Cul-de-sac: A viewer writes regarding the term "cul-de-sac": "I know we live on one. Is there a medical meaning for it?" The answer is of course: "Yes" (or you'd not be reading this here). An anatomic cul-de-sac is a blind pouch or cavity that is closed at one end.

Examples of culs-de-sac in the intestine:

• Colonic diverticulum, a small bulging sac that pushes outward from the colon wall; such diverticuli are the hallmark of diverticulosis;
• Meckel's diverticulum, a single outpouching of the small intestine that occurs in about 1 in every 50 people; and
• The cecum, the first part of the colon, to which the appendix is attached. (The word "cecum" is from the Latin "caecus" meaning "blind" since the bottom of the cecum is a blind pouch, a cul de sac, leading nowhere).

Cul-de-sac, aside from being any "blind pouch or cavity that is closed at one end," is used specifically to refer to the rectouterine pouch (the pouch of Douglas), an extension of the peritoneal cavity between the rectum and back wall of the uterus. From that fact comes:

• Culdoscopy, the introduction of an endoscope through the vagina into the cul-de-sac;
• Culdoscope, the viewing tube (endoscope) that is used to look into the cul-de-sac; and
• Culdocentesis, the aspiration (withdrawal) of fluid from the cul- de-sac.

In French, "cul-de-sac" literally is "bottom of (a) sack." As early as the 13th century, a cul-de-sac was a dead-end street (or a dead-end way), a blind alley.

The third letter in "cul" is silent in French; in English it is spoken. So, in French "cul" is pronounced "ku" and in English "kul".