Intra-abdominal abscesses are a common cause of morbidity and mortality following gastrointestinal surgery.^1,2 Postoperative abscesses may occur at different sites associated with surgery, such as intra-abdominal, intra-parenchymal, pelvic, or retroperitoneal sites. Clinical symptoms are sometimes misleading or even silent in some patients who are physically weak (immunosuppression, chemotherapy, long-term steroids, and the elderly). Symptoms are usually nonspecific, and the determining factor is the size and location of the abscess. Clinical symptoms include fever, localized abdominal pain, abdominal tenderness, nausea, vomiting, or the inability to resume defecation due to associated bowel obstruction. Furthermore, palpable or non-palpable abdominal swelling is present in the presence of the abdominal wall or retroperitoneal fluid. Purulent discharge through an incision or drainage tract indicates a potential collection infection.³ After nearly three decades of development, image-guided percutaneous abscess drainage (PAD) has become a safer and more effective alternative to traditional open surgical drainage.^4–8 Due to the high morbidity and mortality associated with reoperation in these patients, image-guided PAD has become the common treatment for abdominal abscesses^9–11 and has been proven to be an effective and rapid recovery with fewer complications method for the treatment of patients with abdominal abscess.¹²

Pre-procedural assessment

As with other percutaneous interventional procedures, adequate preoperative examination and evaluation of patients are important for the safety and success of image-guided PAD.¹² The Society of Interventional Radiology has made general recommendations for patients’ blood conditions and the use of antibiotics.¹³ The risk of bleeding after PAD is graded according to the location of the abscess and the coagulation status of the patient, and intraperitoneal and retroperitoneal abscess drainage is considered a procedure with moderate bleeding risk; therefore, preoperative laboratory coagulation tests are mandatory. Vitamin K should be administered orally or intravenously when the international normalized ratio is >1.5, and fresh frozen plasma can also be transfused. Prophylactic platelet transfusion is required when platelet count is < 50.000/MCL; activated partial thromboplastin time activated partial thromboplastin time should be < 30 seconds in patients receiving heparin. Treatment with antiplatelet drugs included discontinuation of Clopidogrel 5 days before surgery. If a patient has recently been treated with oral anticoagulants, surgery should be performed after discontinuation. Routine coagulation tests are not altered by aspirin or non-steroidal anti-inflammatory drugs and may not be confirmed.^14,15

Imaging

Ultrasound

Ultrasound detection of postoperative abscesses has several advantages: it is easy to perform, inexpensive, does not involve radiation, and can be performed at the bedside. However, some areas of the body may be difficult to visualize due to large differences in body size, presence of gas in the intestinal cavity, or different surgical sites.³ Complex abdominal abscesses are deep and closely related to surrounding organs and blood vessels, especially those surrounded by intestinal tubes. Due to the influence of intestinal gas, the location of the abscess cavity and drainage tube is mostly poorly displayed by ultrasound. It is difficult to place the drainage tube in the best position under ultrasound guidance, resulting in false-positive or false-negative results, and ultrasound cannot determine the nature of the collection. Abscesses can be localized and, depending on the contents of the abscess cavity, they can often be described as a collection of limited, hypoechoic, anechoic, or even anomalous echoes, with occasional gas-associated echoes. However, hematomas, bile, and lymphocysts have similar ultrasonographic signs. Biochemical analysis and bacterial culture of abscess contents are helpful for diagnosis.³

Computed tomography

Computed tomography (CT) scans are generally considered the standard for detecting postoperative collections and abscesses because CT can visualize the entire abdominal and pelvic cavity with good spatial resolution. CT guidance can eliminate the influence of gas in the bowel on treatment, clearly show the relationship between the abscess cavity and the surrounding organs, judge the nature of abdominal collections, and understand the function of the bowel. Puncture positioning is more accurate than ultrasound guidance. Abscess images usually show a low-density collection (0 to 30 Hounsfield units) associated with circular or oval peripheral enhancement. Spontaneous high-density collections facilitate the diagnosis of hematoma. The presence and complex (relatively simple) features of gas in the collections suggest infection. Turbidness of the abscess cavity with a diluted water-soluble contrast agent can detect an associated fistula or anastomotic fistula.^6,7

