Contributed by
Saint Louis Children's Hospital - Mallinckrodt Institute of Radiology
Kyle Robbins, and Noah Seymore.
History
Premature infant (born 29 weeks EGA) born emergently due to uterine rupture. UAC placement attempted. Now with hypovolemic shock and suspected DIC (disseminated intravascular coagulopathy).
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Question
What is the most likely diagnosis?
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Correct answer
Umbilical artery pseudoaneurysm
Discussion
Umbilical artery catheters (UACs) course from the umbilical artery to the common iliac artery, where they angle and ascend into the aorta. The complication rate of UACs is approximately 9%, with more severe complications due to thromboembolism or perforation. Most commonly perforation results in a hematoma that clots, but when frank hemorrhage and hemoperitoneum occurs, it is life-threatening.
Pseudoaneurysm is a rupture of the arterial wall. There is persistent blood flow, but it is contained by fascia and adjacent thrombus, which has a high risk of progressing to free intraperitoneal hemorrhage. Pseudoaneurysm can be distinguished from simple hematoma by the presence of internal flow on Doppler imaging. Arterial waveforms confirm a persistent connection with the injured artery. Pseudoaneurysms typically occur at the iliac artery or aorta but rarely can be at the umbilical artery. Pseudoaneurysms can occur purely from mechanical trauma, but risk is increased in hypercoagulable patients. They may also be mycotic in nature and are often associated with sepsis. Symptoms can progress to hemodynamic instability, disseminated intravascular coagulation (DIC), and end-organ ischemia. Treatment can range from conservative support via replacement of blood products and observation to emergent surgical intervention, depending on the stability of the patient.
Differential diagnosis
While the location at the dome of the bladder would be typical of a urachal cyst, the flow on color and spectral Doppler imaging would exclude this lesion.
An enteric duplication cyst would be expected to have "gut signature" (layering hypo- and hyper-echogenicity of the walls). This can be difficult to see in cysts that are located deep or have erosions from digestive enzymes (which could also cause internal hemorrhage and echogenic debris, as seen here), but again would not have pulsatile flow on Doppler imaging.
Kaposiform hemangioendothelioma is a rare, invasive vascular tumor that can be a cause of DIC (as a progression of severe Kasabach-Merritt syndrome) but has a much more complex appearance, typically being infiltrative and diffuse rather than well-defined, and more often cutaneous in location.
Additional images
References
- So, M., Kobayashi, D., Anthony, E. et al. Pseudoaneurysm formation after umbilical arterial catheterization: an uncommon but potentially life-threatening complication. J Perinatol 32, 147–149 (2012). https://doi.org/10.1038/jp.2011.93
- Katz ME, Perlman JM, Tack ED, McAlister WH. Neonatal umbilical artery pseudoaneurysm: sonographic evaluation (case report). AJR Am J Roentgenol. 1986 Aug;147(2):322-4. doi: 10.2214/ajr.147.2.322. PMID: 3524162.
- Gibson, K., Sharp, R., Ullman, A. et al. Adverse events associated with umbilical catheters: a systematic review and meta-analysis. J Perinatol 41, 2505–2512 (2021). https://doi.org/10.1038/s41372-021-01147-x