Imaging of horseshoe kidneys and their complications

Combined therapy for managing a clear cell renal cell carcinoma in a horseshoe kidney: A case report

The upper urinary tract is the most common human organ system affected by congenital anomalies. A Horseshoe kidney is a fusion anomaly, it can be described as a fusion across the midline of 2 distinct functioning kidneys. The incidence of renal tumors in a Horseshoe kidney is higher than in the normal population. We present a 60-year-old male patient with a history of Horseshoe kidney and a diagnosis of clear cell renal cell carcinoma who underwent a combined therapeutic approach, guided by interventional radiology. This approach involved selective transarterial embolization and microwave ablation. Three months after surgery and with abdominal MRI follow-up, there is evidence of a non-viable tumor, indicating a favorable response to the intervention.

A triple kidney: Coexistence of normal left kidney and mal-rotated horseshoe anomaly: A rare case report

The occurrence of triple kidneys, involving a normal kidney and a malrotation horseshoe kidney, is an extremely infrequent condition. This case report demonstrates a triple, mal-rotated horseshoe kidneys coexist with an upper junction stone, alongside a normal left kidney showing normal Doppler vascularity, as observed in an ultrasound examination for 18-year-old male complaints of diffuse periumbilical pain and burning micturition. Laboratory investigation revealed normal creatinine level, and presence of urinary tract infection. Management option for this case are antibiotic therapy and surgical intervention for horseshoe kidney stone. Regular monitoring of kidney function, other radiographic imaging studies, and follow-up to assess the efficacy of the treatment, and detect any further complications are essential.

Troubleshooting Tips for Diagnosing Complex Fetal Genitourinary Malformations

Fetal genitourinary anomalies can present a diagnostic challenge for the radiologist. The absence of a normally located kidney may represent agenesis or be secondary to a fusion or migration abnormality. A dilated renal pelvis should prompt evaluation for a specific cause, including ureteropelvic junction obstruction, reflux, or an obstructed duplicated system. Cystic parenchymal changes are characteristic of a multicystic dysplastic kidney but may also be seen in obstructive cystic dysplasia. There are numerous causes of megacystis including chromosomal (trisomy 18 syndrome), obstruction (posterior urethral valves, urethral atresia), or muscular dysfunction (prune belly syndrome, megacystis microcolon intestinal hypoperistalsis syndrome). Important mimics of a large bladder include hydrocolpos and urogenital sinus or cloacal malformation. Complications of genitourinary malformations are common and include oligohydramnios, urinary ascites, and urinoma. Making an accurate diagnosis often requires additional US views beyond those obtained in the standard fetal survey and occasionally performing fetal MRI. The appropriate use of orthogonal T2-weighted sequences, in conjunction with diffusion-weighted images for evaluation of the kidneys and gradient-recalled-echo sequences for evaluation of T1-hyperintense meconium in the colon, can play an integral role in diagnosis. Accurate diagnosis of fetal genitourinary malformations is vital to direct patient counseling and pregnancy management as outcomes are highly variable. Some conditions can be surgically corrected quite simply, some require multiple complex procedures, and some are lethal. The authors offer troubleshooting tips to narrow the differential diagnosis for four observations: unilateral absent kidney, dilated renal pelvis, cystic renal parenchyma, and megacystis and its mimics. ©RSNA, 2023 Test Your Knowledge questions are available in the Online Learning Center.

Horseshoe Kidney: 500 Years From the First Report in the Literature

Horseshoe kidney or ren arcuatus is the most common renal fusion anomaly, with an incidence of 1:500 in the normal population and a male predominance of 2:1. In >90% of cases, the fusion occurs along the inferior pole. It may vary in location, orientation, and arterial and venous anatomy. In 1522, Berengario da Carpi described this renal malformation for the first time in his masterpiece "Isagogae breves" (Introduction to Anatomy). He reported the results of a postmortem examination in the public autopsy room of the University of Bologna, describing "kidneys that are continuous as if they were a kidney, with two emulsifying veins, two emulsifying arteries, two ureteral outlets." In 1564, Leonardo Botallo described and illustrated the features of this atypical anatomical representation, and later, in 1602, Leonard Doldius added further details by examining this anatomical feature during an autopsy. In 1761, Giovanni Battista Morgagni discussed this condition not only as a rare anatomical curiosity found only in necroscopy but also discussed its physiological aspect. In the nineteenth century, with the advent of renal surgery, the horseshoe kidney played a more important role in urological diagnosis and treatment, and its identification became more frequent. With the advent of pyelography, imaging reports of the horseshoe kidney allowed a more accurate representation of the anatomical variants, which was particularly useful in preoperative assessment and outcomes. Berengario da Carpi laid the foundation for a better knowledge of this anatomical anomaly. Five hundred years after the first report in the literature, relevant advances have been made in the management of complications associated with horseshoe kidney and in diagnosis, confirming the need to monitor individuals with this condition who are at higher risk of developing chronic kidney disease.

