Surgical 2
Surg Radiol Anat (1992) 14 : 209-213
Radiologlc Anatomy
Journal of Clinical Anatomy
© Springer-Verlag 1992
Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
O Cussenot 1,2, F Desgrandchamps 1, P Oilier3, P Teillac 1 and A L e Duc 1 t Service d'Urologie, H6pital Saint Louis, 1, avenue Claude Vellefanx, F-75010 Paris, France 2Laboratoire d'Anatomie, Facult6 de M6decine Lariboisi~re-Saint Louis, UER Biom6dicale des Saints P~res, 45, rue des Saints P~res, F-75006 Paris, France 3Service de Radiologie, H6pital Saint Louis, 1, avenue Claude Vellefaux, F-75019 Paris, France
Summary. Horseshoe kidney is a renal fusion which combines three anatomic abnormalities: ectopia, malrotation and vascular changes. These anomalies can be recognised separately to varying degrees in unfused kidneys. Necessary modifications of the standard technique for percutaneous nephrolithotomy (PNL) are directly deducible from analysis of the anatomic data of the imaging of horseshoe kidneys. We report our e x p e r i e n c e with 5 patients (7 kidneys) who underwent PNL for calculi in horseshoe kidneys. The percutaneous approach was performed under ultrasound and fluoroscopic monitoring. In situ disintegration by ultrasonic lithotripsy and nephrostomy drainage were necessary in all cases. Modifi-
Work presented at the 1st European Association of Clinical Anatomy congress, Brussels, Belgium, September 9-10, 1991 Offprint requests : 0 Cussenot, Laboratoire d'Anatomie, UER Biomddical des Saints P6res, 45, rue des Saints P~res, F-75006 Paris
cations of the standard PNL procedure are related to the anatomic changes. The lower abdominal position of a horseshoe kidney necessitates upper or middle calyceal puncture, while the malrotation necessitates a more posterior puncture. Monitoring of the puncture needle by fluoroscopy as it is advanced postero-anteriorly is more difficult and the risk of the surgeon's hand entering the radiation path is increased. The renal pelvis is deep and a long endoscope may be required. Aberrant segmental vessels may create potential hazards. The majority of problems in location can be avoided by use of an ultrasonically guided needle. Percutaneous nephrolithotomy is the treatment of choice for calculi in horseshoe kidneys for the following reasons: the high incidence of recurrent lithiasis in horseshoe kidney and the complexity of repeated surgical approaches diminish the acceptable results of open surgery; difficulties in focussing on the calculi and drainage problems militate against the success of extracorporeal shock wave lithotfip-
sy (ESWL); PNL has a good success rate and the least morbidity.
Bases anatomiques de la chirurgie percutan~e des calculs sur rein en fer ~ cheval R~sum6. Le rein en fer 5 cheval est la malformation reconnue comme la fusion du p61e inf6rieur des reins. Toutefois, elle associe h des degr6s divers trois types d'anomalies anatomiques qui peuvent ~tre reconnues sur des reins non fusionn~s (ectopie, malrotation et vascularisation anormale), Ces modifications observ6es sur des reins en fer h cheval compliqu6s de calculs n6cessitent une adaptation de la t e c h n i q u e de ndphrolithotomie percutan6e directement d~duites des corr61ations radio-anatomiques. Une 6tude r6fl6chie de l'approche percutan6e des reins en fer ?a cheval permet ainsi, une mod61isation des adaptations possibles d'une technique op6ratoire au status anatomique observ6 darts diverses anomalies r6nales. Nous rapportons ici notre exp6rience chez
210
cinq patients (7 reins) traitts pour des calculs sur rein en fer ~ cheval. Les modifications apporttes ~t la technique standard de ntphrolithotomie percutante ont 6t6 principalement une ponction dorsale et une entrte par les calices suptrieurs ou moyen en raison de la malrotation et de ta situation abdominale basse du rein. A condition d'adaptater le geste optratoire ~t une bonne analyse morphologique, la nEphrolithotomie percutante nous semble le traitement de choix des calculs sur rein en fer ~t cheval en raison de la frtquence des interventions pour rtcidives lithiasiques sur ce type de malformation et des anomalies du drainage du syst~me pytlocaliciel qui e x p l i q u e n t les 6checs de la lithotritie extracorporelle.
