A 56-year-old woman presented with a history of breast cancer and multiple myeloma. She had a poor response to chemotherapy, and clinical and laboratory evidence of tumor activity showed bone involvement. CT revealed a lytic lesion in the manubrium of the sternum that had increased metabolic activity on the PET scan. The treating oncologist requested a bone biopsy to stage the tumor and decide whether a more aggressive therapy would be useful. The patient's platelet count was 145 × 10³/μL, and her international normalized ratio (INR) was 1.2.

Unenhanced CT before the biopsy (Fig. 1A) showed disruption of the bony cortex in the anterior and posterior aspects of the manubrium of the sternum. Unenhanced CT performed during the biopsy (Fig. 1B) showed the biopsy needle approaching the target lesion. Three core biopsies were obtained. Immediately after the biopsy, while still on the CT table, the patient became dyspneic, hypoxic, tachycardic, hypotensive, and unconscious. Unenhanced CT was performed immediately after the biopsy (Fig. 1C).

The diagnosis is pericardial injury during percutaneous biopsy, resulting in acute hemopericardium and cardiac tamponade.

Acute onset of dyspnea, hypotension, and tachycardia in a patient undergoing a percutaneous biopsy in the thoracic area can result from tension pneumothorax, severe hypovolemia, or cardiac tamponade. Establishing an accurate diagnosis as soon as possible is a priority. For this patient who is still on the CT table, immediate unenhanced CT can point out the cause of the problem without delay.

Cardiac tamponade is a rare complication in interventional procedures. It has been described as a complication of endovascular catheterization of the great vessels, stent–graft deployment on the aorta, pacemaker implantation, and percutaneous biopsies. Symptoms from a pericardial effusion vary considerably depending on the amount of fluid accumulated. The normal amount of fluid in the pericardial sac is about 20 mL, and volumes greater than 120 mL can generate pressures that reduce the cardiac output, with consequent hypotension (cardiac tamponade). The Beck triad—distention of neck veins, hypotension, and muffled heart sounds—is present in only approximately 30% of patients with cardiac tamponade.

Figure 1A shows a lytic lesion in the sternum, with loss of integrity of the cortex both anteriorly and posteriorly. The great vessels, including the aortic arch and the superior vena cava, are seen behind the lesion with a small amount of infiltrated fatty tissue between them. In this particular patient, there is a high possibility of traversing the posterior wall of the sternum with the biopsy needle, resulting in arterial injury. Figure 1B shows the biopsy needle approaching the target lesion. The needle tip is not seen. This is of extreme importance, especially when the great vessels are so close to the target lesion.

Figure 1C was obtained immediately after biopsy and shows a new ill-defined soft-tissue-density lesion in the anterior mediastinum, with mass effect, displacing the aortic arch posteriorly. This is consistent with the diagnosis of acute anterior mediastinal hematoma. Figure 1D is an axial image at the level of the heart that shows a well-defined soft-tissue density delineating the periphery of the cardiac compartment and surrounding the epicardial fat. This is consistent with the diagnosis of acute hemopericardium.

This case illustrates a fatal complication after percutaneous biopsy of the sternal manubrium: acute hemopericardium followed by cardiac tamponade. The pericardium is a continuous membrane reflected at the base of the heart. These reflections produce recesses and sinuses that extend over the heart base and surround the great vessels [1]. The most cephalic reflection is the superior aortic recess [2], which extends around the ascending aorta and over its anterior and right lateral wall, and usually reflects just caudal to the emergence of the right brachiocephalic trunk. A “high-riding” superior aortic recess is a variation of this recess in which the pericardium extends cephalad, above the aortic arch, and the reflection is located between the brachiocephalic vessels on the right paratracheal region. Choi et al. [2] identified this variation in 2% of ECG-gated chest CT scans.

Why did the patient develop the complication?—The patient had an injury during biopsy either to the ascending aorta or to the aortic arch. The cortical destruction of the manubrium facilitated the anteroposterior traversing of the biopsy needle across the bone thickness. This, combined with the proximity of the great vessels and the lack of needle tip localization, put the patient at a high risk for aortic laceration. In addition, it is possible that this patient had a high-riding pericardium recess that favored the development of acute hemopericardium after the arterial injury.