Magnetic resonance urography of congenital abnormalities - what the radiologist needs to know

Congenital abnormalities of the kidney and urinary tract include a wide range of malformations ranging from asymptomatic to life-threatening conditions. Although pediatric urogenital system imaging is based on the use of US (pre- and postnatal), voiding cystourethrography and scintigraphic study, magnetic resonance (MR) urography plays a fundamental role in the classification and management of congenital abnormalities of the kidney and urinary tract, giving an overview of the different clinical pictures, thanks to its panoramicity and high anatomical detail. In fact the anomalies of the urinary tract are phenotypically variable because they can affect simultaneously several segments of different embryonic derivation, with complex clinical pictures; they can appear both as isolated phenotypes or as complex malformative conditions, involving renal parenchyma, collecting system and bladder. A deep knowledge of this complex embryogenesis and its possible phenotypic patterns allows a correct interpretation of MR urography images. We describe the embryology and pathophysiology of congenital abnormalities of the kidney and urinary tract as well as MR urography technique and findings. Congenital abnormalities of the kidney and urinary tract are classified into four groups: (1) obstruction (proximal, middle and distal), (2) budding with respect to the Wolffian duct (site and number of ureter), (3) ascent and rotation (ectopia, malrotation and fusion of kidney) and (4) anomaly of metanephric differentiation (dysplasia, megapolicalycosis).

OUP accepted manuscript

A 76-year-old gentleman with a background of benign prostatic hyperplasia, hiatus hernia and anxiety was referred to the rapid access haematuria service following an episode of painless visible haematuria. Flexible cystoscopy did not reveal any concerning bladder lesions. CT Urogram demonstrated a horseshoe kidney with a filling defect in the left upper pole moiety suspicious for an urothelial carcinoma. The patient was subsequently referred to the urology services in a tertiary centre. Flexible ureterorenoscopy was performed, with findings of a likely urothelial carcinoma corresponding to the suspicious area on imaging. Biopsy of this lesion revealed a low grade urothelial cancer. The patient proceeded to have a laparoscopic left heminephroureterectomy with an open bladder cuff. The patient recovered well and urinary catheter was removed Day 12 post procedure after the performance of a cystogram. Histology revealed a favourable pTa low grade malignancy, and the patient will require ongoing follow-up moving forward. This case report highlights the operative intricacies in managing patients with horseshoe kidney due to anatomic variations associated with this condition.

Unveiling the confusion in renal fusion anomalies: role of imaging

Renal fusion anomalies are common congenital anomalies of the urogenital tract and have their genesis in the early embryonic period. They are classified into partial fusion anomalies (e.g., crossed fused ectopia, and horseshoe kidney) and complete fusion anomalies (e.g., fused pelvic kidney). Horseshoe kidney is the most common renal fusion anomaly and is characterized by the presence of two distinct functioning kidneys on either side of the vertebral column, with fusion occurring at the inferior poles in majority of the cases. Crossed fused ectopia is characterized by the presence of an ectopic kidney that crosses the midline and fuses with the orthotopic contralateral kidney, whereas fused pelvic (pancake) kidney is a complete fusion anomaly characterized by extensive medial fusion of both kidneys in the pelvis. Fusion anomalies are often associated with abnormalities of renal rotation, migration, and vascular supply, which predispose the kidneys to a number of complications and create difficulty during retroperitoneal surgeries and interventions. They are also associated with other congenital abnormalities of the urogenital tract, gastrointestinal tract, cardiovascular system, and skeletal system. Hence, a thorough understanding of the etiopathogenesis and radiological features of fusion anomalies is important for directing patient management. This review summarizes the embryological basis, clinical presentation and imaging approach to renal fusion anomalies, followed by detailed anatomical and radiological description of the morphological types, and the complications associated with these anomalies.

Multimodality imaging spectrum of complications of horseshoe kidney

Horseshoe kidney is the most common congenital renal fusion anomaly with an incidence of 1 in 400–600 individuals. The most common type is fusion at the lower poles seen in greater than 90% of the cases, with the rest depicting fusion at the upper poles, resulting in an inverted horseshoe kidney. Embryologically, there are two theories hypothesizing the genesis of horseshoe kidney – mechanical fusion theory and teratogenic event theory. As an entity, horseshoe kidney is an association of two anatomic anomalies, namely, ectopia and malrotation. It is also associated with other anomalies including vascular, calyceal, and ureteral anomalies. Horseshoe kidney is prone to a number of complications due to its abnormal position as well as due to associated vascular and ureteral anomalies. Complications associated with horseshoe kidney include pelviureteric junction obstruction, renal stones, infection, tumors, and trauma. It can also be associated with abnormalities of cardiovascular, central nervous, musculoskeletal and genitourinary systems, as well as chromosomal abnormalities. Conventional imaging modalities (plain films, intravenous urogram) as well as advanced cross-sectional imaging modalities (ultrasound, computed tomography, and magnetic resonance imaging) play an important role in the evaluation of horseshoe kidney. This article briefly describes the embryology and anatomy of the horseshoe kidney, enumerates appropriate imaging modalities used for its evaluation, and reviews cross-sectional imaging features of associated complications.