Key words : Horseshoe kidney - Percutaneous surgery - - Lithiasis - - Renal malformations
Horseshoe kidney is one of the commoner renal malformations. It was first described, from autopsy, by De Carpi in 1521. Its radiographic features were described in urographic films by Gutierrez in 1934 and include o b l i t e r a t i o n o f the lower poles of the kidneys, caudal convergence of the axes of the kidneys in the nephrographic stage, calyces which are usually normal in number but wrongly orientated in the secretory stage and pelves in medial position with malrotation and high insertion of the ureters. The estimated incidence of this malformation varies with different autopsy and radioclinical series. The incidence in the general population is from 0.155% to 0.25%. A horseshoe kidney is found in 1/710 autopsies and 1/1500 births [10, 17]. The sex ratio of this malformation is 2 : 1 for males : females.
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
The urologic anomalies associated with horseshoe kidney are assessed by Boatman as 33% (4% of hypospadias or cryptorchidism, 7% of uterovaginal malformations) [5]. Certain chromosomal aberrations are often seen. Thus, 20% of trisomies 21 and 18 and 60% of cases of Turner's syndrome have a horseshoe kidney. The ureteric duplication found in 10% of horseshoe kidneys is no commoner than that seen in normally shaped and situated kidneys. The frequency of clinical manifestations is mainly associated with pelviureteric obstruction and with lithiasis, resulting in a not unusual surgical pathology (10% are s y m p t o m a t i c from childhood). The principal complication of horseshoe kidney is lithiasis (16% to 60%) [10, 16, 19]. The promoting factors are stasis and infection (27% to 41% of horseshoe kidneys are
complicated by infection) [t0, 12, 19] attributable to an anomaly of the pelviureteric junction, which is placed too cranially and often obstructed (15% of true hydronephroses) [7]. Open surgery for horseshoe kidney is difficult because of the position and particular arrangement of these malformed kidneys. Though the periphery of the kidneys can be accessed through the loin, renal mobilisation, vascular control, exposure of the isthmus or the pelviuretetic junction or of bilateral pathology all often require a transperitoneal approach of varying difficulty, particularly after repeated surgery [6, 20]. Developments in endourologic techniques, from percutaneous surgery to extracorporeal lithotripsy, have accelerated progress in the treatment of the renal lithiasis [13, 14]. The techniques of percutaneous surgery applied to renal lithiasis are
Table 1. Summary of clinical findings and procedures Synopsis des observations
previous pa~ents surgery n° interventions anttrieures
residual (size ram) calcul residueli (taille en turn)
procedures
calculi calculs
techniques PNL
1
1X NP PNL SURG
2
ESWL
PNL
LEC
NP
0 NP
CHIR
PNL
PNL
PNL
PNL
NP
NP
NP
NP
4X R
L
PNL
NP R
L
PNL Ib,.._
ESWL
NP
LEC
5 mm
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
Intravenous urography showing a horseshoe kidney. This illustrates the difficulty of percutaneous access to the inferior calyces related to the isthmus because of their medial and juxtaspinal position Urographie intraveineuse montrant un rein e n f e r ~ cheval. Elle illustre la difficult6 de l'acc6s percutan6 des calices inffrieurs annex6s h l'isthme, de part leur situation m6diale et juxta-rachidienne
2t 1
well established and correspond to anatomic bases and to a precise strategy which must be related to the anatomy of the kidney and the parameters of the lithiasis to be treated (number of stones, topography, structure). The horseshoe kidney is an anomaly whose anatomic features impose technical modifications on percutaneous surgery which are directly linked to the structural findings. In fact, the horseshoe kidney comprises virtually constantly anatomic variations of three types : anomalies of position, anomalies of the pelviureteric system and vascular anomalies. This constitutes an important instance of adaptation of a percutaneous surgical technique to the renal anatomic variations since these three types of anomaly encountered in horseshoe kidney may be found separately and to a lesser degree in kidneys which are not fused and without stones.
urinary calculi. The clinical findings are summarised in Table 1. The imaging of the urinary apparatus for the three most recent cases included CT study in addition to routine urography and ultrasaonography (Fig. 1). It is not essential to make axial CT scans since puncture is made in an oblique coronal plane passing upward, forward and medially, depending on the axis of the calyceal stem chosen (Fig. 3), under ultrasonic and fluoroscopic monitoring after retrograde opacification of the pelvi-calyceal cavities. The CT sections obtained in horseshoe kidneys compared with those of normal kidneys illustrate the particular orientation of these malformed organs and show a reduction of the angulation of the catyceat stems in relation to the axis of the renal pelvis in the horizontal plane (Fig. 2).
