A nasogastric tube (NG tube) is a thin, flexible tube inserted through the nose, down the esophagus, and into the stomach. It is used to deliver nutrition, fluids, or medication, or to remove contents for gastric decompression or lavage. Determining the correct length required to reach the stomach is the most critical step for safe and effective placement. Accurate measurement ensures the tube tip rests in the gastric body, preventing serious complications from improper positioning. The standard technique for estimating this length involves using three distinct anatomical reference points.
The Standard Measurement Method (NEX)
The Nose-Earlobe-Xiphoid (NEX) method is the standard procedure for estimating the insertion length. Before measuring, the patient should be positioned upright or in a semi-Fowler’s position, with the head of the bed elevated 30 to 45 degrees. This technique provides the approximate distance the tube must travel from the nasal opening to the stomach.
To start the measurement, the tip of the NG tube is held at the patient’s nostril, which is the intended insertion point. The tube is then extended along a straight line, maintaining a gentle tension, until it reaches the earlobe or the tragus of the ear. This segment estimates the distance the tube must travel through the nasal cavity and the pharynx.
Once the tube reaches the earlobe, it is extended straight down the chest to the xiphoid process, the small, lower tip of the breastbone. This second segment approximates the length of the esophagus. The combined length of these two segments—the total NEX distance—is the point on the tube that should align with the patient’s nostril once the tube is fully inserted.
It is important to hold the tube taut but not stretched during the measurement process to ensure an accurate reading. After the total length is determined, a small piece of tape or a permanent marker is used to clearly mark this distance on the tube. This mark serves as the external reference point for safe insertion depth, indicating when the tube has likely reached the stomach.
Identifying Critical Anatomical Landmarks
The precision of the NEX method relies entirely on the correct identification of the three anatomical landmarks. The starting point is the tip of the nose, or the external nares, which is the opening into the nasal cavity through which the tube will first pass.
The next point in the sequence is the ear, specifically the earlobe or the tragus, which is the small cartilaginous projection in front of the ear canal. Using this point helps determine the length needed to navigate the turns of the upper airway, from the nose, through the nasopharynx, and into the oropharynx.
The third point is the xiphoid process, the small, cartilaginous extension at the lower end of the sternum. To locate it, trace the sternum down to where it ends, typically at the junction with the ribs in the upper abdomen. Accurate identification is important, as it estimates the length required for the tube to enter the stomach, just past the gastroesophageal junction.
Consequences of Mis-Measurement
An inaccurate length measurement can lead to serious adverse events, as the tube tip will not be positioned correctly in the stomach. If the tube is measured too short, the tip may stop while still coiled within the esophagus. This causes the tube to be ineffective for drainage or feeding and significantly increases the risk of the patient aspirating, or inhaling, any administered contents into the lungs.
Conversely, if the tube is measured too long, it risks extending too far past the stomach. An excessively long tube may kink in the stomach, curl upwards into the esophagus, or advance into the duodenum, which is the first part of the small intestine. Placement in the duodenum can cause irritation or, if bolus feeding is used, lead to a condition called dumping syndrome.
The most severe risk of mis-measurement is accidental placement into the airway. When the tube is inserted blindly, an incorrect length determination increases the chance of it entering the trachea and lungs, potentially causing pneumothorax or pneumonitis. The initial measurement directly impacts the safety and success of the entire procedure.