Introduction:

  • Image-guided drainage of abscesses is a cornerstone of interventional radiology practice and is considered a first-line treatment in many pediatric and adult conditions. In children, abscess formation frequently stems from appendicitis—often presenting with delayed surgery and higher rates of perforation—or from other etiologies such as postoperative collections, necrotizing enterocolitis, and various infections. Compared to adults, pediatric patients have unique considerations such as smaller body habitus, different anesthetic requirements, and a greater emphasis on radiation protection. 
  • Transrectal drainage (TRD) of pelvic abscesses offers a minimally invasive alternative to transabdominal or transgluteal approaches. In particular, TRD avoids traversing potentially interposed organs or large vascular structures. However, careful patient selection, appropriate imaging guidance, and adherence to proper technique are imperative to maximize success and reduce complications. 

Indications:

Transrectal drainage of pelvic abscesses is indicated when: 
  1. An intra-pelvic fluid collection is suspected or confirmed to be an abscess that causes fever, leukocytosis, or other signs of infection. 
  2. There is a need for fluid characterization (e.g., to differentiate an abscess from other fluid collections). 
  3. Symptoms warrant interventional management, such as persistent abdominal or pelvic pain, sepsis, or hemodynamic compromise related to infection. 

Contraindications:

All contraindications are considered relative and should be balanced against the severity of the patient’s clinical condition: 
  1. Coagulopathy: Correct any significant coagulopathy (e.g., platelet count < 50,000/μL, INR > 1.5) prior to the procedure if possible. 
  2. Patient instability: Critically unstable patients may not tolerate anesthesia or sedation required for TRD. 

Equipment and Technical Details: 

1. Imaging Equipment 
  • A portable ultrasound (US) machine (e.g., GE Logiq S8 R4) with a 4–8 MHz endocavitary transducer (equipped with a needle-guide attachment such as Civco). 
  • Fluoroscopic capabilities in the angiography suite for wire and catheter confirmation if needed. 
2. Drainage Set 
  • Needles: 18G, 20-cm trocar (Trocar/Biliary Ring/Chiba) or micropuncture sets (21–22G) if preferred. 
  • Guidewire: 0.035-inch stiff guidewire for tract establishment and catheter placement. 
  • Dilators: Sequential dilators to enlarge the tract to accommodate the desired catheter size. 
  • Catheter: Pigtail drainage catheter (commonly 8–12 Fr in pediatric patients), sized according to the abscess cavity and fluid viscosity. 
3. Ancillary Supplies 
  • Sterile probe covers 
  • Drapes and sterile gloves 
  • Local anesthetic (if using conscious sedation in select older/cooperative patients) 
  • Sutures or an adhesive device to secure the drain 
  • Drainage bag. ​
Transrectal pelvic abscess access using a transrectal probe and placement of 12 French pigtail drainage catheter
Pre-Procedural Evaluation:

1. Clinical Assessment and Imaging 
  • Review available imaging (ultrasound, CT, or MRI) to confirm abscess size, location, and the safest access route. 
  • Determine if transrectal ultrasound visualization is feasible. If not, transabdominal ultrasound using the bladder as an acoustic window (with bladder distension) can guide the transrectal needle advancement. 
2. Laboratory Tests 
  • Check coagulation profiles if there is a suspicion of bleeding disorders: PT, PTT, INR, and platelet count. 
  • Basic labs such as CBC to assess for leukocytosis or anemia. 
3. Sedation/Anesthesia 
  • General anesthesia is typically used for pediatric patients undergoing TRD to ensure immobilization and minimize discomfort. 
  • Confirm the need for intubation versus deep sedation in consultation with the anesthesia team, depending on patient age, cooperation level, and overall clinical status. 
4. Antibiotics 
  • Most patients requiring abscess drainage are already on antibiotics. If not, ensure prophylactic antibiotics are administered to cover the anticipated organisms.

