Overview of Paracentesis
Ascites refers to the build-up of excess fluid in the space around your organs in your abdomen, which is known as the peritoneal cavity. This is often a serious indicator of liver cirrhosis, a disease where the liver is progressively damaged, leading to severe health issues.
Paracentesis is a crucial medical procedure used to manage ascites. It helps doctors understand and treat this complex condition. During a diagnostic paracentesis, doctors use a needle to carefully draw fluid from the abdominal area. This fluid is then studied to determine the root cause of the ascites and to check for any infection. In a therapeutic paracentesis, a large amount of the fluid is removed to reduce the discomfort and symptoms caused by ascites.
In managing ascites, a team approach involving different health professionals is important. Timely identification and treatment of ascites can notably improve a patient’s health condition. Given that liver cirrhosis is a major cause of ascites, it is vital for healthcare providers to understand how to carry out a paracentesis procedure effectively.
People with ascites due to liver cirrhosis have a significantly higher risk of death within the first year compared to people with liver cirrhosis who do not have ascites. As a result, it’s crucial to test the excess fluid in all new cases of ascites to swiftly start the appropriate treatment.
Ascites can be categorized into two types, exudative and transudative, based on the nature of the fluid buildup. To distinguish between these two types, a test called the serum-ascitic albumin gradient (SAAG) is performed. The SAAG is related to the blood pressure in the portal vein, which carries blood to the liver. A high SAAG level suggests portal hypertension (a condition of high blood pressure in the portal vein) and transudative ascites. A lower SAAG level indicates exudative ascites.
Transudative ascites commonly results from conditions such as liver cirrhosis, heart failure, alcohol-induced liver inflammation, severe liver failure, a syndrome that results in loss of protein in the urine (nephrotic syndrome), or a blood clot in the portal vein.
Exudative ascites can be caused by conditions including peritoneal carcinomatosis (cancer that has spread to the peritoneal cavity), pancreatitis (inflammation of the pancreas), peritonitis (inflammation of the peritoneum), ischemic colitis (inflammation of the large intestine due to reduced blood flow), and intestinal obstruction.
Anatomy and Physiology of Paracentesis
Paracentesis is a medical procedure where a needle or tube is inserted into the body to drain fluids. This can be done while you’re either lying on your side or on your back, and a scan can guide the doctor. If a scan isn’t used, the doctor usually does this on the lower left side of your belly where it is safer and more effective due to your body’s structure at that point, according to a study by a scientist named Sakai H.
Doctors need to keep a few important factors in mind while performing this procedure:
- The presence of any surgical scars,
- Where your spleen is located,
- The paths of your lower stomach arteries (inferior epigastric arteries), and
- The position of the beginning of your large intestine (cecum) if the procedure is performed on your right lower side of the belly.
To perform a paracentesis, the doctor will first estimate the level of excess fluid in your abdomen by feeling (percussing) your belly and then insert a needle either in the middle or the lower side of your belly (avoiding a certain muscle and an important bone). This reduces the chances of interacting with the lower stomach arteries. While inserting the needle, the doctor will be careful not to puncture any visible veins or surgical scars on your skin. The needle will then be inserted at an angle of 45 degrees, or using a special technique called z-tracking, to reduce the chances of any fluid leaks.
Why do People Need Paracentesis
Diagnostic paracentesis helps doctors understand the cause of your symptoms if you show signs of infection or illness, such as belly pain, fever, or unusual bleeding. It’s often used when you’ve already been diagnosed with a condition known as ‘ascites’, which refers to the buildup of fluid in the abdomen causing swelling. This procedure involves inserting a needle into your belly to collect a small sample of fluid for examination in a lab. It can even be used to discover if you have new-onset ascites by inspecting the collected fluid. This testing can identify the type of fluid, recognise any cancer cells, or give an insight into other potential causes of your symptoms.
Therapeutic paracentesis, on the other hand, can provide relief from discomfort or difficulties with breathing caused by a significant accumulation of fluid in the abdomen. This is especially useful if medication doesn’t help reduce the fluid buildup. In extreme cases, a form of therapeutic paracentesis known as ‘large-volume paracentesis’ (LVP) may be needed. One study showed that using a special pump to slowly remove fluid from the belly into the bladder improved the quality of life for patients with ascites by reducing the need for repeated LVP procedures.
If the buildup of fluid in your abdomen is so severe that it leads to a dangerous condition known as ‘abdominal compartment syndrome’, you could require emergency surgery for relief. In such cases, LVP could help lower the pressure inside your abdomen. Similarly, if you have advanced liver disease causing ascites and difficulty in breathing, paracentesis can bring notable improvements. In a study involving patients with liver problems and ascites, paracentesis made breathing easier, raised oxygen levels in the body, and reduced feelings of breathlessness and fatigue.
