Predictors of Intussusception
ABSTRACT & COMMENTARY
Source: Harrington L, et al. Ultrasonographic and clinical predictors of intussusception. J Pediatr 1998;132:836-839.
Intussusception is the leading cause of acute intestinal obstruction in infants. The classic triad of colicky, intermittent abdominal pain, vomiting, and currant jelly stool appears only in a small proportion, and usually late in the course of cases of intussusception. This study addressed the value of clinical predictors for intussusception to help identify children requiring a screening test as opposed to those who should proceed directly to air enema. The use of ultrasonography as a screening tool for intussusception confirmed by air enema was assessed.
Among 245 candidates, 88 patients were assessed for clinical predictors, 35 of whom were positive for intussusception. Significant positive predictors were right upper quadrant abdominal mass (PPV 94%), gross blood in stool (PPV 90%), blood on rectal examination (PPV 78%), and the triad of intermittent abdominal pain, vomiting, and right upper quadrant abdominal mass (PPV 93%). Negative predictors (such as nonbloody diarrhea, negative stool occult blood test, and pain lasting greater than 30 minutes) were not reliable, as the combination of three or more of 10 clinical features atypical for intussusception had a NPV of just 77%. Of the total 245 cases, intussusception was ruled out by ultrasonography in 97.4%. However, even experienced ultrasonographers (a children's hospital staff radiologist, radiology fellow, or both) missed three cases of intussusception confirmed by air enema.
COMMENT BY HAZEL GUINTO-OCAMPO, MD, FAAP
The diagnosis of intussusception relies heavily on having a high index of suspicion based on historical and examination data. This well-designed prospective study confirms what experienced physicians intuitively knew to be significant positive and negative clinical predictors of intussusception. Interestingly, lethargy occurring between episodes of abdominal pain, believed to be one of the typical signs of intussusception, was not mentioned in the study. The study's limitations include the small proportion of patients assessed for clinical predictors and the generalizability of the findings to institutions lacking skilled and experienced ultrasonographers.
Plain abdominal radiography has always been used as the screening tool for intussusception. Like ultrasonography, the correct identification of intussusception by plain radiography relies heavily on the reader's skill and experience. However, abdominal radiographs are readily available, rapid, and much less expensive. Therefore, ultrasonography should be reserved for patients whose diagnosis remains unclear following plain abdominal radiography. Primary care providers and emergency physicians who bear the brunt of diagnosing intussusception accurately should be trained in identifying plain abdominal radiographic findings suggestive of intussusception. These include the presence of a soft tissue mass, absence of air in the rectum, minimal intestinal gas, and proximal small bowel distension with air fluid levels. (Dr. Guinto-Ocampo is an attending in Pediatric Emergency Medicine at Temple University Hospital in Philadelphia, PA.)
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