The diagnosis of acute appendicitis is most difficult to establish in:

C. Infants younger than 1 year.

DISCUSSION: It is very difficult to establish a firm diagnosis of acute appendicitis in an infant of 1 year or younger since the patient cannot provide a history or be helpful during the physical examination. It is rare to make a definitive diagnosis preoperatively in such infants, and in such cases the appendix is usually perforated at the time of operation. While appendicitis is somewhat more difficult to diagnose in the elderly because of the reduced response to inflammation; nevertheless, it is usually possible to make the diagnosis. With pregnant women it is wise to remember that the enlarging uterus in the last trimester dislocates the appendix higher in the abdomen and that the signs and symptoms follow this anatomic shift accordingly.