CHAPTER 5 Transcatheter fluid drainage

Technique

Although no longer novel, percutaneous fluid drainage (PFD) represents a paradigm shift in the treatment of sterile and infected fluid collections throughout the body, largely replacing traditional surgical incision and drainage and washout operations, which have been relegated to second-line therapies behind image-guided drainage. They are amongst the most common procedures performed in interventional radiology, and are frequently amongst the most satisfying, in that the effects of these procedures can often be immediate and provide significant relief of a patient’s suffering.¹^–⁵

Patient selection

Almost any fluid collection found in the chest, abdomen or pelvis, as well as much of the musculoskeletal system, may be amenable to percutaneous fluid drainage, whether by simple needle aspiration or placement of a drainage catheter, as long as a safe pathway for needle insertion is available and any underlying coagulopathy is corrected.⁶

As with all interventional procedures, coagulopathies must be corrected before intervention (see Chapter 2). Study of previous cross-sectional imaging and plain radiography is crucial in proper patient positioning and sterile preparation. Often, patients with suspected infected fluid collections are already receiving antibiotics at the time of drainage. If not, the decision to provide prophylactic coverage is left to the discretion of the interventional radiologist and should be based on the patient’s current clinical condition. Although there is no consensus regarding first-line antibiotic coverage, commonly a second- or third-generation cephalosporin may be administered within 1 hour of the procedure, with a combination of clindamycin and gentamicin reserved for patients with penicillin allergy.⁷ This prophylaxis does not interfere with cultures of fluid aspirated from the collection. Many of these procedures may be performed with local anesthesia alone; conscious sedation may be provided intravenously for more anxious patients. General anesthesia is indicated for children and uncooperative patients. Proper informed consent must be obtained.

Imaging guidance and access

Of critical importance to the safe performance of drainage procedures is the proper selection of needle access and image guidance. Sonography is preferred because of its low cost, lack of ionizing radiation, and real-time needle localization in multiple planes. Collections located deep within the body or poorly visualized with sonography are drained using intermittent computed tomography (CT) guidance. Fluoroscopy may be used in the drainage of gas-filled collections that can be visualized, although care must be taken to study cross-sectional imaging to ensure safe needle access without traversal of interposed vital organs or structures. In the deep pelvis, transrectal and transvaginal sonography may provide a safe and effective access route to collections that would be otherwise inaccessible.

The route offering the shortest distance from skin to collection is often the preferred access window for needle and catheter placement. This is not always possible, however, because of the interposition of organs or vessels along the access route. Transpleural drainage of high abdominal fluid collections (i.e., perisplenic abscesses or liver abscesses), while often providing the shortest route, is less preferable and should be avoided if a safe subphrenic pathway is available to avoid potential empyema. Prior imaging studies are used in the selection of the access route, as well as in the positional preparation of the patient and choice of imaging modality for drainage guidance. The area to be drained is then examined with the imaging modality of choice to confirm the viability of the chosen access route. The patient is then prepped and draped in a sterile fashion, and local anesthetic is administered to the access site. Local anesthesia should be generously applied to both the skin surface and the deep tissues, particularly at innervated surfaces such as the peritoneum, pleura, or organ capsule (i.e., liver, kidney). Good local anesthesia maximizes patient comfort and minimizes the need for intravenous conscious sedation.

Needle selection is based on the objective of the procedure (i.e., aspiration vs. drainage catheter placement) and location of the collection to be drained. Generally, small-caliber needles (18- to 22-gauge) are chosen with a length sufficient to reach the collection. Eighteen-gauge Chiba and Hawkins needles have thinner walls than comparable spinal needles and are preferable when drain placement is desired, because they accept a 0.035-inch guidewire.

After the application of local anesthesia, a scalpel is used to puncture the skin and underlying fascia to allow for ease of needle and possible catheter insertion. This maneuver is particularly useful when using a sonographic needle guide for real-time imaging.