Material and methods
Anatomic features of horseshoe kidney and implications for the technique of percutaneous nephrolithotomy.
Five patients with a horseshoe kidney were investigated and treated for
Discussion
Fig. 2a,b Diagram of an axial CT section of the abdomen passing through the kidneys and showing the different angles of percutaneous approach for normal kidneys (a) and horseshoe kidneys (b) Sch6ma d'une coupe axiale de l'abdomen (en TDM) passant par les reins et montrant les angles d'attaque percutan6s diff6reuts pour des reins normaux (a) et pour un rein enfer ~tcheval (b)
212
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
This requires a virtually perfect approach to the target of the intrarenal stone since, because of the limited renal mobility, errors in siting the calyceal port of entry cannot be corrected [13, 14]. The usually low position of horseshoe kidneys calls for penetration via the superior or middle calyceal systems if one is not to be hampered by the edge of the iliac crest during m a n e u v e r s to grasp the stone. Access for puncture of the lower calyces is usually hardly possible [11, 18].
The pelvicalyceal system
Fig. 3a,b Diagram showing the different access to normal kidneys (a) and horseshoe kidneys (b) to allow for the malrotation of the pelvicalyceal system and the more caudal abdominal position of horseshoe kidney Schrma montrant t'acc~s percutan6 diffrrent des reins normaux (a) et d'un rein en fer h cheval (b), en tenant compte de la malrotation du systrme pydlocaliciel et de la situation abdominale plus caudale du rein en fer h cheval
Position and relations Horsehoe kidney accounts for the majority of renal fusions. It results, embryologically, from a fusion of the two inferior poles of the metanephrotic blastemes preventing the ascent and rotation on their longitudinal axes of the renal rudiments. Inverted horseshoe kidneys with fusion of the two upper poles are very rare (5% of renal fusions). Horsehoe kidney is also related to the sigmoid kidney where the isthmus joins the upper and lower poles of the two kidneys. Usually, the isthmus consists of renal parenchyma with its own arterial system [4, 10]. Sometimes it is reduced to a simple fibrous bridge. It is situated at the level of the 3rd or 4th lumbar vertebra, always under the origin of the inferior mesenteric artery, which restricts ascent of the horseshoe kid-
ney during ontogenesis. Sometimes it is lower, in the pelvis or at the sacral promontory, due to complete failure of ascent of the metanephic rudiments. Horsehoe kidney may present in two different forms. The fusion of the renal rudiments may be lateral, with one kidney horizontal and one vertical, or it may be median with a more or less broad isthmus. The horseshoe kidney forms a block fixed to the anterior aspect of the spine. It is much less mobile than a normal kidney and therefore puncture of the cavities is often easy as the kidney has no tendency to escape from the pressure of the needle. Maneuvers to mobilise the kidney in the frontal and sagittal planes by means of the rigid nephroscope to determine its position in the cavities should be limited and cautious in order to avoid parenchymal rupture.
Horsehoe kidney always exhibits an absence of axial rotation, with the bases of the calyces posterior and the pelvis anterior, often associated with a high pelviureteric junction.In lateral fusions, one of the two pelvicalyceal systems draining the renal tissue crosses the midline, while the pelvis of the vertical kidney is medialised and that of the horizontal kidney lateralised in relation to the spinal axis. In median fusion, the more the pelves are medialised the narrower the isthmus. These anatomic concepts are essential for the performance of percutaneous neplarolithotomy since, together with the position of the stones and the constant malrotation of the pelvicalyceat system, they condition the direction of renal puncture and of the ssurgical tunnel. Normally, the ideal point of skin entry is lateral, on the posterior axillary line [13, 14, 21]. For the horseshoe kidney it must be posterior, through the abdominal wall, at the lateral border of the spinal and psoas muscles. Posterior puncture avoids the risk of perforating the colon, which may complicate percutaneous surgery for normal kidneys [3]. Since the path of puncture is posterior and tangential to the Xray beam, fluoroscopic monitoring of renal puncture is more difficult and
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
exposes the surgeon's hands to irradiation if care is not taken. As the calyceal groups are posterior in relation to the plane of the renal pelvis. access to the different calyces must be made by a different tunnel for each calyx or by an endopelvic route. The pelvicalyceal space is often large enough to permit endorenal maneuvers, which may benefit from the use of a flexible endoscope to access the inferior and juxta-isthmic calyces.
do not seem to call for a special strategy in the percutaneous approach to horseshoe kidneys. During needle puncture, it is esential to detect a large vein by means of ultrasound in order to avoid serious hemorrhage during dilatation of the tunnel. Finally, one must recognise and respect the rule of papillary entry to take a parenchymo-calyceopelvic path in order not to injure a venous arch or the interlobar vessels of Bertin's column [13, 14, 22, 23].
