The comparison of the incidence of horseshoe kidney in autopsy cases versus urologic patient population

Propensity score-matched analysis comparing retrograde intrarenal surgery with percutaneous nephrolithotomy in anomalous kidneys

BACKGROUND

Endourologic interventions for urolithiasis in patients with anomalous kidneys can be challenging, and comparisons between these interventions are not well studied. We aim to compare the safety, outcomes and complications of retrograde intrarenal surgery (RIRS) versus percutaneous nephrolithotomy (PCNL) in patients with urolithiasis in anomalous kidneys.

METHODS

A propensity score-matched pair analysis (PSM) was performed on pooled patient data from 20 centers. 569 patients with anomalous kidneys (horseshoe kidney [HSK], ectopic kidney, malrotated kidney) and urolithiasis who received either PCNL or RIRS as the primary modality of intervention from 2010 to 2020 were analyzed. Patients were matched based on calculated propensity scores by a regression model using age, sex, comorbidities, stone size, and renal anomaly type as co-variates. Multivariate logistic regression of factors (mode of treatment [PCNL or RIRS], comorbidities, stone size) and their effects on outcomes of stone-free rate (SFR), need to abandon surgery due to intraoperative difficulty, postoperative hematuria and sepsis and were analyzed when applicable.

RESULTS

After PSM, there were a total of 127 pairs in each group. Overall, PCNL conferred a higher SFR compared to RIRS (OR=3.69, 95% CI 1.91-7.46, P<0.001), particularly in HSK (OR=3.33, 95% CI 1.22-9.99, P=0.023), and ectopic kidneys (OR=18.10, 95% CI 3.62-147.63, P=0.002), with no significant difference in malrotated kidneys. There was no significant difference in postoperative sepsis observed. Surgery was abandoned more often in RIRS than PCNL (6.3% vs. 0%, P=0.014). Although PSM provides a robust analysis due to baseline differences in the unmatched cohorts, this study was limited by an inevitable degree of selection bias.

CONCLUSIONS

While both modalities are safe and efficacious, PCNL yields better SFR than RIRS in patients with anomalous kidneys, with no difference in postoperative sepsis rates. Patients may benefit from personalized management best carried out in high volume endourology centers.

Morphological observation of the horseshoe kidney with circumaortic venous ring

In a student course of gross anatomy dissection at Knagawa Dental College in 2010, we found an extremely rare case of the horseshoe kidney with circumaortic venous ring in a 43-year-old Japanese male cadaver. In this case, the kidney consisted of three parts: the original kidneys on both sides and an isthmus between them. The location of each kidney was lower than that of the normal kidney. The hili on both sides opened toward the ventral direction, and the ureters descended in front of the isthmus and entered the bladder normally. This horseshoe kidney had original left and right renal arteries that branched from the abdominal aorta. There were also two surplus arteries. There were three renal veins on the left side, and these renal veins formed the circumaortic venous ring. The anatomical and embryological significance of this anomaly and its associated vascular system are discussed. The anatomy and etiology of these anomalous structures are discussed with references in the literature.

Successful transureteropyelostomy after heminephrectomy of a bilateral hydronephrotic horseshoe kidney: a case report

INTRODUCTION

Horseshoe kidney is a rare congenital malformation that is found in approximately 0.25% of the general population and usually remains asymptomatic.

CASE PRESENTATION

We report a successful transureteropyelostomy after heminephrectomy of the non-functional right moiety in a 25-year-old man with horseshoe kidney who had a combined 50% functional loss and hydronephrosis due to multiple distal ureteral strictures on the functionally remaining left side. Continuous ureteral stenting of the remaining part of the former horseshoe kidney was avoided during a follow-up of 2 years.

CONCLUSION

Urologists are often faced with technically difficult cases that are not responsive to standard operative procedures, and this case illustrates an individual surgical approach in a clinical situation.

Case report: laparoscopic heminephrectomy in a horseshoe kidney using bipolar energy

Aberrant vasculature, functional parenchyma in the isthmus, and abnormal location are all unique features of horseshoe kidney that present technical challenges to laparoscopic management of disease. A 52-year-old man presented with a large renal calculus in a poorly functioning left moiety of a horseshoe kidney and underwent laparoscopic heminephrectomy. The ismthus, which had 2.5 to 3.0 cm of functioning parenchyma, was divided using the PlasmaKinetic Superpulse Generator (Gyrus). No additional hemostatic measure was required. The total operative time was 140 minutes with an estimated blood loss of 160 mL. At follow-up, the right moiety and remaining isthmus exhibited normal function with no extravasation.

Morphological observation of the horseshoe kidney with special reference to the vascular system in 2 Japanese cadavers

Two cases of the horseshoe kidney in Japanese cadaver were reported in this paper. The kidneys and their associated vessels in the retroperitoneal cavity were carefully examined, and the histological examination of the isthmus was performed. In Case 1, four arteries arose from the abdominal aorta. One right and two left renal arteries were distributed to the apical, upper, middle and posterior regions of the kidney, respectively, and the artery of isthmus entered the lower segments and the isthmus. In Case 2, six arteries arose from the abdominal aorta. Among three arteries arose from the inferior end of the aorta and entered the lower segments and the isthmus. Histological study revealed that the isthmuses consisted of collecting tubes, glomeruli and urinary tubules and fibrous connective tissue. The incidence of the horseshoe kidney during the dissecting practice at Tokyo Medical University in a period of 24 years from 1980 to 2003 was estimated to be 0.16% (2 out of the 1,219 cadavers). The anatomical and embryological significance of this anomaly and its associated vascular system were discussed. And the histology of the parenchymal structure of the isthmus in the horseshoe kidney containing either fibrous connective tissue or renal parenchyma was also analyzed in this report.