Sonography and fluoroscopy allow for needle localization under direct imaging guidance (Fig. 5-1). Imaging under CT is performed intermittently during needle insertion, advancing the needle before acquiring a limited CT slice to determine needle location and trajectory. Successful puncture of the collection, wire localization, and drainage placement are all confirmed by CT (Fig. 5-2).

Figure 5-1 Ultrasound-guided drainage of a splenic abscess in a patient with portal hypertension and fever. A, Computed tomography shows a subcapsular splenic fluid collection. Note the enhancing varices in the splenic hilum and pericholecystic fluid around a collapsed gallbladder. B, Coronal sonographic image of the subcapsular cavity. C, A needle is inserted into the fluid collection with real-time sonographic guidance. D, A guidewire was advanced through the needle, over which a 10-Fr pigtail drainage catheter was placed (arrow).E, The cavity has completely collapsed after aspiration. F, A second drainage tube was placed. G, Follow-up tube injection 2 weeks later shows a small residual cavity.

Figure 5-2 Computed tomography (CT)-guided drainage of right lower quadrant abscess. A, CT shows collection of fluid and gas in the right lower quadrant consistent with abscess (arrows). Note radiopaque marking grid overlying the anterior surface of the right lower quadrant. B, Access needle is directed into the collection under intermittent CT guidance. C, A guidewire is advanced and curled in the collection. D, Using Seldinger technique, a pigtail drainage catheter is placed over the wire.

Diagnostic aspiration

Diagnostic aspiration of fluid collections is a useful tool for both diagnosis and treatment. It can be used to obtain a sample to determine the transudative or exudative nature of a collection, can assist in the tailoring of the appropriate antibiotic regimen, and helps determine the appropriate drainage catheter. Aspiration may be performed as a stand-alone procedure or may precede drain placement, because aspiration is the first step in the placement of a percutaneous drain.

As noted in the previous section, small-caliber needles (18- to 22-gauge) are typically selected for aspiration. Alternatively, an over-the-needle catheter system may be employed, such as the Yueh or OneStep catheter systems. These are 4- and 5-French (Fr) catheters that slide into position over the introducer needle, much like a peripheral intravenous catheter. Such systems are useful for aspiration of simple fluid collections of some volume, in which a drainage catheter placement is not indicated, such as a therapeutic thoracentesis or paracentesis (Fig. 5-3).

Figure 5-3 Over-the-needle catheter system for aspiration. A, Yueh catheter with introducer needle in place. B, The catheter is advanced over the needle, allowing for removal of the needle and Luer-lock attachment of an aspiration system, such as a vacuum-container.

Aspiration of fluid confirms needle location in the collection. Fluid characteristics are assessed qualitatively (e.g., color, viscosity, turbidity, odor), and the sample is sent for Gram stain, culture, sensitivity, cytology (if there is concern for malignancy), and other tests as necessary. If catheter placement is to follow, only a small fluid sample (<5 mL) is removed initially, because decompression of the collection may complicate or preclude tube insertion. Conversely, complete aspiration should be performed if imaging shows the collection to be too small for drainage catheter placement, thus assisting in its resolution. Dry aspiration from an 18-gauge needle well positioned within the collection may indicate that the lesion is either very viscous or not drainable. Often, the ability to pass a guidewire, and ultimately a catheter, into the collection determines whether drainage is possible. If not, the tissue may then be biopsied with specimens sent for cytology and microbiology.

Conversion of an aspiration procedure to drainage catheter placement is based on multiple factors. One small, retrospective study found that more than half of all sterile pancreatic fluid collections found in acute pancreatitis treated with long-term catheter drainage underwent bacterial colonization.⁸ Thus, by convention, sterile pleural effusions or ascites are often treated with therapeutic aspiration alone, because placement of an indwelling drainage catheter can promote infection of these collections. The same is true for fluid collections elsewhere, such as joint effusions. Infected collections often require placement of a drainage catheter; however, aspiration may be performed on collections that are too small for placement of a drainage catheter. Drains are placed for symptomatic collections that recur after therapeutic aspiration, such as cysts and pseudocysts. One-step needle aspiration without catheter insertion may be performed in certain locations without expected communication with the gastrointestinal, biliary, or urinary tracts. This approach has reported success rates up to 90% in selected cases.⁶^,⁹^–¹²