213
9.
10.
11.
12.
13.
Vascular system Conclusion In 1925, E]sendrath stressed that the arterial supply of the horseshoe kidney is abnormal in 70% to 80% of cases [4, 6, 9]. He reported on 132 cases collected from the literature and 3 personal cases, with the following findings: a solitary artery (0.7%), one artery for each kidney (19%), one artery for each kidney and one for the isthmus (29%), two arteries for each kidney and one for the isthmus (18%), two arteries for each kidney and one or two for the isthmus derived from the iliac a. (14%), or 6 to 8 arteries from the aorta or iliac aa. (19%) [9]. The ectopic origin of the arteries supplying a horseshoe kidney is very variable, particularly as regards the origin of the accessory vessels supplying the isthmus (lumbar aa., common, external or internal iliac aa., mesenteric aa., celiac trunk of its branches, median sacral a.) [1, 15]. As to venous drainage, great variations have been observed in the origin, number and size of the the veins. Venous return to the inferior vena cava or the iliac veins by aberrant veins may be found [2]. Cases of a retroaortic left renal vein and of an aberrant gonadal vein attached to the lateral border of the right kidney before joining the inferior vena cava h a v e been r e p o r t e d [18]. T h e s e chance variations may complicate percutaneous approach to the kidney. However, the vascular variants
14.
Horseshoe kidney is a malformation likely to be complicated by lithiasis. The treatment of renal calculi has advanced in recent years thanks to the techniques of endourology and extracorporeal lithotripsy. These are applicable to hqrseshoe kidneys provided due respect is paid to the conditions imposed by the special anatomic fe..ares of these malformed kidneys.
References 1.
2.
3.
4.
5.
6.
7.
8.
Adachi B (1929) Das Arteriensystem der Japaner, Bd. 2. Kyoto Marunzen, pp 8788 Baskin LS, Floth A, Stoller ML (1989) The horseshoe kidney: therapeutic considerations with urolithiasis. J Endourology 3 : 51-58 Benoit G, Patriarche C, Delmas V, Jardin A (1985) Anatomie topographique des tiges calicielles: te risque colique. Ann Urol 3 : 190-192 Boatman D, Comell S (1971) The arterial supply of horseshoe kidney. J Radiol 113 : 447-451 Boatman DL, Kolln CF, F l o c k s RH (1972) Congenital anomalies associated with horseshoe kidney. J Urol 107 : 205207 Csontai A, Liptak J, Gaizler Gy, Tanko A, Lantos I (1978) Horseshoe kidney and its therapeutic problems (a review of seventy-one clinical cases). Int Urol Nephrol 10 : 93-101 Culp OS, Winterringer JR (1955) Surgical treatment of horseshoe kidney: comparison of results after various types of operations. J Uro173 : 747-756 Dahlen CP, Schlumberger FC (1957)
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
Surgery of the diseased horseshoe kidney. Am J Surg 93 : 405-409 Eisedrath DN, Phifer FM, Culver HB (1925) Horseshoe kidney. Ann Surg 82 : 735-764 Glenn JF (1959) Analysis of 51 patients with horseshoe kidney. N Engl Med 261 : 684-687 Jones DJ, Wickham JEA, Kellett MJ (1991) Percutaneous nephrolithotomy for calculi in horseshoe kidneys. J Urot 145 : 481-483 Kolln CF, Boatman DL, Schmidt JD, Flocks RH (1972) Horseshoe kidney. A review of 105 patients. J Urol 107 : 203204 Le Duc A (1986) La ndphrolithotomie percutan6e: perspectives d'avenir. Ann Urol 6 : 376-380 Le Duc A (1991) Les complications imm6diates de la chirurgie percutan6e du rein. Progr~s en Urologie 1 : 31-35 Lippert H, Pabst R (1985) Arterial variations in man. J.F. Bergmann-Verlag, Mtinchen, pp 26-27 Mottola A, Selli C (1984) Lithiasis in horseshoe kidney. Acta Urol Belg 52 : 355-360 Nation EF (1945) Horseshoe kidney, a study of thirty-two autopsy