CONTRIBUTOR(S): Claire Speight, Rachel Blake,
Abdominocentesis
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Abdominocentesis is a procedure whereby a needle or catheter are placed into the abdomen, through the skin, so excess free fluid can be removed to gain a diagnosis. The procedure may also be known as a paracentesis or abdominal tap. It is a useful procedure that can be performed on rabbits.
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Why is an abdominocentesis required?
Abdominocentesis is very useful to allow identification of free abdominal (peritoneal) fluid, its biochemical characteristics, cytology (examining the cells), and culture and sensitivity. This is useful to help your veterinarian gain a diagnosis.
What causes free fluid in the abdominal cavity?
The accumulation of fluid (asities) can occur for a variety of reasons. These may be:
- Leakage of intestinal contents: this is usually a consequence of gastrointestinal rupture and septic peritonitis can rapidly occur.
- Leakage of urine from the bladder: any rupture or leakage of urine from the bladder will mean urine can readily enter the abdominal cavity.
- Bleeding into the abdomen from an organ: bleeding can occur from any abdominal organ, with the spleen being the most commonly affected. On post-mortem examination, with cases of RVHD-1, rabbits are often found to have blood within the abdominal cavity, having bled from abdominal organs prior to death.
- Infection: this can arise due to a foreign body entering the abdominal cavity, abscess formation in the abdomen or secondary after gastrointestinal rupture.
- Bile: a small hole anywhere along the bile ducts, which run from the liver to the small intestines, can cause bile to leak into the abdominal cavity.
- Uterine contents: this can happen due to a perforation in the uterus.
- Kidney disease: renal glomerular disease affects the filtering units of the kidneys; the glomeruli. There are lots of reasons for this to happen and one of the signs can be fluid accumulation in the legs and abdomen.
How is it performed?
Abdominocentesis can be performed ‘blind’ or by ultrasonic guidance, using an ultrasound machine. The blind technique involves putting the needle into the abdomen without fully knowing what structures or organs may be beneath, or where the fluid has accumulated. When using an ultrasound, the veterinarian will be able to see where the needle is going in real time, which is much safer for the rabbit.
The technique
If the rabbit is calm, it may be possible to carry the procedure out while the rabbit is conscious. If they are stressed or unlikely to stay still, then sedation will be required. With the rabbit lying on their back, an area of fur will be clipped from the rabbit’s abdomen. The clipped area will be surgically scrubbed to ensure it is clean, to minimize the risk of any infection. Your veterinarian will insert a needle or catheter through the skin and into the abdomen. A sample of the fluid will be collected through the needle and syringe and placed into sample containers, so it can be analyzed. If the rabbit was sedated, a reversal agent will then be given so they wake up quickly.What are the potential risks?
There is a risk of damage from the needle to the abdominal organs, and this is why using an ultrasound to guide the needle to the correct location to obtain a sample of the fluid is important. This will greatly minimize the risk. The most common organs that are punctured, especially when not using an ultrasound for guidance, are the bladder and intestines. The consequences of this can be leakage from these organs of urine or intestinal contents into the abdomen, causing septic peritonitis, which can be fatal. When it is suspected that there is blood within the abdominal cavity, it is important to rule out a clotting disorder, prior to attempting to sample the fluid, as the procedure may cause further bleeding.
How long does the procedure take?
It should only take a matter of a few minutes to perform the procedure, but your veterinarian may want to look at the fluid sample under a microscope to analyze it, so your rabbit is likely to have to stay in hospital for several hours. The veterinarian may want to send a sample of the fluid to an external laboratory, so the results may not be known immediately.
What treatment will my rabbit need?
This depends on the fluid analysis and the reason for it accumulating in the abdomen. Your veterinarian may recommend further diagnostic testing (blood tests, ultrasound, urine tests), exploratory surgery to surgically enter the abdominal cavity or medications. They will be able to discuss the results and recommended next steps with you.