Indications

Most patients undergoing percutaneous management of effusions or abscesses are symptomatic and have had recent imaging studies performed. In fact, these symptoms have typically led to the imaging examination (i.e., most effusions or abscesses are not found incidentally). If the patient is asymptomatic, percutaneous drainage may not be needed as an adjunct to antibiotic or other medical therapy, although diagnostic sampling may be necessary. The patient’s symptoms help categorize the urgency of draining an effusion or abscess. Patients with symptoms of pain, low-grade fever, and a mildly elevated white blood cell (WBC) count do not require urgent attention. However, patients with hypotension, tachycardia, high-grade fever or fever spikes, or a markedly elevated WBC count require decompression as soon as possible.

When percutaneous management of an effusion or abscess is clearly indicated, a decision regarding fluid aspiration versus catheter placement should be made. In general, drainage catheters are placed unless a fluid collection is small, not walled off, or known to be sterile. If aspirated fluid appears purulent, a drainage catheter is generally placed.

Contraindications

There are few contraindications to percutaneous management of effusions or abscesses. Two are lack of a safe route for catheter insertion and uncorrectable coagulopathy, issues that often become evident when reviewing the patient’s imaging studies and laboratory results. Any apparent contraindication should be discussed with the referring service to ascertain the risks versus potential benefits.

To allow percutaneous therapy, the abnormal fluid collection must be clearly visualized on imaging, and there must be an acceptable path from a skin entry site to the abnormality. Although it is often necessary and acceptable to place a needle or catheter through normal organ parenchyma when managing an intraparenchymal abscess, it is often unacceptable to traverse an uninvolved organ or normal bowel. However, some have argued for the benefits of transgastric drainage, and normal hepatic parenchyma may be transgressed if it is the only route to the fluid collection.⁹ It is sometimes possible to create a more direct and safer access route to the target fluid by injecting saline, lidocaine, or CO₂ into the intervening tissues.^10,11 This may displace potential obstacles out of the way, but it also may make the target less conspicuous on imaging. Manual compression of tissues with the ultrasound probe may help displace intervening bowel loops, and alternative patient positioning may help clear a potential passageway. It should be noted that a referring surgeon may accept traversal of diseased bowel if an operation is impending.

All patients being considered for percutaneous intervention should have their coagulation profile evaluated, including platelet counts, prothrombin time, international normalized ratio (INR), and partial thromboplastin time. Although it is difficult to give strict coagulation parameters, the platelet count should be greater than 50,000 and the INR should be 1.5 or lower.¹² All abnormalities are best corrected in conjunction with the referring service. Some patients will need platelet transfusion, fresh frozen plasma, vitamin K, protamine, or other strategies to make the procedure safer.¹³ The medication administration record should also be reviewed. Specifically, drugs such as aspirin, heparin, subcutaneous heparin, and clopidogrel (Plavix) should be sought because they may increase the risk for a hemorrhagic complication without significantly altering the patient’s coagulation profile. Ideally these medications are stopped for a defined period (aspirin and Plavix, 1 week; subcutaneous heparin, 12 hours; intravenous heparin, 2 hours) before percutaneous intervention,¹⁴ but each case must be considered individually.

Equipment

Image-guided procedures are facilitated by ultrasound, fluoroscopy, computed tomography (CT), or a combination of these modalities. Factors that influence which modality is most appropriate include target location, target size, and operator preference. At our institution, percutaneous drainage procedures are typically performed with a combination of ultrasound and fluoroscopy. Ultrasound is used to place a needle into the effusion or abscess, whereas fluoroscopy is used to visualize placement of a drainage catheter. Ultrasound is frequently our preferred modality to access an abnormal fluid collection because it is fast and readily available, produces no ionizing radiation, and allows real-time visualization of needle placement. However, it is operator dependent, and smaller, deeper fluid collections may not be readily seen. Patient body habitus and intervening bowel gas are further detriments to optimal visualization with ultrasonography. Fluoroscopy may be the sole imaging modality if a few criteria are met: the effusion or abscess must be diagnosed on previous cross-sectional imaging, and there must be a previously determined safe passage to this abnormal fluid collection. A recognizable collection of air (air/fluid level) is helpful in ensuring proper needle placement. In our practice, CT is usually reserved for lesions not visible sonographically or fluoroscopically. Abscesses that are deeply located, retroperitoneal, or small in size frequently require CT localization.