When a Person Should Avoid Paracentesis
A paracentesis is a medical procedure that takes out fluid from the belly, but there are a few reasons why it can’t be carried out:
If someone has a condition called disseminated intravascular coagulation, where their blood clots forms abnormally throughout the blood vessels, or if they need an emergency surgery for a severe belly pain, paracentesis can’t be done. These are called absolute contraindications, meaning the procedure is completely ruled out.
There are also relative contraindications for paracentesis – situations where paracentesis is not necessarily ruled out but should be done very carefully. These include if a person is pregnant or has enlarged organs (organomegaly), paralysis of the intestines (ileus), blocked intestines, an overly full bladder, or problems with blood clotting (e.g. having very low platelets counts or a high International Normalized Ratio (INR), which is a measure of how long it takes your blood to clot).
Even with problems in clotting and low platelets (conditions common in cirrhotic patients), paracentesis procedure can be done because the chances of bleeding complications are very low. If someone has severe low platelet count, they should receive extra platelets before the procedure. If someone has a high INR, they should receive fresh-frozen plasma (a blood product that helps with clotting) before and during the procedure. If a patient doesn’t have a history or shows any evidence of active bleeding, certain blood clotting tests might not be required before this procedure.
Also, while performing paracentesis, doctors should avoid inserting the needle/catheter into sites of skin infection, surgical scars, visible bulging belly wall vessels, or bruised areas on the belly wall.
Equipment used for Paracentesis
Some medical centers use ready-to-use kits designed specifically for performing a paracentesis procedure. If you don’t know, a paracentesis is a procedure when a needle is used to remove excess fluid from the abdomen. These pre-made kits have a plastic sheath tube, also known as a cannula, that is attached to a syringe with a valve which can be turned to start or stop the flow of fluid, known as a stopcock.
Another method can involve using a large, hollow needle similar to the ones healthcare facilities use to give patients drips (IVs) or a needle similar to the one used to perform spinal taps or epidurals, which vary between 18-gauge and 20-gauge in thickness. These needles could also attach to a syringe, in order to draw out liquid whilst a special tube attached to the needle aids in draining the fluid from the abdomen.
However, if such specialized kits are not available, medical professionals will need the following equipment:
- Sterile gloves to prevent infection
- Antiseptic swabs for cleaning the skin before the procedure
- A No. 11 blade scalpel, a small knife used in surgeries
- Sterilized drapes/towels for covering the patient and the area around the procedure site
- Chlorhexidine or betadine, which are used to clean the skin
- Lidocaine 1% – this is a local anesthetic to numb the area
- Two injection needles which are 22-gauge
- An 8 French catheter, which is a thin tube placed over an 18-gauge, 7.5 inch (19 cm) needle with a valve that can open to three directions and a self-sealing valve
- A thinner needle for injection, which is 25-gauge
- An introducer needle that is 20-gauge, which is used to assist in inserting catheters or other tubes
- A 20 ml or 60 ml syringe, a pump-like device, to collect a fluid sample
- A tube set with a roller clamp, which controls and directs the fluid flow
- A drainage bag or vacuum container, for collecting and holding the fluid removed
Additionally, they will require 4 x 4 inch (10 x 10 cm) sized gauzes, which is a light fabric used to absorb fluid or blood, and three specimen containers for collecting sample fluid to send for testing. More specifically, these fluid samples are tested for blood cell counts (hematology), chemical tests (chemistry), and growth of microorganisms (microbiology).
Preparing for Paracentesis
Your doctor will talk to you (or the person responsible for making medical decisions for you) about the procedure you’re about to have. They will explain what they will do, the benefits and potential risks, what could go wrong, and other available treatment options. Once you have all the information, you’ll be asked to sign a form giving your permission for the procedure.
The procedure you’re having is called a paracentesis. It involves inserting a needle into your abdomen (tummy area) to remove fluid. Normally, the doctors choose either the right or left lower part of your tummy for this, to the side and higher than your hip bone. There are two recommended spots where they might insert the needle:
- 2 cm below your belly button straight in the middle
- 5 cm up and towards the middle from your hip bone, on either side
For this procedure, you’ll be asked to lay on your side. This position helps move the floaty, air-filled parts of your bowel (a long tube that helps digest food) out of the way in your tummy area. If you have a lot of fluid build-up in your abdomen, you might need to lay flat on your back. Laying on your side can also help doctors spot pockets of fluid in patients with less fluid build-up. It’s important to pee before the procedure starts.
