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Journal of the Anatomical Society of India

Pelvi-Caliceal System In Foetal And Adult Human Kidneys

Author(s): Ningthoujam DD, Chongtham RD & Sinam SS.

Vol. 54, No. 1 (2005-01 - 2005-03)

RIMS, Lamphelpat, Imphal, Manipur.


Kidneys from 40 human foetuses of different age groups and 10 adult kidneys were studied to see the pelvicaliceal anatomy. Meticulous dissection was done specifically to see the pelvis, major and minor calices both in foetal and adult kidneys. Tracing and maping of renal and pelvicaliceal outline from 100 IVU films were also done. Foetal kidneys exhibit different forms of surface lobulation. The number of minor calices in both the upper and lower major calices ranges from 3 to 5 while it was 2 to 4 in the middle calyx when present. Although the anterior and posterior divisions were evident in the upper and lower major calyx, it was most marked and consistent in the middle calyx. The pelvicaliceal anatomy was not the same in the two kidneys of the same individual. The pattern seen in the present study is triangular or tricaliceal (40% in foetus and 51% in the adult), bicaliceal or Y shaped (20% in foetus and 22% in adult) and radiate or multicaliceal (30% in foetus and 15% in adult). There is also variation in each subgroup depending on the length of the infundibulum, direction of the major and minor calices and angle between the pelvis and the ureter. The other types noticed are: absence of pelvis, scanty minor calices, orchid type, etc. The in-depth knowledge of pelvicaliceal anatomy will be of immense value to the clinicians of related specialities .

Key-words: Kidney, minor calyx, major calyx, pelvis, ureter, pelvicalceal system, IVU.


Variations of the collecting system and developmental anomalies of kidney are numerous. The variations in the gross structure of the renal collecting system are probably as numerous as there are individuals and thus can be liked to fingerprints. The bilateral collecting systems present in any single individual are often similar but are rarely identical and not uncommonly, may be quite different even from one another. Not only do the numbers and position of the minor calices vary between the individuals, but their infundibula may be absent or extremely elongated. The number of minor calices varies from 5 to 20 but usually there are 8 to 9 minor calices in adult as reported by Harrison (1972) and 7 to 8 as claimed by Dyson M (1995) and Hollinshead (1975). The minor calices terminate in 2 or 3 major calices which in turn open into the renal pelvis.

According to Sykes (1963), the minor calices in the foetal kidney divide into anterior and posterior divisions although they may be fused in the upper and lower parts of the kidney. Such divisions always persist in the middle or hilar part. He also observed that calices are arranged in three pairs facing cranially in the upper pole, in two pairs facing laterally in the midzone and again in two pairs facing caudally in the lower pole. Gradual fusion of these calices takes place maximally in the upper pole and minimally in the lower pole during the last trimester of pregnancy thus attaining the adult pattern. Fine and Keen (1966) reported the presence of two major calices in majority of cases and also the presence of third major calyx. Edwards et al (1975) described that the renal pelvis are of two types: intrarenal and extrarenal. Anson and McVay (1971) pointed out that the extrarenal type of pelvis is larger than the intrarenal type which is small and lies within the renal sinus. Bruce et al (1967) highlighted that the renal pelvis may lie partly inside and partly outside the renal sinus. Occasinally a pelvis cannot be demonstrated, the ureter dividing into calices. Kabalin(1992) reported that renal pelvis may sometimes be of same calibre as the ureter itself. Didio (1970) described two types of renal pelvis; brachy type where the major calices are usually long and end in a small renal pelvis; and the long type where the major calices are usually short and end in a large renal pelvis.

Graves (1986) classified the pelvicaliceal arrangement into two primary and two intermediate types based on shape of the pelvis and also on the prominence of the calices. Intermediate gradations are also described between these two types. Type A is the classic Y shape, type B the inverted T, type C the balloon and type D the inverted bagpipes. Sampaio (1993) classified the arrangement of pelvicaliceal pattern into two main groups A and B which are subdivided into A-I, A-II, B-I and B-II. In group A-I, a major calyx from the superior and inferior pole represents the primary divisions of the renal pelvis and midzone drainage is provided by minor calices draining to the upper and lower major calices radially. In A-II these two calices draining the midzone cross each other. In type B-I there are a group of minor calices draining into a middle major calyx whereas in type BII there are multiple minor calices draining the midzone and joining the renal pelvis at different points.

