ABSTRACT
For the new edition of this book, we decided to add a few chapters, and the one that we believed was needed is this one covering the role of ultrasound (US) in fetal infection. However, having always in mind what inspired us-from the sign to the diagnosis-we have decided to split the chapter into two sections: (1) US signs possibly indicative of a fetal infection, and (2) the signs that can be expected if a fetus is infected or at high risk of being infected. In most cases, in our routine work at the screening level, we face the former scenario: we perform an US scan and find a suspicious sign in the fetus of a patient who is not known to be at risk (or whom we do not know to be at risk). In this situation, the US finding represents the fulcrum of the whole diagnostic flowchart: what are the chances that this sign is indicative of an infection or a malformation, or-in the case of a soft marker, such as hyperechogenic ileus-indicates that the fetus is perfectly healthy? Second, if we consider an infection likely, what is going to be the prognosis-and, consequently, the diagnostic flowchart? The second scenario is usually seen only in tertiary-care centers where a patient is
referred due to seroconversion or risk of vertical transmission for a viral, bacterial, or protozoan infection. In this case, we already know, or come to know, that the fetus we are going to scan is indeed infected. Hence, the scan is targeted to ascertain whether specific or aspecific signs of infection and, more importantly, damage are present or not. This type of scan-often together with a late magnetic resonance imaging (MRI) (28-30 weeks of gestation)—is of crucial importance in the evaluation of the prognosis, even though, as we will see, its predictive value is somewhat limited. US signs possibly indicative of fetal infection are summarized in Table 11.1. As the reader will see from reading this chapter, these do not change significantly by the type of infection [1].
