Abnormal medullary peritubular capillary morphology Medullary peritubular capillary erythrocyte congestion 2021-06-23T19:01:20Z Substantially increased numbers of red blood cells within capillaries surrounding tubules in the medulla of the kidney. This feature is assessed in histological images as the presence of numerous erythrocytes in a segment of the capillary such that the vessel appears to be congested (not open).