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Horseshoe kidney

From Wikipedia, the free encyclopedia
Horseshoe kidney
Other namesRenal fusion
SpecialtyNephrology

Horseshoe kidney,also known asren arcuatus(in Latin),renal fusionorsuper kidney,is acongenital disorderaffecting about 1 in 500 people that is more common in men, often asymptomatic, and usually diagnosed incidentally.[1][2]In this disorder, the patient'skidneysfuse to form ahorseshoe-shape during development in the womb. The fused part is theisthmusof the horseshoe kidney. The abnormal anatomy can affect kidney drainage resulting in increased frequency of kidney stones and urinary tract infections as well as increase risk of certain renal cancers.[1]

Fusion abnormalities of the kidney can be categorized into two groups: horseshoe kidney andcrossed fused ectopia.The 'horseshoe kidney' is the most common renal fusion anomaly.[3]

Signs and symptoms

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Axial CT image of the abdomen showing a horseshoe kidney.

Although often asymptomatic, the most common presenting symptom of patients with a horseshoe kidney is abdominal or flank pain. However, presentation is often non-specific.[1]Approximately a third of patients with horseshoe kidneys remain asymptomatic throughout their entire life with over 50% of patients having no medical issues related to their renal fusion when followed for a 25-year period.[1]As a result, it is estimated that approximately 25% of patients with horseshoe kidneys are diagnosed incidentally with ultrasound or CT imaging.[1]

Associated conditions

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Patients with a horseshoe kidney can develop sequelae related to the abnormal anatomy and present with symptoms related to them.[citation needed]

Individuals that have a horseshoe kidney may be at increased risk for conditions that generally fall within the following categories:

Intravenous pyelogram showing horseshoe kidney.

Cause

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There have been several proposed factors that may contribute to the development of a horseshoe kidney. Different exposures to the developing fetus such as different teratogens (e.g.thalidomide,ethanol,ACE inhibitors,cocaine,gentamicin,corticosteroids,NSAIDs,andvitamin A) have been hypothesized.[8][2][9]Impairment of a developing embryo's nephrogenic cell migration or abnormal migration of the kidneys due to fetal structural abnormalities is another potential factor.[8][2]However, no definitive genetic cause has been identified.[8][9]

Pathophysiology

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Kidneys are normally located in theretroperitoneal spacebetween the T12 and L3vertebraeafter ascending from the pelvis during development to rest underneath theadrenal glands.[1]In patients with this condition, the horseshoe kidney ascent is commonly arrested by theinferior mesenteric arterydue to the central fusion of the kidneys.[10]However, this is present in only 40% of cases, and, in 20% of cases, the fused kidney remains in the pelvis.[1]Its ascension may also be restricted by its own renal artery.[11]Additionally, during normal development, the kidneys undergo a 90 degree medial rotation while ascending. However, due to the renal fusion, this rotation is impaired resulting in abnormal placement of theureters.This in turn can lead to urinary stasis and drainage issues.[1]Furthermore, approximately 70% of kidneys in normal individuals are supplied by a singlerenal arterywith the remaining 30% having embryonic collateral or accessory arteries.[1]With horseshoe kidneys, the majority are supplied by derivatives of theabdominal aortaorcommon illiac arteriesdepending on the final position of the kidneys.[1][12]

Diagnosis

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Horseshoe kidneys are commonly diagnosed incidentally on abdominal imaging. The diagnosis can be made with many different imaging modalities such asultrasound,intravenous pyelogram,CT,andMRI.[1]

Common features that can be found on imaging include:

  • Midline symmetrical fusion (present in 90% of cases) or lateral asymmetric fusion (present in 10% of cases) of the lower poles[13]
  • Position of fused kidneys are lower than normal with incomplete medial rotation[13]
  • Renal pelvis and ureters are positioned more anteriorly and ventrally cross the isthmus[13][4]
  • Isthmus that may be positioned below the inferior mesenteric artery[13]
  • Variant arterial supply that can originate from the abdominal aorta or common illiac arteries[1][12][13]
  • Lower poles of kidney that extend ventromedially and may be poorly defined[14]