Material and Methods:

The material examined consisted of both foetal and adult kidneys and 100 selected films (200 renal units) of intravenous urogram (IVU). A total of 100 kidneys were dissected and studied. Of these, 80 were of fetuses and 20 belonged to adult. Youngest foetus in the series was of 9 weeks and the oldest was at term. The gestational age were calculated from the menstrual history and crown-rump length. The fetuses were fixed in neutral formalin for 15 days and then dissection was carried out. First the psoas major muscle was identified then the pelvis and ureter were found partly in front of and just medial to it. The ureter was divided at the upper and mid ureteric junction and the kidneys were removed. The shape, position of the hilum and surface lobulation of the kidneys were examined. The renal pelvis was also examined to find out if it was extrarenal or intrarenal. The renal vessels and loose areolar tissues from both the anterior and posterior surfaces of the pelvis were also removed and cleaned. The pelvis was further traced to reach the major and minor calices. The branching pattern of the major and minor calices and their corresponding cap of cortical tissues were delineated.

Further 100 IVU films mostly normal and slightly obstructed renal units were also chosen for the same study. Images of the renal and pelvicaliceal outline were traced to get the outline of kidney, ureter and pelvicaliceal system.


Shape and size: In its most early stage kidney is round or oval shaped and as age advances it assumes gradually its reniform shape (bean shaped). At term it reaches about one tenth of the adult size (Fig 1).

Surface: At 10 weeks the renal surface is smooth and no lobulation is seen yet. As age advances, the surface lobulation is seen at first as faint lines around 14 weeks become more definite at 32-34 wks, becoming less prominent again as it approaches term. Pattern of surface lobulation is very variable such as larger triangular, rectangular or polygonal lobules. Small and numerous irregular lobules also exist looking like a mulberry (Fig. 2). Around term, the lobules number about 13 or 14. Hilum : In the foetal period the hilum is seen better on the anterior surface rather than on the medial border. Only at about term the hilum is seen as an indentation along the medial border (Fig 1.D).

Axis: During foetal period the two developing kidneys are disposed vertically, the two lower poles being nearer than in the adult and sometimes lie over the ureter. Gradually the axis changes and the two lower poles become more separated as in the adult only near the term (Fig. 3).

Pelvicaliceal System:

The pelvis, the upper expanded end of the ureter, shows different shapes depending on the number of major calices draining into it and the angle it makes with the ureter: Triangular or tricaliceal (40 percent), Radiate or multicaliceal (30 percent) and Y-shaped or Bicaliceal (20 percent) and some unusual forms (10 percent) (Fig. 4). The number of minor calices ranges from 8 to 18 (Mode=14).

  • (a) Multicaliceal or Radiate type (30 %)- the pelvis is biggest in this category and is characterised by the presence of upper and lower major calices with three or more minor calices draining independently into the pelvis between the two. In this category no distinct anterior and posterior divisions of middle calyx is seen. Infundibula of the minor calices are so short that they open directly into the pelvis. In such cases renal tissues drained by these minor calices are inseparable (Fig. 5).
  • (b) Triangular type or Tricaliceal (40 %)- the infundibulum is longer and resemble the stalk of a cauliflower. Pelvic space is moderate in size. Three major calices - superior, middle and inferior, formed by the fusion respective minor calices open into it. This is the commonest type of renal pelvis. The position of the middle calyx is variable; sometimes located close to the upper calyx and at others closer to the lower calyx. The three calices are usually of the same size. But in one-fifth of the tricaliceal the upper major calyx was seen as a long thin infundibulum in contrast to the short middle and lower calices (Fig. 6).
  • (c) Y-shaped pelvis or Bicaliceal (20 %): The pelvic capacity is devoid of any room with long caliceal infundibuli. The pelvis is formed by the convergence of two major calices- the upper and lower, which may or may not be symmetrical and the middle calyx is absent. There are different categories in this type also.
  • (i) The classical Y shape or symmetrical where the two stems of the Y are symmetrical and each stem (calyx) receiving 4 to 5 minor calices from the respective upper and lower zone .In this type the mid-zone is drained by calices which drain into either the upper or lower calyx(Fig.7,A). (ii) Asymmetrical type in which one of the two infundibuli is much longer and more dominant(Fig 7,B). Cross drainage i.e. the minor calyx from the lower zone may drain into the upper major calyx or vice versa occurred in 5% of cases.