Probably the most important teaching point in this case is prevention of the complication. From a technical standpoint, needle tip localization during percutaneous biopsy is extremely important. The operator should always know exactly where the needle tip is located. When using a coaxial technique, it is important to know the “throw” of the biopsy needle—how far will the biopsy needle will go beyond the tip of the guiding needle. If the operator is conscious of these factors, the risk of unwanted puncture into a structure will decrease.

What is the management?—Our patient is a true therapeutic challenge. She developed acute decompensation with a very fast and severe change in all vital signs. Her management needs to be fast and to follow the ABCD's of advanced cardiac life support. First, call for help, secure the airway, provide adequate ventilation, assess circulation, and consider the differential diagnosis for specific treatment. These steps are usually performed simultaneously. In this particular case, when the patient was still on the CT table, a quick scan was useful for providing an immediate diagnosis of an acute anterior mediastinal hemorrhage and hemopericardium.

Patients with cardiac tamponade who present with agitation, dyspnea, and deterioration of consciousness may progress rapidly to coma and death [3]. The immediate treatment is percutaneous pericardiocentesis. Removing as little as 30–50 mL of fluid can produce a dramatic hemodynamic improvement. If this is unsuccessful, thoracotomy should be performed immediately.

The traditional approach to pericardiocentesis is the subxiphoid technique, which avoids injury to the coronary arteries. The chest is prepared with povidone–iodine. A 16- to 18-gauge catheter is inserted using a trocar technique between the xiphoid process and the left subcostal margin. The catheter is advanced toward the left shoulder at an angle of 15–20° from the abdominal wall while suction is applied to the syringe. If fluid is found, the catheter is advanced as the needle is withdrawn. Alternatively, a 16- to 18-gauge spinal needle might be used for one-time drainage. If sonography is available, the echocardiographically guided technique is preferred. It differs from the traditional approach primarily in the site of needle entry. A 3- to 5-MHz transducer is placed about 3–5 cm lateral to the left parasternal border. The area of maximal pericardial fluid accumulation and the point where the effusion is closer to the transducer are identified. The track of the needle is calculated, avoiding the inferior rib margin. After skin preparation and sterile dressing of the transducer, a 16-gauge needle is inserted and advanced in the planned trajectory. Once fluid is obtained, the catheter is advanced as the needle is withdrawn. If necessary, a guidewire can be used.

Acute cardiac tamponade after an interventional procedure is uncommon. Prompt, accurate diagnosis is imperative. Sonographically guided pericardiocentesis is the first line of treatment, followed by emergent surgical repair of the causative injury.

A 64-year-old woman presented with weight loss, abdominal pain, and mild jaundice. A diagnostic CT scan (not shown) showed a mass in the head of the pancreas and a lesion in the left lobe of liver segment III. Because the liver lesion seemed to be more accessible, the treating oncologist referred the patient to the interventional radiology service for a percutaneous biopsy of the lesion (Figs. 2A and 2B). The patient's serum bilirubin was mildly elevated at 2.2 mg/dL, her platelet count was 156 × 10³/μL, and her INR was 1.2. The biopsy was technically successful. The patient was discharged in stable condition from the interventional radiology service 3 hours after the procedure.

Forty-eight hours after the biopsy, the patient was admitted to the emergency department with abdominal pain, fever, leukocytosis (WBC, 28 × 10³/μL), and an acute drop in her hemoglobin, from 10.5 to 8.0 g/dL. New CT scans were obtained (Figs. 2C and 2D). After evaluation of the CT scans, the emergency department physician made a clinical diagnosis of hematoma and requested immediate arteriography and embolization.

The diagnosis is biliary peritonitis after liver biopsy.

Complications from percutaneous liver biopsies are uncommon but may be fatal if they are not detected and promptly treated. On average, 2% of patients who undergo percutaneous liver biopsy require hospitalization to treat a procedural complication; abdominal pain is the most common reason. Although mild abdominal pain is a common finding, with no further management needed other than oral analgesia, severe abdominal pain should be considered a sign of a clinically significant complication until proven otherwise. Patients who develop complications usually present suggestive clinical signs shortly after the procedure, 60% within 2 hours and 94% within 24 hours. In our experience, the imaging study of choice to evaluate these patients is unenhanced CT of the abdomen [4, 5]. Possible complications include hemorrhage, infection, pneumothorax, pleural effusion, bile leak, arteriovenous fistula, and puncture of other organs (e.g., intestine, kidney). Most complications can be managed successfully if diagnosed at an early stage [6].

