Patient positioning is a precise action in medicine, used to optimize safety, facilitate procedures, and enhance diagnostic accuracy. The left lateral decubitus position (LLD) is a common, specific body orientation with widespread application. It is utilized across different medical disciplines, from routine imaging to complex surgical interventions and emergency care.
Defining the Position
The term “decubitus” is Latin for “lying down.” The left lateral decubitus position (LLD) means the patient is lying on their left side. In this orientation, the patient’s left side is in contact with the supporting surface, such as a bed or examination table, while the right side faces upwards. This is a specific type of lateral recumbent positioning where the left side is the dependent side.
To ensure stability and comfort, the patient’s arms are typically positioned out of the way, often placed parallel in front of the body. The knees are slightly flexed and stacked, with the upper leg often bent more than the lower leg to prevent rolling. Maintaining straight alignment of the head and spine is important, often achieved with a small pillow or pad placed under the head.
Primary Clinical Applications
The LLD position is deliberately chosen in non-emergency settings to leverage the effect of gravity on internal body structures. A primary use is in diagnostic imaging, particularly abdominal X-rays or computed tomography (CT) scans, to detect free air or fluid within the peritoneal cavity. Placing the patient on their left side for five to ten minutes before imaging allows free air to move upward and pool between the liver and the abdominal wall, making it visible.
This orientation also provides mechanical advantages for various procedures, such as a lumbar puncture. The position helps to maximally flex the spine, which widens the spaces between the vertebrae, allowing easier access to the subarachnoid space for a spinal tap. In complex procedures like certain laparoscopic liver surgeries, the LLD position can improve the surgeon’s field of view, reduce blood loss, and shorten the operation time.
Significance in Emergency Situations
The left lateral decubitus position is frequently used in acute care to prevent aspiration. When a person is unconscious or has a depressed gag reflex, placing them in the recovery position—a modified LLD—allows gravity to drain fluids, such as vomit or saliva, out of the mouth. This prevents fluids from entering the lungs and is a fundamental first aid measure to maintain a clear airway.
The position also plays a specific role in managing circulation in pregnant patients past 20 weeks gestation. When a woman in late pregnancy lies flat on her back (supine), the enlarged uterus can compress the inferior vena cava (IVC). This compression, known as aortocaval compression syndrome, reduces venous return and decreases the mother’s cardiac output by up to 30 to 40%.
Shifting the patient to the left lateral decubitus position—or even a slight left lateral tilt of 15 to 30 degrees—relieves pressure on the IVC. This action helps restore blood flow back to the heart, improving circulation for both the mother and the fetus.