These structures are often obstructed by lymphoid hyperplasia in children, and by fecaliths in adults.
The opening to this structure sometimes features a membranous fold known as Gerlach's valve. A "pseudo" form of damage to this structure may result from Yersinia enterocolitica infection. This structure may be damaged if palpating the left lower quadrant increases the pain in the right lower quadrant, in a positive Rovsing's sign. When diagnosing an ectopic pregnancy, a beta-hCG test can rule out damage to this non-reproductive structure, for which it is often clinically mistaken. This structure is located roughly a third of the way from the anterior superior iliac spine to the (*) umbilicus. Due to their similar presentation, diverticulitis is often referred to as a "left-sided" counterpart to the inflammation of this structure. These structures are often obstructed by lymphoid hyperplasia in children, and by fecaliths in adults. For 10 points, name this vestigial blind-ended tube connected to the cecum in the large intestine, which is surgically removed when inflamed. 
The opening to this structure sometimes features a membranous fold known as Gerlach's valve.
appendix [or vermiform appendix; or cecal appendix; or vermix; or vermiform process]