Once an imaging modality is selected, the interventionalist must decide on an access needle, guidewire, dilators, and drainage catheter. The preferred access needle is at least a few centimeters longer than needed to reach the fluid collection and allows passage of a 0.035- to 0.038-inch guidewire. The guidewire enables progressive dilation and subsequent catheter placement. Dilators should be chosen to at least the size of the drainage catheter. Some advocate dilating to 2 French sizes larger than the catheter. Various types of drainage catheters are available. A locking 10F pigtail catheter is a reasonable standard catheter. If the fluid collection is small, an 8F drain can be used, and if the aspirated fluid appears viscous, a 12F or larger catheter may be placed. Large-bore tunneled catheters are being placed with greater frequency for longer-term home drainage.

The most crucial aspect of percutaneous drainage is determining an access route. The safest and shortest distance between the skin access site and target fluid collection should be sought. Review of available imaging studies and knowledge of anatomic landmarks and the expected location of blood vessels, nerves, and other tissues facilitate avoidance of these structures. Once chosen, the access site is marked, prepared, and draped in sterile fashion. The skin access site is then infiltrated with a local anesthetic, a small incision is made with a scalpel, and the tissues are locally dissected to aid subsequent catheter placement. At this point, either the Seldinger or trocar technique is used to place the drainage catheter. With the Seldinger technique, an access needle is placed into the fluid collection. A wire is passed through the access needle and coiled in the collection. Serial dilation over the wire precedes placement of the catheter over the wire. The catheter is then advanced without a stylet (a metal or plastic stiffener is used instead). The wire is removed, and the catheter is secured in place. The trocar technique does not make use of an access wire. Instead, a sharp stylet passed through the catheter aids its advancement. The tandem trocar approach makes use of a reference needle placed into the fluid collection under imaging guidance. The drainage catheter is then advanced via the trocar technique into the cavity adjacent to the reference needle in the same direction as the reference needle until the fluid collection is entered. The direct trocar approach does not make use of a reference needle. The drainage catheter is simply advanced into the fluid collection based on previous imaging studies. This technique is generally reserved for large superficial collections.

Technical Aspects

Thoracic

Pleural Effusions

Pleural effusions have many causes and can usually be aspirated (thoracentesis) for symptom relief. Malignant pleural effusions tend to recur rapidly, however, and some special strategies are used to deal with these. A reasonable management plan is to place a tunneled drainage catheter (e.g., Denver Pleurx catheter [Denver Biomaterials, Golden, Colo.]) and monitor the patient on an outpatient basis. Autopleurodesis has been shown to occur in 40% to 50% of these patients.¹⁵ If pleurodesis does not occur, a sclerosing agent may be used to scar the parietal and visceral pleural layers together. Such agents include talc, bleomycin, and tetracycline/doxycycline.^16,17

Empyema

Infected pleural fluid collections typically result from pneumonia or are posttraumatic in nature (Fig. 153-1). They can often be successfully managed percutaneously with drains. Infusion of thrombolytic agents into these drains has been used to eradicate the fibrinous components of the inflammatory process.^18,19

Lung Abscess

Lung abscesses are typically secondary to aspiration, hematogenous spread of infection, or spread from an adjacent inflammatory process. More than 80% of lung abscesses respond to the traditional therapy of antibiotics and bronchial lavage. In patients who fail such therapy, percutaneous management may be an alternative to thoracotomy.7,20 A risk of placing a percutaneous drain in the lung is creation of a bronchopleural fistula. Minimizing drainage catheter size and avoiding traversal of normal lung help minimize this risk.

Pericardial Effusions

Interventional radiologists may be asked to drain pericardial fluid. In our experience, this is best approached with ultrasound guidance. Percutaneous creation of a pericardial window with an angioplasty balloon is a safe therapeutic option, particularly in patients with symptomatic malignant effusions.²¹

Abdominal

Hepatic

Pyogenic hepatic abscesses are most frequently sequelae of previous hepatic or biliary surgery, but they may also result from trauma, an infectious process elsewhere in the abdomen (e.g., diverticulitis), or an existing hepatic malignancy (Fig. 153-2). Percutaneous management of these abscesses is quite effective for both pyogenic and amebic hepatic abscesses.^22,23 A subcostal approach is preferred because it is less painful and there is less chance of crossing the pleural space and causing empyema. The intercostal approach is reserved for instances where a subcostal approach is not possible. It should be noted that although drainage of hydatid (echinococcal) hepatic cysts was once considered a contraindication because of the risk of sepsis, the literature now supports percutaneous management. Hypertonic saline can be injected into the cystic cavities as a scolicidal agent.²⁴