Lower pole anatomy and mid-renal-zone classification applied to flexible ureteroscopy: experimental study using human three-dimensional endocasts.

PURPUSE: The aim of this study was to analyze the anatomy of the inferior pole collecting system and the mid-renal-zone classification in human endocasts applied to flexible ureteroscopy. METHODS: 170 three-dimensional polyester resin endocasts of the kidney collecting system were obtained from 85 adult cadavers. We divided the endocasts into four groups: A1--kidney midzone (KM), drained by minor calices (mc) that are dependent on the superior or the inferior caliceal groups; A2--KM drained by crossed calices; B1--KM drained by a major caliceal group independent of both the superior and inferior groups; and B2--KM drained by mc entering directly into the renal pelvis. We studied the number of calices, the angle between the lower infundibulum and renal pelvis and the angle between the lower infundibulum and the inferior mc (LIICA). Means were statistically compared using ANOVA and the unpaired T test (p < 0.05). RESULTS: We found 57 (33.53 %) endocasts of group A1; 23 (13.53 %) of group A2; 59 (34.71 %) of group B1; and 31 (18.23 %) of group B2. The inferior pole was drained by four or more calices in 84 cases (49.41 %), distributed into groups as follows: A1 = 35 cases (41.67 %); A2 = 18 (21.43 %); B1 = 22 (26.19 %); and B2 = 9 (10.71 %). Perpendicular mc were observed in 15 cases (8.82 %). We did not observe statistical differences between the LIICA in the groups studied. CONCLUSIONS: Collector systems with kidney midzone drained by minor calices that are dependent on the superior or on the inferior caliceal groups presented at least two restrictive anatomical features. The mid-renal-zone classification was predictive of anatomical risk factors for lower pole ureteroscopy difficulties.

Renal pelvic diameters in human fetuses: anatomical reference for diagnosis of fetal hydronephrosis.

OBJECTIVE: To evaluate renal pelvis diameters in human fetuses, to establish normative patterns of their growth and size during the second gestational trimester. METHODS: We studied 140 kidneys (70 fetuses; 38 male, 32 female) ranging in age from 12-25 weeks' postconception. The renal pelvis was dissected and the transverse and longitudinal diameters were measured. The renal length, width, and thickness were assessed. To compare the quantitative data in both sexes, Student's t-test was used (P <.05). RESULTS: The mean transverse diameter in male fetuses was 3.61 mm in the right side and 3.58 mm in the left. In female fetuses, it was 3.51 mm in the right side and 3.43 mm in the left. There was no statistical significant difference between the sides either in males (P <.81) or in females (P <.33). There was no significant difference in the mean transverse diameter between male and female fetuses (P <.9). The mean longitudinal diameter in male fetuses was 4.28 mm in the right side and 4.31 mm in the left. In female fetuses, it was 4.17 mm in the right side and 4.33 mm in the left. There was no significant statistical difference between the sides in either males (P <.82) or females (P <.33). There was no significant difference in the mean longitudinal diameter between male and female fetuses (P <.9). CONCLUSIONS: Transverse and longitudinal diameters are useful as parameters for assessment of the renal pelvis in human fetuses.

A proposed new classification for the renal collecting system of cattle.

OBJECTIVE: To evaluate the intrarenal anatomy of kidneys obtained from cattle and to propose a new classification for the renal collecting system of cattle. SAMPLE POPULATION: 37 kidneys from 20 adult male mixed-breed cattle. PROCEDURES: Intrarenal anatomy was evaluated by the use of 3-D endocasts made of the kidneys. The number of renal lobes and minor renal calyces in each kidney and each renal region (cranial pole, caudal pole, and hilus) was quantified. RESULTS: The renal pelvis was evident in all casts and was classified into 2 types (nondilated [28/37 {75.7%}] or dilated [9/37 {24.3%}]). All casts had a major renal calyx associated with the cranial pole and the caudal pole. The number of minor renal calices per kidney ranged from 13 to 64 (mean, 22.7). There was a significant correlation between the number of renal lobes and the number of minor renal calices for the entire kidney, the cranial pole region, and the hilus region; however, there was not a similar significant correlation for the caudal pole region. Major and minor renal calices were extremely narrow, compared with major and minor renal calices in pigs and humans. CONCLUSIONS AND CLINICAL RELEVANCE: The renal collecting system of cattle, with a renal pelvis and 2 major renal calices connected to several minor renal calices by an infundibulum, differed substantially from the renal collecting system of pigs and humans. From a morphological standpoint, the kidneys of cattle were not suitable for use as a model in endourologic research and training.

The pig kidney as an endourologic model: anatomic contribution.

