Introduction:
Transoral robotic surgery (TORS) for oropharyngeal squamous cell carcinoma (SCC) carries a known risk of post-operative hemorrhage, with rates estimated between 1-10% of cases. Prophylactic transcervical arterial ligation (TAL) is a strategy to prevent post-operative hemorrhage. Current literature aims to quantify hemorrhage rates following TAL, but these studies are limited by selection bias with often only those patients at highest risk undergoing the procedure. Our institution adopted TAL in 2014 for all-comers undergoing TORS with concurrent neck dissection, independent of patient-specific risk-factors for hemorrhage. This present study aims to determine the rate of post-operative hemorrhage after TAL in all patients who underwent TORS for resection of oropharyngeal SCC with concurrent neck dissection. Secondary aims are to characterize which vessels were ligated via TAL and the means of arterial ligation intraoperatively.

Methods: An IRB approved retrospective chart review was performed on all patients who underwent TORS at a tertiary care academic center from April 2014 through April 2019. Inclusion criteria included that they underwent TORS for oropharyngeal SCC with concurrent neck dissection and TAL, independent of HPV status or adjuvant therapies received. Patients were excluded if they underwent robotic surgery in other anatomic sites, did not undergo neck dissection at the same time as TORS, or if their detailed operative note was not available for review. Patient demographics, including age, risk factors, diagnosis, as well as operative details including the vessels ligated, the method of ligation, and post-operative complications including post-operative hemorrhage were reviewed. Operative, clinic, and inpatient notes as well as documentation of patient calls were studied from the month following surgery to capture bleeding of any severity, which was then classified using the Mayo Clinic Classification System for Postoperative Hemorrhage.

Results: 144 patients met inclusion criteria. 19 out of 144 (13.2%) patients experienced a post-operative oropharyngeal bleed of any severity despite prophylactic TAL. 7 of 19 (36.8%) patients with post-operative oropharyngeal bleeding had self-limited episodes that were observed without intervention. 11 (57.9%) required control of hemorrhage in the operating room, and 1 (5.3%) was embolized by neurointerventional radiology. Arteries were ligated at the following rates: lingual 90.3% (130), facial 87.5% (126), external carotid 37.5% (54), ascending pharyngeal 27.8% (40), superior thyroid 18.1% (26). Other infrequently ligated arteries (<5%) include the occipital, superior laryngeal, and ascending palatine. In 140 cases vessels were hand tied with silk sutures, in 3 cases vessels were clipped, in 1 case they were cauterized.

Discussion: This is the first study that has subjected all patients to ligation, without selection bias, to assess the rate of post-operative hemorrhage after undergoing prophylactic TAL. This provides a more accurate representation of the true bleeding rate following TAL. We characterized the specific arteries ligated and their potential impact on bleeding rates, and based on our analysis conclude that ligation of 3 or more arteries is not superior to the ligation of 2 arteries in preventing post-operative bleeding.