Sentinel Lymph Node Mapping and Biopsy for Endometrial Cancer at Early Stage with Laparoscopy

This protocol was summarized based on a cumulative experience of sentinel lymph node mapping in at least 500 cases of endometrial carcinoma to help beginners successfully implement this technique. This technique is minimally invasive, reduces complications and medical costs, and improves the detection rate of lymph node metastases through pathological ultrastaging. A learning curve of about 20 cases of SLN mapping is required with experience of injection into the cervix and observation of the first mapped lymph node case on each hemipelvis.

After anesthetizing the patient, use two towel forceps to grasp the skin around the umbilicus and elevate the abdominal wall, then make an approximately 10-millimeter wide incision in the skin of the umbilicus and through the fascia and peritoneum. Next insert a 10-millimeter trocar through the umbilicus, producing the pneumoperitoneum with an intraperitoneal pressure of about 13 to 14 millimeters of mercury, then insert the laparoscope via the trocar. Next make another three five-millimeter wide small incisions in the lower abdomen and insert five-millimeter trocars through the abdominal wall into the cavity.

Then insert instruments for manipulation via these trocars. Identify the fallopian tubes using the laparoscope, then grasp and elevate the tubes close to the fimbriae and tie a ligature around the tube with a 2-0 T silk suture. Before handling or manipulating the uterus, perform peritoneal washings with 100 milliliters of normal saline and collect the washing fluid for cytology.

After opening the fluorescence mode of the endoscopic fluorescence imaging system, lift the unilateral pelvic infundibulum ligament and uterus to reveal the lateral peritoneum and observe the fluorescence lymphatic vessels. To map the sentinel lymph node, or SLN, lift and open the peritoneum, then separate the subperitoneal fat and connective tissues to reveal the necessary structures according to the indication of the green fluorescence lymphatic lines and to protect them from injury. Locate the SLN, which is the first mapped lymph node along the drainage from the parametrium in each hemipelvis and confirm the location using multiple modes, then fully expose the SLNs for complete resection.

Next, using toothless forceps, grasp and elevate the SLN, then perform a complete resection of the lymph node along its periphery in white light and confirm the SLN by multiple modes after resection. Simultaneously resect the enlarged or suspicious lymph nodes during the operation and send them for a pathological examination. Place the removed SLNs in the obturator fossa.

After completely removing the uterus through the vagina, remove the bilateral SLNs entirely through the vagina rather than the five-millimeter trocar opening to avoid fragmentation. After performing a total hysterectomy plus bilateral salpingectomy, indwell a drainage tube for potential residual fluid in the pelvis, then remove the laparoscope and release the gas from the abdomen. Shown here are magnetic resonance images of a 28-year-old female endometrial cancer patient.

An irregular signal on the endometrium located in the lower uterus cavity is visible on the T1 and T2 weighted images. For performing a total hysterectomy along with bilateral salpingectomy and SLN mapping, the cervix was injected with diluted indocyanine green at the three and nine o'clock positions, superficially and deeply. The SLNs and lymphatic vessels were fluorescently labeled, allowing their recognition under various color modes in the pinpoint endoscopic fluorescence imaging system.

Hematoxylin and eosin staining was performed for the MIO invasion in endometrial cancer and the SLN. Immunohistochemistry staining of the SLN with AE1 and AE3 was also conducted. Further immunohistochemistry staining of the SLN with estrogen and progesterone receptors, P53, KI67, MLH1, MSH2, PMS2, and MSH6 revealed a negative metastasis output.

SLN mapping has become an alternative option in early stage uterine-confined endometrium cancer. However, more evidence is required for its application in intermediate to high risk endometrial cancers.