Interventional Radiology Rounds:

145 Interventional Radiology Rounds: University of California, San Francisco Radiologic Management of Abdominal Abscesses Robert K. Kerlan, Jr., Moderator1 Anton C. Pogany2 R. Brooke Jeffrey3 Henry I. Goldberg1 Ernest J. Ring1 This is a selection from the Interventional Radiology Rounds of the University of California, San Francisco (UCSF). It features the staff and guests of the Department of Radiology discussing particularly instructive cases. Dr. Pogany. An 82-year-old woman was admitted to the hospital with a 2-week history of severe postprandial epigastric pain. She described the pain as jabbing or cramping, clearly related to eating, and resolving spontaneously 2 or 3 hr after meals. She had undergone a cholecystectomy 20 years before. Physical examination revealed mild epigastric tenderness and a large ventral hernia, but was otherwise unremarkable. Her initial laboratory values were also normal, including serum amylase and liver function tests. A barium enema showed colonic diverticula and small polyps in the sigmoid colon. An upper gastrointestinal series was normal except for a diverticulum of the descending duodenum. An abdominal sonogram showed mild ductal dilatation, the extrahepatic bile duct measuring 1 5 mm in diameter. Although the sonogram showed no evidence of stones, body computed tomography (CT) demonstrated a focus of increased density within the ampullary segment of the common bile duct, which was thought to represent a calculus. Dr. Kerlan. Dr. Goldberg, what would you recommend as the next diagnostic test? Dr. Goldberg. I think you must consider not only what the next diagnostic step should be, but also what the next therapeutic step should be. In a patient with obstruction in the ampullary region, the one test that is both diagnostic and therapeutic is endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and/or stone extraction, if a calculus is documented. Dr. Pogany. ERCP was performed and demonstrated a dilated common duct with an 8 mm calculus in its distal segment. The papilla was located on the posterior surface of a large duodenal diverticulum. A 1.2 cm sphincterotomy was performed, and the stone was noted to pass spontaneously. After the procedure, the patient did well for 2 days. On the third day, she developed a fever of 39#{176}Cand a white blood cell count of 10,200/mm3 with a left shift. The serum amylase level remained normal. Dr. Kerlan. Dr. Ring, what is your assessment of this patient s course after the endoscopic sphincterotomy? Dr. Ring. With this history, a perforation of the duodenum must be strongly considered. Part and parcel of making a cut Received March 28, 1984; accepted July 10, 1984. 1 Department of Radiology, University of California School of Medicine, San Francisco, CA 94143. Address reprint requests to A. K. Kerlan, Jr. 2 Department of Radiology. Veterans Administration Medical Center, San Francisco, CA 94121. 3 Department of Radiology, San Francisco General Hospital. San Francisco, CA 94122. AJR 144:145-149, January 1985 0361-803X/85/1441-0145 American Roentgen Ray Society

