Appropriate equipment (see Table 27.1) should be assembled at the bedside prior to the procedure and easily accessible to the operator during the procedure, without the operator changing position. An assistant is optional and dependent on the operator, but he or she will be helpful if there is concern of patient cooperation or a larger effusion is to be drained requiring changing syringes.

After selecting an appropriate entry site, the entry site can be marked using a ball-point pen with the pen tip retracted. The pen’s aperture can be pressured to the site to leave an impression of the selected entry site before cleansing the area. The selected entry point is cleansed appropriately with an antiseptic solution followed by removal of the antiseptic solution using the alcohol wipes. After cleansing the area, caution should be exercised to avoid contaminating the site by further palpation with an unsterile gloved finger. If further palpation is desired, then a sterile glove can be used or a sterile 4 × 4 gauze can be placed over the area and palpation done over the sterile gauze to preserve the site’s antiseptic condition. Some topical anesthesia is obtained by spraying the site with ethyl chloride until the area “frosts.” Alternatively, a small amount of lidocaine can be injected subcutaneously into the proposed injection area.

When advancing the needle into the joint cavity, the patient experiences discomfort when the needle passes through the skin and again when it crosses the synovium. Less discomfort is experienced when the skin and synovium is crossed quicker as opposed to slowly and deliberately. Once the needle is introduced into the joint cavity, fluid should flow easily into the syringe if using a needle gauge of 20 or larger. If no fluid can be aspirated, or fluid stops flowing, the most common cause is that synovial tissue or solid material (clot, fibrin, cartilage fragments, etc.) within the fluid is obstructing the needle. Rotating the needle or injecting back a small amount of the aspirated fluid into the joint cavity may remove the obstruction. At that point. gentle negative pressure can be placed and the fluid may aspirate. As the total effusion approaches complete drainage, the synovial lining becomes closer to the needle tip and further difficulty is typically experienced or fresh blood now appears in the aspirated fluid. Discomfort by the patient is common at this point, and a decision to continue aspirating at the patient’s discomfort should be weighed by the benefit of removing more fluid at this time. Once sufficient fluid is removed, the needle can be withdrawn and appropriate hemostasis applied to the injection site. Alternatively, if steroids or medication are planned to be injected after aspiration,
the syringe can be separated from the needle that remains in the joint and a syringe with the medication attached to the needle and the medication injected. This situation where an injection follows an aspiration is where a hemostat can be helpful to grasp the hub of the needle while changing syringes. Injecting medication into a joint cavity should not require much pressure on the plunger, although the larger the discrepancy between a large syringe bore and a small-gauge needle, the greater the pressure required. If significant pressure is required, the needle has left the joint space and should be positioned again properly.