Figure 2A shows mild to moderate dilatation of the biliary ductal system. The hypodense lesion is located in segment III of the left hepatic lobe, immediately anterior to what appears to be a prominent portal triad. Figure 2B shows the needle path during the percutaneous biopsy. The needle is in the target lesion.

Figures 2C and 2D are axial images from unenhanced CT of the liver 48 hours after biopsy; they show a large low-density homogeneous perihepatic fluid collection that was not present on CT before the biopsy.

Figure 3 is a contrast-enhanced CT scan of a different patient that shows a subcapsular hematoma. Note the heterogeneous high-density perihepatic fluid collection, suggestive of the presence of blood.

As mentioned previously, abdominal pain is not uncommon after percutaneous liver biopsy. Right upper quadrant and shoulder pain may be seen in up to 30% of cases. The pain is usually dull and self-limiting and responds well to analgesia. When pain is intense or does not respond to analgesia as expected, the patient must be evaluated for possible procedural complications. Our patient presented with severe abdominal pain 48 hours after biopsy, leukocytosis, and a large perihepatic fluid collection that was not present in the previous scan. The differential diagnosis included acute biloma versus hematoma. Biloma was strongly considered because the fluid collection was homogeneous and of low density (10 HU). Hematomas tend to be heterogeneous and have higher densities (40–60 HU) indicative of the presence of blood (Fig. 3). An accurate diagnosis is important because the management is different. If doubt exists, a diagnostic sample of the fluid can be obtained percutaneously.

Bleeding after liver biopsy is relatively common. Sonographic evaluation of asymptomatic patients after liver biopsy revealed that bleeding might be present in up to 23% of cases [7]. Bleeding may be parenchymal, subcapsular (most common), or intraperitoneal (most serious), or it may present as hemobilia (rare). On the other hand, a bile leak is a rare but potentially serious complication, especially in a patient with obstructive dilated bile ducts. A bile leak can present as a biloma or as biliary peritonitis. A biloma is the result of a low-rate biliary leak. Such a leak may take weeks to develop, and the diagnosis is usually made on follow-up scans. A biloma is usually a cystic lesion of low attenuation in or around the liver that may be septate or contain debris [7]. Biliary peritonitis results from a less-contained bile leak. The bile causes chemical irritation of the peritoneum (peritonitis) and impairs the host's local defense system by its detergent lytic effect, predisposing the patient to peritoneal infection and sepsis. An infection usually presents as free peritoneal fluid that might be associated with peritoneal thickening and contrast enhancement. The reported mortality rate from biliary peritonitis is 20–50%, but death is largely related to the cause of the leak and to the comorbidity of the patient. Biliary peritonitis is more often seen secondary to cholecystitis or peptic ulcer perforation in older patients, factors that contribute to infection, sepsis, and its high associated mortality rate [8].

Why did the patient have the complication?—Figure 2B shows the biopsy needle at the target lesion. Most probably, the needle traversed an obstructed intrahepatic bile duct, and the high intraductal pressure in the biliary system caused the bile to escape through the needle track once the needle was removed. The bile followed the path of least resistance, subsequently forming a large biliary leak.

What is the treatment?—The first step is to stabilize the patient. Establish a good IV line, start fluid resuscitation, and start antibiotic therapy. Biliary leaks need to be treated mainly to prevent sepsis. Small bilomas may be treated only with analgesia, antibiotics, and fluid management, but if the condition persists or worsens, they need to be drained. On the other hand, biliary peritonitis needs to be treated emergently with drainage, antibiotics, and control of the leak surgically, endoscopically, or percutaneously.

This patient required diagnostic fluid aspiration to rule out hemorrhage and to confirm the diagnosis of biliary leak. The recommended maneuver is to insert a needle percutaneously using sonographic guidance. If the aspirated fluid is bile, a sample should be sent for culture and antibiotic sensitivity. The collection can then be drained by placing a catheter. If the aspirated fluid is blood, the patient should be stabilized with IV fluids, should be typed and cross-typed for possible transfusion of blood products, and should undergo emergency diagnostic angiography with possible embolization.