We present detailed anatomic findings on collecting system anatomy and renal morphometry in the pig and compare these findings with previous findings in humans. We studied three-dimensional polyester resin corrosion endocasts of the pelviocaliceal system obtained from 100 kidneys (50 pigs). Eighty kidneys were evaluated morphometrically, considering length, cranial pole width, caudal pole width, thickness, and weight. The pig collecting system was classified into two major groups (A and B). Group A (40%) was composed of kidneys in which the mid-zone is drained by calices dependent on the cranial or the caudal caliceal group or both. Group B (60%) kidneys have the mid-zone drained by calices independent of the polar groups. Group B includes two subtypes (B-I and B-II). The pig collecting system showed only angles smaller than 90 degrees between the caudal (lower) infundibulum and the renal pelvis. Renal morphometric measurements revealed the following means: length 11.8 cm, cranial pole width 5.64 cm, caudal pole width 5.35 cm, thickness 2.76 cm, and weight 98 g. As in human kidneys, one may group the pig collecting system into two groups. Nevertheless, in pigs, we did not find a subdivision of Group A. The incidence of collecting systems in Groups A and B and the subtypes of Group B in pigs are different from those in humans. Also different from humans, in pigs, we found only angles smaller than 90 degrees between the caudal (lower) infundibulum and the renal pelvis. Except for the length, the means of the other morphometric measurements of the pig kidney are smaller than those of humans. From an anatomic standpoint, despite the differences pointed out, we conclude that the pig kidney is a good animal model for endourologic research and training.

Comparative follow-up of patients with acute and obtuse infundibulum-pelvic angle submitted to extracorporeal shockwave lithotripsy for lower caliceal stones: preliminary report and proposed study design.

Nowadays, there is a consensus that the poor success rate of extracorporeal shockwave lithotripsy (SWL) is in the treatment of lower caliceal stones. The gravity-dependent position of the lower-pole calices is postulated to be the main factor hindering the spontaneous passage of stone debris that results from SWL. Nevertheless, we proposed that there are some particular features of the inferior-pole collecting system anatomy that could contribute to fragment retention. We studied the influence of the lower infundibulum-pelvic angle on fragment retention, considering 74 patients submitted to SWL for the treatment of lower-pole nephrolithiasis in a Lithostar Plus machine. At a mean follow-up of 9 months, 75% of the patients presenting an angle of greater than 90 degrees between the lower infundibulum where the stone was located and the renal pelvis became stone-free within 3 months. On the other hand, only 23% of the patients presenting an angle smaller than 90 degrees between the lower infundibulum where the stone was located and the renal pelvis became stone-free during the follow-up. Determination of the angle between the renal pelvis and the infundibulum of the inferior pole calix where the stone is located is very important, because the angle will differ in the same kidney, depending on stone location. Although preliminary and based on a small series of patients, our data suggest that an acute pelvic-lower pole infundibular angle hinders the spontaneous discharge of fragments after SWL. Also, use of the proposed technique of pelvic-lower pole infundibular angle measurement will be important for unifying angle evaluation by other investigators.

Morphological study of the pyelo-calyce-pyramidal system in human kidney

Los autores estudiaron el sistema pielo-cálice-piramidal en relación a los aspectos siguientes: número de pirámides renales, número de cálices mayores, número de cálices menores y forma de la pélvis renal. Fueron utilizados 80 riñones humanos, derechos e izquierdos, provenientes de cadáveres adultos, de ambos sexos, con distintas causas de muerte, previamente fijados en formol al 10 por ciento. Este material fué disecado para extraer restos peritoneales y tejido pararrenal. Luego, los riñones fueron seccionados frontalmente a nivel del seno renal para el retiro de los vasos, nervios y grasa perirrenal. La media correspondiente a las pirámides renales, cálices mayores y cálices menores fueron, respectivamente: 8,26ñ1,38; 2,13ñ0,4 y 7,96ñ1,44. La relación entre el número de cálices menores y cálices mayores fue 3,74 y entre pirámides renales y cálices menores fue 1,04. En relación a la forma de la pelvis renal, se observó el predominio del tipo bifurcado simple en el 43,75 por ciento; seguida de las formas ramificada, en el 20 por ciento, bifurcada alargada, en el 12,5 por ciento, trifurcada, en el 11,25 por ciento y ampollar, en el 10 por ciento de los casos. En 2,5 de las observaciones, se verificó la presencia de una pelvis renal doble

Limitations of extracorporeal shockwave lithotripsy for lower caliceal stones: anatomic insight.

