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Information Sheets > Spiral CT: Findings in Acute Appendicitis

The primary CT signs which are considered pathognomonic for appendicitis include:

the presence of an enlarged, inflamed appendix with a diameter greater than 8 mm in children (6 mm in adults)
Visualization of an appendicolith

SAN DIEGO, CA -- May 6, 2003 -- Computed tomography-guided interventional procedures offer highly accurate and conservative therapies for patients with back pain, decreasing the need for pain medications and delaying the need for surgical treatment, according to a recent study.

"CT-guided procedures are done without any patient sedation and imply no major risks," says Diego Aguirre, MD, of Fundacion SantaFe de Bogota Medical Center and El Bosque University, Bogota, Colombia, and co-author of the study. They are minimally invasive procedures performed primarily by radiologists, who inject anesthetic and steroidal anti-inflammatory drugs into the probable site to "block" where the pain is originating.

To determine the value of CT-guided interventional "blocks," Dr. Aguirre and Sonia Bermudez, MD, studied 120 patients with an average age of 61 years old. "To date, we found that less than 3% of patients who underwent a CT guided interventional procedure needed surgical treatment for pain management," says Dr. Aguirre. Since these CT guided procedures are also diagnostic tools, the rate of surgeries doesn't imply failure of the procedure, he notes.

Although the study considered back pain in general, Dr. Aguirre says, "Around 90% of the patients were referred for management of low back pain specifically."

Dr. Aguirre says the patients had a variety of symptoms including numbness and severe back pain that radiated to the legs, hip, or groin areas. He adds that most of the patients also described progression of the pain during physical activities.

Patients with low back pain are usually treated with rest, oral non-steroidal anti-inflammatory drugs (NSAIDs), physical therapy, spinal manipulation, and, in severe cases, with surgery, Dr. Aguirre says, "In our study, patients diminished the consumption of analgesic drugs for back pain. In most of the patients treated, blocks are considered a complement of the treatment that could also include physical therapy," he adds.

"While interventional procedures have been available for many years, only recently have they shown an increasing potential in the management of patients with back pain, especially under CT guidance," says Dr. Aguirre.

This practice has extensive experience in the conservative treatment of back pain, including:

facet block – for localised back pain
periradicular block – for radicular symptoms
sacro-iliac joint block
focal pain block

With perforation, the position of an appendicolith may change as it is free to move within the peritoneal cavity. Secondary CT signs which are suggestive of, but not diagnostic for, appendicitis include:

Pericaecal inflammatory process with obscuration of the fat plane anterior to the psoas muscle
Periappendiceal fatty infiltration
Inflammatory changes or abscess in the right lower quadrant, with or without visualization of an abnormal appendix or appendicolith
Pelvic abscess
Thickening of the cecum (arrow-head sign) and terminal ileal wall (seen in 50% of children and 5% of adults with appendicitis)
Small bowel obstruction (seen in 30% of children and 10% of adults with appendicitis)
Free fluid in the pelvis

If perforation occurs, an abscess may be identified, most commonly seen in the right lower quadrant (periappendiceal), but also possible between loops of adjacent bowel (interloop abscess), in the pelvic cul-de-sac, within the mesentery, or in a perihepatic or subdiaphragmatic location. Generalized peritonitis may also develop following appendiceal perforation. Hepatic abscesses which occur secondary to septic mesenteric thrombophlebitis may be detected as hypodense lesions in the liver; lymphomatous or leukemic lesions may have a similar CT appearance.

A false positive CT diagnosis of appendicitis may be made in the presence of small bowel obstruction, a gangrenous infarcted cecum, mucocele of the appendix, or neoplastic or inflammatory processes involving the cecum or terminal ileum.

CT assessment for appendicitis may hampered by the presence of normal fluid-filled bowel loops which may be confused with an abnormal appendix or with radiodense pits and medications in the distal ileum which may be mistaken for an appendicolith. False negative CT examinations may occur in slender patients and children in whom there is a paucity of peri-appendiceal and retroperitoneal fat.