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Journal of the Anatomical Society of India

Horseshoe Kidney with Extrarenal Calyces - A Case Report

Author(s): Mohanty, C; Ray, B; Samaratunga, U; Singh, G.

Vol. 51, No. 1 (2002-01 - 2002-06)

Department of Anatomy, Institute of Medical Sciences, Banaras Hindu University, Varanasi INDIA.


The present report is on horseshoe kidney with extrarenal calyces observed in a female cadaver. Two small calibre renal arteries supplied the upper segment of the organ on either side. A single accessory artery originated from the right side of the aorta and branched to supply the right and left middle segments as well as the well developed connecting bridge. All the major and few minor calyces were extrarenal on both sides. Association of extrarenal calyces and horseshoe kidney seems to have not been documented in the available literature. The anomaly could be due to a disparity resulting from slow development of the metanephric tissue or to a relatively rapid development of the ureteric bud.

Key words: horseshoe kidney, extrarenal calyces.

Introduction :

Horseshoe kidney occurs in 0.25 percent of the general population (Allen, 1951) and are seen in approximately 1 out of 300 pyelographies (Dees, 1941; Lowsley, 1952). However, horseshoe kidney with extrarenal calyces is a rare association and seems to have not been described in literature. The present report is on a case of horseshoe kidney with extrarenal calyces which the authors encountered during routine dissection.

Case Report

The anomaly was observed in an approximately forty year old female and the cause of her death could not be ascertained. The anomaly seemed to be solitary as there was no other obvious external or internal malformation including that of urogenital system. The upper poles of the kidneys were at the level of the L1 vertebra. The lower poles were fused and the connecting bridge occupied a position between L3 and L4 vertebrae. The connecting bridge was well developed measuring 46 mm in width while the maximum width of the right and the left kidneys were 33 mm and 31 mm, respectively.

The right renal artery originated from the aorta at L1 vertebral level. It was 4 mm in diameter and after 51 mm of its origin, it divided into two branches to enter the upper part of the right hilum. The left renal artery was 7 mm in diameter and immediately after its origin, it also divided into two branches. Each branch again divided into two before entering the upper part of the left hilum. An accessory renal artery originated from the right side of the abdominal aorta at the level of the upper border of L3 vertebra just above the connecting bridge. It was 8 mm in diameter and little to the right of the median plane, it divided into three branches about 13 mm from its origin. The left and the right branches entered the respective hilum while the middle one divided to supply the lower renal segments and the connecting bridge. A single renal vein drained the left side while the right side was drained by two veins.

The renal pelvis on both sides were lying anteriorly and the ureters crossed the connecting bridge on the ventral aspect. The calyceal system was bilaterally extrarenal; the pelvis, the major and minor calyces being located outside the renal parenchyma. On each side, three major calyces and few minor calyces were observed outside the renal hilum.


The calyceal system in the present case was extrarenal on both sides. As far as it could be reviewed, no case was found in literature describing association of horseshoe kidney and extrarenal calyces. The anomaly could be due to a disparity resulting from slow develpment of the metanephric tissue or to a relatively rapid development of the ureteric bud. If the ureteric bud has rapid or precocious development, the calyceal system could well develop prior to its coalescence with the nephrogenic mass. Conversely, lag in the growth of the nephrogenic mass could delay its attachment to the collecting system. permitting extrarenal development of the first or second order of the collecting system (Malament et al; 1961).

The horseshoe kidney is usually located at the level of the lower lumbar vertebrae, since its ascent is prevented by the root of the inferior mesenteric artery. As they ascend, the fusion prevents normal rotation and each renal pelvis remains anterior to the kidney. Considerable variation in the amount of functioning parenchyma at the connection is known. In the present case, the connecting bridge was quite well developed with an independent vascular supply. While situated in the pelvic cavity, horseshoe kidneys may acquire branches from the distal aorta, iliac or hypogastric arteries. The vessels may have varied origin from the aorta at the levels of the T12 to the internal iliac artery at the lower levels. The total number of vessels may vary from 4 to 7 and the vessel size from 2 mm to 8 mm (Olsson and Wholey, 1964). By means of resin casts, Graves (1969) described 6 basic patterns of blood supply to the horseshoe kidneys. In the present case, the arterial supply some-what resembled to the Graves type H-S IIb, where the upper segments of the kidney are supplied by single arteries on either side. The two lower segment arteries, instead of arising from either side of aorta, fuse to form a common trunk and arise from the anterior surface. However, the arterial arrangements of the present case had certain variations. The main renal arteries were smaller in calibre and mainly supplied the upper segments. The single accessory renal artery was quite well developed and originated from the right side of aorta. It not only supplied the lower segments and the connecting bridge but also gave a branch each to the right and left hilum. These hilar branches from the accessory artery possibly supplied the middle segments as there is no collateral circulation between the renal segments even in extremes of variations (Graves, 1969).


  1. Allen, A.C: The Kidney : Medical and Surgical Diseases, Grune & Stratton, Inc., New York: p. 94 (1951)
  2. Dees, J.E. (1941) Clinical importance of congenital anomalies of upper urinary tract. Journal of Urology, 46 : 659 666.
  3. Graves, F.T. (1969): Arterial anatomy of congenitally abnormal kidney. British Journal of Surgery, 56 : 533-541.
  4. Lowsley, O.S. (1952): Surgery of horseshoe kidney. Journal of Urology, 67. 565-578.
  5. Malament, M., Schwartz, B., Nagamatsu, G.R. (1961): Extrarenal calyces : their relationship to renal disease. American Journal of Roentgenology, 86 : 823-829.
  6. Olsson, O., Wholey, M. (1964): Vascular abnormalities in gross anomalies of kidneys. Acta Radiologica Diagnosis, 2: 420-432.

Missing Image

Fig. 1. Photograph of the dissection showing the horseshoe kidney, its vascular supply and the extrarenal calyces.

Missing Image

Fig. 2. A digrammatic representation of the photograph (Fig. 1) 1-Right renal pelvis, 2-Left renal pelvis, 3-Right renal artery, 4-Left renal artery, 5-Accessory renal artery, 6-Inferior mesenteric artery, 7-Superior mesenteric artery, 8-Coeliac trunk, 9-Inferior vena cava, 10-Right renal vein, 11-Left renal vein, 12-Accessory renal vin, 13-Abdominal aorta, 14-Right common iliac artery, 15-Left common iliac artery.

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