Patterns that do not fit into these three patterns constituted 10 percent. They were middle major calyx draining directly to the ureter and the pelvis looking like direct continuation of the middle calyx; infundibula or the major calices forming the pelvis appear to be two only in anterior view and three in posterior view; the middle calyx infundibulum may be so short and drain directly on the anterior surface of the pelvis or extreme cross drainage from the opposite poles. In one case, a small portion of the anterior surface of the kidney drained into the stem of the middle calyx (Fig 8).

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Fig. 1: Photograph of kidneys 14 wks to 24 wks showing size and shapes.

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Fig. 2 : Photographs of kidneys in situ. Note the difference in the axes between A & B (parallel axis) and C (oblique).

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Fig. 3: Photograph of kidneys (foetal) showing various types of lobulations at different age periods.

Pelvi-Caliceal System In Foetal And Adult Human Kidneys : Ningthoujam DD et al.

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Fig. 4: Schematic diagram of various shapes of pelvis

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Fig. 5: Photograph of Multicaliceal or Radiate pelvis. A- Fig. 7 : Photographs of Bicaliceal or Y-shaped pelvis fromAdult kidney, B-Foetal kidney. adult kidney A-Asymmetrical and Intrarenal, B-Symmetrical & extrarenal.

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Fig. 6: Photograph of Tricaliceal or Triangular pelvis A-Adult kidney, B-Foetal kidney.

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Fig. 7 : Photographs of Bicaliceal or Y-shaped pelvis from adult kidney A-Asymmetrical and Intrarenal, B-Symmetrical and extrarenal.

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Fig. 8: Photograps of uncommon pelvicalical pattern in adult A-Early division of pelvis into calices; lower calyx drainingthe midzone also. B-Middle calyx in line with the ureter; uppr and lower calices joining it at right angles to form thepelvis. C-Dominant lower calyx; note the same size of pelvis and lower calyx.

Tricaliceal pattern is the most numerous followed by multicaliceal, bicaliceal and others in that order (Table I).

IVU study findings:

The IVU tracings and direct study of the films reveal patterns similar to those found in the specimens. The pelvis is found to be more roomy when extrarenal than intrarenal (Fig. 9,A&B). The pelvis can be classified depending upon the number of major calices which drain into the pelvis, as bicaliceal (Y-shaped) in 22%, tricaliceal (triangular) in 51%, and multicaliceal (radiate) in 15% and other uncommon types (12%) compared to 20%, 40%, 30% and 10% respectively in the specimen (Fig. 10 & Table I). The change indicates that 50% of multicaliceal pattern in foetal kidneys matured into mostly tricaliceal pattern. The shape and size of the pelvis is determined by the length and number of major calices. In bicaliceal type, the shape of the pelvis varies from the absence of pelvis (predominantly intrarenal) to large extrarenal pelves and the midzone of the renal parynchyma is drained either to the upper or lower calyx.

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Fig. 9: Intrarenal (A) & Extrarenal (B) Pelvis as seen in IUV. Note the roomy pelvis in (B) in contrast to the small pelvis in (A).

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Fig. 10: Different types of common pelvicaliceal pattern as seen in IVU. (A) Bicaliceal or Y-shaped, (B) Tricaliceal or Traiangular, (C) Multicaliceal or Radiate.

Table - I In tricaliceal pattern there is an additional middle

No. of foetal kidneys studied by dissection=80 No. of renal units studied by IVU=200
Pattern observed In Foetal Kidneys In Adult IVU
No. % No. %
Tricaliceal 32 40 102 51
Bicaliceal 16 20 44 22
Multicaliceal or Radiate 24 30 30 15
Others 8 10 24 12

major calyx between the upper and lower calices. The middle calyx may be closer to either the upper or lower major calyx or may look like a part of either of the two. The infundibula are short when the pelvis is intrarenal and long when extrarenal. In multicaliceal type there are two or three independent calices draining directly into the renal pelvis between the upper and lower major calices (Fig. 11). The uncommon forms includes the pelvis with absent calices in 4 or all minor calices springing directly from the renal pelvis in 8, megacalices in 4 and drooping lower major calyx (“orchid” calices) in 8 (Fig 12).