146 KERLAN ET AL. AJR:144, January 1985 Fig. 1 -A, Plain film of abdomen. Retroperitoneal gas in right upper quadrant and gas within bile ducts. B, Midabdominal CT image. Fluid collection (arrow) and gas in right retroperitoneum. Incidental large ventral hernia. through the sphincter of Oddi is the risk of transmural disruption and subsequent retroperitoneal abscess formation. Other complications that could conceivably account for this clinical picture would include pancreatitis or cholangitis from an impacted stone that was not previously recognized. To evaluate this problem, a plain abdominal film should be obtained. If that is not diagnostic, CT is indicated. Dr. Kerlan. Dr. Burke, would you interpret the plain film of the abdomen (fig. 1A)? Dr. Burke. Gas is present in the biliary tree, an expected finding after successful endoscopic sphincterotomy. However, there is also gas in the retroperitoneum outlining the lateral aspect of the right psoas muscle. These findings strongly suggest the presence of a duodenal perforation. Dr. Kerlan. Dr. Goldberg, what is the frequency of complications related to endoscopic sphincterotomy? Dr. Goldberg. Acute complications range from 4% to 1 0% [1, 2], the most common being hemorrhage. Cholangitis and pancreatitis occur less often. Clinically significant duodenal perforation is fairly unusual. Combining the experience of Dunham et al. [3] and Byrne et al. [4], perforation occurred in less than 1 % f over 1 300 patients. It is likely many minor perforations occur that are not manifested clinically. Dr. Pogany. There continues to be a question regarding the proper therapy for a recognized perforation after sphincterotomy. However, conservative management with nasogastric suction and parenteral antibiotics is generally the initial step [3,4]. In this patient, medical management was initiated, but her spiking fevers and abdominal pain continued. After 6 days, a CT scan was obtained (fig. 1 B). Dr. Jeffrey, would you discuss the findings? Dr. Jeffrey. This contrast-enhanced CT image of the midabdomen demonstrates an abnormal fluid collection in the right retroperitoneal area as well as gas lateral to the right psoas muscle. With this patient s history, a retroperitoneal abscess must be considered the leading diagnosis. Dr. Pogany. Despite the fact that a sizable abscess was demonstrated by the CT scan, further medical management was attempted. During the next 5 days, the patient continued to have spiking fevers and deep abdominal pain. A follow-up CT scan showed interval enlargement of the abscess. Dr. Kerlan. Because of the deep location of the abscess, CT guidance was used for percutaneous abscess drainage. With the patient in the supine oblique position, a 1 6-gauge needle sheath was passed from a lateral approach into the fluid collection, and 20 ml of purulent fluid was aspirated. Subsequently, the sheath was exchanged for a 1 2-French sump drainage tube under fluoroscopic observation. A small volume of water-soluble contrast medium was injected during the procedure (fig. 2A), and an irregular cavity without an apparent communication to the duodenum was demonstrated. Dr. Pogany. Do you often use CT guidance for abdominal abscess drainage? Dr. Kerlan. It depends on the size and location of the fluid collection. Large, readily palpable collections in the abdomen can be drained easily by almost any technique. Deep collections located adjacent to vital structures should be drained using CT or sonographic guidance. We have often placed small catheters under CT guidance and then transferred the patient to the fluoroscopy suite to position large-bore catheters. Dr. Pogany. Once an abscess has been drained percutaneously, is it advisable to irrigate the cavity with saline or antibiotic solution? Dr. Jeffrey. At the time of initial drainage, we generally aspirate as much as possible and do not irrigate. Contrast

AJR:144, January 1985 INTERVENTIONAL RADIOLOGY ROUNDS 147 Fig. 2.-A, Sinogram during percutaneous abscess drainage fails to show duodenal fistula. B, Sinogram through sump tube 3 days after percutaneous drainage procedure. Fistula to descending duodenum (arrows). material is injected to help position the drainage catheter, but we use very small volumes, and certainly less than the volume of fluid we evacuate. This prevents overdistension of the abscess cavity, which may precipitate severe septicemia. Though some investigators advocate irrigation of the cavity with an antibiotic solution on the initial day of drainage [5], in our experience this leads to an increased incidence of postprocedural septicemia. Septicemia has occurred despite the administration of parenteral antibiotics and injection of less than 1 0 ml of irrigant. Dr. Pogany. Why was a relatively large-bore sump drainage tube placed rather than a small angiographic catheter? Dr. Kerlan. To my knowledge, a controlled trial has not been conducted comparing the effectiveness of small- and large-bore drainage catheters. However, excellent results have been obtained using relatively small polyethylene catheters [6] as well as larger sump drainage tubes [5]. The main determinant should be the viscosity of the fluid. If a cavity contains very thin fluid, adequate drainage can often be achieved with a 7- or 8-French catheter. But usually the aspirated fluid is viscous. A large-bore sump tube allows the application of low, continuous suction, making possible a more complete evacuation of the abscess. I would also add that administration of mucolytic agents such as N-acetylcysteine (Mucomyst, Mead Johnson) through the drainage tube may be useful [7]. We use 1 0-20 ml of a 1 0% solution every 6-8 hr in abscesses that contain exceptionally viscous debris. Dr. Ring. Large catheters are put in partly for medical reasons and partly for less substantiated reasons. Having been around from almost the beginning of percutaneous abscess drainage, I realized that small-bore catheters could effectively drain most fluid collections. However, referring surgeons, who generally place 30- to 40-French tubes for drainage of abscess cavities, complained that small tubes would be inadequate. To encourage confidence in the procedure, it was necessary to develop methods for inserting very large-bore catheters [8]. Dr. Pogany. After 3 days of low, continuous suction, the drainage fluid became remarkably less viscous and appeared to contain bile. In addition, the output of the tube increased from 30 ml during the initial 24 hr period to 275 ml by the third day. The patient was returned to the fluoroscopic suite for a sinogram. Dr. Burke, would you interpret this study (fig. 2B)? Dr. Burke. Water-soluble contrast medium fills an irregular cavity in the right midabdomen. From the cephalic aspect of this cavity, a tract extends into the descending duodenum, apparently entering it through a perforation adjacent to the papilla. Dr. Pogany. Dr. Ring, how often have you detected unsuspected bowel fistulas during the course of abdominal abscess drainage? Dr. Ring. I believe a great deal depends on the aggressiveness of the fistulogram. On the day of the drainage, we have been unable to demonstrate communication with other structures consistently in patients subsequently proven to have fistulas. However, if a repeat sinogram is obtained after several days of continuous suction, a fistula can be demonstrated in a much higher percentage of cases. If the character of the fluid makes one suspicious that a fistula is present, or the quantity exceeds 50 mi/24 hr, a more aggressive approach is warranted. This should include gentle probing of the abscess cavity in areas of beaking with guide wires and angiographic catheters. Contrast material may then be injected directly into the areas where a fistulous tract could potentially exist.

