Classic Teaching About Intussusception in Adults Needs Revision
Abstract & commentary
Synopsis: Intussusception can be encountered as an incidental finding at CT and MR imaging of adults. Contrary to conclusions drawn from surgical data, the majority of such intussusceptions in adults are not due to a mass acting as a lead point.
Source: Warshauer DM, et al. Radiology 1999;212:853-860.
For years, standard radiologic dictum has stated that no cause for intussusception is generally found in infants—allowing nonsurgical therapies such as a fluoroscopically monitored enema to be used as definitive therapy in many cases. In contrast, intussusception in adults has been said to frequently have a lead point, thus often requiring surgical exploration for definitive evaluation and treatment. Modern cross-sectional imaging techniques are demonstrating the characteristic findings of intussusception (e.g., a bowel-within-bowel configuration, typically with mesenteric fat included within it) with increasing frequency, even in patients in whom that diagnosis is unsuspected and seemingly dissonant with clinical findings.
To assess the clinical significance of intussusception detected at computed tomography (CT) or magnetic resonance (MR) imaging in adults, Warshauer and colleagues from the University of North Carolina School of Medicine retrospectively reviewed the clinical records and CT and MR images of 33 patients who had one or more intussusceptions shown on those images. The 33 patients (24 male, 9 female) ranged in age from 18 to 84 years (median age, 41 years). Twenty-nine patients had abdominal symptoms at the time they were imaged, including 24 with abdominal pain. The intussusception was enteroenteric in 29 patients and involved the colon in four others. Only 10 (30%) patients, including all four with intussusception involving the colon, were shown to have a neoplastic lead point; seven of the lead points were malignant, and three were benign. In nearly half (48%) of the patients in whom no lead point was identified, the intussusception was considered to be idiopathic.
Warshauer et al found some statistically significant differences in the imaging appearances of enteric intussusceptions: those without a lead point were shorter (median length, 4 cm vs 10.8 cm) and smaller (median diameter, 3 cm vs 4 cm), and they less often caused obstruction (4.3% vs 50%). Warshauer et al suggest that not all intussusceptions discovered at imaging require further work-up—particularly those in younger patients with a transient, small, enteroenteric intussusception that does not obstruct the bowel.
Comment by David M. Panicek, MD
This study was reportedly undertaken in an attempt to reconcile a discrepancy between classic radiologic teachings and Warshauer et al’s clinical experience with intussusception. My own experience has been similar: none of the radiologic tests that I recommended for several patients with unsuspected intussusceptions shown on CT in adult patients in recent years has demonstrated a mass that could have been a lead point—even though virtually all of the patients in my practice have cancer, placing some of them at risk for metastasis to bowel.
The findings of this study are an excellent example of how conclusions can be markedly affected by the manner in which the underlying data are collected. When examined from the perspective of findings at surgery, the majority of cases of adult intussusceptions have been found to be due to a lead point. However, cross-sectional imaging now allows us to discover a larger number of intussusceptions, including those that apparently occur as a transient phenomenon and that are not associated with a mass acting as a lead point. Such intussusceptions may produce intermittent symptoms or none at all. As a result of this new perspective, it is no longer necessary to recommend intensive work-up of every intussusception that is incidentally demonstrated at CT or MR imaging in an asymptomatic patient. (Dr. Panicek is Professor of Radiology, Department of Radiology, Memorial-Sloan Kettering Cancer Center, New York, NY.)
Intussusception in adult patients:
a. is usually due to a lead point in the bowel.
b. may often be a transient phenomenon.
c. should be aggressively worked-up when shown at CT or MR imaging.
d. usually involves the colon.