In the final analysis, the choice of imaging method was usually related to the difficulty of abscess puncture and the safety of various puncture routes. The selection of fluid collection channels should consider the following factors: the shortest path for collection puncture while avoiding intervention with other tissue structures, planning the easiest angle and reproducibility of the maneuver, and a location that is comfortable for the patient and convenient for drainage tube care. When draining collections within solid organs, paths should be considered through a minimal number of normal organs to minimize bleeding events and normal tissue contamination. The following organs should avoid crossing during PAD: the pancreas, gallbladder, bowel, spleen, kidneys, prostate, bladder, and blood vessels. It can pass through the stomach and liver to treat abscesses in the upper abdomen, which are otherwise inaccessible. An intercostal approach should be performed directly above the adjacent ribs to avoid damage to the neurovascular bundle. When planning intra-abdominal collection drainage, the inferior epigastric artery should be carefully located; these vessels were prevented from being invaded by selecting the skin medial to the linea alba or lateral to the rectus abdominis muscle to enter the needle.¹⁰

Drainage catheter

Most drainage catheters are made of kink-resistant polyurethane material, often with a hydrophilic coating to aid in deployment. These tubes often contain multiple side holes on the inner side to increase the flow. The catheter kit contained a sharp trocar that could be reinforced with metal materials and loaded coaxially with a flexible catheter. These catheters are indispensable tools when choosing the Seldinger or trocar techniques. The success of drainage depends on several factors, and the choice of catheter size is undoubtedly one of the most important factors. In general, we choose to follow the “better big than small” principle because small catheters are prone to kinking and clogging, and for abscesses with large amounts of purulent fluid, larger catheters are needed to ensure adequate drainage speed.^16,17 In most cases, calibers of 8 to 16 Fr are sufficient, and oversizing is rarely necessary.³

Procedure approach

Scans are routinely performed at the beginning of surgery to accurately locate abscesses. During CT scan, the patient was placed in the supine or lateral position on the CT examination table, and CT scan was performed (scanning parameters: voltage, 120 kV; current, 80–120 mA; slice thickness, 5 mm; slice spacing, 5 mm). The optimal puncture point and puncture route were determined based on the location and size of the abscess. After the body surface was marked, a CT scan was performed to determine the angle and depth of the puncture. With ultrasound, the physician who performs the operation can mark the skin at an access point close to the sensor. Routinely disinfect the skin puncture site, lay sterile drapes, 2% lidocaine 5 mL local anesthesia puncture site, percutaneous puncture is performed after the effect of anesthesia.

The radiologist has two options: puncturing the abscess and securing the drainage catheter. The Seldinger technique uses an 18-gauge pointed hollow needle (trocar) to step the needle according to a predetermined puncture angle and depth, and intermittent CT scans are performed to ensure that the puncture needle does not damage the surrounding organs and blood vessels. Wait for CT to show the tip in the abdominal abscess (usually a reduction in resistance can be felt), exit the needle core, purulent fluid was observed after being pumped back along the needle sheath, take 5 mL sent germiculture and drug susceptibility studies, insert the guide wire, makes the guide wire head end located in the abscess cavity and coiled, and retains the guide wire, exit the needle sheath, then into the drainage tube along the guide wire, make sure the head of the drainage tube is located in the abscess cavity, then slowly remove the guide wire, drainage tube tip into loops, CT scan was performed to determine appropriate drainage tube position. Connect the end of the drainage tube to a T-junction and bandage and fix it. To reduce inconvenience for patients, ensure that the drainage tube is fixed in a position that can make patients feel comfortable. After fixation, a drainage bag was connected to drain the pus and fully drain the abscess contents; it was necessary to wash the abscess cavity with normal saline repeatedly and intermittently after the operation to achieve the best results.

The trocar technique uses a catheter with a stylet to directly puncture the lesion site, which is generally suitable for palpable superficial abscesses and is usually performed under ultrasound guidance. After identifying the vessels of the upper and lower abdominal walls at the level of the abdominal wall using color echo-Doppler, the direct puncture path was determined. The abscess is then directly punctured, and after entering the abscess cavity, the catheter is delivered to the reinforcement and barrel and held in place with a pigtail locking device.⁸

Post-procedural catheter care

Routine care of the drain is also critical to the success of PAD. The closed drainage system needed to flush the drainage tube, preferably with at least 10 mL of sterile normal saline every 8 hours. As many patients do not meet the criteria for the removal of the drainage tube at discharge, it is important to teach patients and their relatives the correct principles of catheter care. Requirements for catheter removal include the patient’s temperature and peripheral blood cell count within the normal range and a drainage volume < 10 mL/day.¹²

Abscess after gastrointestinal surgery

According to a report, PAD appears to be more beneficial in the treatment of postoperative abscesses than non-postoperative abscesses.¹⁸ Benoist et al¹⁹ studied 73 patients with PAD failure after postoperative abdominal abscess treatment and found that lack of antibiotic use and abscess diameter < 5 cm were the only two independent factors associated with PAD failure. In the failure group, some patients with small abscesses may have developed persistent sepsis after removal of the drainage tube and required reoperation due to inadequate drainage and other reasons. Therefore, when the abscess drainage is insufficient, the catheter should be replaced with a larger diameter drainage tube or moved to a position that can adequately drain. This adaptive drainage method may be an important factor in improving the prognosis of the patients.