Catheter insertion

Choice of catheter size and type is determined by the type and character of the fluid to be drained. Air and thin fluids are drained with 8- and 10-Fr catheters. Viscous fluids and fluids containing particulates require larger drainage catheters ranging from 12- to 26-Fr. Most drainage catheters have an inner retention mechanism, such as the locking pigtail (Cope loop) or Malecot drains (Fig. 5-4).

Figure 5-4 Locking pigtail catheters. These catheters contain a Cope loop retention system with side holes within the loop for drainage. Note the lower catheter, commonly used for biliary drainage, contains larger side holes that extend along the shaft.

Drainage catheters may be placed using different techniques: direct trocar, tandem-trocar, and Seldinger.

The direct trocar technique can be safely performed on large superficial collections. After application of local anesthesia, the skin is incised with a scalpel and the incision spread with a Kelly clamp. The catheter is directly inserted into the collection with the inner cannula and stylet. The stylet is then removed and the cannula is aspirated. The catheter is then inserted over the cannula or guidewire.

The tandem-trocar technique is a variation of the trocar technique, in which the distance between the skin and collection is measured by imaging and marked on the catheter shaft. The catheter, with the metal cannula and stylet, is placed in the skin hole next to the previously inserted needle and advanced into the collection under imaging guidance. The stylet is removed, and material can be aspirated. A 0.035-inch guidewire is then advanced through the cannula, and the catheter is inserted over the cannula and guidewire into the collection. Use of the guidewire decreases the risk of perforation of the back wall of the cavity, disrupts septations allowing for better drainage, and assists in the coiling of the pigtail catheter.

The Seldinger technique is the most common method of catheter placement and is suitable for drainage of all collections, particularly those that are small or difficult to access. After access has been achieved with an 18-gauge needle, a 0.035-inch guidewire is inserted through the needle and coiled in the collection (see Fig. 5-2). The tract is serially dilated and the catheter is inserted over the guidewire using the metal cannula without the stylet. The catheter is then advanced over the cannula and wire and coiled in the collection.

After catheter insertion, postplacement imaging is performed to document proper catheter location. The collection is then evacuated. Fluid levels determined by specific gravity are not uncommon, and one can often find a collection that initially yields thin fluid, followed by viscous aspirate and finally serosanguineous fluid. The fluid can become blood tinged when the cavity is nearly empty and suction is applied to the dry walls of the former collection (Fig. 5-5).

Figure 5-5 Ultrasound-guided placement of a drainage catheter in a right lower quadrant abscess using Seldinger technique. A, Computed tomography demonstrates right lower quadrant fluid collection. B, Ultrasound-guided access into the collection. The guidewire has been placed through the needle into the collection (arrows).C, Ultrasound shows the pigtail drain inside the collection. D, Fluoroscopic image demonstrates the location of the catheter within the right lower quadrant.

Catheter care

A large-bore, three-way stopcock is attached to the catheter hub. The cavity is irrigated with 10- to 20-mL aliquots of normal saline until the aspirated fluid is clear. To prevent bacteremia and sepsis, avoid overdistention of the collection.

The catheter is then secured to the skin such that it does not kink or pull with patient movement. Catheters are often secured to the skin with 2-0 nonabsorbable suture. Alternatively, an adhesive retention device may be used. Adhesive tape wrapped around the catheter and applied to the skin may provide added security.

Gravity drainage to a collection bag is typical in most cases, particularly when the fluid being drained is nonviscous. Thicker material may require a suction drainage bag or application of low intermittent wall suction, as well as frequent irrigation to break up viscous material and prevent catheter clogging. Continuous low wall suction is used for thoracic collections. Drains placed in the pleural space are connected to a Pleur-evac water-seal device, which contains a fluid collection chamber and a safety mechanism to prevent excessive suction. The Pleur-evac is then attached to wall suction (Fig. 5-6). High-output collections, which often involve gastrointestinal and urinary fistulas, may require continuous low wall suction to keep the cavity dry and promote healing.

