Assertion: isthmus | /r/AtLocation | 20% of cases
Facets:
Source sentences:
text: In approximately 40% of cases, the isthmus lies at the level of L4, just beneath the origin of the inferior mesenteric artery; in 20% of cases, the isthmus is in the pelvis; and in the remaining cases, it lies at the level of the lower poles of normally placed kidneys.25