Diagnostic paracentesis was performed using a 5-French needle; a total of 800 mL of turbid bile was aspirated. Percutaneous transhepatic cholangiography followed (Fig. 4) because the patient seemed to have obstruction of the biliary system from a mass in the head of the pancreas. After corroboration of the obstructed bile duct system and the existence of a persistent bile leak, a percutaneous internal–external biliary drainage catheter was placed to relieve the obstruction and to control the leak.

Note: This case is an example of severe bile peritonitis after percutaneous liver biopsy. A high index of suspicion and accurate diagnosis are essential to direct precise and life-saving management.

A 52-year-old man with diabetes and a seizure disorder was hospitalized with a hemorrhagic stroke. The patient underwent decompressive craniotomy and was unable to tolerate oral feedings. His physician requested placement of a gastrostomy tube for enteral nutrition support. The laboratory workup showed no specific abnormality and the coagulation profile was normal.

A fluoroscopically guided percutaneous gastrostomy was attempted, initially without gastropexy. A 14-French gastrostomy tube was advanced after tract dilation, but during this maneuver access to the stomach was lost. A second attempt to place the tube was then conducted. In the second attempt, gastropexy was performed and the tube was successfully placed in the stomach. Abdominal radiography was performed to confirm the position of the gastrostomy tube (Fig. 5A). Abdominal distention and signs of acute peritoneal irritation were found (Fig. 5B). CT of the abdomen was ordered (Figs. 5C, 5D, 5E, and 5F). Shortly after the CT was performed, the patient developed respiratory failure followed by hypotension. Cardiac arrest was diagnosed and the patient was intubated. His neurologic status continued to deteriorate. CT of his head (not shown) showed increased cerebral edema. Support was withdrawn and the patient died 72 hours after gastrostomy tube placement.

The diagnosis is peritonitis after percutaneous placement of gastrostomy tube.

The complication rate associated with percutaneous gastrostomy tube placement is approximately 2.2% for major and 5.9% for minor complications. Surgical and endoscopic gastrostomy complication rates range from 5% to 10% for major and from 3% to 10% for minor complications. The 30-day mortality rate in these patients ranges from 4% to 15% depending on the underlying condition, but the procedure-related mortality rate for percutaneous gastrostomy is 0.5% [9, 10]. The most common minor complications are skin site infection and fluid leakage around the catheter. The most serious complications after gastrostomy tube placement include peritonitis, bowel perforation, solid organs (liver or spleen) traversed, aspiration, and significant hemorrhage [11].

Figure 5A shows that the gastrostomy tube is in good position in the stomach. Contrast material clearly shows gastric rugae. No contrast leakage is identified. Figure 5B is the 24-hour thoracoabdominal radiograph with contrast material through the gastrostomy tube that confirms the tube is in the stomach; there is no evidence of a leak. No other major abnormalities are evident in this film.

Figures 5D, 5E, and 5F are contrast-enhanced abdominal CT scans performed after the patient developed signs of peritonitis; they show a large pneumoperitoneum. The gastrostomy tube is seen in the stomach. No evidence is seen of contrast material leaking into the peritoneal cavity, but contrast material is in the colon, at the splenic flexure, and in the descending colon.

The complication in this patient was colonic perforation during percutaneous gastrostomy, with consequent spillage of colonic contents into the peritoneum and subsequent severe peritonitis.

Pneumoperitoneum is frequently seen after percutaneous gastrostomy and is not considered a complication unless it increases progressively or is associated with signs of peritoneal irritation. Peritonitis is extremely uncommon, but in debilitated patients it results in major morbidity or death. It can occur as a result of tube dislodgement or from bowel perforation.

Why did this patient have a complication?—Figures 5C, 5D, 5E, and, 5F show a large pneumoperitoneum with gastrointestinal contrast material in the stomach and left colon. No contrast agent is noted in the small intestine. The contrast material in the colon could be residual contrast material from a previous administration, but if that were the case, one would expect it to be more diluted. The administration of contrast material through the gastrostomy tube shows that the gastrostomy tube is in the stomach, but careful evaluation of Figure 5E shows that the splenic angle of the colon is traversed by the track of the gastrostomy tube. The large pneumoperitoneum and peritonitis are most probably related to spillage of gastric and colonic contents into the peritoneal cavity.