Figure 5-6 Dry-suction water-seal chest drain. A, This drainage system contains a graduated chamber for collecting fluid, a water seal chamber to evaluate for air leak, and a pressure regulator. B, The water-seal chamber is filled with saline. This connection is then attached to suction. Tubing to the right is attached to the chest tube. C, Water-seal chamber. Air bubbles in this chamber indicate an air leak within the chest tube system.

Postprocedure care

Postplacement, drainage catheters require routine maintenance to ensure proper function and complete resolution of the collection. The catheter, its connections, and its fixation devices are checked daily for all inpatients and during clinic visits for outpatients. Dressings should be changed daily, and the drain site must be kept clean and dry.

All drainage catheters require regular irrigation to maintain patency. Without regular irrigation, all drainage catheters will occlude, regardless of their size. Proper irrigation involves the following steps:

• Place a syringe in the stopcock and aspirate residual fluid

• Inject 10 to 20 mL of normal saline

• Aspirate the irrigant

• Reflush the catheter with 5 mL of normal saline

Routine irrigation is performed two to three times each day. This maneuver may be performed by the floor nurses on inpatients, and by the patient or caretaker for outpatients. Viscous collections may require more frequent irrigation (e.g., every 4 to 6 hours). Daily catheter output is recorded, with the amount of irrigant solution subtracted to obtain the true drainage output.

A 2- to 4-mg dose of tissue plasminogen activator (t-PA) in 10 to 20 mL or more of normal saline may be instilled in drains that are properly positioned in viscous collections that are refractory to drainage after normal routine irrigation. Typically, such collections are loculated (e.g., infected hematomas). In such cases, t-PA is infused through the catheter, which is then capped for 1 to 2 hours to allow the t-PA to liquefy the collection. The catheter is then reopened to drainage. Several prospective studies suggest that routine catheter flushing using fibrinolytics instead of saline decreases the total time to abscess resolution, length of hospital stay, and therefore total cost of care.¹³^,¹⁴ In general, the patient’s acute condition resolves within 24 to 48 hours after drain placement.

Clinical management: postprocedure imaging, catheter manipulation and removal

Management of drainage catheters is based on the patient’s clinical course and the output of the drainage catheter (Table 5-1):

1. If the patient’s clinical status significantly improves or resolves, and the catheter output has decreased to an immeasurable amount (<10 mL/day), the catheter may be removed, unless a fistula is suspected or present.

2. If the patient’s condition fails to improve or worsens after drain placement, and catheter output has decreased, cross-sectional imaging may be obtained for further evaluation. These patients may require repositioning or exchange of the drain, upsizing of the catheter, a more frequent irrigation regimen (or supplementation with fibrinolytics), or placement of a new drain in a different collection.¹⁵ CT is the preferred imaging modality, because it provides a complete survey of the anatomic compartment and allows for assessment of the drain in relation to the fluid collection as well as visualization of any other undrained collections. Chest radiographs are useful to assess diffuse thoracic collections after drain placement. Chest CT is helpful in the case of a loculated thoracic fluid collection.

3. If the patient’s condition fails to improve or worsens, and the catheter output has remained stable or increased, the drainage catheter is left in place and routine maintenance continued. In such cases, further investigation may be required to look for another source of the patient’s condition.

4. If the patient’s condition has improved, but drainage output has remained stable or increased, a catheter sinogram is indicated to evaluate for a fistula or to evaluate the size of the cavity before possible cyst or lymphocele sclerosis.

Table 5-1 Algorithm for Percutaneous Fluid Drain Management

Clinical Status
	Improved	Stable/Declined
Decreased drainage output	Remove catheter	Reimage and reassess
Increased or stable output	Sinogram to evaluate for fistula	Leave catheter in place and continue maintenance