Quantifying Lymph Nodes During Lymph Node Transplantation: The Role of Intraoperative Ultrasound

Quantifying lymph nodes in vascularized lymph node transfer (VLNT) has been performed using preoperative percutaneous ultrasound. The higher resolution and accuracy of intraoperative ultrasound (IOUS) over transcutaneous ultrasound has been demonstrated in the radiology literature for the identification and characterization of finer structures including hepatic lesions, pancreatic lesions, and biliary or pancreatic ducts. We hypothesize that IOUS during VLNT would be a superior method to quantify and map lymph nodes in our flaps. A prospectively collected database of patients undergoing VLNT over 3 years (October 2014 to October 2017) was reviewed. Patients who underwent IOUS during flap harvest, before pedicle ligation to simultaneously map and quantify the number of lymph nodes were included in the study. Twenty-one patients with an average age of 58.7 years and a mean BMI of 32.3 underwent VLNT with IOUS for chronic lymphedema during the study period. Extremity lymphedema was classified as Campisi IB (n = 7), IIA (n = 7), IIB (n = 5), and IIIA (n = 2). There were 14 superficial circumflex iliac artery flaps, including 4 performed concomitantly with a deep inferior epigastric perforator flap, 1 transverse cervical artery flap, and 6 omental flaps. The average number of lymph nodes transferred per IOUS was 4.3 for superficial circumflex iliac artery flaps, 4 for the transverse cervical artery flap, and 5.2 for the omental flaps. Intraoperative ultrasound allows the lymphatic surgeon to precisely map the location of lymph nodes which can guide intraoperative decision making. As there is no data correlating the number of lymph nodes transferred and outcomes after VLNT, developing a precise intraoperative quantification method is important.