Summary
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.
Keywords
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Article info
Publication history
Published online: May 31, 2016
Accepted:
April 10,
2016
Received:
December 19,
2015
Identification
Copyright
© 2016 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.
