The inferior thyroid veins--the ultimate guardians of the trachea

The inferior thyroid veins and their multiple tributaries are the ultimate guardians of the cervical trachea. Deeply embedded in the pretracheal fat pad, this plexus of veins is consistently encountered during low tracheostomy that accompanies conservation laryngral procedures as well as in tracheal reconstruction. In a high tracheotomy, the handling of the thyroid isthmus is simplified by an appreciation of these veins. Even cricothyrotomy is potentially complicated by hemorrhage sebsequent to a tear in a tributary of the inferior thyroid venous system. A cadaver study, employing 10 embalmed head and neck specimens, was performed to elucidate the tributary patterns of these veins. In every dissection there was at least one and as many as five veins overlying the trachea just below the thyroid isthmus. In 7 of 10 dissections a confluence of right and left inferior thyroid veins formed a large thyroid ima vein draining into the left innominate vein, and in 1 of 10 cases the thyroid ima vein drained into the right innominate. This confluence was present at a level which would be encountered in low tracheostomy or tracheal repair procedures. Six of 10 dissections presented large tributaries of the inferior thyroid veins overlying the cricothyroid membrane. An awareness of such anatomical considerations should result in safer surgical procedure performed in a dry operative field.