Mixed Bag for Monday, June 1st, 2026

History

A 13-day old full-term male with no pertinent birth history presents with respiratory stress, lethargy, loose stools, pale skin, and cold extremities.

Images (Click any image to enlarge)

Question

What is the most likely diagnosis in the lower extremities given patient history and abdominal imaging findings?

Your answer

Please log in to see your results.

Correct answer

Intravascular air

Discussion

In the setting of pneumatosis and portal venous gas seen on imaging, this patient was presumed to have necrotizing enterocolitis (NEC) despite being full-term and without other known risk factors. He was promptly taken to the OR where he was found to have NEC totalis and underwent resection of most of the small bowel and colon. Unfortunately, his clinical status continued to deteriorate with intravascular air identified on bilateral lower extremity radiographs, and subsequently confirmed on ultrasound to represent air emboli in the bilateral popliteal arteries. Given multisystem organ failure, the decision was ultimately made to transition him to comfort care measures.

As NEC is usually associated with preterm birth (70% of cases) and formula feeding, this case was unusual in that the patient was full-term and fed with a combination of breastmilk and formula. It is suspected that underlying bacterial enteritis was the trigger that ultimately led to his clinical deterioration. In neonates, an inappropriate inflammatory response to gut mucosal irritants may allow for the translocation of gut bacteria and air into the bowel wall, subsequently evolving into NEC. Plain x-ray is the gold standard for diagnosis of NEC with imaging showing pneumatosis intestinalis, as well as possible bowel dilation, portal venous gas, and/or free air.

Vascular air embolism is a rare and often deadly condition in neonates that is most commonly seen in the setting of mechanical ventilation. There have, however, been several case reports attributing intravascular air to concurrent NEC as was observed in this case. Multimodality imaging—including x-ray, doppler ultrasound, echocardiography, and CT—may be utilized to facilitate prompt diagnosis and characterization of the full extent of intravascular air, which is most lethal when the cerebral or coronary arteries are involved.

In the case of this patient, the underlying cause of NEC was presumed to be enteropathogenic Escherichia coli (EPEC), which was identified in stool samples. In developing countries, EPEC is frequently cited as an endemic cause of long-term diarrheal disease, but is less often associated with severe disease, particularly in higher income countries. Moreover, in cases when E. coli is found to have caused NEC, the enterohemorrhagic strain (EHEC) is more commonly implicated rather than EPEC.

Differential diagnosis

·      Necrotizing fasciitis

Additional images

References

• Ginglen JG, Butki N. Necrotizing Enterocolitis. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 8, 2023.
• Guner YS, Malhotra A, Ford HR, Stein JE, Kelly LK. Association of Escherichia coli O157:H7 with necrotizing enterocolitis in a full-term infant. Pediatr Surg Int. 2009;25(5):459-463. doi:10.1007/s00383-009-2365-3.
• Mueller M, Rausch-Phung EA, Tainter CR. Escherichia coli Infection. In: StatPearls. Treasure Island (FL): StatPearls Publishing; December 14, 2025.
• Tobias J, Kassem E, Rubinstein U, et al. Involvement of main diarrheagenic Escherichia coli, with emphasis on enteroaggregative E. coli, in severe non-epidemic pediatric diarrhea in a high-income country. BMC Infect Dis. 2015;15:79. Published 2015 Feb 21. doi:10.1186/s12879-015-0804-4.
• Zhou Q, Lee SK. Vascular Air Embolism in Neonates: A Literature Review. Am J Perinatol. 2025;42(14):1819-1824. doi:10.1055/a-2508-2733.