A description of various aspects involved in the percutaneous drainage of collections and abscess.

1. Percutaneous Drainage
Of Collections and
Abscess
Dr.Suhas Basavaiah
Resident (MD Radio-Diagnosis)

2. INTRODUCTION
Percutaneous abscess drainage (PAD) has evolved from revolutionary to routine,
replacing open surgical abscess drainage in all but the most difficult or
inaccessible cases.
Originally only patients with simple fluid collections were candidates for PAD;
however, researchers have convincingly demonstrated that both septated and
viscous fluid collections may be successfully treated percutaneously, particularly
with the adjunctive use of lytic agents.
An aggressive practical approach with relatively simple devices and techniques
may yield a high success rate with few complications.
Marked growth in last 20 years
All types of simple and complex collections drained in the chest,abdomen and
pelvis
Requires ability to assess CT and US images and familiarity with drainage
equipment

3. Collection Assessment-Imaging
 Aim - shortest, safest route to site drain in the most dependent position
 Avoid major vessels
 Avoid transgressing bowel
 Assessment of nature of fluid-echogenicity ; septations

4. IMAGING – US or CT
CT
good visualisation
opacified bowel
not limited by ileus or depth
US
real time
portable
operator dependent
Size+site of collection ; operator preference

5. Ultrasound guided percutaneous drainage is one form of image guided procedure,
allowing minimally invasive treatment of collections that are accessible by ultrasound
study.
It has several advantages and disadvantages over CT, which include:
Advantages
 is a dynamic study, allowing greater precision to control needle insertion
 not exposes patient to ionising radiation
 does not require as wide a range of staff, compared to CT-guided procedures
Disadvantages
 deeper targets may not be as well visualised on ultrasound (e.g. retroperitoneal
nodes)
 bowel gas may obscure visualization
 attenuation of the sound beam on larger patients

6. Indications
Indications for percutaneous drainage are broad: essentially any abnormal fluid collection in
the patient which can be accessible. Examples include:
 complicated diverticular abscess
 Crohn disease related abscess
 complicated appendicitis with appendicular abscess
 tuboovarian abscess
 post-surgical fluid collections
 hepatic abscess (e.g. amebic or post-operative)
 renal abscess or retroperitoneal abscess.
 splenic abscess
 Contraindications
The only common contraindications are:
 biopsy target is not accessible
 patient has a bleeding diathesis

7. Laboratory parameters for a safe procedure
Interventional procedures like percutaneous drainage require special attention
to coagulation indices.There are widely divergent opinions about the safe
values of these indices for percutaneous biopsies.The values suggested below
were considered based on a literature review.
Complete blood count: Platelet > 50000/mm3 (Some institutions determine
other values between 50000-100000/mm3)
Coagulation profile:
international normalized ratio (INR) ≤1.5 1
normal prothrombin time (PT), partial thromboplastin time (PTT)
Some studies show that having a normal INR or prothrombin time is no
reassurance that the patient will not bleed after the procedure

8. Pre-procedure evaluation
 Review other diagnostic studies first to clarify the collection that is
requested to be drained.
 An ultrasound study should be done prior to biopsy to decide the access
angle and check the relationship of the collection to adjacent structures.
 In general, the shortest possible route is preferred, as long as it does not
traversing other structures.

9. Equipment
Needle
 Typical abscess fluid is readily aspirated through an 18-gauge needle
 Viscous or debris-laden fluid is more likely to cause a false-negative aspirate
with a 21-gauge needle as only clear supernatant may return through the
needle.
 An 18-gauge needle is easier to control and image and accepts a 0.038-inch
guidewire.
 There is no clinically significant difference in needle trauma between the 18
and 22-gauge needles when a catheter is placed through the same tract.
 The 21-gauge needle may be used to minimize trauma for a challenging
localization, low-probability fluid collection, or personal preference.

11. Equipment (contd.)
Catheters
 6F-24F catheters
 Locking or non-locking-VIP at removal
 Sump or non-sump-2nd lumen containing air which prevents cavity
collapsing around catheter tip

13. Guidewire
A variety of guidewires are available for PAD with different properties and
prices. Guidewires should meet the following specifications:
 Stiff enough to guide dilators and catheter into abscess
 Not too stiff to prevent easy coiling of wire shaft within abscess
 Floppy tipped enough to encourage wire to coil within the abscess and not
perforate the abscess wall
 Short enough to make use convenient

15. Localization Techniques
 Any modality may be used to assist needle placement.
 Prior to ready availability of CT fluoroscopy, patient assessment may be
performed with CT scanning, with the PAD procedure performed with US
localization.
 Conventional fluoroscopy can be used as an adjunct to US.
 US guidance allows real-time imaging and does not involve radiation
exposure.
 CT fluoroscopy is increasingly available and facilitates "one-stop-shopping."
 The diagnostic CT and PAD may now be performed readily in one setting.