What is the management?—The first step in the management of this complication is identification of the problem. Colonic perforation during gastrostomy tube placement is uncommon. The interventional radiologist performing these procedures should be aware of the possibility of traversing the colon during gastrostomy tube placement so it can be prevented. In the unfortunate setting of perforation of the colon, the complication needs to be promptly identified and managed. In this patient, surgical referral for an emergent laparotomy is indicated, but because of the patient's deteriorating condition, the family decided to stop supportive care.

The ideal scenario would be to prevent the complication. When it is difficult to visualize the bowel, especially the transverse colon, a dose of oral contrast material given the night before will aid in visualizing the large bowel at the time of the procedure. If the colon lies anterior to the stomach, percutaneous gastrostomy tube placement should not be performed and the patient should be referred for surgical gastrostomy.

This case was also complicated by the inability of the operator to gain adequate access to the stomach during tube placement. Retentive gastropexy (i.e., placement of suture anchoring devices) is helpful in some cases, but its routine use for gastrostomy tube placement is controversial. The advantage of using suture anchors is that the anterior wall of the stomach is apposed to the abdominal wall and, in case of tube dislodgement, it is relatively easier to gain access to the stomach. However, some authors [10] believe that the cost, the increased risk of bleeding and infection from the extra punctures and sutures, and the increase in procedure time, do not justify the routine use of suture anchors. The use of suture anchors is indicated in cases in which apposition of the gastric and abdominal wall is critical—for example, in patients with ascites or poor healing (steroid use, poorly controlled diabetes mellitus, malnourishment) or in procedures in which considerable manipulation is anticipated, such as gastrojejunostomy.

Cancer patients with tumors in the area of the puncture are at a higher risk of bleeding and failure of track maturation with secondary leaking.

Note that percutaneous gastrostomy tube placement is a safe and quick procedure. It is not free of complications, but careful planning avoids most serious complications. In our experience, the ideal imaging method before the procedure is CT with oral contrast material. Such a study shows whether the liver, spleen, and colon are located anterior to the stomach. If so, the operator can be confident that percutaneous gastrostomy is contraindicated and may refer the patient for open surgical gastrostomy tube placement to avoid unnecessary complications.

A 56-year-old woman with chronic obstructive pulmonary disease (COPD) was found to have a lung mass in the left upper lobe during routine chest radiography. The lesion was not present in a chest radiograph obtained 6 months earlier. CT was performed to better characterize the lesion (Fig. 6A). After discussion with the treating physician, the patient was scheduled for a percutaneous needle biopsy of the left lung lesion. The biopsy was performed under CT guidance using a coaxial technique. A 19-gauge guiding needle was advanced to the edge of the lesion, and a fine-needle aspirate was obtained using a 22-gauge needle. Follow-up CT was performed immediately after the first aspiration (Fig. 6B).

The patient's vital signs were stable and she had no respiratory difficulties. Using the same percutaneous access, a Bentson wire was advanced via the guiding needle to gain access into the pleural space. The track was dilated and an 8-French all-purpose drainage catheter was placed to evacuate the pneumothorax.

The cytology of the lesion was reported to be non–small lung cell cancer. The patient was not a candidate for surgical therapy because of her severe COPD. The case was discussed, and it was decided to treat the lesion with radiofrequency ablation. The ablation procedure was performed with the patient under conscious sedation and in the prone position using CT guidance (Fig. 6C). The lesion was treated with a 3.5-mm probe. The procedure was technically successful and the patient tolerated it adequately. The chest tube was placed on water seal and kept in place. Chest radiography was performed 24 hours after radiofrequency ablation (Fig. 6D).

The diagnosis is pneumothorax as a complication of lung mass biopsy and radiofrequency ablation in a patient with COPD.

Bleeding and pneumothorax are the most frequent complications after percutaneous lung biopsy procedures. Pneumothorax has been reported to occur in 10–60% of patients, with chest tube placement required in 2–20%. Bleeding is the second most common complication; most series report rates of 6% or less. Frequently, the hemorrhage is self-limiting and requires only patient repositioning to place the bleeding site in the most dependent position. Even if initially dramatic, these bleeding episodes usually subside in 10–15 minutes. Significant bleeding requiring transfusion or surgical or endovascular treatment is reported to occur in 0–3% of cases. The mortality rate from bleeding is estimated at 0.01–0.10% for this procedure.

