Stones in the gallbladder may cause obstruction and the accompanying acute attack.

Occasionally, subependymomas cause ventricular obstruction and, in these cases, treatment is indicated.

However heavy infection may cause intestinal obstruction, diarrhea and weight loss.

Even without crystal formation, a thick protein matrix may cause urethral obstruction by itself.

For example, from the ileum to the colon, causing obstruction.

Once the stones develop, over time they may grow large enough to cause obstruction and renal failure.

An annular pancreas causing obstruction may also be the cause.

Rarely, the fish slip inside the mouth and can cause acute respiratory obstruction with fatal consequences.

A diphtheritic membrane may form in the trachea, causing obstruction.