Horseshoe Kidney in Conjunction With Autosomal Dominant Polycystic Kidney Disease: A Case Report

Horseshoe kidney in the presence of autosomal dominant polycystic kidney disease is a rare occurrence of two relatively common and unrelated renal findings. Visualization of multiple, bilateral cysts along with fusion of the kidneys by a midline isthmus can usually isolate these diagnoses. Accurate sonographic evaluation is essential in determining the degree of disease progression and possible complications associated with these diseases. Sonography is also useful in identifying extrarenal involvement and eliminating differential diagnoses.

Congenital Anomalies of the Upper Urinary Tract: A Comprehensive Review

The upper urinary tract is the most common human system affected by congenital anomalies. Congenital anomalies of the kidneys and ureters comprise a wide spectrum of disorders ranging from simple variants with no clinical significance to complex anomalies that may lead to severe complications and end-stage renal disease. They may be classified as anomalies of renal form, which are subclassified as structural anomalies (eg, persistent fetal lobulation, hypertrophied column of Bertin, and dromedary hump) and fusion anomalies (eg, horseshoe kidney and pancake kidney); anomalies of renal position (eg, renal malrotation, simple renal ectopia, and crossed renal ectopia) and renal number (eg, renal agenesis and supernumerary kidney); and abnormalities in development of the urinary collecting system (eg, pyelocaliceal diverticulum, megacalycosis, ureteropelvic junction obstruction, duplex collecting system, megaureter, ectopic ureter, and ureterocele). US is usually the first imaging modality used because of its low cost, wide availability, and absence of ionizing radiation. Intravenous urography and voiding cystourethrography are also useful, mainly for characterization of the collecting system and vesicoureteral reflux. However, intravenous urography has been replaced by CT urography and MR urography. These imaging methods not only allow direct visualization of the collecting system but also demonstrate the function of the kidneys, the vascular anatomy, adjacent structures, and complications. Comprehension of congenital anomalies of the upper urinary tract is crucial for an accurate diagnosis and correct management. The authors discuss the spectrum of these anomalies, with emphasis on embryologic development, imaging findings, clinical manifestations, and complications. Online supplemental material is available for this article. ^©RSNA, 2021.

Embryology of the urogenital tract; a practical overview for urogynecologic surgeons

INTRODUCTION AND HYPOTHESIS

Urinary tract anomalies are one of the most common birth defects. Nevertheless, they prove challenging to diagnose as a result of variable presenting symptoms. We aimed to perform a review of urogenital tract development, highlight common congenital upper urinary tract anomalies encountered by urogynecologists and tools to facilitate diagnosis.

METHODS

Multiple searches were performed utilizing resources such as PubMed and the TriHealth library database to access publications related to embryology of the urinary tract and urinary tract anomalies. Each citation was reviewed.

RESULTS

Congenital urinary tract anomalies account for up to 20% of all birth defects and occur more often in females. The true incidence of these malformations is unknown as some can remain clinically insignificant throughout life. In addition, patients may present with non-specific complaints such as urinary tract infections, nephrolithiasis or urinary incontinence. Therefore, unsuspected anomalies pose a risk of delayed diagnosis and potential injury during urogynecologic surgery. Imaging modalities such as computed tomography or magnetic resonance imaging are the most common diagnostic tests. Management and treatment options range from observation to surgical resection with the goal of optimizing long-term functionality and prevention of chronic sequelae.

CONCLUSION

Patients with urinary tract anomalies can present with vague complaints often encountered by urogynecologists. It is crucial to understand the embryologic development of urinary tract anomalies to help facilitate diagnosis and guide care within the office and operating room setting.

A Horseshoe Kidney With Solid Mass: A Case Report

Sonography can be used to detect horseshoe kidneys. Sonographic findings for horseshoe kidney commonly include an isthmus connection occurring anterior to the aorta and just inferior to the inferior mesenteric artery. This anomaly can occur with or without complications. Each kidney is associated with its separate collecting system, leading to increased risk for complications. This case study describes the importance of identifying a horseshoe kidney, isthmus, and blood supply to ensure prompt intervention if needed. A case report of a horseshoe kidney with a solid mass, in the isthmus, is provided.

Incidentally detected pancake kidney: a case report

Background

Congenital anomalies of the urinary system are very common and have extremely varied presentation. Among them, the most rarely found structural anomaly is the pancake kidney. When both kidneys are fused along their medial surfaces to form a round-shaped single renal mass, it is termed as pancake kidney. In this case report, a pancake kidney was incidentally detected in a girl. The majority of individuals who have pancake kidney are usually asymptomatic but surgeons should be aware of coexisting malformation of other organs and its potential risk of developing malignancy.

Case presentation

A 12-year-old Bengali girl presented to our out-patient department with mild, dull aching, lower abdominal pain and dysuria. She had no history of fever, hematuria, menstrual abnormality, pelvic inflammatory disease, or trauma. Urine examination showed traces of albumin and 10–12 pus cells/high-power field. She had normal kidney function test but a digital X-ray of her kidney, ureter, and bladder region failed to demonstrate bilateral renal tissue shadows. Ultrasonography of her whole abdomen showed normal intra-abdominal organs except for empty bilateral renal fossa. A multi-detector computed tomography scan of her whole abdomen revealed one round-shaped mass measuring approximately 9 cm (vertical) × 10 cm (horizontal) in the pelvic cavity. That mass was finally identified as a pancake kidney. She was prescribed antibiotics based on urine culture and sensitivity test that cured her symptoms. She was advised to follow-up regularly in our out-patient department to evaluate her kidney function and to rule out any neoplastic change.

