Even though the radiographic features of COVID-19 in children have been thoroughly reported [9], data describing imaging findings in MIS-C are limited. Recently, a prospective observational study summarizing chest and abdominal imaging findings has been published [14].
To the best of our knowledge, for the first time we report here a detailed analysis on the PoCUS findings in the ED patients with confirmed MIS-C [7].
In our case-series, PoCUS was performed in 11 children with MIS-C within 24 h from hospitalization. Most patients presented to the ED for fever and abdominal pain in good clinical condition. However, the development of cardiac injury in all children during hospitalization (median NT-pro BNP level of more than 8500 ng/l) is consistent with the already reported clinical instability of MIS-C patients, who are at risk for sudden cardiovascular worsening [4]. For this reason a strict clinical, laboratory and imaging monitoring is strongly recommended.
In our case-series, despite initial fair clinical condition, PoCUS revealed early cardiac hypokinesis in almost half of our patients and IVC dilatation in three [15]. As a consequence, PoCUS allowed early identification of cardiopulmonary involvement, even before the patients developed symptoms suggestive for cardiovascular impairment/shock.
The PoCUS findings also showed abdominal free fluid in more than half of our patients, confirming the frequent involvement of gastrointestinal tract previously described [2, 14].
Children with MIS-C tend to develop a clinical condition of fluid overload due both to contractile cardiac pump deficit and to endotheliitis with subsequent capillary leak syndrome. In this context, the ability of PoCUS to simultaneously explore multiple systems and detect polyserositis promotes adequate therapeutic management of fluid balance.
Finally, all our patients presented at least one alteration at LUS examination, with the predominance of the interstitial pattern, underlying an inflammatory and edemigenous genesis [16]. Furthermore, pathological findings in the X-ray were reported in only 3/11 cases (27%), suggesting its marginal role in the initial evaluation (Fig. 2) [17].
PoCUS has unquestionable advantages: the ability to explore at a first sight the multi-organ involvement typical of MIS-C; the possibility of being performed at any moment by a pediatrician in the ED; and the opportunity to be repeated without any risk during the follow-up.
We are aware of the limits of our study (i.e., the retrospective nature of the analysis and the small sample size). However, if our data will be confirmed by further research on larger samples, PoCUS might be considered as a useful and non-invasive tool in the first evaluation of children with suspected MIS-C, although a specific MIS-C-correlated ultrasound pattern has not been identified. Moreover, it could play a key role to help physicians also in the therapeutic management of fluid balance, as well as in the following monitoring of these pediatric patients, at risk for cardiovascular deterioration.