Influenza-associated Intussusception: “You Too, Intussusception”

To the Editors: Intussusception is the leading cause of acute gastrointestinal obstruction in infants and young children, requiring prompt treatment. Some idiopathic pediatric intussusceptions are associated with viral infections. Recently, Townley et al1 reported a significant decrease in the incidence of intussusception during the COVID-19 lockdown in Australia, suggesting that viral infection–associated intussusception is more frequent than previously considered. Coincidentally, we encountered a case of influenza A–associated intussusception, a condition that has been rarely reported in the literature. This case provided us with several key lessons. A 3-year-old boy experienced vomiting and abdominal pain the day after testing positive for the nasopharyngeal influenza A antigen. Diagnosed with influenza-associated gastroenteritis, he received a single dose of peramivir (10 mg/kg). When his abdominal pain increased, he was transferred to us. Examination revealed a temperature of 36.9 °C, a heart rate of 124 bpm, a blood pressure of 90/50 mm Hg and a respiratory rate of 30 breaths/min. The cardiorespiratory systems were normal. There was tenderness in the upper abdomen without a palpable mass. Laboratory tests showed a normal white blood cell count (5600/μL) and slightly increased C-reactive protein (1.5 mg/dL). Real-time polymerase chain reaction detected influenza A (H1N1) pdm09 viral RNA in the throat and rectal specimens. Abdominal ultrasonography revealed a target sign (Fig. 1A) in the right upper abdomen, and contrast-enhanced computed tomography confirmed ileocolonic intussusception with enlarged, clustered mesenteric lymph nodes and intestinal edema (Fig. 1B and C). This condition was diagnosed as influenza A–associated intussusception, and a contrast enema (6-fold dilution of meglumine amidotrizoate in water-soluble contrast) was performed. Fluoroscopic radiography during the procedure revealed a partial contrast shade defect (Fig. 1D), confirming intussusception. Eight enema procedures normalized the interstitial condition, and the patient was discharged without sequelae or recurrence.FIGURE 1.: A: Abdominal ultrasonography in the right upper abdomen reveals a “target sign,” indicative of intussusception. The ileum (open arrowhead) slides into the colon (black arrowhead). The black arrow indicates the swollen mesenteric lymph node. B and C: Contrast-enhanced computed tomography of the abdomen of the horizontal (B) and coronal (C) sections in the arterial phase shows ileocolonic intussusception. The open and black arrowheads indicate the ileum and colon, respectively. The black arrows indicate the enlarged, clustered mesenteric lymph nodes and intestinal edema. D: The fluoroscopic radiograph image during the contrast enema examination showed a partial contrast shade defect in the colon (open arrow), confirming intussusception.This case offers several key lessons. First, influenza can cause intussusception. Adenovirus, cytomegalovirus and rotavirus are common causes of idiopathic pediatric intussusception.1 While the influenza virus typically presents with respiratory symptoms, it can also cause gastroenteritis, with a reported incidence of 4%-23%.2 The present case highlights the need to consider intussusception as a potential complication of influenza-associated gastrointestinal symptoms. Second, this case provides insight into the mechanism of influenza A virus–associated intussusception. Abdominal ultrasonography and contrast computed tomography revealed mesenteric lymph node swelling at the leading point and surrounding intestinal edema, findings aligning with previous reports.1 More broadly, irrespective of the viral species, clinicians should be aware of the potential for intussusception in children with viral diseases. While spontaneous resolution of intussusception is reported,3 “hidden” “incomplete” intussusception may exist among children with viral infections. Finally, the present case demonstrated viral evidence of influenza A (H1N1) pdm09 viral RNA in both throat and rectal specimens via real-time polymerase chain reaction, indicating the potential of influenza viruses to infect the gastrointestinal tract and lymph nodes.4 COVID-19, while devastating, provides new insights into medical research. The COVID-19 lockdown highlighted potential links between viral infections and certain disorders, such as Kawasaki disease.5 As Shakespeare might say, “You too, Brute?”—and now, “You too, intussusception.” We hope that similar studies will continue to advance our understanding of “pediatric infectious diseases.” Acknowledgment The authors were involved in patient care.