and nine surgical cases. J Urol 53 : 762-770 Peartree RJ, Ruotolo RA, Khuri FJ, Valva JR, (1986) Percutaneons stone removal in horseshoe kidney. Urology 28 : 41-43 Pitts WR, Muecke EC (1975) Horseshoe kidney: 40 years of experience. J Urol 113 : 743-746 Proca E (1981) Anterior transperitoneat approach for stone removal in horseshoe kidney (its advantage for bilateral stones). Br J Urol 53 : 201-205 Sampaio FJB, Mandarim de Lacerda CA (1988) 3-Dimensional and radiological pelviocaliceal anatomy for endnurology. J Urol 140 : 1352-1355 Sampaio FJB, Aragao AHM (1990) Anatomical relationship between the renal venous arrangement and the kidney collecting system. J Urol 144 : 1089-1093 Sampaio FJB, Aragao AHM (1990) Anatomical relationship between the intrarenal arteries and the kidney collecting system. J Urol 143 : 679-681 Segttra JW, Kelatis PP, Burke EC (1972) Horseshoe kidney in children. J Urol 108 : 333-336 Wilson C, Azmy AF (1986) Horseshoe kidney in children. Br J Urol 58 : 361363
Received November 20, 1991~Accepted in final form April 6, 1992
Surg Radiol Anat (1992) 14 : 209-213
Radiologlc Anatomy
Journal of Clinical Anatomy
© Springer-Verlag 1992
Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
O Cussenot 1,2, F Desgrandchamps 1, P Oilier3, P Teillac 1 and A L e Duc 1 t Service d'Urologie, H6pital Saint Louis, 1, avenue Claude Vellefanx, F-75010 Paris, France 2Laboratoire d'Anatomie, Facult6 de M6decine Lariboisi~re-Saint Louis, UER Biom6dicale des Saints P~res, 45, rue des Saints P~res, F-75006 Paris, France 3Service de Radiologie, H6pital Saint Louis, 1, avenue Claude Vellefaux, F-75019 Paris, France
Summary. Horseshoe kidney is a renal fusion which combines three anatomic abnormalities: ectopia, malrotation and vascular changes. These anomalies can be recognised separately to varying degrees in unfused kidneys. Necessary modifications of the standard technique for percutaneous nephrolithotomy (PNL) are directly deducible from analysis of the anatomic data of the imaging of horseshoe kidneys. We report our e x p e r i e n c e with 5 patients (7 kidneys) who underwent PNL for calculi in horseshoe kidneys. The percutaneous approach was performed under ultrasound and fluoroscopic monitoring. In situ disintegration by ultrasonic lithotripsy and nephrostomy drainage were necessary in all cases. Modifi-
Work presented at the 1st European Association of Clinical Anatomy congress, Brussels, Belgium, September 9-10, 1991 Offprint requests : 0 Cussenot, Laboratoire d'Anatomie, UER Biomddical des Saints P6res, 45, rue des Saints P~res, F-75006 Paris
cations of the standard PNL procedure are related to the anatomic changes. The lower abdominal position of a horseshoe kidney necessitates upper or middle calyceal puncture, while the malrotation necessitates a more posterior puncture. Monitoring of the puncture needle by fluoroscopy as it is advanced postero-anteriorly is more difficult and the risk of the surgeon's hand entering the radiation path is increased. The renal pelvis is deep and a long endoscope may be required. Aberrant segmental vessels may create potential hazards. The majority of problems in location can be avoided by use of an ultrasonically guided needle. Percutaneous nephrolithotomy is the treatment of choice for calculi in horseshoe kidneys for the following reasons: the high incidence of recurrent lithiasis in horseshoe kidney and the complexity of repeated surgical approaches diminish the acceptable results of open surgery; difficulties in focussing on the calculi and drainage problems militate against the success of extracorporeal shock wave lithotfip-
sy (ESWL); PNL has a good success rate and the least morbidity.
