Abdominocentesis
Summary of the Procedure:
| Indications | To confirm the presence of abdominal fluid, including blood. To collect abdominal fluid for analysis. If the purpose is to drain a large volume of ascites, then a catheter should be used as described for diagnostic peritoneal lavage (DPL). |
| Limitations | Small volumes of fluid (at the very least 5 mL/kg is needed) and localized fluid will not be detected. Occlusion of the needle by fibrin (in cases of chronic effusions) will result in false negative or low yield samples. |
| Complications | Trauma to abdominal organs. |
| Contraindications | Injury that precludes positioning for the procedure. Skin infection at entry site (choose another site). |
| Supplies/instruments | 18-22 ga needle, 19–21 ga butterfly, 18-22 ga over-the-needle IV catheter (extra-side holes may be cut with a scalpel blade along the catheter tip but this will increase tissue drag and weakens catheter).
Syringe. EDTA, red top vacutainer vials for sample storage prior to submission for cytology +/- other diagnostics. +/- Lidocaine; sedation. |
| Position | Most commonly dorsal or lateral recumbency; can also perform standing. |
| Restraint | Most commonly awake or under sedation; can be performed under anaesthesia |
Landmarks:
- Simple abdominocentesis of one site: 1-3 cm caudal to the umbilicus along the linea alba or slightly paramedian. In the standing animal the most ventral point may be used.
- “Four-quadrant” abdominocentesis: the abdomen is divided into 4 quadrants, imagining the umbilicus as your centre point and dividing the abdomen from this point. The 4 quadrants are: cranial left and right; caudal left and right. Four-quadrant abdominocentesis may increase the sensitivity of the procedure, especially if localized fluid may be present.
- Note the location of the caudal superficial epigastric vessels when choosing your puncture sites.
- Note: at least 5-6 ml of fluid per kg of body weight is needed in the abdominal cavity to obtain fluid by centesis.
Details of the Procedure – Abdominocentesis:
- Surgically prepare entry site(s).
- Optionally infiltrate entry site with lidocaine in nonanesthetized animal.
- Most often the animal is in lateral or dorsal recumbency. Can also perform the procedure with the animal standing, but this can be more difficult to do.
- Insert needle caudal to umbilicus, as described in landmarks above.
- Watch for fluid collection within the needle hub.
- Once fluid is obtained, attach a syringe or other collection system and aspirate fluid.
- Remove needle and perform cytologic and chemical analysis on lavage fluid.
Details of the Procedure – 4-Quadrant Approach:
- If the abdominocentesis of one site does not yield fluid, the 4-quadrant approach can be used.
- Insert the needle/catheter described into each of the centre of the 4 quadrants as described above: cranial left and right; caudal left and right.
- At each site, aspirate with a syringe after the needle is inserted.
Details of the Procedure – Diagnostic Peritoneal Lavage:
- In some cases, if fluid is not obtained using the 1 site or 4-quadrant approach but intra-abdominal pathology is still suspected, a “diagnostic peritoneal lavage” can be performed.
- In this case, infuse warm (37C) isotonic crystalloid fluid, 20 ml/kg, in one of the abdominocentesis landmarks.
- Remove the needle and gently roll animal from side to side (or allow animal to sit up and briefly walk).
- Perform abdominocentesis as described above, and remove lavage fluid for cytology.