Treatment

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Symphysiotomy,which involves separating the fused isthmus in order to release the kidneys, used to be a recommended treatment for this condition but has fallen out of favor due to complications and minimal benefit.[1][15]Furthermore, kidneys can remain in their original abnormal location after the surgery.[1][16]Instead, management focuses on treating the sequelae should the patient become symptomatic.[citation needed]

While treatment typically does not differ from that of patients with normal kidney anatomy,[17]kidney stones can warrant a different approach.Extracorporeal shockwave lithotripsy,a possible treatment for kidney stones, can be less effective in patients with horseshoe kidneys due to the abnormal anatomy causing difficulties with localizing the energy to the stones. Also, due to the kidney obstruction that can commonly occur with this renal fusion, clearance of the resulting stone fragments can also be impaired.[1]For this reason, prior to any treatment with shockwave lithotripsy, a UPJ obstruction must first be ruled out as it significantly impair successful treatment.[4]For stones that are less than 1.5 cm,ureteroscopyand shockwave lithotripsy can be first utilized.[4]For stones larger than 1.5 cm or when previous treatment has failed, the stones can instead be removed through a minimally invasive procedure known aspercutaneous nephrolithotomy.[4]

Compared to patients with normal kidneys, patients with horseshoe kidneys who undergo treatment with percutaneous nephrolithotomy experience no difference in complications or stone clearance.[4]

Patients will also typically require imaging before any abdominal surgery as the vascular supply to the abnormal kidney can be highly variable between patients.[1]Additionally, the horseshoe kidneys can have a close association with colon which can increase risk of bowel injury.[1]

Epidemiology

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There is an incidence of 1 in every 500 individuals within a normal population.[1][2]

Males are more likely to develop a horseshoe kidney with a preponderance of 2:1.[1][2]

Certain genetic diseases can predispose patients to developing a horseshoe kidney:

