Puncture, Aspiration, Injection and Reaspiration (PAIR)
Updated :
September 1, 2025
Background
PAIR (Puncture, Aspiration, Injection, and Reaspiration) is a minimally invasive surgical method chosen primarily for the treatment of Cystic Echinococcosis more familiarly known as hydatid disease. A parasitic disease, caused by Echinococcus granulosus leading to the development of hydatid cysts, where the liver and lungs are usually affected.
Components
Puncture
Through puncture a thin needle is passed through the skin to the hydatid cyst usually with guidance from an ultrasonic or CT scan. It is important in this step to gain exposure to the cyst cavity while at the same time avoid damaging the cyst and causing it to leak or rupture into surrounding tissue.
Aspiration
The cystic fluid is evacuated with the needle through a process of aspiration. This downgrades the internal pressure in the cyst as well as minimizes chances of accidental puncture. Invasive procedures such as puncture of a cyst or aspiration are done to ensure that the cyst contains the hydatid components.
Injection
Upon aspiration, a scolicidal agent is instilled into the cyst to kill parasitic components. Scolicidal agents include hypertonic saline solution, ethanol, or cetrimide although any agent safe for endoscopic use can be used as a scolicidal agent.
The scolicidal solution is left within the cysts long enough to sterilize the protoscolex (this takes about 15-30minutes).
Reaspiration
After the interval, post treatment, the scolicidal agent is again removed from the cyst by the process of aspiration. It also helps to clean the cyst cavity to the extent as possible by washing out the cyst and getting rid of the solution. However, sometimes, a drainage catheter may be left in place for some other form of additional drainage.
Indications
Cysts at Risk of Rupture
Cysts can cause complications such as rupture and compression of close structures because of their size, and if found in certain organs then surgery may not be advisable, for such cysts PAIR can be applied.
Inaccessible Locations for Surgery
Patients with hydatid cysts in sites that are challenging to undergo surgery or highly risky (for example, complicated liver cysts or cysts that are close to blood vessels).
Patients Unfit for Surgery
It is used in those patients who are unlikely to undergo surgery because of medical conditions, age, or high surgical risks.
Contraindications
Superficial or communicating cysts: Any cyst which is located near important organs, pleura or large blood vessels can rupture during the procedure.
Multiple cysts in multiple organs: The respond to PAIR may not be effective because the condition may require systemic or surgical management.
Non-accessible cysts: Therefore, if the cyst is inaccessible for aspiration by carrying out percutaneous cyst puncture, then PAIR should not be attempted. Cyst rupture: The already ruptured cyst into the biliary tract or other structures tends to spread their contents or trigger severe anaphylactic reactions.
Outcomes
Periprocedural care
EquipmentÂ
Ultrasound machine
Syringes
Catheters
Needle
Scolicidal Agents
Local Anesthetia
Antiseptic Solutions
Sterile Gauze
Dressing Materials
Drainage Bags or Bottles
Patient preparation
Pre-procedure Evaluation
History and Physical Examination: The patient’s history must be complete, including known allergies to anesthetic agents, comorbid conditions, and previous treatments.
Imaging: Ultrasound studies or a CT scan or MRI should be performed to establish the diagnosis and indicate the sizes and locations of the cysts and the types as well as the best approach to obtain punctures.
Specific serology for echinococcosis and for other potential infective diseases that might show a cross-reaction in echinococcal serology.
Assessment of Comorbidities: Previous cardiovascular and liver disease or other serious conditions should be assessed and controlled before the surgery is performed.
Patient position: The patient is usually placed in the supine position because of reasons of accessibility especially if the cyst is situated in the anterior segments of the liver.
If the cyst is part of the sacrum, the patient may be tilted to one side (lateral decubitus position) or the semi-supine position.
Ultrasound guided PAIR
Step 1-Puncture:
Preparation: The patient should be placed in the correct position and the area overlying the cyst adequately prepared in sterile manner.
Imaging Guidance: Ultrasound or CT imaging should be done first to detect the location of the cyst and plan the puncture with the use of a needle. Step 2-Needle insertion: Under imaging guidance, a thin needle most often a 16- to 18-gauge needle is inserted directly into the cyst. Step 3-Aspiration: Fluid Aspiration: It is done by using a syringe. The aspirated fluid is analyzed; therefore, it also contains cytology or microbiological culture.
