May Be Caused by

 Common

Air bubbles

Arterial collaterals

Blood clot

Multiple calculi

Varicosities

Venous collaterals

 Uncommon

Cholesteatoma

Endometriosis

Eosinophilic ureteritis

Granulomas

Leukoplakia

Malacoplakia

Papillomatosis

Polyps

Schistosomiasis haematobium

Squamous metaplasia

Strictures

Submucosal hemorrhage

Transitional cell carcinoma

Tuberculosis

Ureteritis cystica