Procedure:

Patient Positioning and Preparation 
1. Patient Position 
  • Place the patient supine on the angiography table. 
  • Elevate the hips on a bolster and abduct the thighs (frog-leg position) to allow access to the rectum. 
  • Prep and drape the perineal area and lower abdomen in a sterile fashion. 
2. Preliminary Examination 
  • Perform a digital rectal examination to assess patency, confirm no obvious obstruction or mass, and to help guide the introducer or trocar during the transrectal approach. 

Imaging Guidance and Needle Access 
1. Transrectal Ultrasound Setup 
  • Cover the endocavitary ultrasound probe with a sterile sheath. 
  • Insert the probe transrectally and locate the abscess under real-time ultrasound guidance. 
  • If using a transabdominal approach for ultrasound visualization, the probe is placed externally over the lower abdominal wall, using the distended bladder as an acoustic window to visualize the abscess. 
2. Needle Advancement 
  • Attach a needle-guide to the endocavitary probe (if using transrectal ultrasound guidance). 
  • Advance the 18G, 20-cm trocar needle through the rectal wall into the abscess under continuous ultrasound visualization. 
  • Confirm needle tip position within the fluid collection (e.g., anechoic or hypoechoic cavity) by slight aspiration of fluid. 

Guidewire and Tract Dilation 
1. Guidewire Insertion 
  • Pass a 0.035-inch stiff guidewire through the needle and coil it within the abscess cavity. 
  • Confirm the guidewire position using both ultrasound and, if necessary, fluoroscopy in the angiography suite. 
2. Tract Dilation 
  • Withdraw the needle over the guidewire. 
  • Under fluoroscopic (or ultrasound) guidance, sequentially dilate the transrectal tract to accommodate the planned pigtail drainage catheter size. 
 
Catheter Placement and Securement 
1. Pigtail Catheter Placement 
  • Advance the pigtail drainage catheter over the stiff guidewire into the abscess cavity. 
  • Under ultrasound or fluoroscopy, confirm the catheter tip position within the fluid collection. 
  • Form the pigtail loop and engage the locking mechanism to prevent displacement. 
2. Fluid Aspiration and Laboratory Analysis 
  • Aspirate abscess fluid through the catheter and send the sample for microbiologic and biochemical analysis (culture, Gram stain, etc.). 
3. Secure the Catheter 
  • Suture or use a fixation device to anchor the catheter to the skin. 
  • Attach the catheter to a drainage bag. Position the bag below the pelvic level to facilitate gravity drainage. 
4. Completion of Other Procedures 
  • If other image-guided procedures (e.g., percutaneous aspiration of additional collections, pleural drain placement, or central venous catheter insertion) are planned during the same session, perform them before the transrectal drainage if feasible. 

Post-Procedural Care:

  • Monitor hemodynamics, temperature, pain, and drain output closely. Provide analgesics as needed. 
  • The interventional radiology team rounds daily to assess drain output, clinical status, and address any issues (e.g., potential tube displacement or blockage). 
  • The catheter should be flushed daily (or twice daily) with 10 ml of normal saline (5 ml to the patient, 5 ml to the drainage bag). 
 
Follow-Up and Drain Removal:

1. Clinical Assessment 
  • Monitor for improvement in fever, leukocytosis, and abdominal/pelvic pain. 
  • Confirm decreasing drain output (<10 mL/day is often used as a threshold). 
2. Imaging Confirmation 
  • If clinically indicated (e.g., persistent high output, ongoing fever), obtain repeat ultrasound or CT to evaluate residual abscess or fistula formation. 
  • Perform a tube injection study under fluoroscopy to evaluate for possible fistula if output remains unexpectedly high. 
3. Drain Removal 
  • Coordinate with the primary (medical and/or surgical) team. 
  • Remove the drain once clinical (fever resolution, normalized inflammatory markers) and radiologic (resolution or near-resolution of the abscess) endpoints are met. 
 