Figure 6A, an unenhanced axial CT image, shows an ill-defined heterogeneous solid lesion located in the posterior segment of the left upper lobe. Bilateral bullae are identified with peripheral predominance. Figure 6B, an unenhanced axial CT image obtained immediately after the biopsy, shows a 20–30% left pneumothorax. Figure 6C, an unenhanced axial CT image obtained immediately after chest tube placement, shows complete pulmonary expansion. Figure 6C, a posteroanterior chest radiograph obtained after radiofrequency ablation with the chest tube on water seal, shows a 40% left pneumothorax. The chest tube is still in the left pleural space.

Solitary pulmonary nodules (SPNs) in patients younger than 35 years who have no history of malignancy or smoking are most often benign (granulomas, hamartomas, inflammatory lesions). These can be followed up with serial chest radiographs at 3- to 6-month intervals for at least 2 years. An SPN in an older patient with no clear benign characteristics (fat, coarse calcification) has a 50% chance of being malignant, so tissue diagnosis is recommended. If the SPN has malignant characteristics (e.g., risk factors, size, margins), thoracotomy and resection may be the first line of treatment. If the SPN is indeterminate, especially in an endemic area of granulomatous disease, a biopsy can obviate an unnecessary thoracotomy.

Percutaneous biopsy devices consist of needles classified basically by size and tip configuration. According to the tip configuration, there are aspiration needles and cutting needles. Aspiration needles are thin-walled cannulas. Examples are the spinal and Chiba needles. Gentle motion of the needle passing through the tissue yields cellular samples for cytologic evaluation. Cutting needles are designed to provide histologic cores for examination, rather than cytologic specimens. The two major mechanisms used are the Tru-Cut and the Menghini. The Menghini-type needles are beveled-tip cannulas that collect cylindrical cores of tissue as the needle is advanced and suction is applied. The Tru-Cut–type needles are cannulas that use a notched stylet. After the stylet is advanced, tissue is deposited in the notch. Then the cannula is advanced over the stylet, cutting the tissue sample deposited in the notch. There are three general categories according to the needle size, as shown in Table 1.

Several biopsy techniques have been described. The single-pass technique uses multiple needle passes and withdraws the needle after each pass. The tandem technique involves the placement of a small-caliber needle under imaging guidance. After confirmation of the correct position, one or more biopsy needles of the same length are placed parallel to this needle to the same depth, and samples are then obtained. The coaxial technique uses a thin-walled guiding needle through which the biopsy needle is introduced and withdrawn for every sample taken.

It is important to remember that some tumors may have areas of necrosis, hematomas, or fibrous tissue. Sampling these areas may result in false-negative findings. To reduce this possibility, it is useful to have a cytopathologist available during the procedure. The immediate evaluation of the samples may guide the interventional radiologist to obtain additional samples from different areas or to obtain tissue cores for better lesion characterization. The risk of pneumothorax increases with the number of passes though the pleura and the length of time the needle is kept in the pleura. For this reason, numerous operators prefer to use the coaxial technique, which, if performed properly, will cross the pleura only once. The risk of pneumothorax is also higher in patients with smaller lesions, in patients with lesions located close to the pleura but not abutting it [12], and in patients with severe COPD.

Lung biopsies are usually performed to investigate the possibility of malignancy. An accurate cytologic diagnosis may be sufficiently good that histologic cores are not necessary. If so, small-caliber needle aspirations are usually sufficient. Medium- or large-caliber needles are necessary when good tissue samples are required for histologic analysis—for example, in cases of metastatic disease of an unknown primary source. This is how a cytopathologist on-site improves the diagnostic yield and at the same time reduces number of needle passes to a minimum [13, 14].

Why did the patient develop this complication?—Pneumothorax is a common complication of lung biopsy in patients who have transpleural punctures (up to 60% incidence). Severe COPD with peripheral bullae is a well-recognized aggravating risk factor. The resistance in the air outflow at the bronchi might predispose the air to take the path of the needle instead and fill the pleural space until the pressures equalize.

