Abdominocentesis, also known as paracentesis, is a diagnostic and sometimes therapeutic procedure involving the insertion of a needle or catheter into the abdominal (peritoneal) cavity to collect fluid for analysis or to relieve pressure.
I. Purpose and Indications
Abdominocentesis is performed to:
Diagnose the cause of abdominal fluid accumulation (ascites):
Heart failure
Liver disease
Kidney disease
Hypoproteinemia
Neoplasia (cancer)
Inflammation/Infection (peritonitis, pancreatitis)
Trauma (hemoabdomen – internal bleeding, uroabdomen – ruptured bladder)
Chylous effusion (lymphatic leakage)
Bile peritonitis (gallbladder rupture)
Evaluate for internal hemorrhage or organ rupture following trauma.
Detect peritonitis (inflammation/infection of the peritoneum).
Therapeutically remove large volumes of fluid to improve patient comfort, especially to relieve respiratory distress caused by pressure on the diaphragm.
Monitor the progression or resolution of certain abdominal conditions.
II. Contraindications (Relative)
While there are few absolute contraindications if fluid is causing clinical signs, relative contraindications include:
Coagulopathy (bleeding disorder): Increases the risk of hemorrhage. Careful consideration and correction if possible are vital.
Pyoderma or infection at the proposed puncture site: Increases the risk of introducing bacteria into the peritoneal cavity.
Marked bowel distension (e.g., Gastric Dilatation Volvulus – GDV, severe ileus): Increases the risk of bowel perforation.
Little to no fluid suspected: Increases the risk of organ puncture without diagnostic yield. In such cases, diagnostic peritoneal lavage (DPL) or ultrasound-guided abdominocentesis is preferred.
III. Equipment Needed
Clippers and Antiseptic Scrub: Chlorhexidine or povidone-iodine solution.
Sterile Gloves and Drape (optional but recommended for large volume taps).
Local Anesthetic: 2% Lidocaine (optional, for skin infiltration).
Needles/Catheters:
Small gauge needle (20-22 gauge, 1-1.5 inch): For small dogs or initial attempts.
Over-the-needle IV catheter (18-20 gauge): Safer as the catheter is flexible if left in place, reducing organ damage risk.
Blunt-tipped centesis catheter (e.g., Mila Abdominocentesis Catheter): Safest option, specifically designed to minimize organ trauma.
Butterfly catheter: Can be useful for small amounts of fluid or if multiple attempts are needed.
Syringes: 3, 6, 12 ml for fluid aspiration.
Collection Tubes:
EDTA (lavender top): For cell counts (Red Blood Cells, White Blood Cells) and cytologic examination.
Plain/Red top: For biochemical analysis (protein, glucose, lactate, creatinine, bilirubin, triglycerides) and culture.
Microscope Slides: For direct smears (optional).
Scalpel blade (No. 11 or 15): For a small stab incision if using a larger catheter.
Bandage materials: Small adhesive bandage or gauze.
IV. Procedure Steps
Patient Preparation:
Obtain informed consent from the owner.
Stabilize the patient: Address shock, severe pain, or respiratory distress before the procedure if possible.
Determine Sedation/Anesthesia: Most stable dogs tolerate the procedure with minimal restraint. Local anesthetic can be used at the skin site. Sedation may be required for anxious or painful patients.
Positioning:
Lateral recumbency: Most common, especially for larger volumes of fluid. Allows fluid to pool ventrally.
Standing or Sternal recumbency: Can be used, but fluid may be harder to access.
Standing with front feet elevated: Can help fluid pool caudally.
Aseptic Preparation:
Clip a wide area of hair from the ventral abdomen, extending from the xiphoid to the pelvis.
Perform a sterile surgical scrub (at least 3 alternating applications of scrub and alcohol).
Choosing the Insertion Site(s):
The most common site is the right caudal abdomen, 1-2 cm lateral to the ventral midline and 1-2 cm caudal to the umbilicus. This site generally avoids the spleen (on the left), bladder (midline caudal), and liver (cranial abdomen).
Four-quadrant approach: If a single site is unsuccessful, four sites around the umbilicus (cranial, caudal, left, right) can be attempted.
Ultrasound guidance: Ideally used to identify the largest pockets of fluid and avoid vital organs.
Local Anesthesia (Optional):
Infiltrate 0.5-1 ml of 2% lidocaine subcutaneously at the chosen site. Wait 2-3 minutes for the anesthetic to take effect.
Fluid Collection:
Stab Incision (if using a large catheter): Create a small stab incision through the skin with a scalpel blade. This facilitates catheter placement and reduces drag.
Needle/Catheter Insertion:
Attach a 3, 6, or 12 ml syringe to the chosen needle/catheter.
Insert the needle/catheter perpendicular to the skin, then angle it slightly cranially (to avoid the bladder) or caudally (to avoid the liver/spleen depending on site).