Conclusions

This condition can be managed conservatively, if the individual remains asymptomatic, by regular monitoring of renal function. Surgeons should remain alert for the development of infections, any obstructive manifestations leading to calculus formation, and any malignant changes. The individual should be careful in avoiding trauma to low-lying pelvic kidney. Extensive surgeries should be avoided and only selective procedures should be done so that the patient may lead a normal lifestyle.

A deadly trap for para-aortic lymph node dissection in patients with horseshoe kidney as a complication: a case report

Horseshoe kidney is a rare congenital renal dysplasia. It is often associated with various anatomical abnormalities, including renal vessel and ureter variability, which increase unpredictable surgical risks. This current report describes the case of a 42-year-old woman diagnosed as having cervical squamous cell carcinoma complicated by horseshoe kidney. She underwent laparoscopic radical hysterectomy, bilateral oophorectomy and lymph node dissection, including dissection of the pelvic, presacral and para-aortic lymph nodes. The surgery was challenging, but no serious complications occurred. Postoperative multi-slice computed tomography angiography confirmed the anatomical variation of the renal location, ureter and renal vessels. To our knowledge, this is the first reported case of cervical carcinoma complicated with horseshoe kidney.

The level of origin of renal arteries in horseshoe kidney vs. in separated kidneys: CT-based study

Purpose

Horseshoe kidney is a rare congenital anomaly with potential clinical implications. The aim of this study was to determine the number of renal arteries and veins and the level at which the arteries branched off their parental vessels in individuals with horseshoe kidney (HSK) and in persons with separated kidneys (SK).

Materials and methods

The analysis included computed tomography angiography studies of 331 patients (83 HSK and 248 SK). The number of renal vessels and diameters of renal arteries were determined, along with the level at which they branched in relation to other ramifications (four groups of origin were proposed) and their entrance of the vessels to the kidney.

Results

Number of renal arteries in HSK group was 4.57 ± 1.39 per patient and 2.4 ± 0.43 in SK group (p < 0.0001). The distribution of branching level of renal arteries in HSK group was: I group ~ 57%, II group ~ 27%, III group ~ 15% and IV group < 1%, whereas in SK group the distribution was respectively: I group ~ 99%, II group < 1%, III and IV group − 0% (p = 0.0001). In HSK group, diameter of renal arteries branching above the IMA was 4.61 ± 1.58 mm, as compared with 3.96 ± 1.34 mm for the arteries branching below (p = 0.0004). Number of veins was 566 in SK group (87.70% of kidneys were supplied by single vein) and 323 in HSK group (9.64% kidneys were supplied by two veins) (p < 0.0001).

Conclusion

In HSK group, renal arteries significantly more often branch off their parental vessels below the origin of IMA and such vessels are usually smaller.

Pancake kidney: when it is not a problem

Pancake kidney is a very rare congenital anomaly involving complete fusion of medial renal parenchyma. The interface is devoid of any intervening septum. As described, the kidneys form a single lobulated mass in pelvic location. However, dual collecting systems are retained, and the shortened, anteriorly seated ureters enter the bladder normally. This condition is usually discovered incidentally but may confer a heightened susceptibility to recurrent urinary tract infections or stone formation, given the likelihood of anomalous collecting system rotation and the potential for ureteral stasis or obstruction. Excretory urography, the customary method of detection, has been replaced by ultrasonography, CT, MRI, and radionucleotide scanning. Herein, we present a male patient with a pelvic pancake kidney, never symptomatic. A conservative approach of regular follow up visits and laboratory testing was elected, thus avoiding any unnecessary investigations or extensive surgery.

Pictorial review: Renal ultrasound

Ultrasound (US) is the first-line imaging modality for evaluating azotemic patients for urinary obstruction and renal size. US is also valuable for distinguishing congenital variants and simple cystic lesions from renal masses. Doppler US is effective in detection of renal calculi and evaluation of vascular pathology. Unfortunately, renal US is limited in distinguishing causes of medical renal disease. The kidneys have a complex internal architecture with a highly variable appearance on US. This article illustrates non-neoplastic renal conditions, including normal and embryological variants, parenchymal, cystic, and vascular diseases. Renal infections, calcifications, and trauma and fluid collections are also discussed, with an emphasis on distinguishing US features and pathophysiology.

Role of magnetic resonance urography in pediatric renal fusion anomalies

Renal fusion is on a spectrum of congenital abnormalities that occur due to disruption of the migration process of the embryonic kidneys from the pelvis to the retroperitoneal renal fossae. Clinically, renal fusion anomalies are often found incidentally and associated with increased risk for complications, such as urinary tract obstruction, infection and urolithiasis. These anomalies are most commonly imaged using ultrasound for anatomical definition and less frequently using renal scintigraphy to quantify differential renal function and assess urinary tract drainage. Functional magnetic resonance urography (fMRU) is an advanced imaging technique that combines the excellent soft-tissue contrast of conventional magnetic resonance (MR) images with the quantitative assessment based on contrast medium uptake and excretion kinetics to provide information on renal function and drainage. fMRU has been shown to be clinically useful in evaluating a number of urological conditions. A highly sensitive and radiation-free imaging modality, fMRU can provide detailed morphological and functional information that can facilitate conservative and/or surgical management of children with renal fusion anomalies. This paper reviews the embryological basis of the different types of renal fusion anomalies, their imaging appearances at fMRU, complications associated with fusion anomalies, and the important role of fMRU in diagnosing and managing children with these anomalies.

