Detection apparatus and method

A detection apparatus configured to position a tip of a tubular element within a region of a body of a subject, the detection apparatus comprising:

• a syringe comprising a housing, the housing defining a cavity including a fluid chamber and configured to be coupled to a tubular element, the syringe further comprising a plunger partially contained within the housing and partially external to the housing, the plunger comprising a distal gasket seal that provides a fluid-tight seal with the housing;
• and
• a biasing unit operable to maintain a substantially constant biasing force on a volume of fluid contained in the fluid chamber, the biasing unit comprising a biasing element,
• wherein the volume of fluid within the fluid chamber is distal to the biasing element, the fluid chamber being defined by the cavity and the plunger, and
• wherein the plunger is configured to be proximally withdrawn and to thereby compress the biasing element, wherein proximal withdrawal of the plunger results in proximal withdrawal of the distal gasket seal, and wherein the syringe delivers the fluid from the tubular element when the biasing force is greater than a resistance to flow of the fluid from the tip of the tubular element.