Appendiceal intussusception happens when appendix segment is pulled into itself or into the cecum. This condition can mimic various chronic and acute abdominal conditions. It is an important entity to recognise since it could be mistaken for a caecal mass.
Appendiceal intussusception is a rare condition, with an estimated incidence of 0.01% of patients who underwent appendectomy 1.
Symptoms of appendiceal intussusception have been divided into four groups:
- asymptomatic patients
- symptoms similar to acute appendicitis
- symptoms consistent with intestinal intussusception: abdominal pain and vomiting occur for several days; bowel movements may be normal, or less frequently, there is constipation, diarrhoea or melaena
- a prolonged history of intermittent severe attacks of right lower quadrant abdominal pain. Vomiting and melaena may be present
The diagnosis is rarely made preoperatively because of its variable presentation and unspecific symptoms.
Appendiceal intussusception can occur without any underlying abnormality. Anatomical variations of the appendix and pathological conditions such as tumours or polyps, endometriosis, parasitism, cystic fibrosis, fecaliths and foreign bodies, have all been described as possible causes.
In most cases the radiographic findings are normal. When there is associated small bowel obstruction, abdominal radiographs can demonstrate features thereof (i.e. dilated small bowel loops with air-fluid levels).
Ultrasonography has a role, especially in children. Longitudinal sonograms may show the inverted appendix protruding into the caecal lumen.
Similar findings to the intestinal intussusception can be seen, which include:
CT is the most commonly used diagnostic modality. A CT scan can clearly show the appendix invaginated into the caecal lumen (see case 1).
The appearance of bowel-within-bowel, which identifies the appendix surrounded by the caecum, can be seen.
On imaging, differential considerations include
- 1. Laalim SA, Toughai I, Benjelloun el B et-al. Appendiceal intussusception to the cecum caused by mucocele of the appendix: Laparoscopic approach. Int J Surg Case Rep. 2012;3 (9): 445-7. doi:10.1016/j.ijscr.2012.04.019 - Free text at pubmed - Pubmed citation
- 2. Langsam LB, Raj PK, Galang CF. Intussusception of the appendix. Dis. Colon Rectum. 1984;27 (6): 387-92. Pubmed citation