A kit comprising: an intraosseous device comprising: a hub having a first end, a second end, and an opening extending from the first end to the second end; and a cannula extending from the second end of the hub to a distal end spaced from the hub by a first length, the cannula defining a lumen in fluid communication with the opening of the hub; an ejector comprising: a head; and an elongated member extending from the head to a distal end spaced from the head by a second length at least as large as the first length, the elongated member configured to be inserted into the lumen of the cannula; and an assistive device comprising a body including a first end and a second end, the body defining a channel having a longitudinal axis and configured to removably receive a portion of the cannula and prevent passage of the hub through the channel, the body further including at least one protrusion (524 extending laterally outward relative to the longitudinal axis of the channel; where the assistive device is configured to receive the portion of the cannula in the channel of the assistive device such that, if the elongated member is inserted into the lumen of the cannula through the opening in the hub, the head and assistive device can be pushed together to cause the distal end of the elongated member to push a biological sample through the distal end of the cannula, characterized in that a lateral portion of the channel in the body of the assistive device is open between the first end of the body and the second end of the body such that a portion of the intraosseous device is laterally insertable into the channel. an intraosseous device comprising: a hub having a first end, a second end, and an opening extending from the first end to the second end; and a cannula extending from the second end of the hub to a distal end spaced from the hub by a first length, the cannula defining a lumen in fluid communication with the opening of the hub; a hub having a first end, a second end, and an opening extending from the first end to the second end; and a cannula extending from the second end of the hub to a distal end spaced from the hub by a first length, the cannula defining a lumen in fluid communication with the opening of the hub; an ejector comprising: a head; and an elongated member extending from the head to a distal end spaced from the head by a second length at least as large as the first length, the elongated member configured to be inserted into the lumen of the cannula; and a head; and an elongated member extending from the head to a distal end spaced from the head by a second length at least as large as the first length, the elongated member configured to be inserted into the lumen of the cannula; and an assistive device comprising a body including a first end and a second end, the body defining a channel having a longitudinal axis and configured to removably receive a portion of the cannula and prevent passage of the hub through the channel, the body further including at least one protrusion (524 extending laterally outward relative to the longitudinal axis of the channel; where the assistive device is configured to receive the portion of the cannula in the channel of the assistive device such that, if the elongated member is inserted into the lumen of the cannula through the opening in the hub, the head and assistive device can be pushed together to cause the distal end of the elongated member to push a biological sample through the distal end of the cannula, characterized in that a lateral portion of the channel in the body of the assistive device is open between the first end of the body and the second end of the body such that a portion of the intraosseous device is laterally insertable into the channel.