Mei Xiang, the National Zoo’s female panda, has been coy with her keepers.

      The giant panda may be pregnant, the zoo announced last week, and after several failed attempts, she cooperated for an ultrasound this morning.

      The zoo live-tweeted the ultrasound this morning, which ended when Mei Xiang left her training cage to go back to her enclosure. Zoo officials announced through Twitter that the ultrasound was inconclusive.

      [View the story “Panda Pregnancy” on Storify]

      It is difficult to determine whether a panda is pregnant. The animals only have a 24 to 48- hour window every year to conceive. And they can display signs of pregnancy when they are, in fact, not. This is called a pseudopregnancy.

      Mei Xiang, who was artificially inseminated on April 29 and April 30, has had five consecutive pseudopregnancies. Xiang has had one cub, Tai Shan, born in 2005.