148 KERLAN ET AL. AJR:144.January 1985 Dr. Kerlan. Over the past 1 6 months, 22 abscesses were drained percutaneously at UCSF. Fistulas were subsequently identified in 1 2 of these patients, leading from the gastrointestinal tract, biliary tree, or pancreatic duct to the abscess cavity. It is interesting to note that in only three of the 12 patients was the fistula identified on the day of the initial drainage. Dr. Pogany. How does the demonstration of a fistula alter the management of the abscess? Dr. Ring. Demonstrating the location of a fistula allows better control of the drainage. The tip of the drainage tube can be positioned immediately adjacent to the gastrointestinal tract perforation and placed to continuously suction. We then position a second drainage tube in the most dependent part of the abscess cavity and place a nasogastric or nasoduodenal suction tube to diminish leakage of bowel contents through the gastrointestinal perforation. Enteric or parenteral hyperalimentation should also be initiated to facilitate healing of the fistula [9]. Dr. Pogany. In this case, a torque-control guide wire was advanced through the tract, and a 5-French sheath was manipulated superiorly to the site of duodenal perforation. A second sheath and guide wire were passed inferiorly into what remained of the abscess cavity. Then, 1 2-French sump drainage tubes were placed over the guide wires, and continuous suction was applied. To provide enteric alimentation, a feeding tube was passed through the nose and into the jejunum just beyond the ligament of Treitz (fig. 3A). Dr. Kerlan. After 1 week of low, continuous suction of both sump tubes and another 2 weeks of gravity drainage, the sinogram was repeated. Dr. Burke, would you interpret this film (fig. 3B)? Dr. Burke. This sinogram was obtained through the drain age catheters after the tubes had been retracted into the percutaneous tract. A small mature tract has developed. No abscess cavity is present. Fig. 3.-A, 1 2-French sump drainage catheter positioned in fistulous tract. Additional sump tube placed in dependent part of abscess cavity. Mercury-tipped feeding tube is passed into proximal jejunum. B, Sinogram after 3 weeks of drainage. Abscess cavity has healed and fistulous tract has matured (arrows). Dr. Pogany. The patient was then placed on clear liquids, and her diet was advanced rapidly without difficulty. The drainage tubes were removed, and the remaining fibrous tract closed quickly. Discussion Percutaneous abscess drainage has become one of the most valuable interventional radiologic procedures. Using a variety of imaging techniques, most abdominal abscesses can be safely evacuated with this technique. In our experience, real-time sonographic imaging is the most efficient method for guiding punctures into fluid collections located adjacent to the abdominal wall. CT guidance has been most useful for smaller abscesses located more centrally within the abdomen. This allows avoidance of major vascular structures and bowel when the drainage needle is positioned. However, fluoroscopic observation is very useful for the subsequent manipulation of guide wires and drainage catheters. Fluoroscopic guidance greatly facilitates the drainage of abdominal abscesses. In comparison with surgical exposure, fluoroscopy offers an ideal method of identifying fistulous tracts and undrained recesses. Drainage tubes can be positioned adjacent to sites of alimentary tract perforation as well as in the most dependent part of the abscess cavity. The dynamic process of abscess healing may also be observed through periodic sinograms. If follow-up sinograms show drainage catheters in suboptimal position, the catheters may be repositioned easily and accurately using standard guide wire and catheter techniques. ACKNOWLEDGMENT We thank Gala FitzGerald for editorial assistance. REFERENCES 1. Liquory C, Loriga P. Endoscopic sphincterotomy: analysis of 155 cases. Am J Surg 1978;1 36:609-614

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