Prenatal diagnosis of horseshoe kidney by measurement of the renal pelvic angle

OBJECTIVE

The aim of this study was to evaluate the usefulness of measurement of the angle between bilateral renal pelves on axial views in the prenatal ultrasonographic diagnosis of horseshoe kidney.

METHODS

We retrospectively measured the renal pelvic angle in 19 fetuses with horseshoe and 20 fetuses with normal kidneys in the second and third trimesters. Renal pelvic angle was defined as the angle between the long axis of the renal pelves on the axial view of the abdomen. We compared the renal pelvic angles of horseshoe and normal kidneys with unpaired t-test. Taking 140 degrees as a cut-off value, we calculated the sensitivity, specificity and accuracy of pelvic angle measurement for the prenatal diagnosis of horseshoe kidney.

RESULTS

The mean pelvic angles in the fetuses with horseshoe kidney were 116 degrees and 110 degrees in the second and third trimester, respectively. In the normal fetuses, the equivalent angles were 172 degrees and 161 degrees. The difference between the two groups was statistically significant (P < 0.01). Using 140 degrees as the discriminating criterion, the sensitivity, specificity and accuracy of renal pelvic angle measurement for the prenatal diagnosis of horseshoe kidney were all 100%. Fifteen of 19 fetuses with horseshoe kidney had no other abnormality. Four (21%) fetuses had severe complex abnormalities which were associated with trisomy 18 in three cases.

CONCLUSION

Observation and measurement of the renal pelvic angle is a simple and useful method in the prenatal diagnosis of the horseshoe kidney.

Determining the incidence of horseshoe kidney from radiographic data at a single institution

PURPOSE

An estimated 150,000 children are born with birth defects each year. One of the most frequent genitourinary abnormalities is horseshoe kidney (HSK). The incidence of HSK in the population is estimated to be 1/400 to 1,600 births based on autopsy data from the 1940s and 1950s. We prospectively evaluated the incidence of HSK based on radiographic studies to determine the contemporary incidence of HSK.

MATERIALS AND METHODS

In a 6-month period patients undergoing abdominal computerized tomography, renal ultrasonography and excretory urography were screened for HSK. After identification medical charts were reviewed for demographics, history, study indication and findings. A literature review of 12 studies of 825 patients with HSK was compared with the current series with regard to common associated findings.

RESULTS

From 15,320 radiographs 23 patients were identified with HSK for an overall incidence of 1/666. Computerized tomography, excretory urography and ultrasound identified 16, 5 and 2 patients, respectively, while 16 were male, 7 were female, 20 were adults and 3 were children. The most common concomitant urological disorder was nephrolithiasis in 9 patients (39%), prompting operative intervention in 4. The radiographic incidence of HSK closely matched data from autopsy series and yet it differed from that in current radiographic series using ultrasound in the perinatal period.

CONCLUSIONS

Our radiographic evaluation of the HSK incidence closely matches past autopsy series. This finding suggests that the incidence of HSK remains stable despite an increasing number of birth defects. Moreover, it appears that radiographic studies can accurately estimate the incidence of congenital anatomical disorders. Our data suggest that HSK is a relatively benign condition with a low requirement for operative intervention in these incidentally identified patients.

The endourological management of complications associated with horseshoe kidney

PURPOSE

Horseshoe kidneys are the most common renal fusion anomalies. Ureteropelvic junction obstruction, urolithiasis and renal malignancies are the most common complications that occur in this patient population. Endourological management of these complications has decreased perioperative morbidity. We identified the applications of minimally invasive surgery for treating complications secondary to horseshoe kidney.

MATERIALS AND METHODS

A comprehensive literature review of the different endourological approaches in the management of complications secondary to horseshoe kidney was performed using MEDLINE.

RESULTS

Ureteropelvic junction obstruction can be managed by percutaneous endopyelotomy or laparoscopic pyeloplasty with good results. Small stones associated with horseshoe kidney are best managed by shock wave lithotripsy, while stones that have failed management by shock wave lithotripsy or are greater than 2 cm. are best managed percutaneously. All patients should undergo metabolic evaluation. Ureteroscopy or shock wave lithotripsy is associated with a higher residual stone rate than the percutaneous approach. Laparoscopic nephrectomy is a safe and feasible option for benign and malignant horseshoe kidney diseases.

CONCLUSIONS

Endourological techniques can be safe and effective for treating complications secondary to horseshoe kidney.

Morphological study of a horseshoe kidney with special reference to the vascular system

This is a morphological study on an autopsy case of horseshoe kidney found in a 79-year-old-female cadaver. This kidney consisted of two distinct renal masses that were connected at their lower poles by a parenchymal isthmus that was located in the front of the abdominal aorta at the level of the fourth lumbar vertebra. The kidney was supplied by four arteries arising from the abdominal aorta. The distribution of intrarenal arteries showed that the nature of segmental arteries in the present case was basically the same as in the normal kidney, except that the isthmus had its own blood supply from the artery directly arising from the aorta approximately 28 mm below the origin of the inferior mesenteric artery. Venous drainage from the kidney, including the isthmus, was taken by three veins that opened independently into the inferior vena cava. No congenital malformations were found in other organs. We discuss the anatomical and embryological significance of this anomaly and its associated vascular system.

[Pathologic horseshoe kidney. Report of 13 cases]

The authors report a series of 13 horseshoe kidneys observed over a 22-year period. All patients are men with a mean age of 39 years (20-65 years). The clinical features were dominated by abdomino-lumbar pain (nine cases). The horseshoe kidney was associated with renal stones in nine cases, uretero-pelvic junction syndrome in five cases and pyonephrosis in one case. The specific anatomic and surgical features of this rare malformation are emphasized and the therapeutic features of each uropathy associated with horseshoe kidney are discussed.