DOI:10.2214/AJR.06.0103
AJR 2006; 187:W325-W326
© American Roentgen Ray Society
Preoperative CT Diagnosis of Appendiceal Intussusception
Jonah Luzier,
Peter Verhey and
Nora Dobos
Oregon Health Sciences University Portland, OR 97239
WEB—This is a Web exclusive article.
An 8-year-old boy presented to his primary care provider with a 1-week
history of vague persistent periumbilical abdominal pain, intermittent
constipation, and a single episode of emesis. Sonography was performed and
reportedly showed a donutlike mass of concentric high- and low-echogenicity
bands. The preliminary diagnosis of intussusception was made, and the child
was referred to our institution for further evaluation and treatment.
Initial physical examination revealed a soft abdomen with mild
periumbilical tenderness and no clinical findings to suggest an acute abdomen.
Laboratory values, including blood gas and WBC, were within normal limits.
Given the subacute clinical history and relatively nonspecific clinical and
laboratory findings, abdominopelvic CT was performed before exploratory
laparoscopy using our routine appendicitis protocol. This protocol includes
overlapping 3.0-mm helical images after the administration of a
weight-appropriate dose of IV contrast material, in addition to water-soluble
oral and rectal contrast material. Additional sagittal and coronal
reconstructions were generated at the radiologist's request.
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Fig. 1A —CT findings in 8-year-old boy with abdominal pain. Axial
(A and B) and coronal (C) views show cecal
intussuscipiens (arrow) and appendiceal intussusceptum
(star). Note inflammation and venous congestion of appendix.
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Fig. 1B —CT findings in 8-year-old boy with abdominal pain. Axial
(A and B) and coronal (C) views show cecal
intussuscipiens (arrow) and appendiceal intussusceptum
(star). Note inflammation and venous congestion of appendix.
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Fig. 1C —CT findings in 8-year-old boy with abdominal pain. Axial
(A and B) and coronal (C) views show cecal
intussuscipiens (arrow) and appendiceal intussusceptum
(star). Note inflammation and venous congestion of appendix.
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Fig. 1D —CT findings in 8-year-old boy with abdominal pain.
Laparoscopic photographs show cecal intussuscipiens (arrow) and
appendiceal intussusceptum (star). (Courtesy of G. Zallen, Portland,
OR)
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Axial and coronal CT showed intussusception of the base of the appendix
into the cecum (Figs. 4A-4C), appendiceal enlargement to 1.0 cm, diffuse
appendiceal wall thickening, and hyperemia of the distal portion of the
appendix. Minimal periappendiceal stranding was present. The diagnosis of
nonperforated appendiceal intussusception with inflammation and venous
congestion of the appendix was made.
The patient was subsequently taken to surgery and an appendiceal
intussusception was confirmed laparoscopically (Fig. 4D). After several
unsuccessful manual reduction attempts, distal cecectomy and appendectomy were
performed without complication. The remainder of the patient's brief hospital
stay was uneventful.
Appendiceal intussusception is extremely rare, with a reported incidence of
0.01% [1]. Patients often
present with weeks to months of intermittent abdominal pain, nausea and
vomiting, melena ("currant jelly stool"), fever, or constipation
[2]. Occasionally, patients can
be asymptomatic or present with symptoms of acute appendicitis
[1]. The most common causes of
appendiceal intussusception in children include appendiceal inflammation
secondary to fecalith, foreign body, hypertrophic lymphoid follicle, parasite,
lipoma, and hamartomatous polyp. Other causes seen exclusively in the adult
population include mucocele, adenocarcinoma, carcinoid, endometriosis, and
metastases [2,
3].
Several hundred cases have been reported since appendiceal intussusception
was first described in 1858; however, to our knowledge only 11 prospectively
diagnosed and surgically confirmed cases have been reported
[1,
2]. All were diagnosed with
barium enema, sonography, or endoscopy. We present the first described case,
to our knowledge, of surgically confirmed appendiceal intussusception
prospectively diagnosed on CT.
In most cases of appendiceal intussusception, radiography findings are
normal unless a small-bowel obstruction exists. Sonography may identify the
classic target lesion or "donut sign" associated with
intussusception. However, the location is often presumed to be ileocolic or
ileoileal because of lack of anatomic landmarks. Visualization of a cystic
structure smaller than 6 mm in diameter in the center of a target lesion may
be considered characteristic of but not pathognomonic for appendiceal
intussusception [1]. The
frequency of this finding in cases of appendiceal intussusception remains
undocumented.
The appearance of appendiceal intussusception on lower endoscopy is
described as a polypoid 1- to 1.5-cm cecal lesion that occasionally has a
central dimple. However, even experienced examiners have been fooled. The
literature describes multiple instances in which these "lesions"
have been biopsied or initially misdiagnosed as a polypoid tumor
[2]. Barium enema is described
as producing a classic coiled-spring appearance in appendiceal intussusception
[4], with lack of filling of
the appendix.
Intussusception has classically been described as a having a target,
layered, sausage-shaped or reniform appearance on CT; when present, this
appearance is virtually pathognomonic. The limitations of CT primarily relate
to its use of ionizing radiation and the risk of allergy to contrast material.
However, as this case shows, CT can provide excellent anatomic detail in
addition to assessing the presence of complications of intussusception. In
addition, with modern CT scanners, isotropic voxel reconstructions in nonaxial
planes provide additional diagnostic certainty by allowing direct
visualization and differentiation of the distal ileum and ileocecal valve from
the cecal tip and appendix.
Note—The authors thank Garret Zallen, OHSU Department of Surgery, for
providing intraoperative laparoscopic photographs.
References
- Koumanidou C, Vakaki M, Theofanopoulou M, et al. Appendiceal and
appendiceal-ileocolic intussusception: sonographic and radiographic
evaluation. Pediatr Radiol 2001;31
: 180-183[CrossRef][Medline]
- Ozumer G, Davidson P, Church J. Intussusception of the vermiform
appendix: preoperative colonoscopic diagnosis of two cases and review of the
literature. Int J Colorectal Dis 2000;15
: 185-187[CrossRef][Medline]
- Choi SH, Joon KH, Kim SH, et al. Intussusception in adults: from
stomach to rectum. AJR 2004;183
: 691-698[Free Full Text]
- Levine MS, Trenkner SW, Herlinger H, et al. Coiled-spring sign of
appendiceal intussusception. Radiology1985; 155:41
-44[Abstract/Free Full Text]
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