"ER" viewers have dwindled as the years have gone by for various reasons, some having nothing to do with "ER" (10 tonight, WPXI).

Still, the changes in staff had to have had some impact. Some viewers might have bailed when Dr. Susan Lewis (Sherri Stringfield) departed on a train early in season three. Others swore off the show after Carol (Julianna Margulies) left on a plane with Doug (George Clooney) in 2000 or when Dr. Mark Green (Anthony Edwards) died in 2002.

I always mourned the 1999 departure of Jeanie Boulet, the sensitive, HIV-positive "ER" regular played by Gloria Reuben. Tonight, Reuben and Boulet are back as Boulet rushes her son to the ER after he takes a fall in gym class.

In a conference call with reporters last month, Reuben said the idea of her character's return came about at the end of last season before the "ER" writers started plotting stories for the current season.

Boulet was the first prime-time, HIV-positive series regular character who showed how it was possible to live with HIV. Reuben and the producers decided her character would not be killed off when it came time for her to depart originally so as not to send a negative message about living with HIV.

"If somebody's HIV-positive and they get emotionally connected to a character whom they've been watching for years live with the virus and meet certain challenges ... and just kind of what happens on a day to day basis, if by the end of it they see that this person dies from the virus, yeah, that's television and it's make-believe, but I think it goes deeper than that, especially when it comes to this issue," she said.

Even after her stint on "ER," Reuben said she only became an AIDS activist a few years ago after reading about the high death rates among African-American women with AIDS.

Reuben said she's only slated for a single "ER" episode now, pending the outcome of the writers' strike and whether or not a Steven Bochco pilot she filmed for TNT gets picked up to series.