One of the most repetitive tasks performed in research or medical laboratories is pipetting. Repetitive-strain injuries can occur when pipetting for extended periods of time. You may be at risk if you feel weakness or pain in your thumb or wrist when you use your pipetting hand.

Studies have found that there is a significant increase in the risk of hand and shoulder discomfort when laboratory workers pipet for more than 300 hours per year. That is the equivalent of two hours per day for a 50-week work year. Many lab workers pipette for longer periods each day. Typical symptoms include pain in the thumb (De Quervain’s syndrome), forearm and elbow (tendonitis or tenosynovitis), trigger finger, finger pain (digital-nerve injury), and shoulder pain.

There are many steps that can be taken to prevent the onset of repetitive-strain injuries associated with pipetting:

Work Technique And Work Habits

  • Keep your neck in a neutral position and avoid jutting your chin forward or bending your neck down when pipetting. Adjust the height of the chair so that you do not need to strain.
  • Sit back in the seat to keep your back supported. If you sit back and your feet no longer reach the ring or the floor, adjust the ring or get a footstool.
  • If your stool lacks back support you can tilt the seat forward or use a seat wedge to position the back and the pelvis in a better position.
  • Maintain neutral arm postures as much as possible. Keep the elbows close by the side of your body. To achieve this position, sit close to your workbench, hold objects close to the body, and adjust your chair up or down to the proper height of the bench.
  • Keep your wrist in a neutral or straight position as if you are shaking hands when pipetting. Do not twist or rotate the wrist. Alternate hands if possible, or use both hands to operate the pipette.
  • Use as little pressure as possible when pipetting. Try to press the plunger with as light a touch as possible. Use a light touch to get pipette tips on the pipette. Do not use excessive force when changing tips. Tip ejectors can require large forces to operate. Newer models are available with low force levels.
  • Drop pipette tips into a low beaker; try not to have to reach up if you do not have to. Make sure that the trigger mechanisms on the pipette require low force levels to activate
  • Alternate the position of objects held in your hand. Alternating between the thumb and the first finger and the first and second fingers will vary the task. Even when alternating, don’t forget to take breaks every 20 minutes to allow muscles to rest and the blood to flow back into your fingers.
  • Avoid long sessions of repetitive motion by varying your activities. Rotate pipetting tasks with your co-workers. Change your position and work task frequently. For example, take a two-minute break for every 20 minutes of pipetting.

Work Tools/Equipment

  • Use an electronic pipetter when possible. Always select a pipetter that is a comfortable size and weight for your hand.
  • Use a latch-mode for repetitive pipetting tasks
  • Exchange traditional pipets for light touch models.
  • Use pipettes that use the pointer finger to aspirate and the thumb to dispense.
  • Select a pipetter with an aspiration rate control that will allow you to select the speed of pipetting so that you can maintain a reasonable pace.
  • Use thin-wall pipette tips that fit correctly and are easy to eject.
  • Clean pipetters on a scheduled basis.
  • Use gloves that fit properly. Gloves that are too big or small cause undue stress.
  • Wear supportive shoes and stand on cushioned mats if you must stand for prolonged periods when pipetting.
  • Use padding or larger buttons when possible to reduce pressure on your body. Pad equipment to increase ease of gripping. Elbow pads can be worn to reduce pressure on the arms while working at a bench. Apply padding to the edge of the work surface to avoid resting your elbows on hard or sharp edges.

Work Environment

  • Always work at a cutout in the lab bench. This will allow you to work as close to the bench as possible while sitting against the back of your chair.
  • Keep trays and other supplies that are used frequently in close reach.
  • Adjust the workstation or your chair so that you do not have to work with your arm in an elevated position. Try to keep your work at waist level.
  • If using a computer at the same time as pipetting, be sure to position yourself correctly at the computer. Your computer keyboard should be placed on an adjustable height and angle keyboard tray. You may have to remove unused cabinets or drawers beneath the countertop to install a keyboard tray. Sit all the way back in the chair; use the tray to lower the keyboard and mouse and position the elbows and wrists in a neutral position; and place the monitor in front of you and at a level where the eyes gaze slightly downward.

Always try to plan ahead. Think about how your work tasks affect your body mechanics and adjust accordingly.