16. PATIENT PREPARATION
 IV access
 Fasted for > 2 hours
 Coagulopathy excluded
 Informed consent

17. PROCEDURE
Ultrasound guided percutaenous drainage may be performed with a single or
multiple stage technique.
 Consider conscious sedation
 Clean skin
 Anaesthetise skin
 Skin incision large enough for passage of catheter
 Consider tract dissection

18. TROCAR TECHNIQUE
 Reference needle in collection
 Catheter assembly advanced to the same depth ,in the same plane
 Remove stylet and aspirate
 Advance catheter over stationary stiffener

19. SELDINGER TECHNIQUE
 18g needle in collection
 Pass 0.035 wire into collection
 Dilate tract
 Pass catheter and stiffener over wire
 When inside collection pass catheter alone

20. POST-INSERTION OF DRAIN
 Aspirate fluid
 Re-image:?need for 2nd drain
 Secure drain-it is always more difficult to re-puncture a partially drained
collection

21. POST-PROCEDURE CARE
Post-procedure care
 The patient's basic vital signs should be monitored for 4 hours post procedure (pulse,
blood pressure, SpO2), or as long as deemed necessary.
 Aspirate 8hrly with a 50ml. Syringe
 Irrigate with 10ml. of saline
 Dependent position of bag
 The patient should remain in bed for 2 hours. After this time period mobilization and oral
intake is permitted.
 Removal-clinical improvement and drainage of <10ml. per day or collection resolved on
re-imaging
 The entry site should be reviewed on a daily basis. If output from the collection ceases, it
may mean that the collection is no longer present or that the drain is clogged.

22. TIPS - INSERTION
 Ensure adequate skin incision
 Avoid kinking wire(no fluoroscopy)
 Ideal wire-stiff enough to allow passage of dilators and catheter but will coil
within abscess and not perforate posterior wall
 Cut thread flush with catheter hub
 3-way tap

23. IF COLLECTION PERSISTS WITH LOW
FLOWS
 Catheter displacement
 Catheter/tubing blocked or kinked
 Upsizing catheter
 Septation/loculation

24. If Collection Persists with high flows
 Expect to find a fistula
 Can occur from bowel, bile and pancreatic duct, renal tract
 Exclude distal obstruction ; underlying bowel disease ; proximal diversion ;
parenteral feeding
 Bile leak postlap.chole.- drain plus cbd stent

25. IF THERE IS PRESENCE OF GROSS BLOOD
 Place the catheter
 Let the blood drain into the bag
 Since blood is a potent irritant and toxic to omentum, it has to be drained
regardless to avoid fatal complications like peritonitis and adhesions

26. COMPLICATIONS
 Viscus perforation
 Catheter dislodgement
 Damage to vessels
 Peritonitis
 Diaphragm rupture

27. MINIMIZING COMPLICATIONS
 Broad spectrum antibiotics
 Correct coagulopathy
 Adequate sedation + analgesia-beware the restless patient
 Good bowel opacification at CT
 Post procedure catheter management
 Beware collections adjacent to implants-aspirate>drain
 Discuss cases with clinical team

28. PITFALLS
 The procedure was not indicated.
 Failure to obtain informed consent
 Failure to perform the procedure in a reasonable manner and deviation from
the standard of care.
 Failure to promptly recognize and react to a complication.
 Failure to adequately treat the complication according to an adequate
standard of care.

29. CONCLUSION
 Assess pre-procedure imaging
 Minimise complications related to PAD
 Involvement in post procedure catheter management
 Practical knowledge of needles, wires and catheters

30. References
Emedicine , percutaneous drainage of abscess and post operative collections
Radiopedia , USG guided percutaneous drainage
American College of Radiology. Percutaneous catheter drainage of infected
intra-abdominal fluid collections
Haaga JR,Weinstein AJ. CT-guided percutaneous aspiration and drainage of
abscesses.
Lang EK, Springer RM, Giorioso LW, Cammarata CA. Abdominal abscess
drainage under radiologic guidance: causes of failure.