Your doctor will use an ultrasound machine to help guide them during the procedure. This tool uses sound waves to create pictures of the inside of your body. It helps your doctor to identify the best spot for the needle and to ensure there’s enough fluid to remove. By using ultrasound, your doctor can increase the chance of a successful paracentesis and avoid performing an unnecessary invasive procedure. They will either mark the best spot for needle entry on your skin or use the ultrasound images in real time to guide the needle. The ultrasound is also used to prevent the needle from going into your bowels or a full bladder. It’s very important to steer clear of areas with large veins, scar tissue, or infected skin to avoid complications.
How is Paracentesis performed
In the past, a medical procedure called paracentesis, which is used to remove fluid build-up from the abdomen, was performed in hospitals, especially for patients receiving comfort care. However, some patients might find it tough to get to the hospital. For these patients, a procedure done at home, called home-based palliative paracentesis (HBPP), is a good option. This approach was shown to be safe, effective, and more convenient in a study by Ota et al. Another study, by Kunin et al., revealed that home-based paracentesis improved symptoms in patients receiving peritoneal dialysis, a process to clear wastes from the body because the kidneys have failed, without the need for episodic fluid exchanges.
Before the procedure, it’s essential to make sure the patient’s bladder is empty. Sterile preparations should then be made to keep the skin clean and infection-free. Local anesthesia, a medicine that numbs a small part of your body, is used on the skin and other soft tissue at the site where the procedure will happen. A syringe attached to a needle or catheter (a flexible tube) is inserted into the skin either perpendicular or in a zig-zag manner. The latter technique is thought to reduce the chance of leakage of body fluids after the procedure.
As the needle is inserted, a pullback is applied to the syringe until fluids obtained from the abdomen start to flow steadily into the syringe. This is an essential step in the procedure. After a sufficient amount of fluid has been obtained, the needle or cathicle is removed, or additional fluid may be drained if desired.
In a study by Kelil and his team, it was reported that using wall suction and plastic canisters for fluid drainage and collection were safe alternatives to using evacuated glass bottles, reducing procedure costs.
The abdominal fluid collected during the procedure should be sent to a laboratory for analysis. The analysis can reveal if the patient has an infection, like spontaneous bacterial peritonitis, a severe infection in the abdomen. If the lab results show a high number of white blood cells called neutrophils or if the doctor strongly suspects an infection, antibiotics should be started.
In the hospital, more advanced tests can be performed to determine the cause of the fluid build-up in your abdomen. For example, albumin, a protein present in blood and body fluids, can be measured to help find out if there is a specific kind of high blood pressure in the liver called portal hypertension. This is calculated by subtracting the albumin concentration in your abdominal fluid from the amount of albumin in your blood. If this calculation, known as SAAG, is greater than 1.1, it suggests a high chance of portal hypertension. Conversely, a SAAG less than 1.1 rules out portal hypertension.
Possible Complications of Paracentesis
Paracentesis is a generally safe procedure to remove fluid from your belly, but there might be some issues that could occur. These complications include, but are not limited to:
– Fluid continuously leaking from the spot where the needle was put in. Typically, your doctor can treat this by putting in a simple stitch.
– Bleeding or building up of blood (known as hematoma) in the wall of the belly
– An infection in the wound
– Accidentally poking a hole in nearby blood vessels or organs (this is very rare)
– Low blood pressure after removing a large amount (more than 5 to 6 liters) of fluid. To prevent this, your doctor might give you a protein called albumin if they’re removing more than 5 liters of fluid.
– Spontaneous bleeding into the peritoneal cavity, the area that contains your organs like your liver, stomach and intestines
– Accidentally cutting the catheter (the tube used to remove fluid) and losing it in the belly
– Hepatorenal syndrome, a condition that affects the kidneys and liver
There might also be an accumulation of fluid under the skin caused by leakage from where the fluid was taken out.
What Else Should I Know About Paracentesis?
Ascites is a medical condition where fluid builds up in the space between the lining of the abdomen and the organs, also known as the peritoneal space. This condition can develop due to a variety of illnesses. A procedure known as paracentesis can be carried out to help figure out the reason for this fluid buildup. In this procedure, the doctor drains the fluid from the abdominal cavity, which can not only provide relief from symptoms, but also help identify the cause, such as an infection, liver disease, or high blood pressure in the liver’s blood vessels (portal hypertension).
Doctors often use a bedside ultrasound machine to find the best spot to drain the fluid, which makes the procedure more likely to succeed.
A study looking back at 97 patients found that having this procedure done early can actually lower death rates in cases of spontaneous bacterial peritonitis or SBP, an infection in the peritoneal fluid. This research showed that emergency doctors often order an early paracentesis.
