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Medial extent of the anterior Gerota's fascia : an anatomic study using cadaver and CT

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大 M放射훌훌횡슐誌 第25 卷 第 2’!)! pp. 314 - 319, 1989 Journal 01 Korean Radiol앵 ical Society, 25121 314 - 319, 1989

국문초록

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, Kyung Hee University Hospital

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 Gerota陳의 정확한 解곰U 를 알기 위하여 2예으l 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뼈IJ 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 나 인성 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 study the anatomy of the perirenal space, authors dissected two cadavers and reviewed 50 computed tomographic (CT) scans, laying special emphasis on the medial extent of the anterior layer

。 f Gerotas fascia. It is concluded that, below the renal hilus level, anterior layers of the right and left Gerotas fascia fuse 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 with the parietal peritoneum or adjacent organs. Therefore, the right and left perirenal spaces may communicate across the midline, anterior to the lower aorta and vena cava. Thus, 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 1989년 2월 27 일에 채택되었음. Recieved ]an. 24, Accepted Feb. 27, 1989

- 314-

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- Jae Hoon Lim, et al.: Medial Extent 01 the Anterior Gerotas Fascia: An Anatomic study using cadaver and CT -

Introduction

There has been extensive studies on the anato- my of Gerota’s fascia as well as perirenal and pararenal spaces 1- 8). It is generally accepted that the inferior aspect of the perirenal space (apex of the renal cone) is open inferiorli-8). It is also generally agreed that the anterior and posterior layers of Gerota’s fascia fuse laterally to form the lateroconal fasciaZ- 8

). However

,

the superior and rnedial extent of the anterior and posterior layers of Gerota’s fascia has been a subject of controve-

patients using 10 mm collimation and 9 sec scan times

,

and a GE c1/f 8800 scanner in seven pat- ients using 10 mm collimation and 10 sec scan tim- es. Consecutive CT scans through the upper abd- omen were performed during deep inspiration, with the patient supine

,

at intervals of 10 to 15 rnm. Oral and intravenous contrast media were adrninistered in the majority. Intravenous antisp- asmodics was administered to inhibit bowel per- istalsis.

Results.

rs/ - 8) and thus assumptions and explanations of Review of anatomic dissections of the Gerotas 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 siderably discordant5,6,9- 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- Gerotas fascia in normal and pathology, and he- otas 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 cIinical peritoneum below the pancreas, or partly with the

significance. pancreas.

Computed tomography depicted variable medial Materials and Methods extent of Gerotas fascia in terms of the level of

Two cadavers were dissected concentrating par- ticular importance on the medial extent of the anterior layer of Gerota’s fascia. The posterior parietal peritoneum and small bowel mesentery were reflected anteriorly and anterior layer of Gerotas fascia was exposed.

A total of 50 CT scans

,

in which Gerotas fascia was cIearly visualized over at least 6 cm in cran- iocaudal extent

,

were reviewed and the medial extent of the anterior layer of Gerotas fascia was recorded. Gerota’s fascia was less than 2 mm in thickness in 25 cases

,

but was thickened by mal- ignancy, pancreatitis, hemorrhage or edema in 25 cases. Computed tomographic scans were per- formed with a Toshiba TCT -80A scanner in 43

the kidney. The fascia was normaIly less than 2 mm thick, but more extensive and thickened in patients with local malignancy, pancreatitis, retro- peritoneal hemorrhage or edema. Gerotas fascia was visible over a greater extent in these patients

Around the hilus level of the kidneys, the ante- rior layer was visualized in some half of the cases, slightly more frequently visualized in the left side (Table 1). MediaIly from the lateroconal fascia

,

the anterior layer extended towards the midline

,

ended in the paramedian plane lateral to the inf- erior vena cava and aorta in 26 % (right 13 cases, left 13 cases)of the time (Fig. 2a). In some 20 % of the cases (right 7 cases, left 13 cases), the fascia ended at the midline anterior to the great vessels

,

but did not cross the midline (Fig. 3). In 6 %(3 - 315 -

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- 大韓放射線醫學會註25 卷 第 2 1989 -

Fig. 1. Cadaveric dissection of the left perirenal area The anterior layer of Gerotas fascia (glis tening membrane covering the left kidn- ey)stretched medially anterior to the aorta and inferior mesenteric artery (large arrowhea ds)seen through the Gerotas fascia. The small bowel mesenteric root (long arrow)is not clear- ly separated from the anterior Gerotas 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 Gerotas fasc- ia(small arrowheads)and kidney (K)within. P=

