The blue dye may be seen in lymphatic channels flowing into a now palpable lymph node (Figure 7). This node should be blue and hot. The node is dissected free, as are any neighboring lymph nodes that are faintly blue or have significant radioactivity counts (Figure 8). Significant radioactivity is identified as a level ≥ 10 percent of the counts of the hottest sentinel node or a level greater than two or three times the background activity of the axillary tissue. A small cluster, usually two or three lymph nodes, is excised (Figure 9), as often there is more than one sentinel node. The nodal basin is scanned with the probe to verify that no other hot areas or potential sentinel lymph nodes exist. The probe demonstrates a basal background level (Figure 9). The nodal cluster removed is examined and the lymph nodes are separated. One node, the principal sentinel lymph node, should be blue and quite hot (Figure 10A). In this illustration, lymph nodes B and C are considered sentinel lymph nodes, as they have significant radioactivity counts. Any other regional nodes that have any blue coloration are also considered sentinel nodes, even if they do not have elevated radioactivity counts. A final visual and gamma probe survey is performed about the operative site and careful hemostasis is obtained.
Subcutaneous tissue and Scarpa's fascia are closed with interrupted 00 absorbable sutures. The skin is approximated with fine 00000 subcuticular sutures. Adhesive skin strips and a dry sterile dressing are applied.
In most cases, this procedure can be performed in an ambulatory surgery setting. The patient returns home when discharge criteria for this surgery are met. The patient is given written instructions concerning activities and signs of bleeding or infection. Simple oral pain medication should suffice. At the follow-up visit, the surgeon reviews the pathology findings with the patient, who may require a formal lymphadenectomy if any sentinel lymph nodes show metastases.