Notable cases

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References

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  1. ^abcdefghijklmnopqrstuvwxyKirkpatrick JJ, Leslie SW (2018).Horseshoe Kidney.StatPearls Publishing.PMID28613757.Retrieved2019-01-16.{{cite book}}:|work=ignored (help)
  2. ^abcdefghTaghavi K, Kirkpatrick J, Mirjalili SA (October 2016). "The horseshoe kidney: Surgical anatomy and embryology".Journal of Pediatric Urology.12(5): 275–280.doi:10.1016/j.jpurol.2016.04.033.PMID27324557.
  3. ^Glodny B, Petersen J, Hofmann KJ, Schenk C, Herwig R, Trieb T, et al. (January 2009). "Kidney fusion anomalies revisited: clinical and radiological analysis of 209 cases of crossed fused ectopia and horseshoe kidney".BJU International.103(2): 224–35.doi:10.1111/j.1464-410X.2008.07912.x.PMID18710445.
  4. ^abcdefWein, Alan J.; Kavoussi, Louis R.; Partin, Alan W.; Peters, Craig Andrew (2015-10-23).Campbell-Walsh Urology(Eleventh ed.). Philadelphia, PA.ISBN9780323263740.OCLC931870910.{{cite book}}:CS1 maint: location missing publisher (link)
  5. ^Jung M, Rai A, Wang L, Puttmann K, Kukreja K, Koh CJ (October 2018). "Nephrolithiasis in a 17-Year-Old Male With Seckel Syndrome and Horseshoe Kidneys: Case Report and Review of the Literature".Urology.120:241–243.doi:10.1016/j.urology.2018.05.023.PMID29894776.S2CID48353132.
  6. ^Pawar AS, Thongprayoon C, Cheungpasitporn W, Sakhuja A, Mao MA, Erickson SB (January 2018)."Incidence and characteristics of kidney stones in patients with horseshoe kidney: A systematic review and meta-analysis".Urology Annals.10(1): 87–93.doi:10.4103/UA.UA_76_17.PMC5791465.PMID29416282.
  7. ^abcdeShah HU, Ojili V (2017)."Multimodality imaging spectrum of complications of horseshoe kidney".The Indian Journal of Radiology & Imaging.27(2): 133–140.doi:10.4103/ijri.IJRI_298_16.PMC5510309.PMID28744072.
  8. ^abcKirkpatrick JJ, Joshua J.; Leslie SW, Stephen W. (2021).Horseshoe Kidney.StatPearls [Internet]: Treasure Island (FL): StatPearls Publishing.PMID28613757.
  9. ^abWoolf AS, Winyard PJ, Hermanns MH, Welham SJ (2003). "Maldevelopment of the human kidney and lower urinary tract: an overview.". In Vize PD, Woolf AS, Bard JB (eds.).In The kidney.Academic Press. pp. 377–393.doi:10.1016/b978-012722441-1/50023-3.ISBN9780127224411.
  10. ^Oktem H, Gozil R, Calguner E, Bahcelioglu M, Mutlu S, Kurkcuoglu A, et al. (2008). "Morphometric study of a horseshoe kidney".Medical Principles and Practice.17(1): 80–3.doi:10.1159/000109596.PMID18059107.
  11. ^Suwannakhan A, Meemon K (2019-05-28)."Horseshoe kidney with extrarenal calyces and malformed renal vessels".European Journal of Anatomy.20(4): 355–359.
  12. ^abNatsis K, Piagkou M, Skotsimara A, Protogerou V, Tsitouridis I, Skandalakis P (August 2014). "Horseshoe kidney: a review of anatomy and pathology".Surgical and Radiologic Anatomy.36(6): 517–26.doi:10.1007/s00276-013-1229-7.PMID24178305.S2CID7889789.
  13. ^abcdeGutiérrez M (2013)."Renal anomalies of position, shape and fusion: radiographic analysis"(PDF).Revista de la Federación Ecuatoriana de Radiología.6:24–30.
  14. ^Nahm AM, Ritz E (November 1999)."Horseshoe kidney".Nephrology, Dialysis, Transplantation.14(11): 2740–1.doi:10.1093/ndt/14.11.2740.PMID10534525.
  15. ^Oderda M, Calleris G, Allasia M, Dalmasso E, Falcone M, Catti M, et al. (February 2017). "Robot-assisted laparoscopic pyeloplasty in a pediatric patient with horseshoe kidney: surgical technique and review of the literature".Urologia.84(1): 55–60.doi:10.5301/uro.5000188.PMID27516351.S2CID25468419.
  16. ^Pitts WR, Muecke EC (June 1975). "Horseshoe kidneys: a 40-year experience".The Journal of Urology.113(6): 743–6.doi:10.1016/S0022-5347(17)59571-3.PMID1152146.
  17. ^Al Otay A, Sarhan O, El-Tholoth HS, Alhelaly A, Al Akrash H, Al Ghanbar M, et al. (July 2018)."Different managements of horseshoe kidney stones, any difference in the outcome?".Urology Annals.10(3): 287–290.doi:10.4103/UA.UA_116_17.PMC6060601.PMID30089987.
  18. ^"Renal Pathology".Retrieved2008-11-26.
  19. ^Cereda A, Carey JC (October 2012)."The trisomy 18 syndrome".Orphanet Journal of Rare Diseases.7(1): 81.doi:10.1186/1750-1172-7-81.PMC3520824.PMID23088440.
  20. ^Kleta R, Brämswig JH (July 2000)."Horseshoe kidney and Turner syndrome".Nephrology, Dialysis, Transplantation.15(7): 1094.doi:10.1093/ndt/15.7.1094-b.PMID10862660.
  21. ^Ranke MB, Saenger P (July 2001). "Turner's syndrome".Lancet.358(9278): 309–14.doi:10.1016/S0140-6736(01)05487-3.PMID11498234.S2CID42096888.
  22. ^Niamien-Attai C, Bacchetta J, Ranchin B, Sanlaville D, Cochat P (October 2017). "[Renal abnormalities in Down syndrome: A review]".Archives de Pédiatrie.24(10): 1013–1018.doi:10.1016/j.arcped.2017.07.014.PMID28893484.
  23. ^Parkinson."Mel Gibson Interview - part one".BBC.
  24. ^Paget ET."Autopsy Report: Sam Kinison"(PDF).Autopsy Files.
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