Renal ectopia pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: : Cafer Zorkun M.D., PhD.
Overview
Pathophysiology
- Normal ascent of the kidneys is required for formation of the extraperitoneal perirenal fascial planes.
- Ectopia (or renal agenesis) results in failure of development of fascial layers in the flanks on the side not occupied by renal tissue.
- Lack of restraining fascia leads to possible malposition of bowel into the extraperitoneal fat of the empty renal fossa and relaxation of mesenteric supports for bowel loops in this region.
Crossed-fused renal ectopia
- Crossed ectopy = kidney located on the opposite side of the midline from its ureter. [1] [2] [3] [4]
- In 90% of crossed ectopy, there is at least partial fusion of the kidneys (the remainder demonstrate two discrete kidneys on the same side, crossed-unfused ectopy)
- Due to improper renal ascent in embryogenesis (4th-8th week of fetal life - normally, the kidney reaches its appropriate position at L2 level at the end of the 2nd month)
- Fusion of the kidneys within the pelvis leads to crossed-fused renal ectopia.
- Abnormally situated umbilical artery prevents normal cephalic migration. Another theory is that the ureteric bud crosses to the opposite side and induces nephron formation in the contralateral metanephric blastema.
References
- ↑ Dunnick, N.R., Sandler, C.M., Newhouse, J.H., and Amis, E.S. Textbook of uroradiology, 3rd Edition. Lippincott Williams and Wilkins, 2001.
- ↑ Dyer, R.B., Chen, M.Y., and Zagoria, R.J. Classic signs in uroradiology. Radiographics, 2004; 24:S247-S280.
- ↑ Gay, S.B., Armistead, J.P. Weber, M.E., and Williamson, B.R.J. Left infrarenal region: anatomic variants, pathologic conditions, and diagnostic pitfalls. Radiographics 1991; 11: 549-570.
- ↑ Meyers, M.A., Whalen, J.P., Evans, J.A. and Viamonte, M. Malposition and displacement of the bowel in renal agenesis and ectopia: new observations. AJR, 1972; 117,2: 323-333.