Bases anatomiques de la chirurgie percutan~e des calculs sur rein en fer ~ cheval R~sum6. Le rein en fer 5 cheval est la malformation reconnue comme la fusion du p61e inf6rieur des reins. Toutefois, elle associe h des degr6s divers trois types d'anomalies anatomiques qui peuvent ~tre reconnues sur des reins non fusionn~s (ectopie, malrotation et vascularisation anormale), Ces modifications observ6es sur des reins en fer h cheval compliqu6s de calculs n6cessitent une adaptation de la t e c h n i q u e de ndphrolithotomie percutan6e directement d~duites des corr61ations radio-anatomiques. Une 6tude r6fl6chie de l'approche percutan6e des reins en fer ?a cheval permet ainsi, une mod61isation des adaptations possibles d'une technique op6ratoire au status anatomique observ6 darts diverses anomalies r6nales. Nous rapportons ici notre exp6rience chez
210
cinq patients (7 reins) traitts pour des calculs sur rein en fer ~ cheval. Les modifications apporttes ~t la technique standard de ntphrolithotomie percutante ont 6t6 principalement une ponction dorsale et une entrte par les calices suptrieurs ou moyen en raison de la malrotation et de ta situation abdominale basse du rein. A condition d'adaptater le geste optratoire ~t une bonne analyse morphologique, la nEphrolithotomie percutante nous semble le traitement de choix des calculs sur rein en fer ~t cheval en raison de la frtquence des interventions pour rtcidives lithiasiques sur ce type de malformation et des anomalies du drainage du syst~me pytlocaliciel qui e x p l i q u e n t les 6checs de la lithotritie extracorporelle.
Key words : Horseshoe kidney - Percutaneous surgery - - Lithiasis - - Renal malformations
Horseshoe kidney is one of the commoner renal malformations. It was first described, from autopsy, by De Carpi in 1521. Its radiographic features were described in urographic films by Gutierrez in 1934 and include o b l i t e r a t i o n o f the lower poles of the kidneys, caudal convergence of the axes of the kidneys in the nephrographic stage, calyces which are usually normal in number but wrongly orientated in the secretory stage and pelves in medial position with malrotation and high insertion of the ureters. The estimated incidence of this malformation varies with different autopsy and radioclinical series. The incidence in the general population is from 0.155% to 0.25%. A horseshoe kidney is found in 1/710 autopsies and 1/1500 births [10, 17]. The sex ratio of this malformation is 2 : 1 for males : females.
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
The urologic anomalies associated with horseshoe kidney are assessed by Boatman as 33% (4% of hypospadias or cryptorchidism, 7% of uterovaginal malformations) [5]. Certain chromosomal aberrations are often seen. Thus, 20% of trisomies 21 and 18 and 60% of cases of Turner's syndrome have a horseshoe kidney. The ureteric duplication found in 10% of horseshoe kidneys is no commoner than that seen in normally shaped and situated kidneys. The frequency of clinical manifestations is mainly associated with pelviureteric obstruction and with lithiasis, resulting in a not unusual surgical pathology (10% are s y m p t o m a t i c from childhood). The principal complication of horseshoe kidney is lithiasis (16% to 60%) [10, 16, 19]. The promoting factors are stasis and infection (27% to 41% of horseshoe kidneys are
complicated by infection) [t0, 12, 19] attributable to an anomaly of the pelviureteric junction, which is placed too cranially and often obstructed (15% of true hydronephroses) [7]. Open surgery for horseshoe kidney is difficult because of the position and particular arrangement of these malformed kidneys. Though the periphery of the kidneys can be accessed through the loin, renal mobilisation, vascular control, exposure of the isthmus or the pelviuretetic junction or of bilateral pathology all often require a transperitoneal approach of varying difficulty, particularly after repeated surgery [6, 20]. Developments in endourologic techniques, from percutaneous surgery to extracorporeal lithotripsy, have accelerated progress in the treatment of the renal lithiasis [13, 14]. The techniques of percutaneous surgery applied to renal lithiasis are
Table 1. Summary of clinical findings and procedures Synopsis des observations
previous pa~ents surgery n° interventions anttrieures
residual (size ram) calcul residueli (taille en turn)
procedures
calculi calculs
techniques PNL
1
1X NP PNL SURG
2
ESWL
PNL
LEC
NP
0 NP
CHIR
PNL
PNL
PNL
PNL
NP
NP
NP
NP
4X R
L
PNL
NP R
L
PNL Ib,.._
ESWL
NP
LEC
5 mm
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
Intravenous urography showing a horseshoe kidney. This illustrates the difficulty of percutaneous access to the inferior calyces related to the isthmus because of their medial and juxtaspinal position Urographie intraveineuse montrant un rein e n f e r ~ cheval. Elle illustre la difficult6 de l'acc6s percutan6 des calices inffrieurs annex6s h l'isthme, de part leur situation m6diale et juxta-rachidienne
2t 1
well established and correspond to anatomic bases and to a precise strategy which must be related to the anatomy of the kidney and the parameters of the lithiasis to be treated (number of stones, topography, structure). The horseshoe kidney is an anomaly whose anatomic features impose technical modifications on percutaneous surgery which are directly linked to the structural findings. In fact, the horseshoe kidney comprises virtually constantly anatomic variations of three types : anomalies of position, anomalies of the pelviureteric system and vascular anomalies. This constitutes an important instance of adaptation of a percutaneous surgical technique to the renal anatomic variations since these three types of anomaly encountered in horseshoe kidney may be found separately and to a lesser degree in kidneys which are not fused and without stones.