Pancreas tail, K=Top of the left kidney

Table 1. Medial extent of anterior layer of Gero- ta’s fascia at the level of the hilus of

the kidneys. (N =50)

Extent Right Left

Fusion with contralateral layer 3 3

Midline 7 13

Paramedian 13 13

Not clearly visualized 27 21

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 Gerotas 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. 2. CT scans of a patient with stomach cancer (Reprinted, with the permission of Clinical Radiology, from the reference 8)

(a) CT scan through the hilus of kidneys showing thickened anterior and posterior layers of Gerotas fascia (arrowheads) Posterior layers fuse with the quadratus lumborum (Q)at their lateral margins (curv ed arrows)

(b) CT scan below the lower poles of kidneys shows continued downward extension of the right anterior Gerotas fascia (arrowhe- ads)anterior to the right ureter (U)and inf enor vena cava

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- Jae Hoon Lim, et aL Medial Extent of the Anterior Gerotas Fascia: An Anatomic study using cadaver and CT -

Fig. 3. Spontaneous perirenal hernorrhage in a patient with hypernephrorna. Non-enhanced scan. CT scan through the renal hilus level showing rig- ht anterior layer (arrow heads)extending to the lateral rnargin of the inferior vena cava (V). K

= Kidney parenchyma, H = Hernatorna, TR = Transversalis abdorninis

was the anterior layer clearly visualized.

Discussion

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 the vena cava and aorta1). Congdon and Edson, and Tobin described occasional continuity of the both side anterior layer across the midline2,4).

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- ding the great vessels5). RecentIy

,

some authors studied the extent of Gerota’s fascia with CT scans.

Feldberg found occasional continuity of the anterior Gerota’s fascia across the midline at and below the left renal vein7). Kneeland et al., with the CT scans of cadaver and patients in vivo,

showed unequivocal communication of the peri- renal spaces across the midline, behind the cont- inuous anterior Gerota’s fascia by fusion of each side, at the lower lumbar leveI9).

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 Gerotas 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- eIand et al., studied by CT and cadaver dissect- ion9). Above this level, the anterior layer was no longer seen. Probably it may blend with the post- erior parietal peritoneum8) or with adjacent organ- s, such as the duodenum or pancreaslO) as in our cadaver dissection(Fig. 1).

Clinical significance of the midline crossing of the anterior Gerotasfascia has been discussed.

Contralateral extension of urine and blood after

Fig. 4. CT scan of a patient with lyrnphorna showing fusion of the thickened right and left Gerotas fascia (arrows) across the rnidline anterior t。

the inferior vena cava (V)and aorta (A). Note fusion of the right posterior layer (arrowhead) with the lateral rnargin (curved arrow) of the quadratus lumborurn (Q). RK=Right kidney infiltrated by lyrnphorna, LK=Left kidney. P

=Psoas muscle infillrated by lyrnphorna, PH

= Pancreas head - 317-

(5)

- 大韓放射線훌훌學會註 : 25 卷 第 2 1989 -

Fig. 5. Phlegmonous pancreatitis showing medial ext.

ent 01 the anterior and posterior layers 01 Gerotas lascia

(a) CT scan through the upper part 01 the kidneys. Posterior layer 01 right Gerotas lascia (arrowhead)luses (curved arrow)with the diaphragm lar lateral to the quadratus lumborum (QL). Right anterior lascia is partly visualized. Left anterior lascia is obliterated \open arrows)by the swollen pancreas and considered to play a role as a barrier to inflammatory extension into the perirenal space

(b) CT scan through the renal hilus level. Lelt anterior layer (arrows)extends towards the midline, anterior to the aorta, blends with the posterior wall 01 the 3rd portion 01 the duodenum (D3). Posterior layers (arrow.

heads)luse with the lateral margin 01 the quadratus lumborum (QL)

traumatic rupture of a kidney (Fig. 6) or bilateral perirenal hemorrhage by rupture of abdominal aortic aneurysm can be explained by the presence of the anterior Gerotas fascia crossing the midl- inell,12), Kneeland et aL, discussed communication

of both perirenal fascia across the midline through a narrow channel around the great vessels behind the anterior renal fascia9). Midline continuity of anterior Gerotas fascia confines the pancreatic in- flammatory process within the anterior pararenal 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- ney is diffiωlt to see on CT scans8). When the fas미 a comes in contact with the adjacent organs, such as the pancreas or duodenum, the fascia blends with these organs and thus the fascia is not visualized on CT (Fig. 5).

