation of anatomy occurring from pa 1895 tient to patient and level to level. In fact, it is 2. Congdon ED , Edson JN. The cone of renal fascia in difficult to generalize these great variation of the th e adu1t white male. Anat R ec 80:289-305, 1941 retroperitoneal fascial anatomy, and simple dia 3. Mitchell GAG. Th e renal fascia. Br ] Surg gram for this complicated anatomy will undou 3 7.257-266, 1950 btedly have its intrinsic weakness. However, gen 4. Tobin CE. The renal fascfa and its relation to the eral conclusion can be drawn from CT study by tran sversaJis fascia. Anat Rec 89:295-310. 1944 observing the well visualized normal or patholo 5. Meyers MA. Dynamic radiology 01 the abdomen norm al and pathologic anatomy, 3rd ed. 180-185, gically thickened Gerota’s fascia and this is the 257, Springer-Verlag, New York 1988 basis of our report. 6_ Love L, Meye rs MA , Churchill RJ, et al. Computed In conclusion, the anterior layer of Gerota’s fas tomography of extraperitoneal spaces. A]R cia fuses with the contralateral layer (Fig. 7) , at 136.781-789, 1981 least at the renal hilus level and more or less 7. Feldberg MAM. Computed tomog raph y 01 the re similar in the lower level. Above this level the troperitoneum : an anatomical and pathological atlas fascia disappears, and probably blends with the with emphasis on the fascial planes. 15-31, 4-46, 60, posterior parietal peritoneum, or adjacent organs. Martinus Nijhoff, Dordrecht 1983 8. Lim JH, Yoon Y, Lee SW, et al. S uperior aspect of the perirenal space:anatomy and pathological cor relation. CJinical Radiology 39:368-372, 1988 9. Kneeland JB. Auh YH, Rubenstein W, et al. Perire nal space: CT evidence for communica tion across midJine. Radiology 164:657-664, 1987 10. Feldberg MAM, Ko ehl er PR, van Waes PFGM Fig. 7. Schematic drawing of Gerota’s fa scia a:t the Psoas compartment disease studied by computed renal hilus level showing fusion of the right tomography: analysis of 50 cases and subject revi and left anterior layers (AG)across the midl ew. Radiology 148;505-512, 1983 ine. Note the lusion 01 the posterior layer (PG)with the lateral margin 01 th e quadratus 1l. Somogyi J , Cohen WN , Om ar MM, et al. Com lumborum (Q). A=Aorta. V=Inlerior vena ca munication of right and left perirenal spaces demon va. K=Kidney, P=Psoas, TF=Transversalis strated by computed tomography. ] Comput Assist lascia Tomogr 3:270-273, 1979 12. Ro se n A, Korobkin M, Silverman PM, et al. CT Acknowledgments: The authors with to their diagn osis of ruptured abdominal aortic aneurysm thanks to Dr Stephen J Golding, The Churchill A]R 143.265-268, 1984 Hospital, Oxford, for his kind permission to inclu de his cases.

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