A surgical access port or trocar is provided. The trocar has a trocar seal housing and a trocar cannula with an optical obturator insertable through the trocar seal housing and the trocar cannula. The trocar is configured to access a body cavity, to maintain positive pressure and to prevent loss of surgical insufflation gas used in laparoscopic procedures. The trocar seal housing can be releasably attached to the trocar cannula. The trocar seal housing may also have a shield and/or alignment channel that provide protection or assist in operation of instrument and zero seals housed in the trocar seal housing.