urinary calculi. The clinical findings are summarised in Table 1. The imaging of the urinary apparatus for the three most recent cases included CT study in addition to routine urography and ultrasaonography (Fig. 1). It is not essential to make axial CT scans since puncture is made in an oblique coronal plane passing upward, forward and medially, depending on the axis of the calyceal stem chosen (Fig. 3), under ultrasonic and fluoroscopic monitoring after retrograde opacification of the pelvi-calyceal cavities. The CT sections obtained in horseshoe kidneys compared with those of normal kidneys illustrate the particular orientation of these malformed organs and show a reduction of the angulation of the catyceat stems in relation to the axis of the renal pelvis in the horizontal plane (Fig. 2).
Material and methods
Anatomic features of horseshoe kidney and implications for the technique of percutaneous nephrolithotomy.
Five patients with a horseshoe kidney were investigated and treated for
Discussion
Fig. 2a,b Diagram of an axial CT section of the abdomen passing through the kidneys and showing the different angles of percutaneous approach for normal kidneys (a) and horseshoe kidneys (b) Sch6ma d'une coupe axiale de l'abdomen (en TDM) passant par les reins et montrant les angles d'attaque percutan6s diff6reuts pour des reins normaux (a) et pour un rein enfer ~tcheval (b)
212
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
This requires a virtually perfect approach to the target of the intrarenal stone since, because of the limited renal mobility, errors in siting the calyceal port of entry cannot be corrected [13, 14]. The usually low position of horseshoe kidneys calls for penetration via the superior or middle calyceal systems if one is not to be hampered by the edge of the iliac crest during m a n e u v e r s to grasp the stone. Access for puncture of the lower calyces is usually hardly possible [11, 18].
The pelvicalyceal system
Fig. 3a,b Diagram showing the different access to normal kidneys (a) and horseshoe kidneys (b) to allow for the malrotation of the pelvicalyceal system and the more caudal abdominal position of horseshoe kidney Schrma montrant t'acc~s percutan6 diffrrent des reins normaux (a) et d'un rein en fer h cheval (b), en tenant compte de la malrotation du systrme pydlocaliciel et de la situation abdominale plus caudale du rein en fer h cheval
Position and relations Horsehoe kidney accounts for the majority of renal fusions. It results, embryologically, from a fusion of the two inferior poles of the metanephrotic blastemes preventing the ascent and rotation on their longitudinal axes of the renal rudiments. Inverted horseshoe kidneys with fusion of the two upper poles are very rare (5% of renal fusions). Horsehoe kidney is also related to the sigmoid kidney where the isthmus joins the upper and lower poles of the two kidneys. Usually, the isthmus consists of renal parenchyma with its own arterial system [4, 10]. Sometimes it is reduced to a simple fibrous bridge. It is situated at the level of the 3rd or 4th lumbar vertebra, always under the origin of the inferior mesenteric artery, which restricts ascent of the horseshoe kid-
ney during ontogenesis. Sometimes it is lower, in the pelvis or at the sacral promontory, due to complete failure of ascent of the metanephic rudiments. Horsehoe kidney may present in two different forms. The fusion of the renal rudiments may be lateral, with one kidney horizontal and one vertical, or it may be median with a more or less broad isthmus. The horseshoe kidney forms a block fixed to the anterior aspect of the spine. It is much less mobile than a normal kidney and therefore puncture of the cavities is often easy as the kidney has no tendency to escape from the pressure of the needle. Maneuvers to mobilise the kidney in the frontal and sagittal planes by means of the rigid nephroscope to determine its position in the cavities should be limited and cautious in order to avoid parenchymal rupture.