In one study, 143 patients who underwent gastrointestinal surgery at Mie University Hospital and developed symptomatic abdominal abscesses between January 2002 and March 2010 were enrolled, and 104 patients underwent image-guided PAD as initial treatment. Of these patients, 47 (45.2%) underwent gastrointestinal surgery for malignant disease and 41 (39.4%) for inflammatory bowel disease. The 1-year success rate after PAD was 85.6% (n = 89), including 24 patients who required repeat drainage due to poor response to treatment. The failure group included six patients who underwent emergency surgery for peritonitis and nine who underwent or required elective surgery for intestinal fistula.²⁰

Abdominal abscess after gastric cancer surgery

Radical gastrectomy for patients with gastric cancer requires extensive lymph node dissection, which causes greater damage to the patient’s abdomen²¹ and can easily lead to complications such as intra-abdominal infection and intra-abdominal lymphatic leakage. Removal of infection foci, reduction of intra-abdominal pressure, and adequate drainage are basic principles for the treatment of complicated intra-abdominal abscesses. In one study, 31 patients with complex abdominal abscesses underwent CT-guided percutaneous catheter drainage after gastric cancer surgery. A total of 47 CT-guided percutaneous catheter drainage operations were performed in 31 patients and 47 drainage catheters were placed. The intubation time was 25 to 45 minutes (mean, 36.8 minutes), and the extubation time was 13 ± 3.2 days. Twenty-seven (87.1%) patients were cured after intubation and their body temperature returned to normal. CT performed 3 days later showed that the abdominal abscess had disappeared. The main complications of CT-guided percutaneous catheter drainage are injury to the abdominal organs and blood vessels, resulting in perforation and hemorrhage. To reduce and avoid damage to the abdominal organs, especially the bowel, before puncture, a contrast agent, such as meglumine, can be administered to show the position of the bowel and reduce the possibility of bowel injury; during puncture, the needle can be inserted evenly and forcefully to avoid damage to the abdominal organs and blood vessels. Postoperative complications included complications related to the drainage tube, with prolapse and blockage of the drainage tube being the most common complications. If the drainage is prolapsed, the drainage tube can be placed again; if the drainage tube is blocked or the drainage is not smooth, it may be related to retrograde infection of the drainage tube or displacement of the drainage tube, and the drainage tube needs to be flushed or adjusted.

Postoperative anastomotic leakage of Crohn’s disease

Most patients with Crohn’s disease require at least one bowel surgery, and the incidence of postoperative complications is higher than that for other benign intestinal diseases.^22,23 Anastomotic leakage is a common and serious complication after bowel resection and re-anastomosis, with an incidence of approximately 1% to 30%.²⁴ If not treated in time, anastomotic leakage can lead to serious consequences such as abscess formation, peritonitis, and sepsis.²⁵ In a retrospective study, Xie et al²⁶ found that in patients with Crohn’s disease, the incidence of complications after percutaneous drainage was lower than in the surgical group. Gutierrez et al²⁷ found that approximately two-thirds of patients with percutaneously drained Crohn’s abdominal abscesses did not require follow-up surgery for the abscess within 1 year. Furthermore, in a prospective study by Casola et al²⁸ that used percutaneous drainage as a treatment, 15 patients with Crohn’s disease successfully drained percutaneous abscesses without complications or the development of cutaneous fistulas. The duration of drainage ranged from 8 days to 6 weeks, and three patients required surgery during follow-up due to complete resolution of the abscess.

Image-guided percutaneous drainage for the treatment of postoperative gastrointestinal abscesses is becoming increasingly mature. Being familiar with the specific operation of various drainage techniques and fully understanding their differences will help to successfully plan and place the drainage catheter to achieve adequate drainage of postoperative abscesses and reduce the occurrence of complications.

None.

No potential conflict of interest relevant to this article was reported.