Challenging case of horseshoe kidney double fracture

INTRODUCTION

Renal injuries occur in 10% of blunt abdominal traumas, 7% of these occur in kidneys with congenital or acquired disorders. Trauma of horseshoe kidney is an uncommon finding.

PRESENTATION OF A CASE

We present the case of 31 year-old caucasian man with no remarkable personal records, who was brought to our Trauma Unit soon after being involved in a motorcycle collision. A Contrast Enhanced - Multi Detector Computed Tomography (ce-MDCT) revealed a double disconnection of a horseshoe kidney. The patient was not aware of bearing such abnormality.

DISCUSSION

Trauma of horseshoe kidney is an uncommon finding. The abdominal ce-MDCT scan is the diagnostic tool of choice since the renal anatomy, injury grading and vascular or urinary tract abnormalities are well depicted and easily identified. The conservative management of these injuries is associated with a lower rate of nephrectomies and kidney failure while selective trans-catheter renal embolization is a challenging treatment option. However surgery can be a treatment of choice and should be aimed to preserve renal function.

CONCLUSION

the interest in our case lies in the rarity and particular anatomical aspect of such injuries and the implication related to its management in an emergency setting.

Congenital Renal Fusion and Ectopia in the Trauma Patient

We present two separate cases of young male patients with congenital kidney anomalies (horseshoe and crossed fused renal ectopia) identified following blunt abdominal trauma. Despite being rare, ectopic and fusion anomalies of the kidneys are occasionally noted in a trauma patient during imaging or upon exploration of the abdomen. Incidental renal findings may influence the management of traumatic injuries to preserve and protect the patient's renal function. Renal anomalies may be asymptomatic or present with hematuria, flank or abdominal pain, hypotension, or shock, even following minor blunt trauma or low velocity impact. It is important for the trauma clinician to recognize that this group of congenital anomalies may contribute to unusual symptoms such as gross hematuria after minor trauma, are readily identifiable during CT imaging, and may affect operative management. These patients should be informed of their anatomical findings and encouraged to return for long-term follow-up.

The horseshoe kidney: Surgical anatomy and embryology

Horseshoe kidneys are a common, yet enigmatic, renal malformation. This review critically appraised the literature surrounding the embryology, etiology and clinical anatomy of horseshoe kidneys. The systematic literature search produced 104 articles, and 56 primary and further secondary references. There were several etiological theories regarding horseshoe kidneys. The established view was that during ascent, the kidneys come into close apposition as they pass through an arterial fork. Another possible mechanism related to lateral flexion of the trunk or rotation of the caudal embryo; the association of asymmetrical horseshoe kidneys with a number of vertebral conditions supported this hypothesis. More recent animal models implicated the notochord and sonic hedgehog signaling. Furthermore, it has been suggested that the isthmus may be the result of ectopic mesenchymal tissue. Surgical anatomy of the horseshoe kidney is complex, due to variability in location, orientation and blood supply. Both arterial and venous anatomy is highly variable. This raised the question of whether anomalous blood supply is the cause or result of abnormal renal position. In the majority of cases, the isthmus contained functional renal parenchyma. In over 90% of cases, fusion between the kidneys occurred at the lower pole. Despite commonly being quoted as 'held back by the inferior mesenteric artery' at L3, in reality the isthmus was only found immediately inferior to this in 40% of cases.

Reverse U-shaped horseshoe kidney accompanied by gibbus deformity and spina bifida

Horseshoe kidney (HSK) is the most common fusion anomaly of kidneys. Diagnosis of horseshoe kidneys is made by the demonstration of an isthmus or band of renal tissue between the lower poles of the kidneys. Connection between the upper poles of the kidneys is extremely rare. Several types of skeletal anomalies can be seen concomitantly with HSK. In our present case, where the patient was a 3-year-old male, the connection of renal tissue was located between the upper poles of the kidneys. Furthermore, there was an accompanying spina bifida and Gibbus deformity secondary to anterior hypoplasia of the T10 vertebral body.

