Overview
Definition:
Percutaneous abscess drainage (PAD) is a minimally invasive procedure where a radiologist or surgeon uses imaging guidance (ultrasound, CT, or fluoroscopy) to insert a catheter through the skin into a localized collection of pus (abscess) to allow for its evacuation and drainage
Surgical oversight ensures appropriate patient selection, procedural planning, and management of potential complications, integrating the interventionalists' role within broader surgical patient care.
Epidemiology:
Abscesses are common, occurring in various locations from superficial skin collections to deep intra-abdominal, thoracic, or pelvic abscesses
Incidence varies by anatomical site and underlying predisposing factors like infection, inflammation, or surgical intervention
Deep abscesses are more common in immunocompromised patients or those with chronic diseases.
Clinical Significance:
PAD offers a less invasive alternative to open surgical drainage, reducing hospital stay, morbidity, and recovery time
Effective drainage is critical for controlling infection, preventing sepsis, and facilitating healing
Surgical oversight is paramount to ensure the procedure is performed in the right patient, for the right indication, with appropriate follow-up and management of any associated surgical conditions.
Indications
Indications For Drainage:
Localized, accessible abscesses amenable to percutaneous access
Common sites include abdominal (e.g., hepatic, splenic, renal, pelvic, pancreatic), thoracic (e.g., empyema, lung abscess), and soft tissue abscesses
Septic shock secondary to an undrained abscess is an absolute indication for urgent drainage.
Contraindications:
Absolute contraindications are rare and typically relate to the patient's inability to tolerate the procedure or lack of a safe percutaneous access route
Relative contraindications include uncorrected coagulopathy, inaccessible abscesses, or widespread intra-abdominal sepsis where diffuse irrigation may be more appropriate.
Surgical Evaluation:
A surgeon's role includes assessing the patient's overall condition, determining the etiology of the abscess, identifying potential risks, and ensuring the chosen drainage method is optimal
Pre-operative assessment for comorbidities is crucial
The surgeon often collaborates closely with the interventional radiologist.
Preoperative Preparation
Patient Assessment:
Thorough history and physical examination to assess for sepsis, organ dysfunction, and comorbidities
Review of imaging findings to precisely localize the abscess and plan the trajectory of the drain.
Imaging Guidance:
Ultrasound is often preferred for superficial and abdominal abscesses due to real-time visualization
CT is superior for complex or deep-seated abscesses and for better anatomical delineation
Fluoroscopy may be used for drainage of specific organs like the biliary system or urinary tract.
Laboratory Investigations:
Complete Blood Count (CBC) with differential to assess for leukocytosis and left shift
Coagulation profile (PT, INR, aPTT) is essential, especially if anticoagulation is present or planned
Blood cultures, urine analysis, and appropriate cultures from suspected primary sites should be obtained.
Antibiotic Therapy:
Empirical broad-spectrum antibiotics should be initiated promptly, especially in patients with signs of systemic infection, pending culture results
The choice of antibiotics should cover likely pathogens based on the abscess location and patient's risk factors.
Procedure Steps
Access Technique:
Under local anesthesia and imaging guidance, a small skin incision is made
A needle is advanced into the abscess cavity, and pus is aspirated to confirm correct placement
A guidewire is then passed through the needle into the abscess
The needle is removed, and a drainage catheter (e.g., pigtail catheter, Malecot catheter) is inserted over the guidewire into the abscess cavity.
Catheter Selection:
The size and type of catheter depend on the abscess size, viscosity of the pus, and location
Larger bore catheters may be necessary for thick or loculated pus
Multiple catheters may be placed for complex or multiloculated abscesses.
Lavage And Irrigation:
After catheter placement, the abscess cavity may be lavaged with sterile saline or antibiotic solutions to remove debris and ensure complete drainage
This is particularly important for loculated abscesses
The irrigating fluid should be allowed to passively egress through the drainage catheter.
Securing The Drain:
The catheter is secured to the skin with sutures or adhesive dressings to prevent dislodgement
A collection bag is attached to the catheter to monitor the volume and character of the drained fluid.
Postoperative Care
Monitoring Fluid Output:
The drainage output is meticulously monitored
A significant decrease in output, change in character from purulent to serous or clear fluid, suggests effective drainage
Prolonged high output may indicate persistent infection or a leak.
Pain Management:
Adequate analgesia is essential
Pain can be managed with oral or intravenous analgesics, depending on the severity and patient's condition
Local wound care for the drain site is also important.
Antibiotic Management:
Antibiotic therapy should be continued based on culture and sensitivity results and the patient's clinical response
Duration of therapy is guided by clinical improvement and resolution of inflammatory markers.
Imaging Follow Up:
Serial imaging (ultrasound or CT) is typically performed to assess the resolution of the abscess cavity and the position of the drain
The need for repeat aspirations or drain repositioning is determined based on these findings.
Complications
Procedural Complications:
Hemorrhage, pneumothorax (if near pleural cavity), injury to adjacent organs (e.g., bowel, kidney, liver), seeding of infection, vasovagal syncope
Catheter malposition or dislodgement.
Postprocedural Complications:
Secondary infection of the drainage tract, cellulitis at the insertion site, fistula formation, persistent or recurrent abscess, sepsis, pain, and discomfort related to the drain.
Prevention Strategies:
Meticulous technique, careful imaging guidance, appropriate catheter selection, adequate anticoagulation reversal if necessary, securing the drain appropriately, and close post-procedure monitoring
Prompt management of any identified complications.
Management Of Complications
Bleeding:
Management depends on severity
Minor bleeding may resolve spontaneously
Significant hemorrhage may require interventional radiology coil embolization or, rarely, surgical exploration.
Infection:
Localized infection at the drain site is treated with local wound care and appropriate antibiotics
Systemic infection requires adjustment of antibiotic therapy and consideration of drain repositioning or alternative drainage methods.
Fistula Formation:
Fistulas may close spontaneously after drain removal
If persistent, management options include endoscopic closure, surgical intervention, or specialized fistula management techniques.
Failed Drainage:
If initial drainage is unsuccessful or the abscess recurs, repeat aspiration, repositioning of the drain, or consideration of surgical drainage may be necessary
Multidisciplinary discussion is often beneficial.
Key Points
Exam Focus:
PAD is a cornerstone in managing localized abscesses
Understand indications, contraindications, and the role of surgical oversight in patient selection and complication management
Be prepared to discuss imaging modalities and catheter types.
Clinical Pearls:
Always confirm pus aspiration before advancing a guidewire to avoid misplacement
Consider the viscosity of pus when selecting catheter size
Close follow-up with imaging is crucial to ensure abscess resolution.
Common Mistakes:
Failure to adequately assess coagulopathy, choosing the wrong imaging modality for guidance, inadequate drain size for thick pus, and insufficient post-procedure monitoring
Overlooking the need for ongoing surgical assessment and management.