For radiofrequency ablation, a 14-gauge coaxial needle is used to traverse the pleura and reach the lesion. Although medium-caliber needles do not significantly increase the risk of complications of percutaneous lung biopsies, the use of large-caliber needles has proven to do so. In addition, radiofrequency ablation requires the coaxial system to be across the pleura for several minutes, usually between 5 and 8 minutes. Even with all these apparent aggravating risk factors for development of pneumothorax during radiofrequency ablation, studies show no increased rate when compared with percutaneous lung biopsy procedures in general [15].

What is the management?—Management of pneumothorax can be expectant if the pneumothorax is small and asymptomatic. A large, symptomatic, or growing pneumothorax is an indication for chest tube placement. Almost all patients with COPD and pneumothorax will require chest tube placement. A small-bore chest tube (7- to 14-French) is sufficient in most patients. Larger tubes (24-French) might be needed in patients with persistent leaks or at high risk of developing them (i.e., patients undergoing ventilation). Most air leaks (80%) resolve within 7 days. The chest tube is withdrawn 24 hours after leak cessation. Surgical care, consisting of video-assisted thoracic surgery, pleurodesis, or thoracostomy, is indicated for persistent air leaks of more than 7 days or for recurrent pneumothorax.

This patient had a second pneumothorax that probably resulted from trauma caused by the radiofrequency ablation needle. It was not considered a recurrence of the pneumothorax from the first procedure. The first chest tube was not effectively treating this pneumothorax and was therefore changed to a larger-bore catheter and repositioned. This procedure was successful in resolving the pneumothorax.

A 53-year-old woman with a recent kidney transplant presented to the emergency department with rising serum creatinine levels, which had increased from a baseline of 2.0 mg/dL to a maximum of 6.1 mg/dL. Sonography of the transplanted kidney revealed hydronephrosis of the allograft. The patient was referred to the interventional radiology service for placement of a percutaneous nephrostomy tube. Pertinent laboratory results showed a normal INR, hemoglobin of 10.5 g/dL, hematocrit of 32%, and a WBC of 8.1 × 10³/L. A dose of prophylactic IV antibiotics (fluoroquinolone, 500 mg IV) was given before the procedure. The procedure was performed in the angiography suite with the patient under conscious sedation. A 5-French percutaneous access system was used to gain access to the renal system under sonographic guidance. Antegrade nephrostography was performed (Figs. 7A and 7B). The distal stenosis was negotiated using a combination of angiographic catheter and heparin-coated wire.

An 8-French all-purpose drainage catheter with extra side holes was advanced into the urinary bladder (Fig. 7C) in an internal–external nephroureteral stent fashion.

Immediately after the procedure, the patient's urine output via the drainage bag was found to be grossly bloody. She was hemodynamically stable and the laboratory parameters had no significant change. Antegrade pyelography (Fig. 7D) was performed 24 hours after stent placement.

The diagnosis is persistent hematuria after percutaneous nephrostomy tube placement.

The complications of performing percutaneous nephrostomies and stenting stenotic ureters of transplanted kidneys are basically the same as those in native kidneys [16]. However, in patients with a kidney transplant it is especially important to avoid infectious complications because these patients are immunosuppressed. These patients should be treated with prophylactic IV antibiotics 1 hour before the procedure. Sonographic guidance is advised to gain access into the kidney in order to reduce the bleeding.

Figure 7A, a selected image during antegrade pyelography, shows successful access into a superior pole calyx with a 22-gauge access needle. Figure 7B, another image during antegrade pyelography, shows an angiographic catheter placed in the distal ureter. Note the faint opacification of the distal ureter, showing a severe stenosis at the ureter-to-bladder anastomosis. The image shows evidence of multiple filling defects in the collecting system that are probably clots. Figure 7C, an image during nephroureteral stent placement, shows that the nephroureteral stent has been successfully passed across the stenosis into the bladder. A small filling defect is still seen in the renal pelvis. Figure 7D, an image from antegrade pyelography performed via the nephroureteral stent, shows large filling defects in the renal pelvis consistent with large intrapyelic clots. The nephroureteral stent is in good position.

