OrphaNet reference

Retroperitoneal fibrosis 

May Cause

Anterior indentation on rectosigmoid junction

Dilated bile ducts

Displacement of pelvic ureter

Extrinsic pressure deformity of bladder

Increased presacral space

Increased retrogastric or retroduodenal space

Inferior vena cava obstruction

Lateral deviation of upper ureter

Lesion of perinephric space

Malposition of kidney

Medial deviation of upper ureter

Obstruction of ureter

Paraspinal soft-tissue mass

Presacral mass

Rectal disease

Small urinary bladder

Ureteral stricture

May Be Caused by

 Common

Drug reaction

Ergotamine

Hydralazine

Idiopathic retroperitoneal fibrosis

Methysergide

 Uncommon

Amyloidosis

Carcinoid

Connective tissue disease

Crohn disease

Diverticulitis of colon

Extravasated contrast medium

Fungal disease

Hemorrhage, traumatic or bleeding disorder

Histoplasmosis

Lymphogranuloma venereum

Lymphoma

Mediastinitis

Nodular sclerosing Hodgkin disease

Pancreatitis

Perforated appendicitis

Postoperative state

Radiation fibrosis

Retractile mesenteritis

Retroperitoneal extension of scirrhous or desmoplastic carcinoma of stomach, colon, or prostate

Riedel thyroiditis

Sclerosing agent for hemorrhoids

Thorotrast

Trauma

Tuberculosis

Urinary extravasation

Weber-Christian disease