Other factors, such as resolution of the scanner,

blurring caused by long scan time, or lack of peri-

Fig. 6. CT scan of a patient with left renal trauma Contrast media leaks into the anteromedial part of the left perirenal space (arrows) and extends towards the midline (open arrow) anterior to the aorta (A). U=Ureter

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- Jae Hoon Lim. et a1.: Medial Extent 01 the Anterior Gerotas 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 visualization of the anterior layer in spite of the fact that the anterior layers do exist and fuse each other in the midline.

Another factor to be borne in mind as well is individual variation of anatomy occurring from pa- tient to patient and level to level. In fact, it is difficult to generalize these great variation of the retroperitoneal fascial anatomy, and simple dia- gram for this complicated anatomy will undou- btedly have its intrinsic weakness. However, gen- eral conclusion can be drawn from CT study by observing the well visualized normal or patholo- gically thickened Gerota’s fascia and this is the basis of our report.

In conclusion, the anterior layer of Gerotas fas- cia fuses with the contralateral layer (Fig. 7), at least at the renal hilus level and more or less similar in the lower level. Above this level the fascia disappears

,

and probably blends with the posterior parietal peritoneum, or adjacent organs.

Fig. 7. Schematic drawing of Gerotas fascia a:t the renal hilus level showing fusion of the right and left anterior layers (AG)across the midl- ine. Note the lusion 01 the posterior layer (PG)with the lateral margin 01 the quadratus lumborum (Q). A=Aorta. V=Inlerior vena ca- va. K=Kidney, P=Psoas, TF=Transversalis lascia

Acknowledgments: The authors with to their thanks to Dr Stephen J Golding

,

The Churchill Hospital, Oxford, for his kind permission to inclu- de his cases.

REFERENCES

l. Gerota D. Beiträge zur Kenntnis des Befestigun gsapparates der Niere. Archives für Anatomie und Entwickelungsgeschichte. Anat Abteil 19.'265-285, 1895

2. Congdon ED, Edson JN. The cone of renal fascia in the adu1t white male. Anat Rec 80:289-305, 1941 3. Mitchell GAG. The renal fascia. Br ] Surg

37.257-266, 1950

4. Tobin CE. The renal fascfa and its relation to the transversaJis fascia. Anat Rec 89:295-310. 1944 5. Meyers MA. Dynamic radiology 01 the abdomen

normal and pathologic anatomy, 3rd ed. 180-185, 257, Springer-Verlag, New York 1988

6_ Love L, Meyers MA, Churchill RJ, et al. Computed tomography of extraperitoneal spaces. A]R 136.781-789, 1981

7. Feldberg MAM. Computed tomography 01 the re- troperitoneum: an anatomical and pathological atlas with emphasis on the fascial planes. 15-31,4-46,60, Martinus Nijhoff, Dordrecht 1983

8. Lim JH, Yoon Y, Lee SW, et al. Superior 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 communication across midJine. Radiology 164:657-664, 1987

10. Feldberg MAM, Koehler PR, van Waes PFGM Psoas compartment disease studied by computed tomography: analysis of 50 cases and subject revi- ew. Radiology 148;505-512, 1983

1l. Somogyi J, Cohen WN, Omar MM, et al. Com munication of right and left perirenal spaces demon strated by computed tomography. ] Comput Assist Tomogr 3:270-273, 1979

12. Rosen A, Korobkin M, Silverman PM, et al. CT diagnosis of ruptured abdominal aortic aneurysm A]R 143.265-268, 1984

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수치

Table  1.  Medial  extent  of  anterior  layer  of  Gero- Gero-ta’ s  fascia  at  the  level  of  the  hilus  of
Fig.  3.  Spontaneous  perirenal  hernorrhage  in  a patient  with  hypernephrorna.  Non-enh anced  scan
Fig.  5.  Phlegmonous  pancrea titis  showing med ial  ext.

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