Advance steadily and carefully. A “pop” sensation may be felt as the needle/catheter penetrates the peritoneal lining.
If using an over-the-needle catheter, once the “pop” is felt and fluid begins to flow into the syringe, advance the flexible catheter into the abdomen while holding the stylet still, then remove the stylet. This reduces the risk of organ damage.
Gently aspirate with the syringe.
If no fluid is obtained, try:
Rotating the needle/catheter slightly.
Advancing or withdrawing the needle/catheter by a few millimeters.
Applying gentle external pressure to the abdomen.
Trying a different quadrant.
Do NOT redirect the needle/catheter without withdrawing it to the subcutaneous tissue first, as this increases organ damage risk.
Post-Procedure:
Once sufficient fluid is collected, withdraw the needle/catheter quickly.
Apply gentle pressure to the site for a few minutes.
A small adhesive bandage may be placed.
V. Sample Analysis
The collected fluid should be analyzed for:
Gross Appearance:
Color: Straw-yellow (normal), red/pink (hemorrhage), cloudy (infection/inflammation), green/brown (bile/ruptured GI), milky (chylous).
Turbidity: Clear (normal), turbid (cells/protein).
Odor: Foul-smelling (septic peritonitis).
Cell Counts (EDTA tube):
Total Nucleated Cell Count (TNCC): Elevated in inflammation/infection.
Red Blood Cell Count (RBC): Elevated in hemorrhage.
Cytology (EDTA tube, direct smear):
Types of cells: Neutrophils (degenerate vs. non-degenerate), macrophages, lymphocytes, eosinophils, mast cells, neoplastic cells.
Presence of bacteria (intracellular vs. extracellular).
Fungal elements.
Biochemical Analysis (Red top tube):
Total Protein (TP): Elevated in exudates.
Glucose: Decreased in septic peritonitis (bacteria consume glucose).
Lactate: Elevated in septic peritonitis (anaerobic metabolism).
Creatinine: Significantly higher than serum creatinine in uroabdomen.
Bilirubin: Significantly higher than serum bilirubin in bile peritonitis.
Triglycerides: Elevated in chylous effusion.
Packed Cell Volume (PCV): Compare to peripheral blood PCV to differentiate hemorrhage from iatrogenic blood contamination.
Culture and Sensitivity: If infection is suspected.
VI. Interpretation of Results (Brief Overview)
Normal Peritoneal Fluid: Clear to pale yellow, very low cellularity (<500 cells/µL), low protein (<2.5 g/dL).
Transudate: Clear, low cellularity (<1000 cells/µL), low protein (<2.5 g/dL). Caused by conditions like heart failure, hypoproteinemia.
Modified Transudate: Slightly cloudy, moderate cellularity (1000-7000 cells/µL), moderate protein (2.5-5.0 g/dL). Caused by conditions like heart failure, liver disease, early neoplasia.
Exudate: Cloudy, high cellularity (>7000 cells/µL), high protein (>3.0 g/dL). Often indicates inflammation, infection (septic peritonitis), or neoplasia.
Hemorrhagic Effusion (Hemabdomen): Red/frank blood. PCV of fluid similar to peripheral blood PCV. Caused by trauma, coagulopathy, ruptured tumor (e.g., hemangiosarcoma).
Uroabdomen: Fluid creatinine is significantly higher than serum creatinine (typically >2:1 ratio).
Chylous Effusion (Chyloabdomen): Milky white fluid with high triglyceride concentration.
Bile Peritonitis: Green/yellow-brown fluid with high bilirubin concentration.
VII. Potential Complications
“Dry tap”: No fluid obtained, most common complication.
Organ Laceration: Puncture of the spleen, liver, bowel, bladder, or major blood vessels. (Minimized by careful technique, proper site selection, and ultrasound guidance).
Hemorrhage: From the puncture site or internal organs. Exacerbated in coagulopathic patients.
Peritonitis: Introduction of bacteria into the abdominal cavity (rare with aseptic technique).
Pain/Discomfort.
Iatrogenic Pneumothorax: Extremely rare, but possible if the needle is advanced too cranially and penetrates the diaphragm and thoracic cavity.
Abdominocentesis is a valuable diagnostic tool that can provide critical information for managing a variety of abdominal conditions in dogs. While generally safe, adherence to sterile technique and careful execution are paramount to minimize risks.
============================
#Abdominocentesis, #CanineAbdominocentesis, #DogAbdominocentesis, #VetMed, #VeterinaryMedicine, #DogHealth, #CanineHealth, #PetHealth, #AscitesInDogs, #AbdominalFluid, #VetDiagnostics, #DiagnosticProcedure, #FluidAnalysis, #VetLife, #Veterinarian, #VetTech, #SmallAnimalVet, #EmergencyVet, #AbdominalTap, #FluidDrainage, #DogCare, #PetCare, #HealthyDogs, #PeritonealFluid, #AnimalHealthcare
Add comment