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Fig. 11: Different subtypes of Bicaliceal (A), Tricaliceal (B), and Multicaliceal (C) pelvis as seen in IVU.

Megacalices & (D) Drooping lower calyx.

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Fig. 12: Different uncommon pelvicaliceal pattern as seen in IVU (A) Absent pelvis, (B) Minor calices from pelvis, (C) Megacalices and (D) Drooping lower calyx

Divisions of the pelvicaliceal systems:

The branching of pelvis into major calices and further into minor calices is not symmetrical in its anterior and posterior aspect. Apart from the upper, middle and lower calices, there are anterior and posterior branches of each calyx which drain into the minor calices from the renal parenchyma both from the anterior and posterior aspects. Such a finding is more marked in the middle calyx (Fig. 13). Two or three minor calices from the anterior and posterior aspects of the kidney converge at varying angles to form middle major calyx. The upper and lower major calices are formed by the convergence of 4-5 minor calices draining from all aspects of the poles. These minor calices can be designated as apical, apicoposterior, apicoanterior, anterior and posterior according to position and direction. The first three groups can either open individually to the upper major calyx or may join to form a common stalk before joining it. Calices draining the mid zone of the kidney occasionally drains into the upper or lower major calyx and a definite middle major calyx is lacking. Minor calyx from one pole may drain into the major calyx of opposite pole e.g minor calyx of lower pole may join the upper major calyx and vice versa (Fig. 14).

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Fig. 13: Photograph showing anterior (AD) and posterior(PD) divisions of major calices in foetal kidney.

In the IVU all the major calices, the anterior minor calices and some of the posterior minor calices (mostly of the middle calyx that are seen as end-on dense images) only are identifiable. But in the direct study of foetal and adult kidney specimen the branching pattern could be visualized in greater depth including the divisions. The number of major calices were two to three and that of minor calices were six to twelve. The frequency of minor calices identified in the IVU is depicted in Table II.

Table - II

No. of renal units studied by IVU = 200
Number of
Minor Calices
In Number of
Renal Units
6 48 24
8 72 36
9 74 37
12 6 3

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Fig. 14: Crossed drainage of calicus in IVU. ote the minorcalices (indicated with the arrows) arising from theupper and lower major calices crossing each otherin crossed-swords fashion.

Unusual pattern occurred in 12% of cases. Whenever the middle calyx is missing, the minor calices from the mid zone drain into the upper and lower major calices. In 2% of cases the calices could not be delineated well but had a distinct large renal pelvis.


During foetal period the renal axis is almost vertical unlike the oblique axis in the adult and gradually the two lower poles become separated wider at term but has not attained the adult form as yet. The findings of lobulations of the foetal kidney varying with age and increasing in number to a maximum of 14 lobules by the 28 th week is similar to the findings reported by Sykes (1963), however the pattern of lobulation is different from what had been described by Sykes as two types only either as regular polygonal areas or two transverse lobar clefts on both surfaces. In the present study various types were found –triangular, rectangular, and mulberry besides polygonal type. This present study also revealed that each lobule had a corresponding minor calyx when the lobulations were regular and smaller in number but in mulberry type all the lobules did not have a corresponding minor calyx probably due to the presence of compound papillae. Lobulations were less numerous and not as well delineated at term as described by Sykes (1963). It is also evident that the number of minor calices in the foetus is more than that in the adult and this suggests the merging of minor calices during the course of development. In the present study the pelvis is formed by the confluences of the major calices both in the foetus and adult. In majority of cases the pelvis is intrarenal although there are some borderline cases in between the two. Further the lesser number of multicaliceal pattern and a higher percentage of tricaliceal and bicaliceal pattern in adults compared to foetus supports the theory of merger of minor calices during development and maturation of pelvicaliceal system.

