Appendicitis - acute or subacute process that causes the lumen of the appendix (which is a blind sac) to become obstructed with buildup of pressure and eventual rupture.
Mass - rarely an appendiceal mass is found on CT scan or during intra-abdominal surgery (laparotomy)
Abscess - if found secondary to appendicitis it must be drained. If it is diagnosed preoperatively care currently is to have an interventional radiologist (a radiologist who does procedures) drain the abscess via a percutaneously (through the skin) placed catheter that is left in place to decompress the cavity and allow it to "heal from the inside out". The appendix is then removed at about 6 weeks. If it is found during surgery it must be decompressed and a drain left in place in the abcess cavity by the surgeon.
Existing appendiceal rupture with defined abscess cavity.
Appendicitis in setting of adjacent inflammatory bowel disease (e.g., a Crohn's disease flare-up in the contiguous terminal ileum or cecum.
Clinical diagnosis - appendicitis remains a clinical diagnosis primarily. There is no set of invariably ocurring signs and symptoms. The two most common are anorexia (loss of appetite) and pain, although there are many cases of appendicitis that have neither of these. Other signs and symptoms included pain around the umbilicus that "moves" to the right lower quadrant, fever, nausea, vomiting, diarrhea, rigid and board-like abdomen, and worsening pain on walking. Appendicitis is most difficult to clinically diagnose in the very young and very old and in patients who are diabetic or on steroids.
Radiographic diagnosis - there are three radiographic studies that are commonly used to help diagnose appendicits, although in clear-cut clinical cases none is absolutely required. The most widely used is computed tomography (CT) of the abdomen and pelvis with 5 mm cuts. For best results this should be performed with intravenous dye, dye given by mouth (or PO), and dye given per rectum (although this is often not done as it is uncomfortable for the patient and radiology technician both.) Findings consistent with appendicitis are stranding in the mesentery, non-visualization of the appendix lumen, fluid in the pelvis, and an enlarged and thickened appendix, especially if it is seen in cross-section. It must be noted that a normal CT does not rule appendicitis. Studies have shown that a CT can miss appendicitis, especially in the early stages, in up to 10% of cases.
Although less widely used today, plain-film radiography (aka "a flat plate") can be helpful in showing an opacity in the right lower quadrant that could be suggestive of an fecolith (insissipated stool in the mouth of the appendix).
The third radiology test that is sometimes used in children is an ultrasound of the right lower abdomen. This test is easy to perform, non-invasive, and has no radiation exposure, but it is of limited help as it is sometimes difficult to visualize the appendix (either normal or inflamed). It is almost never used in adults due to the larger body habitus.