Edema

Edema is the accumulation of excess fluid in the interstitial spaces of body tissues, causing swelling. On ultrasound, edema appears as increased fluid content that may manifest in different ways depending on the location: subcutaneous edema shows as a thickened, hypoechoic layer beneath the skin; bowel wall edema appears as wall thickening; and cerebral edema shows as increased brain echogenicity on neonatal cranial ultrasound. In obstetrics, fetal hydrops represents severe generalized edema, with fluid accumulating in body cavities and beneath the fetal skin. Identifying edema on ultrasound helps guide the diagnosis of underlying conditions such as heart failure, kidney disease, liver disease, and allergic reactions.