Gross Anatomical Dissection of a Horseshoe Kidney: The Eighth Specimen in Our Medical School

Horseshoe kidney is a known congenital renal anomaly. During a gross anatomy dissection course for students in 2014, a horseshoe kidney was found in an 80-year-old female. The isthmus was formed by the fusion of the right and left kidneys at their lower poles and resulted in a U-shaped kidney. Both sides of the renal hilum opened ventrally. Four surplus renal arteries entered the horseshoe kidney. The first surplus renal artery arose from the right side of the abdominal aorta, and entered the lower part of the renal hilum. The second surplus artery arose from the ventral side of the abdominal aorta, and entered the left inferior part of the left renal hilum.The third surplus artery also arose from the ventral side of the abdominal aorta and entered the inferior border of the left part of the isthmus. The fourth surplus artery arose from the bifurcation of the common iliac arteries and distributed to the inferior border of the middle of the isthmus. One surplus renal vein arose from the lower border of the middle of the isthmus, descended dorsally to the abdominal aorta and the right common iliac artery, and then entered the upper wall of the left common iliac vein. The isthmus was made up of renal parenchymal structures. These findings will be useful as regards research and surgery on the horseshoe kidney. This was the eighth case of horseshoe kidney in our laboratory.

Multi-modality imaging review of congenital abnormalities of kidney and upper urinary tract

Congenital abnormalities of the kidney and urinary tract (CAKUT) include a wide range of abnormalities ranging from asymptomatic ectopic kidneys to life threatening renal agenesis (bilateral). Many of them are detected in the antenatal or immediate postnatal with a significant proportion identified in the adult population with varying degree of severity. CAKUT can be classified on embryological basis in to abnormalities in the renal parenchymal development, aberrant embryonic migration and abnormalities of the collecting system. Renal parenchymal abnormalities include multi cystic dysplastic kidneys, renal hypoplasia, number (agenesis or supernumerary), shape and cystic renal diseases. Aberrant embryonic migration encompasses abnormal location and fusion anomalies. Collecting system abnormalities include duplex kidneys and Pelvi ureteric junction obstruction. Ultrasonography (US) is typically the first imaging performed as it is easily available, non-invasive and radiation free used both antenatally and postnatally. Computed tomography (CT) and magnetic resonance imaging (MRI) are useful to confirm the ultrasound detected abnormality, detection of complex malformations, demonstration of collecting system and vascular anatomy and more importantly for early detection of complications like renal calculi, infection and malignancies. As CAKUT are one of the leading causes of end stage renal disease, it is important for the radiologists to be familiar with the varying imaging appearances of CAKUT on US, CT and MRI, thereby helping in prompt diagnosis and optimal management.

Congenital anatomic variants of the kidney and ureter: a pictorial essay

Congenital renal parenchymal and pelvicalyceal abnormalities have a wide spectrum. Most of them are asymptomatic, like that of ectopia, cross fused kidney, horseshoe kidney, etc., while a few of them become complicated, leading to renal failure and death. It is very important for the radiologist to identify these anatomic variants and guide the clinicians for surgical and therapeutic procedures. Cross-sectional imaging with a volume rendered technique/maximum intensity projection has overcome ultrasonography and IVU for identification and interpretation of some of these variants.

Left Renal Vein Compression and Horseshoe Kidney: An Extraordinary Association

OBJECTIVE

Our aim was to report the importance of an awareness of renal artery variations if surgical procedures are indicated in this region. Presentation and Intervention: A 41-year-old female patient was admitted to our hospital for preoperative staging of the rectum carcinoma. A computed tomography (CT) scan clearly revealed the presence of normally positioned small right and left renal arteries, and a large aberrant renal artery originating from the distal abdominal aorta in a case with a horseshoe kidney (HSK). A multidetector CT angiography was performed using a 256-detector row CT scanner to obtain an image of vascular structures and associated pathologies.

CONCLUSION

In this patient with HSK, the left renal vein compression was unusual and the CT examination provided a good delineation of vascular and urinary tract anomalies.

Glomerular filtration rate measured by (99m) Tc-DTPA renal dynamic imaging is significantly lower than that estimated by the CKD-EPI equation in horseshoe kidney patients

AIM

Gate's glomerular filtration rate (gGFR) measured by (99m) Tc-DTPA renal dynamic imaging and estimated GFR (eGFR) estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation are two indexes used to evaluate renal function. However, little is known about whether gGFR can be used to accurately assess renal function in horseshoe kidney (HSK) patients with renal fusion anomalies.

METHODS

Nineteen HSK patients (HSK group) diagnosed by renal imaging and 38 CKD patients with "normal kidney shape" (non-HSK group) matched to the HSK patients in terms of gender, age and biochemical indicators at Chinese PLA General Hospital were enrolled in this study. Gender, age, serum total protein (TP), albumin (ALB), blood urea nitrogen (BUN), serum creatinine (Scr), gGFR and eGFR were recorded and analyzed using χ(2) test, t-test, and Wilcoxon test which was presented as median(IQR).

RESULTS

(1) There were no significant differences in gender, age, TP, ALB, BUN, Scr, or eGFR between these two groups. (2) In HSK patients, the renogram showed abnormal renal axis with the lower poles orientated medially. The timed uptake curve showed that the isotope excretion in the HSK group was slower than that in the non-HSK group. (3) For all HSK patients, gGFR was significantly lower than eGFR (range -12.52 mL/min per 1.73m(2) to -93.18 mL/min per 1.73m(2) ). There was no significant difference in eGFR between the HSK [96.42 (36.02) mL/min per 1.73 m(2) ] and non-HSK groups [94.46 (33.00) mL/min per 1.73 m(2) ]. The gGFR of the HSK group [41.18 (16.60) mL/min per 1.73m(2) ] was much lower than that of the non-HSK group [86.42(26.40) mL/min per 1.73m(2) , P < 0.001] and the eGFR of the HSK group (P < 0.001). The gGFR and eGFR of the non-HSK group were not significantly different.

