Seldinger technique and its risks
The classical Seldinger technique (Seldinger technique) involves several sequential steps. First, an ultra-thin 19-G needle with a stylet (or an introducer needle) is inserted into the fluid collection. Then, a 0.035-inch guidewire is advanced through the lumen of the needle or introducer. Once correct guidewire placement is confirmed, the tract is sequentially dilated using dilators. Only after a sufficiently wide tract has been formed is the catheter itself placed over the guidewire.
Despite its widespread use, tract dilatation has several significant disadvantages:
- Duration and pain: The process takes a long time and causes marked pain, especially when instruments pass through muscle masses.
- Contamination risk: When changing dilators prior to final catheter placement, there is an increased risk that abscess contents may leak beyond the drained cavity.
- Technical difficulties: In confined spaces, dilator manipulation can lead to guidewire buckling, making catheter advancement impossible.
Ultrasound-guided placement
An alternative is ultrasound-guided drainage placement. This procedure is performed under direct visual guidance immediately after antiseptic skin preparation. An important difference is that using a preliminary guiding needle is not mandatory here. The needle is used only when the physician needs to aspirate a sample of the collection contents beforehand. This is done to assess the consistency and viscosity of the fluid in order to properly select the diameter of the catheter to be placed.
Catheter Management
Successful placement is only the first step. Proper care is required to maintain system patency and optimize the drainage process.
System flushing Catheters must be flushed with normal saline every 8–12 hours. The standard flush volume is 5 ml of fluid directed toward the patient and 5 ml toward the drainage bag. The manipulation is performed via a three-way stopcock. For very small or, conversely, giant collections, this volume may be adjusted.
Monitoring and complication detection The physician must daily monitor the volume and nature of the output in the drainage bag. Any abrupt changes may signal the development of complications, such as hemorrhage or fistula formation. If pain, resistance, or accidental dislodgement occurs during flushing, it indicates obstruction or displacement. In such situations, contrast media administration directly into the catheter under fluoroscopic guidance is indicated to determine the cause.
Catheter removal guidelines
The issue of drain removal is raised when the patient's clinical condition is good and the output (drainage volume) decreases to ≤ 10 ml per day.
- If persistent clinical improvement is observed and inflammatory markers have returned to normal, the drain can be removed without additional imaging studies.
- If symptoms persist or there is doubt that the cavity is adequately emptied, a follow-up CT or ultrasound is mandatory before removal.
- In cases where an intestinal fistula is suspected, contrast injection through the catheter must be performed prior to tube removal.
Minimizing complications
To reduce the risk of adverse outcomes, the following rules must be followed:
- Thoroughly review preliminary imaging data (CT or ultrasound) before starting the procedure.
- Select the safest, shortest, and straightest percutaneous access route, preferably at an angle.
- Avoid injury to underlying organs, vital structures, and contamination of sterile zones.
- Position the working end of the drain in the most dependent part of the cavity.
- Cross one body cavity to drain another only when strictly necessary. For example, if an intercostal approach is used to drain the abdominal cavity, the physician must closely monitor the patient for signs of infection spread and be prepared for emergency chest tube placement if effusion develops.
Briefly: answers to topical questions
What complications can occur during percutaneous drainage of fluid collections?
Complications include catheter displacement and dislodgement, hemorrhage, infection, and injury to adjacent structures.
- Catheter displacement (catheter dislodgement) — a frequent occurrence, requires reliable fixation and patient education
- Hemorrhage — for example, injury to the intercostal artery during thoracic cavity drainage, pseudoaneurysm after nephrostomy
- Drain retraction — catheter displacement into the gastric lumen during transgastric drainage of a pseudocyst
- Infection — iatrogenic infection, risk of spread when crossing one cavity to drain another
- Pneumothorax — associated with thoracentesis
- Catheter obstruction — clogging by dense detritus in pancreatic necrosis, requires contrast administration for diagnosis
- Fistula formation — may lead to prolonged catheter retention
What drugs are used for clot lysis when flushing a drain with viscous contents?
Sources confirm intraluminal administration of urokinase and alteplase to restore patency in long-term vascular catheters during thrombosis in patients with stage C5–C5D CKD. Concentrations are specified: urokinase — 5000 IU/ml, alteplase — 1 mg/ml; exposure time — 40 minutes. The use of these drugs for flushing drains with viscous contents is not confirmed by sources.
The rule of three "P"s for safe drainage: Direct access (shortest path), Permanent flushing (every 8-12 h), Output check (remove at ≤ 10 ml/day).
Class and exam questions
Is a guiding needle always necessary when placing a drain under ultrasound guidance?
No, its use is not mandatory. The needle is used primarily when it is necessary to take a sample of the contents to assess its viscosity before choosing the appropriate catheter diameter.
What does pain or resistance during catheter flushing indicate?
These are classic signs of drainage tube obstruction (clogging) or displacement. In this case, fluoroscopy with contrast administration through the catheter must be performed.
Can a drain be placed into the abdominal cavity through the pleural cavity?
This is permitted only in extreme cases. With such access, there is a high risk of infecting the adjacent cavity, so the physician must be prepared to promptly place a chest tube if effusion appears.
What else to study on this topic
- Clinical case: Ultrasound-assisted transgastric drainage of a pancreatic pseudocyst
- Migration complications: retraction of the drainage catheter into the lumen of the stomach or intestine
- Management tactics for patients with developing intestinal fistulas during drainage
- Selection of catheter diameter and type depending on the viscosity of the aspirated fluid
- Action algorithm for guidewire buckling during tract dilatation
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Drainage Catheter Insertion Technique" and 2,199 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the "Interventional radiology" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.