Intussusception is reliably and rapidly diagnosed with ultrasonography. Prior to ultrasonography, abdominal radiographs, in two views, should be obtained to see if intussusception is a likely diagnosis and to identify contraindications for reduction by enema. A normal plain abdominal radiograph generally cannot exclude the diagnosis of intussusception.10 However, the presence of air in the cecum in at least two of three views (supine, lateral, and prone) has a negative predictive value of 98%.11 Enemas should not be performed in patients with radiographic evidence of intestinal perforation, such as intraperitoneal air or ascites, or pneumatosis intestinalis. In addition, evidence of complete bowel obstruction may be considered a relative contraindication for enema reduction, as the clinical status of these patients may place them at higher risk of aspiration, bacterial translocation, and perforation.
Ultrasonography tends to be of greater utility in patients with a nonspecific history, normal physical examination, or atypical clinical pattern. Ultrasound findings of intussusception include a large sonographic target, bull's eye, or doughnut sign on the transverse or cross section (Fig. 48-1), and a sleeve or pseudo-kidney sign on the longitudinal section of the intussusception. The sensitivity and specificity of this imaging modality approaches 100% when performed by an experienced ultrasonographer.12 A diagnostic strategy based on initial ultrasonography followed by contrast enema was more cost-effective when compared with diagnostic contrast enema alone.13 However, in clinically obvious cases, proceeding directly to a reduction enema can be considered. Spiral computed tomography (CT) scan can also be employed to diagnose equivocal cases, but this test is not commonly used for this diagnosis in children and requires exposure to radiation.
Ultrasonography showing “target” sign of intussusception on a transverse view.
Once intussusception is diagnosed, treatment should be instituted rapidly. Nontoxic, hydrated children with a provisional diagnosis of intussusception should be kept nil per os. Those who appear dehydrated should receive a bolus of intravenous crystalloid, followed by balanced isotonic fluids pending measurement of serum electrolyte levels. A nasogastric tube may be inserted for decompression based on presence and severity of bowel obstruction. For patients without contraindications, the emergency physician in consultation with the pediatric surgeon and radiologist can determine whether pneumatic or hydrostatic enema reduction should be employed.
Pneumatic (air) or hydrostatic (contrast media) enemas are the first line of therapy and are successful in more than 85% of cases.14 Reduction of an intussusception is most commonly monitored with fluoroscopy (Fig. 48-2) but can also be monitored by ultrasonography. If pneumatic or hydrostatic pressure techniques fail to reduce the intussusception, a repeat effort at nonoperative reduction is one option. Should reduction techniques fail, operative therapy is necessary.
Reduction of intussusception by air contrast enema. Arrow shows location of intussusception.
If the patient has had prolonged symptoms (more than 1 to 2 days) or signs of peritonitis or the clinician has a high suspicion that there is a pathologic lead point (e.g., patients older than age 5 years or lead point seen on ultrasonography), laparotomy should be considered. This procedure allows for manual reduction, inspection of the bowel, and resection of necrotic segments or the pathologic lead point. Laparotomy is also indicated if successful reduction cannot be achieved with pneumatic or hydrostatic enema.
Once reduced, intussusception may recur in up to 10% of cases; this is usually in the first 72 hours, but occasionally it can occur later in time.2 Traditionally, patients have been admitted to the hospital for observation, but some authors have suggested that only a brief period of emergency department observation may be needed.15–17 Recurrent symptoms should prompt repeat investigations to rule out the presence of an intussusception. Multiple recurrences should prompt an investigation into whether a pathologic lead point is present.