CONCLUSION

gGFR measured by (99m) Tc-DTPA renal dynamic imaging is significantly lower than eGFR estimated by the CKD-EPI equation, which indicates that isotope renogram cannot accurately evaluate the GFR of HSK patients.

Renal outcome of children with horseshoe kidney: a single-center experience

OBJECTIVE

To assess the clinical features, additional abnormalities, and renal consequences of children with horseshoe kidney (HSK).

METHODS

The medical records of 41 children with HSK followed in our pediatric nephrology clinic between the years of 2004 and 2014 were retrospectively reviewed.

RESULTS

There were 22 girls (53.6%) and 19 boys (46.4%) aged 60 (2-192) months. The median follow-up time was 48 (12-120) months. HSK was incidentally found in 12 patients (29.3%), and 5 patients (12.2%) were prenatally diagnosed. Urinary tract abnormalities including vesicoureteral reflux (n = 8), ureteropelvic junction obstruction (n = 7), and duplex system (n = 3) were identified in 18 patients (43.9%). Eight children (19.5%) had bladder dysfunction, and 9 patients (21.9%) had additional systemic abnormalities. Urinary tract infection had been detected in 17 patients (41.4%). Seven patients (17%) required surgical intervention including pyeloplasty (n = 3), ureteroneocystostomy (n = 3), and upper pole heminephrectomy (n = 1). Renal scarring (RS) occurred in 10 patients (24.4%). Six patients (14.6%) developed proteinuria and 4 (9.8%) complicated with hypertension. Three patients (7.3%) progressed to chronic kidney disease (CKD). Multivariate logistic regression analysis showed that proteinuria, hypertension, and RS are independently associated with CKD.

CONCLUSION

Children with HSK might be examined for additional urologic and nonurologic abnormalities. Patients might be closely followed up for the increased risk of urinary tract infection and RS. Proteinuria, hypertension, and presence of RS seem to be the major determinants for progression to CKD in children with HSK.

Transplantation of a horseshoe kidney found during harvest operation of a cadaveric donor: a case report

A 34-yr-old female was diagnosed as being brain dead. Preoperative ultrasound revealed no abnormal focal lesions. However, the horseshoe kidney was identified during organ harvest. En bloc nephrectomy was performed. The kidney was divided at the midline of isthmus. The divided right kidney was discarded due to numerous arteries and veins. The divided left kidney was transplanted. After declamping, the kidney was well perfused and started clearing. Resistive index was 0.72. Glomerular filtration ratio was 84.69 mL/min on postoperative day 14. The horseshoe kidney can be successfully transplanted and could be a good solution for the shortage of organ donors.

Extraordinary cause of complete colonic obstruction in children: urinary retention

Complete colonic obstruction in children may occur secondary to congenital, and acquired factors related to the gastrointestinal system. Herein, we report an extraordinary presentation of complete colonic obstruction due to extensive urinary retention in a 3-year-old boy. The possible underlying mechanism was detected as urinary infection in a child with horseshoe kidney. The treatment of the bladder symptoms and urinary infection relieved the obstruction of the colon. To our knowledge, especially in children, colonic obstruction due to urinary retention has not been reported in the literature.

Anderson-Hynes pyeloplasty with isthmotomy and lateropexy in horseshoe kidneys with pelviureteric junction obstruction in children

OBJECTIVE

The objective of this study was to evaluate the results of Anderson-Hynes pyeloplasty with isthmotomy and lateropexy in horseshoe kidney with pelviureteric junction obstruction (PUJO).

MATERIALS AND METHODS

Medical records of patients of horseshoe kidney with PUJO operated in our institute between June 1998 and June 2012 were reviewed. Anderson-Hynes pyeloplasty with isthmotomy and lateropexy was performed in all patients. The surgical outcome was evaluated with emphasis on the changes in degree of hydronephrosis by ultrasonography, renal drainage and function assessed by diuretic renal scans.

RESULTS

We studied the records of eight children of horseshoe kidney having unilateral PUJO. Obstruction was caused by a crossing lower-pole vessel in two cases, a high ureteral insertion in three and narrowing of the PUJ in three cases. Post-operative follow-up (median 4.4 years, range 18 months to 10 years) revealed improved renal function and good drainage in all cases. Hydronephrosis disappeared in 3, 4 showed Grade 1 and one showed Grade 2 hydronephrosis. All children are doing well and have no symptoms.

CONCLUSION

Anderson-Hynes pyeloplasty with isthmotomy and lateropexy is a highly effective and safe procedure for treating PUJO in horseshoe kidney in children.

