Assistant principals aid the principal in the overall administration of the school. Some assistant principals hold this position for several years to prepare for advancement to principal jobs; others are career assistant principals.n larger school systems, a principal is often assisted by someone known as a vice-principal (Republic of Ireland: deputy principal) or assistant principal.
Causes. Pressure on the bladder during delivery is the main cause of a ruptured bladder, although a weakness in the bladder wall may make it susceptible to a rupture. In older horses, a ruptured bladder may be caused by an accident or related to a urinary obstruction.
There are many causes of hydronephrosis. In adults, the conditions that most often cause hydronephrosis include: 1  Kidney stones âSalts and minerals that are present in urine can form small hard stones that may become lodged in the kidneys or urinary tract.ther possible causes of hydronephrosis include: 1  Blood clots in the kidney or ureter. 2  Narrowing or stricture of the urinary tract due to injury, infection, birth defects or surgery.