Patient preparation
Before performing percutaneous drainage, it is necessary to ensure that a number of conditions are met. Reviewing up-to-date diagnostic imaging data is mandatory.
The patient must sign an informed consent. An intravenous access and recent coagulation profile results are mandatory. If drainage of a potentially infected cavity is planned, prophylactic antibiotic therapy is prescribed. When using conscious sedation, the patient must remain nil per os (NPO) for 6 hours. The authors prefer a combination of midazolam and fentanyl.
Aspiration or catheter?
Percutaneous drainage catheter placement is significantly superior to simple needle aspiration. Aspiration is not suitable for treating collections that communicate with the biliary or urinary tracts, as well as the intestinal lumen.
The only exception where aspiration alone is acceptable is small fluid collections where it is technically impossible to place a catheter (e.g., small interloop abscesses in the setting of immunosuppression).
Tandem-trocar technique
This method (tandem-trocar technique) involves introducing a drainage catheter (usually 8–16 F) parallel to a thin guiding needle.
Main steps:
- CT grid marking to select a safe trajectory.
- Insertion of a guiding needle (20-G) into the abscess after local anesthesia.
- Fluid sampling for microbiological culture.
- Catheter selection (10–12 F for thick pus, 8–10 F for liquid contents).
- Insertion of the catheter with a stylet parallel to the needle to a pre-measured depth.
- Removal of the stylet and catheter fixation (often forming a pigtail loop).
The advantage of the method is speed and the elimination of the need for sequential tract dilation. The disadvantage is the risk of catheter deflection by the dense abscess capsule. In case of unsuccessful placement, complete system removal is required.
Post-insertion management and flushing
After successful catheter fixation and bag connection, the contents are evacuated. To accelerate healing, disrupt adhesions, and improve outflow, flushing with normal saline is used.
Important rule: the volume of saline injected during flushing must under no circumstances exceed the volume of fluid evacuated from the cavity. This is necessary to prevent abscess overdistension and reduce the risk of bacteremia.
Seldinger technique
The Seldinger technique involves placing a catheter over a metal guidewire passed through a puncture needle.
This method provides maximum control over the procedure and is preferred if there is a high risk of puncturing (transgressing) the posterior wall of the drained cavity.
Briefly: answers to topical questions
What are the absolute contraindications to image-guided percutaneous drainage?
An absolute contraindication to pleural drainage is hepatic hydrothorax. Fluid collections communicating with the intestinal lumen, biliary, or urinary tracts should not be treated exclusively with percutaneous aspiration — catheter placement is preferred in all other cases. Percutaneous drainage is used in suitable patients who do not require emergency surgery.
What complications can occur during or after percutaneous abscess drainage?
During the drainage of collections, there is a risk of bacteremia associated with cavity overdistension and excessive manipulation. In infected walled-off pancreatic necrosis, catheter obstruction by dense necrotic debris may occur, making aspiration impossible.
What types of drainage catheters and fixation methods are used in diagnostic radiology besides the pigtail type?
In addition to pigtail catheters, straight catheters and Malecot-tipped catheters are used for drainage, which are convenient for a small renal pelvis volume. The following methods are used to secure drainage catheters:
- Adhesive devices — used to secure the tube to the skin.
- Surgical suture — thread fixation (polyamide is preferred). The skin should not be included in the stitch, as the suture should secure only the tube itself.
- Locking system (locking system) — used for additional fixation of the catheter loop.
Class and exam questions
Why is simple abscess aspiration not recommended?
Aspiration ensures complete cavity evacuation in only 60% of cases and is strictly contraindicated when the collection communicates with the bowel, biliary, or urinary tracts.
What is the essence of the tandem-trocar technique?
A catheter with a stylet is inserted into the fluid collection parallel to a previously placed guiding needle.
What is the main rule when flushing an inserted drain?
The volume of injected saline must be less than or equal to the volume of aspirated fluid to avoid cavity overdistension and bacteremia.
When is the Seldinger technique preferred?
The Seldinger technique is chosen when more precise control of catheter placement is required, especially with a high risk of accidental puncture of the abscess posterior wall.
What else to study on this topic
- Assessment of content viscosity during initial puncture
- Drainage specifics in immunosuppression (Crohn's disease)
- CT marking with a radiopaque grid
- Formation of the fixation loop (pigtail)
- Application of the Seldinger technique in pneumothorax
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