In addition to gravity-dependent position, we suppose that other particular anatomic features may be important in the retention of stone debris in lower calices after extracorporeal shockwave lithotripsy (SWL). We analyzed the inferior-pole collecting system anatomy in 146 three-dimensional polyester resin corrosion endocasts of the pelviocaliceal system. In 74% of the cases, there was an angle of greater than 90 degrees formed between the lower infundibulum and the renal pelvis, and in 26%, the angle was 90 degrees or less. In 60%, there was a lower infundibulum 4 mm or larger in diameter. The inferior pole was drained by multiple calices disposed in two rows in 57% of the cases and by one midline caliceal infundibulum in 43%. We believe that the physician must appreciate these anatomic features when considering SWL to treat calculi located in lower calices.

Intrarenal access: 3-dimensional anatomical study.

In an attempt to determine the best route to puncture and access the kidney collecting system we studied 62, 3-dimensional polyester resin endocasts of the pelvicaliceal system together with the intrarenal vessels. A retrograde pyelogram was obtained, and the arterial and venous trees were injected with red and blue resins, respectively. When the resin was still in the gel state, the kidneys were positioned at 30 to 45 degrees and the collecting system was punctured under radioscopy. Since the resin is not opaque to x-ray the operator was not able to visualize the vessels while puncturing. After puncture, the needle was maintained in place, the contrast medium was removed and the pelvicaliceal system was filled with yellow resin. After the resin had set, the renal organic matter was corroded in acid and the endocast was obtained (with the needle in the original position). This type of preparation allowed us to examine the needle tract and the vessels damaged during the puncture. In the same kidney we punctured the superior pole, mid kidney and inferior pole. In some cases we also punctured the renal pelvis. We performed 104 punctures through an infundibulum, 39 through a fornix of a calix and 12 through the renal pelvis. Due to a high percentage of vascular lesions, intrarenal access through an infundibulum should be avoided. Also, renal pelvis puncture should be avoided. Regardless of the kidney region, puncture through a fornix of a calix was safe.

Inferior pole collecting system anatomy: its probable role in extracorporeal shock wave lithotripsy.

In addition to the gravity-dependent position, we believe that other particular anatomical features may be important in the retention of stone debris in the lower calices after extracorporeal shock wave lithotripsy (ESWL). We analyzed the inferior pole collecting system anatomy in 146, 3-dimensional polyester resin corrosion endocasts of the pelviocaliceal system. The inferior pole was drained by multiple calices disposed in 2 rows in 56.8% of the cases and by 1 midline caliceal infundibulum in 43.2%. In 60.3% of the cases there was a lower infundibulum equal to or greater than 4 mm. in diameter and 39.7% had a lower infundibulum smaller than 4 mm. in diameter. In 74.0% of the cases an angle of greater than 90 degrees was formed between the lower infundibulum and the renal pelvis, and in 26.0% the angle was 90 degrees or smaller. We believe that the physician should consider these anatomical features when suggesting ESWL to treat calculi in the lower calices.

Anatomical relationship between the intrarenal arteries and the kidney collecting system.

The anatomical relationship between the intrarenal arteries and the renal collecting system was studied in 82, 3-dimensional endocasts. Some anatomical details that have importance for urologists were observed. The arterial supply related to the upper caliceal group arises from 2 arteries that encircle these calices (in 86.6% 1 trunk originated from the anterior division and 1 from the posterior division of the renal artery). The artery to the mid kidney courses horizontally in the mid renal pelvis in 64.6% of the cases while the arterial supply to the inferior pole (front and back) arises from the inferior segmental artery of the anterior division in 62.2%. The posterior segmental artery is related to the upper infundibulum or to the junction of the pelvis with the upper calix in 57.3% of the cases and to the middle posterior aspect of the renal pelvis in 42.7%.

3-Dimensional and radiological pelviocaliceal anatomy for endourology.

The renal collecting system was studied in 100, 3-dimensional corrosion casts and also in 40 casts with the corresponding pyelograms. Some anatomical details that have great importance for endourology were observed and discussed, including the presence of perpendicular minor calices draining into the surface of the collecting system (11 per cent of the cases), crossed calices in the mid kidney with consequent formation of a region that we termed the inter-pelviocaliceal region (17.1 per cent), position of the calices related to the lateral kidney margin (in 52.9 per cent the anterior and posterior calices were superimposed or alternately distributed), position of the calices related to the polar regions (superior pole with a midline caliceal infundibulum in 98.6 per cent and inferior pole with paired calices in 57.9 per cent) and to the mid kidney (with paired calices in 95.7 per cent), and bilateral symmetry of the casts (37.1 per cent). The urologist must appreciate these anatomical structures during operations on the collecting system.