Complications: 
​
Although the reported overall complication rate is low, the following may occur: 
  • Catheter Displacement or Migration: The most common issue, requiring repositioning or exchange. 
  • Hemorrhage: Potentially from vascular injury during needle or catheter placement. 
  • Infection or Sepsis: Transient bacteremia may occur; appropriate antibiotic coverage is crucial. 
  • Rectal or Bowel Injury: Rare if careful visualization and proper technique are used. 
  • Fistula Formation: A persistent connection may develop if there is ongoing inflammation or underlying bowel communication. 

Overall success rates of image-guided abscess drainage are high (81–100% in pediatric series), with most collections resolving within a few days if adequately drained and appropriately treated. 

References: 

  1. Santiago J, Surnedi M, Padua HM, et al. Image-Guided Transrectal Drainage of Pelvic Abscesses in Children. Eur J Pediatr Surg. 2024;34(5):464-469. doi:10.1055/s-0044-1779278 
  2. Hogan MJ. Appendiceal abscess drainage. Tech Vasc Interv Radiol. 2003;6(4):205–14.  
  3. Price MR, Haase GM, Sartorelli KH, Meagher Jr DP. Recurrent appendicitis after initial conservative management of appendiceal abscess. J Pediatr Surg. 1996;31(2):291–4.  
  4. Coley BD, Shiels 2nd WE, Elton S, Murakami JW, Hogan MJ. Sonographically guided aspiration of cerebrospinal fluid pseudocysts in children and adolescents. AJR Am J Roentgenol. 2004;183(5):1507–10. 5. Sidhu MK, Hogan MJ, Shaw DW, Burdick T. Interventional radiology for paediatric trauma. Pediatr Radiol. 2009;39(5):506–15. Epub 2008 Dec 17. 6. Hultman CS, Herbst CA, McCall JM, Mauro MA. The efficacy of percutaneous cholecystostomy in critically ill patients. Am Surg. 1996;62(4):263–9. 7. Feola GP, Shaw CA, Coburn L. Management of complicated parapneumonic effusions in children. Tech Vasc Interv Radiol. 2003;6(4):197–204.  
  5. Alexander AA, Eschelman DJ, Nazarian LN, Bonn J. Transrectal sonographically guided drainage of deep pelvic abscesses. AJR Am J Roentgenol. 1994;162(5):1227–30.  
  6. Gervais DA, Brown SD, Connolly SA, et al. Percutaneous imaging-guided abdominal and pelvic abscess drainage in children. Radiographics. 2004;24:737–54.  
  7. Gervais DA, Hahn PF, O’Neill MJ, Mueller P. CT-guided transgluteal drainage of deep pelvic abscesses in children: selective uses as an alternative to transrectal drainage. AJR Am J Roentgenol. 2000;175(5):1393–6.  
  8. Slovis T. Radiation safety. In: Reid J, editor. Pediatric radiology. Cleveland, OH: Cleveland Clinic Center for Online Medical Education and Training; 2006.  
  9. Cravero JP, Blike GT, Beach M, et al. Incidence and nature of adverse events during pediatric sedation/ anesthesia for procedures outside the operating room: report from the Pediatric Sedation Research Consortium. Pediatrics. 2006;118:1087–96. 
  10. Walser E, Rzaz S, Hernandex A, Ozkan O, Kathuria M, Akinci D. Sonographically guided transgluteal drainage of pelvic abscesses. AJR Am J Roentgenol. 2003;181:498–500.  
  11. Koral K, Derinkuyu B, Gargan L, Lagomarsino EM, Murphy JT. Transrectal and fluoroscopy-guided drainage of deep pelvic collections in children. J Pediatr Surg. 2010;45(3):513–8.  
  12. Harisinghani MG, Gervais DA, Hahn PF, et al. CT-guided transgluteal drainage of deep pelvic abscesses: indications, technique, procedure-related complications, and clinical outcome. Radiographics. 2002;22(6):1353–67.  
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