Assessment: The specific nature of the cyst or contents may suggest the types of the aspirated fluid appearance whether clear, blood stained or purulent.
Step 4-Injection:
Administration of Sclerosant: A sclerosant, ethanol or hypertonic saline, is instilled into the cyst through a direct puncture. This agent will also eradicate any surviving living cystic cells and enable the eradication of the cyst.
Volume: The amount of the sclerosant depends on the size of the cyst.
Step 5-Reaspiration: Post-Injection Aspiration: In this case, the injected material has been injected and some of the surrounding fluid may then be aspirated possibly at about 10-15 minutes. It will be very important to avoid some of these complications and ensures that the sclerosant meets the lining of the cyst appropriately. Step 6-After Care Monitoring: The complication or side reaction to the procedure, such as infection or hemorrhage of the patient, ought to be monitored. Follow-up: This is done sometimes weeks or months after the procedure by employing an ultrasound or CT scan with a view of checking up whether the treatment has been effective, or recurrence has ensued.
Complications
Cyst Rupture and Dissemination
This also results in spillage of the contents of the cyst into adjacent tissues or body cavities during the time of an incomplete evacuation, poor technique, or a rupture, which may lead to secondary echinococcosis in even higher proportions.
Biliary Fistula
Most commonly evident in the liver cysts there is a possibility to communicate with the biliary system to form biliary fistula for the cyst fluid to ingress into the biliary tree. This would be accompanied by jaundice and inflammation of the bile duct and biliary tract peritonitis and cholangitis.
Infection The cyst may acquire a secondary infection, which can lead to the development of an abscess, and which may necessitate interventions such as drainage or antibiotics. Lung complications Complications of lung cysts include pneumothorax (air in the pleural cavity), pleuritis, or a bronchopleural fistula (abnormal communication between the bronchial tree and the pleural cavity) occur as an effect of the procedure.
»
Home » Procedure » Puncture, Aspiration, Injection and Reaspiration (PAIR)
Puncture, Aspiration, Injection and Reaspiration (PAIR)
Updated :
September 1, 2025
PAIR (Puncture, Aspiration, Injection, and Reaspiration) is a minimally invasive surgical method chosen primarily for the treatment of Cystic Echinococcosis more familiarly known as hydatid disease. A parasitic disease, caused by Echinococcus granulosus leading to the development of hydatid cysts, where the liver and lungs are usually affected.
Components
Puncture
Through puncture a thin needle is passed through the skin to the hydatid cyst usually with guidance from an ultrasonic or CT scan. It is important in this step to gain exposure to the cyst cavity while at the same time avoid damaging the cyst and causing it to leak or rupture into surrounding tissue.
Aspiration
The cystic fluid is evacuated with the needle through a process of aspiration. This downgrades the internal pressure in the cyst as well as minimizes chances of accidental puncture. Invasive procedures such as puncture of a cyst or aspiration are done to ensure that the cyst contains the hydatid components.
Injection
Upon aspiration, a scolicidal agent is instilled into the cyst to kill parasitic components. Scolicidal agents include hypertonic saline solution, ethanol, or cetrimide although any agent safe for endoscopic use can be used as a scolicidal agent.
The scolicidal solution is left within the cysts long enough to sterilize the protoscolex (this takes about 15-30minutes).
Reaspiration
After the interval, post treatment, the scolicidal agent is again removed from the cyst by the process of aspiration. It also helps to clean the cyst cavity to the extent as possible by washing out the cyst and getting rid of the solution. However, sometimes, a drainage catheter may be left in place for some other form of additional drainage.
Cysts at Risk of Rupture
Cysts can cause complications such as rupture and compression of close structures because of their size, and if found in certain organs then surgery may not be advisable, for such cysts PAIR can be applied.
Inaccessible Locations for Surgery
Patients with hydatid cysts in sites that are challenging to undergo surgery or highly risky (for example, complicated liver cysts or cysts that are close to blood vessels).
