Appendicitis: Pathology review

While in the Emergency Department, Bella, a 22-year-old woman, presents with abdominal pain that started 6 hours ago. The pain was initially located around the umbilical area but it has migrated to the right lower quadrant in the past few hours. The pain is sharp, like being stabbed with a knife and it gets worse with movement. A physical examination showed tenderness of the right lower quadrant with moderate guarding and a low-grade fever of 100.4°F. Shortly after, Edward, who’s 11, presents with generalized abdominal pain with vomiting and diarrhea. On examination, he appears ill and has a temperature of 104°F. His abdomen is tense with generalized tenderness and guarding. No bowel sounds are present. Blood tests were ordered in both cases, detecting an increased white blood cell count of 12,000 cells per microliter with 85 percent neutrophils.

Now, both people have appendicitis. Now the appendix is the little close-ended hollow tube that’s attached to the cecum of the large intestine, and sometimes it’s called the vermiform appendix, where vermiform means “worm-shaped.” Normally, the appendix can be found in a retrocecal location, as well as pre-ileal, post-ileal, pelvic subcecal, and paracecal. Its function is actually unknown, though some theories suggest it might be a “safe-house” for the gut flora and that it plays a part in the lymphatic and immune system.

Ok, so appendicitis usually occurs because something gets stuck and obstructs the appendix. That something could be a fecalith, which is a hardened lump of fecal matter, a piece of undigested material like gum or seeds, or even a clump of intestinal parasites like pinworms. Another cause of obstruction could be lymphoid follicle growth, also called lymphoid hyperplasia, and a high yield fact is that unlike a fecalith, this is more common in children. Now, because the intestinal lumen is always secreting mucus and fluids from its mucosa, fluid and mucus build up in the obstructed appendix, which increases the pressure inside. This makes it grow in size and it will physically push on the nearby afferent visceral nerve fibers, causing abdominal pain.