Lymph nodes frequently can be found around the inamed tissue. The appearance of the lymph nodes depends not only on the nature of the infection but also on its strength. In addi­tion to lymph nodes, blood vessels can always be detected, even in nodes with a diameter smaller than 1cm (Fig.6.1). Furthermore, an abscess of the neck caused by infective agents can be seen as a neck swelling. Abscesses must be detected as early as possible, to begin specic therapy and reduce the possibility of complications. It is important to dif­ferentiate between an abscess and a phlegmon of the neck tissue. Thus, it is a further purpose of the ultrasound exami­nation to detect even small abscesses within the neck tissue or even in lymph nodes. Sometimes abscesses are difcult to detect, especially when they are small. They are character­ized by different sonographic features. Usually they are hypoechoic, whereas the hypoechogeneity depends on the consistency of the uid (Video 6.1). Furthermore, a hyper­echoic acoustic shadow often can be seen behind the uid area of the abscess. Duplex sonography often shows hyper­vascularization of the surrounding tissue, whereas the liquid area does not have blood vessels (Video 6.2).