The invention includes devices and methods for obtaining samples of blood or other bodily fluids with reduced levels of contamination. Fluid obtained from a subject may be contaminated by skin cells, bacteria, fungi, viruses, phages, their respective RNA, DNA, and/or other undesirable molecules, or disinfectants. A first amount of fluid is injected from the subject through an distal needle and a proximal needle penetrates a first portion of a device having a sequestration chamber with sub-atmospheric pressure therein. A first portion of the fluid, containing contaminants, is deposited into the sequestration chamber. The proximal needle is then moved through a second portion of the sequestration chamber and into a collection container. Because contaminants are removed from the sample, analysis and diagnosis of a subject's condition becomes more reliable and accurate. Additional devices and methods can be used to obtain relatively uncontaminated samples from cell culturing vessels.