Patients Unfit for Surgery
It is used in those patients who are unlikely to undergo surgery because of medical conditions, age, or high surgical risks.
Superficial or communicating cysts: Any cyst which is located near important organs, pleura or large blood vessels can rupture during the procedure.
Multiple cysts in multiple organs: The respond to PAIR may not be effective because the condition may require systemic or surgical management.
Non-accessible cysts: Therefore, if the cyst is inaccessible for aspiration by carrying out percutaneous cyst puncture, then PAIR should not be attempted. Cyst rupture: The already ruptured cyst into the biliary tract or other structures tends to spread their contents or trigger severe anaphylactic reactions.
EquipmentÂ
Ultrasound machine
Syringes
Catheters
Needle
Scolicidal Agents
Local Anesthetia
Antiseptic Solutions
Sterile Gauze
Dressing Materials
Drainage Bags or Bottles
Patient preparation
Pre-procedure Evaluation
History and Physical Examination: The patient’s history must be complete, including known allergies to anesthetic agents, comorbid conditions, and previous treatments.
Imaging: Ultrasound studies or a CT scan or MRI should be performed to establish the diagnosis and indicate the sizes and locations of the cysts and the types as well as the best approach to obtain punctures.
Specific serology for echinococcosis and for other potential infective diseases that might show a cross-reaction in echinococcal serology.
Assessment of Comorbidities: Previous cardiovascular and liver disease or other serious conditions should be assessed and controlled before the surgery is performed.
Patient position: The patient is usually placed in the supine position because of reasons of accessibility especially if the cyst is situated in the anterior segments of the liver.
If the cyst is part of the sacrum, the patient may be tilted to one side (lateral decubitus position) or the semi-supine position.
Ultrasound guided PAIR
Step 1-Puncture:
Preparation: The patient should be placed in the correct position and the area overlying the cyst adequately prepared in sterile manner.
Imaging Guidance: Ultrasound or CT imaging should be done first to detect the location of the cyst and plan the puncture with the use of a needle. Step 2-Needle insertion: Under imaging guidance, a thin needle most often a 16- to 18-gauge needle is inserted directly into the cyst. Step 3-Aspiration: Fluid Aspiration: It is done by using a syringe. The aspirated fluid is analyzed; therefore, it also contains cytology or microbiological culture.
Assessment: The specific nature of the cyst or contents may suggest the types of the aspirated fluid appearance whether clear, blood stained or purulent.
Step 4-Injection:
Administration of Sclerosant: A sclerosant, ethanol or hypertonic saline, is instilled into the cyst through a direct puncture. This agent will also eradicate any surviving living cystic cells and enable the eradication of the cyst.
Volume: The amount of the sclerosant depends on the size of the cyst.
Step 5-Reaspiration: Post-Injection Aspiration: In this case, the injected material has been injected and some of the surrounding fluid may then be aspirated possibly at about 10-15 minutes. It will be very important to avoid some of these complications and ensures that the sclerosant meets the lining of the cyst appropriately. Step 6-After Care Monitoring: The complication or side reaction to the procedure, such as infection or hemorrhage of the patient, ought to be monitored. Follow-up: This is done sometimes weeks or months after the procedure by employing an ultrasound or CT scan with a view of checking up whether the treatment has been effective, or recurrence has ensued.
Complications
Cyst Rupture and Dissemination
This also results in spillage of the contents of the cyst into adjacent tissues or body cavities during the time of an incomplete evacuation, poor technique, or a rupture, which may lead to secondary echinococcosis in even higher proportions.
Biliary Fistula
Most commonly evident in the liver cysts there is a possibility to communicate with the biliary system to form biliary fistula for the cyst fluid to ingress into the biliary tree. This would be accompanied by jaundice and inflammation of the bile duct and biliary tract peritonitis and cholangitis.
Infection The cyst may acquire a secondary infection, which can lead to the development of an abscess, and which may necessitate interventions such as drainage or antibiotics. Lung complications Complications of lung cysts include pneumothorax (air in the pleural cavity), pleuritis, or a bronchopleural fistula (abnormal communication between the bronchial tree and the pleural cavity) occur as an effect of the procedure.
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