Sequential effects of spadetail, one-eyed pinhead and no tail on midline convergence of nephric primordia during zebrafish embryogenesis

Midline convergence of organ primordia is an important mechanism that shapes the vertebrate body plan. Here, we focus on the morphogenetic movements of pronephric glomerular primordia (PGP) occurring during zebrafish embryonic kidney development. To characterize the process of PGP midline convergence, we used Wilms' tumour 1a (wt1a) as a marker to label kidney primordia, and performed quantitative analyses of the migration of the bilateral PGP. The PGP initially are approximately 350 μm apart in a wild type embryo at 10h post fertilization (hpf). The inter-PGP distance decreases exponentially between 10 and 48 hpf, while the anterior-posterior (A-P) dimension of each PGP increases linearly between 10 and 12 hpf, then decreases substantially between 12 and 24 hpf. Using mutants in the Nodal receptor cofactor one-eyed pinhead (oep) and the T-box transcription factors spadetail (spt) and no tail (ntl), we were able to define distinctive regulation underlying these sequential phases of PGP midline migration. Zygotic oep mutants (Zoep(-/-)) exhibited defects in midline convergence after 16 hpf. Spt is necessary for PGP convergence from 10 hpf, whereas ntl's effect on convergence does not begin until 24 hpf. Notably, we observed normal cardiac convergence in spt(-/-) and ntl(-/-) embryos implying that these novel roles of spt and ntl in PGP migration cannot be explained simply by generalised effects on midline convergence. These findings demonstrate that quantitative approaches to developmental migration allow the parsing of early patterning events, and in this instance suggest that the zebrafish may offer insights into midline urogenital migration anomalies in humans.

A case with mega cisterna magna renal and ear anomalies: is this a new syndrome?

Background. Extrarenal pathologies may be associated with renal position and fusion anomalies. According to the literature, our patient is the first horseshoe kidney case that had mega cisterna magna, arachnodactyly, and mild mental retardation. Case Report. A 9-year-old boy admitted because of the myoclonic jerks. He had a dysmorphic face, low-set and cup-shaped ears, arachnodactyly, and mild mental retardation. The patient's laboratory findings were normal except for a mild leucocytosis and hypochromic microcytic anemia. His cerebrospinal fluid was cytologically and biochemically normal. Cranial MRI revealed 1.5 cm diametered mega cisterna magna in the retrocerebellar region. Although there were no significant epileptical discharges in the electroencephalography, there were slow wave discharges arising from the anterior regions of both hemispheres. Because he had stomachache, abdominal ultrasonography was performed, and horseshoe kidney was determined. Abdominal CT did not reveal any abnormalities except the horseshoe kidney. There were not any cardiac pathologies in echocardiography. He had normal 46XY karyotype and there were no repeated chromosomal derangements, but we could not evaluate for molecular and submicroscopic somatic changes. He was treated with valproic acid and myoclonic jerks did not repeat. Conclusion. We suggest that the presence of these novel findings may represent a newly recognized, separate syndrome.

Congenital renal anomalies detected in adulthood

Objective

To document the types of congenital renal anomalies detected in adulthood, the clinical presentation and complications of these renal anomalies, and the most useful imaging modality in detecting a renal anomaly.

Materials and methods

This study was approved by the institutional review board and informed consent was waived. Between January 2007 and January 2011, the clinical data and imaging studies of 28 patients older than 18 years diagnosed with renal anomaly at the authors’ institution were retrospectively reviewed. Renal anomalies in this study included only those with abnormality in position and in form.

Results

Of these 28 patients, 22 underwent imaging studies and their results constituted the material of this study. Of the 22 patients, 14 had horseshoe kidneys (HSK), four had crossed renal ectopia and four had malrotation. Sixteen patients were men and six were women. The patients ranged in age from 19 to 74 years (mean age 51.1 years). Clinical presentations were abdominal pain (13), fever (13), haematuria (4), palpable mass (2), asymptomatic (2), polyuria (1) dysuria (1), blurred vision (1), and headache with weakness of left extremities (1). Imaging studies included abdominal radiograph (15), intravenous pyelography (IVP) (8), retrograde pyelography (RP) (4), ultrasonography (US) (7), and computed tomography (CT) (9). Associated complications included urinary tract stones (17), urinary tract infection (16), hydronephrosis (12), and tumours (2). Abdominal radiograph suggested renal anomalies in nine out of 15 studies. IVP, RP, US and CT suggested anomalies in all patients who had these studies performed. However, CT was the best imaging modality to evaluate anatomy, function and complications of patients with renal anomalies.

Conclusion

HSK was the most common renal anomaly, with abdominal pain and fever being the most common presentations. UTI and stones were the most common complications. IVP, RP, US and CT can be used to diagnose renal anomalies but CT is the best imaging modality to evaluate renal anatomy, function and its complications.

Retroperitoneal lymphatic malformation in child with horseshoe kidney

We describe a 12-year-old girl with a retroperitoneal lymphatic malformation (LM) and horseshoe kidney. The imaging characteristics of the lesions are reported. Retroperitoneal LM coexisting with horseshoe kidney is extremely rare. We hypothesized that they might share the similar etiologic factors. Imaging examinations are helpful in the definition of the 2 lesions and the relationship between them, but no characteristic findings are available to diagnose retroperitoneal LM before surgery. Surgical excision is ideal to treat LM, and the prognosis is good. Although asymptomatic horseshoe kidney need not be treated, it is important for patients to receive regular follow-up because of the propensity for various complications.