Edwards (1975) described the two types of renal pelvis as intrarenal and extrarenal depending on whether the pelvis is outside or inside the renal sinus and the formation of pelvis by the union of two major calices and sometimes by three which is in agreement with that of Fine and Keen (1966). Anson and McVay (1971) pointed out that the extrarenal pelvis is larger than the intrarenal type and when it is intrarenal type it is small and consists of only minor calices. In the present study, in majority of cases, the pelvis is intrarenal although there are some borderline cases in between the two. In majority of the cases (33%) pelvis is formed by the confluence of the three major calices both in the foetus as well as in the adult. Usually major calices are three in number viz. superior, middle and inferior calices but the number of minor calices draining into the upper and lower calices range from 3-5 in number whereas that of the middle calyx is limited to 2-4 from anterior and posterior aspects but in some cases the pelvis has only the upper and lower calyces and in such cases midzone drainage is done by the minor calices in close proximity which joins the neighbouring major calices. In 12 renal units (3%) studied, pelvis could not be demonstrated since the ureter directly bifurcated into calices as has been reported by Bruce et al (1967) and Kabalin (1992). The present study has already highlighted the occurrence of Y shaped type of pelvis and in this type there is hardly any room and caliber of the each stem of Y is almost same as that of the upper ureter. DiDio (1970) described two types of pelvis- Longi and Brachi type. In Longi type the major calices are usually long, end in a small pelvis (ramified type) and in Brachi type major calices are usully short and end in a large renal pelvis (ampullary type). The present study revealed that pelves are variable and categorised them into (i) Radiate or Multicaliceal, (ii) Triangular or Tricaliceal and (iii) Y-shaped or Bicaliceal depending on the number of calices which directly drains and forms the pelvis. The most spacious one is the multicaliceal (radiate) followed by the tricaliceal (tricaliceal) and the least roomy or spacious is the bicaliceal (Y-shaped) pelvis. The radiate type of the present study would correspond with the ampullary type and the triangular with that of ramified type.

A simpler classification than that of the Grave's and Sampaio's is to group them as bicaliceal whenthere are two major calices, tricaliceal when there arethree major calices and radiate when there are multiple calices draining into the renal pelvis although the direction and the site of the drainage of the minor calices may vary in each category. The comparison of the two well known classifications and the simplified grouping are shown in Fig. 15 and Table III.

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Fig. 15: Diagrammatic comparison of Graves', Sampaio's and the Simplified Classification of the present study. Note that the subtypes of the first two will fit into one of the common types of Simplified Classification of the present study.

Table - III

Grave's Classic Y, Type A Inverted T, Type B Balloon, Type C Bagpipes, Type D
Sampaio's Type A-I Type A-II Type B-I Type B-II
Simplified(present study) Bicaliceal or Y-shaped Tricaliceal or Triangular Multicaliceal orRadiate

In the IVU study, though the pelvicaliceal system was broadly categorized, there were minor differences within each category also. The pattern was not consistent and even the pattern on the two sides were not the same in many cases (15%). On occasions the calices would be larger than the pelvis itself. The intrarenal or extrarenal type of renal pelvis could be well visualized when the kidney was mildly obstructed. The anterior and posterior minor calices were seen well though the angle that they make with the major calyx could not be measured. Grunberger and Sharma (1997) quoted Brodel's (Brodel, 1901) description of caliceal distribution within the kidney where he observed that posterior calices are directed slightly posterior to the convex lateral border and project at an angle of 20 0 behind the frontal plane whereas the anterior calices are directed into the convex anterior region, project at an angle of 70 0 . They also quoted Hodson's (Hodson, 1972) observation that anterior calices project laterally and posterior calices project medially. This arrangement is the exact mirror image of that of Brodel. Hodson (1972) also pointed out that Brodel type of arrangement was infrequent. Kaye (1983) confirmed Brodel's observation. Kaye and Reinke (1984) also studied CT scans of the kidneys and observed that right kidney frequently follow a Brodel type of arrangement whereas left kidneys frequently show a Hodson type of distribution. A predominant Brodel type of pattern in the right kidneys and a Hodson type of pattern in the left kidneys was also confirmed by Sampaio et al (1988). A few cases of malrotation were also noted. The present study noted the variable degree of angles the anterior and posterior calices make with the frontal plane as they approach the pelvis.

The knowledge of such wide ranging pattern of pelvicaliceal system and in particular the presence of anterior and posterior minor calices, the angles they make with the pelvis, direction of the minor calices and cross drainage would help the surgeons and interventional radiologists in planning and executing their procedures more accurately.


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Pelvi-Caliceal System In Foetal And Adult Human Kidneys : Ningthoujam DD et al.

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