It has proclaimed their utter failure to encircle, pursue, obstruct and intercept us. A stricture is a narrowing of the urethra severe enough to obstruct flow. These attempts to obstruct Caesar's legislation proved ineffective. Casts obstruct the airflow, and can result in the overinflation of the opposite lung. Very large tumors may obstruct cerebrospinal fluid drainage. Fish is the most common food to obstruct the airway and cause choking. Shumate also admitted conspiracy to obstruct justice. Cancer of the bladder, prostate or ureters can gradually obstruct urine output. The word is derived from a verb meaning primarily "to obstruct, oppose". Syrinxes usually result from lesions that partially obstruct CSF flow. On campaigns, the ancients did not obstruct those in a narrow pass. These oxalates can form larger kidney stones that can obstruct the kidney tubules. It is an offence to obstruct or assault an IO. It does not however obstruct the phagocytic or other defense roles of granulocytes. Players can tackle using their hands or use their whole body to obstruct opponents.