Simultaneity lateral cavity and bottom cavity are linked each other, which prevent cavitation damage of sidewalls and soleplates.

If oil got into the production pipe from the bottom, then barriers that would have impeded its flow up the cavity around that pipe would have made little difference.

For atypical renal cyst, a careful exploration for bottom of cyst cavity in operation is helpful to prevent misdiagnosing duplicated kidney complicated with hydronephrosis as large renal cyst.