A needle assembly comprising a housing, a first needle hub provided by the housing, a first hollow needle portion mounted to the first needle hub and extending from the first needle hub in a distal direction. A second needle hub is provided by the housing. A second hollow needle portion is mounted to the second needle hub and extends from the second needle hub in a proximal direction, opposite to the distal direction, wherein a hollow flashback chamber is arranged within the housing between the first needle portion and the second needle portion. The flashback chamber communicates with the inner lumen provided within the first and second hollow needle portion and is connected to the atmosphere by a passage and wherein a filter is provided within the passage, which is designed such that it is permeable for air to pour out of the flashback chamber into the atmosphere.