Horsehoe kidney always exhibits an absence of axial rotation, with the bases of the calyces posterior and the pelvis anterior, often associated with a high pelviureteric junction.In lateral fusions, one of the two pelvicalyceal systems draining the renal tissue crosses the midline, while the pelvis of the vertical kidney is medialised and that of the horizontal kidney lateralised in relation to the spinal axis. In median fusion, the more the pelves are medialised the narrower the isthmus. These anatomic concepts are essential for the performance of percutaneous neplarolithotomy since, together with the position of the stones and the constant malrotation of the pelvicalyceat system, they condition the direction of renal puncture and of the ssurgical tunnel. Normally, the ideal point of skin entry is lateral, on the posterior axillary line [13, 14, 21]. For the horseshoe kidney it must be posterior, through the abdominal wall, at the lateral border of the spinal and psoas muscles. Posterior puncture avoids the risk of perforating the colon, which may complicate percutaneous surgery for normal kidneys [3]. Since the path of puncture is posterior and tangential to the Xray beam, fluoroscopic monitoring of renal puncture is more difficult and
O Cussenot et al : Anatomical bases of percutaneous surgery for calculi in horseshoe kidney
exposes the surgeon's hands to irradiation if care is not taken. As the calyceal groups are posterior in relation to the plane of the renal pelvis. access to the different calyces must be made by a different tunnel for each calyx or by an endopelvic route. The pelvicalyceal space is often large enough to permit endorenal maneuvers, which may benefit from the use of a flexible endoscope to access the inferior and juxta-isthmic calyces.
do not seem to call for a special strategy in the percutaneous approach to horseshoe kidneys. During needle puncture, it is esential to detect a large vein by means of ultrasound in order to avoid serious hemorrhage during dilatation of the tunnel. Finally, one must recognise and respect the rule of papillary entry to take a parenchymo-calyceopelvic path in order not to injure a venous arch or the interlobar vessels of Bertin's column [13, 14, 22, 23].
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Vascular system Conclusion In 1925, E]sendrath stressed that the arterial supply of the horseshoe kidney is abnormal in 70% to 80% of cases [4, 6, 9]. He reported on 132 cases collected from the literature and 3 personal cases, with the following findings: a solitary artery (0.7%), one artery for each kidney (19%), one artery for each kidney and one for the isthmus (29%), two arteries for each kidney and one for the isthmus (18%), two arteries for each kidney and one or two for the isthmus derived from the iliac a. (14%), or 6 to 8 arteries from the aorta or iliac aa. (19%) [9]. The ectopic origin of the arteries supplying a horseshoe kidney is very variable, particularly as regards the origin of the accessory vessels supplying the isthmus (lumbar aa., common, external or internal iliac aa., mesenteric aa., celiac trunk of its branches, median sacral a.) [1, 15]. As to venous drainage, great variations have been observed in the origin, number and size of the the veins. Venous return to the inferior vena cava or the iliac veins by aberrant veins may be found [2]. Cases of a retroaortic left renal vein and of an aberrant gonadal vein attached to the lateral border of the right kidney before joining the inferior vena cava h a v e been r e p o r t e d [18]. T h e s e chance variations may complicate percutaneous approach to the kidney. However, the vascular variants
14.
Horseshoe kidney is a malformation likely to be complicated by lithiasis. The treatment of renal calculi has advanced in recent years thanks to the techniques of endourology and extracorporeal lithotripsy. These are applicable to hqrseshoe kidneys provided due respect is paid to the conditions imposed by the special anatomic fe..ares of these malformed kidneys.
References 1.
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Adachi B (1929) Das Arteriensystem der Japaner, Bd. 2. Kyoto Marunzen, pp 8788 Baskin LS, Floth A, Stoller ML (1989) The horseshoe kidney: therapeutic considerations with urolithiasis. J Endourology 3 : 51-58 Benoit G, Patriarche C, Delmas V, Jardin A (1985) Anatomie topographique des tiges calicielles: te risque colique. Ann Urol 3 : 190-192 Boatman D, Comell S (1971) The arterial supply of horseshoe kidney. J Radiol 113 : 447-451 Boatman DL, Kolln CF, F l o c k s RH (1972) Congenital anomalies associated with horseshoe kidney. J Urol 107 : 205207 Csontai A, Liptak J, Gaizler Gy, Tanko A, Lantos I (1978) Horseshoe kidney and its therapeutic problems (a review of seventy-one clinical cases). Int Urol Nephrol 10 : 93-101 Culp OS, Winterringer JR (1955) Surgical treatment of horseshoe kidney: comparison of results after various types of operations. J Uro173 : 747-756 Dahlen CP, Schlumberger FC (1957)
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Received November 20, 1991~Accepted in final form April 6, 1992