Two to ten percent of patients with a transplanted kidney experience urologic complications [17–19]. Urinary leaks and ureteric strictures account for most of these complications. The distal ureter, near the ureteroneocystostomy, is the area most commonly affected, probably because of surgical manipulation and technique [16]. Leaks, which are also more common in this location, can eventually cause stenosis by induction of periureteral fibrosis. When the mid or proximal segments of the ureter are involved, the strictures are usually caused by necrosis from focal rejection or vascular insufficiency. Other possible causes such as intraluminal blood clots or extrinsic compression from adjacent structures are unusual. It is estimated that the rate of post-transplantation ureteral stenosis is 9.7% at 5 years [17].

It is not uncommon for the nonobstructed transplanted kidneys to have a mild ectatic appearance on imaging studies. This is thought to be a product of graft denervation and to some degree of vesicoureteral reflux through the ureteroneocystostomy. Because of this, antegrade pyelography is helpful in evaluating the collecting system when renal function is deteriorating. If a stricture is found, balloon dilatation and subsequent stent placement [20], or stent placement alone [16, 19], are excellent treatment options. Obstructed grafts appear to have better survival when treated with stents as opposed to surgical intervention [21]. A substantial increase of the glomerular filtration rate during the 10 days after decompression is a reliable predictor of recovery. Surgical correction is preferred if the ureteral stenosis is caused by extrinsic compressions from adjacent structures such as blood vessels or the spermatic cord, although percutaneous nephrostomy is useful for diagnosis and as a temporizing measure to improve renal function preoperatively.

Why did the patient develop the complication?—The overall complication rate from percutaneous nephrostomy is low. The procedure-related mortality rate is 0.2%. The major-complication rate is about 4–6%, with hemorrhage and sepsis accounting for most [22].

Hemorrhage associated with percutaneous nephrostomy is usually self-limiting. It is not uncommon to have mild hematuria immediately after percutaneous nephrostomy tube placement. This mild hematuria usually clears in 24–72 hours. Small asymptomatic hematomas are seen in approximately 13% of patients after percutaneous nephrostomy placement; this is not a worrisome sign and treatment is not usually necessary. Serious vascular trauma is suspected when the bleeding persists for more than 3–5 days, when there is frank hematuria in the drainage bag, or when there is a decrease in the hematocrit or hemoglobin levels. Persistent bleeding after percutaneous nephrostomy tube placement is usually the result of a lobar artery laceration. Care in accessing the relative avascular posterolateral region (Brödel line) of the kidney, avoiding the more prominent anteromedial vessels, may decrease the incidence of this complication [23]. Sonographic guidance is invaluable to avoid highly vascularized areas of the kidney. The use of small-caliber needles (21–22 gauge) has not been shown to be safer than the use of medium-caliber (18-gauge) needles [24].

What is the management?—Upsizing of the nephrostomy tube is the first maneuver. This usually resolves the hematuria [22, 23]. In this patient, a larger nephrostomy tube was placed and the stent was internalized by placing a double J stent (Fig. 7E). The collecting system was irrigated repeatedly with saline, and the output was observed. The nephrostomy output cleared and remained free of blood. Seven days later, the nephrostomy tube was removed after patency of the stent and a clean collecting system were seen (Fig. 7F).

If bleeding is severe, with bright red blood in the drainage bag, or if the hemoglobin and hematocrit levels decrease, arteriography should be performed to search for an arterial injury. An injury may present as a small pseudoaneurysm, an arterial laceration, or an arteriovenous fistula. These lesions are best treated with superselective embolization and coil placement.

A 23-year-old man presented to the emergency department with a 10-day history of right lower quadrant abdominal pain. He had no significant surgical or medical history. Relevant laboratory tests revealed a normal INR (1.1), an elevated WBC (14 × 10³/μL), and normal hemoglobin and hematocrit levels. The patient was admitted for further diagnostic workup and management. Contrast-enhanced CT was performed on admission (Figs. 8A, 8B, and 8C).

The patient was diagnosed with an appendiceal abscess. Evaluation for percutaneous drainage was requested. The interventional radiologist in charge decided to perform the procedure under sonographic guidance. A 21-gauge needle was advanced into the central portion of the fluid cavity, and a 10-French all-purpose drainage catheter was placed under fluoroscopic guidance (Figs. 8D, 8E, and 8F). A total of 20 mm of purulent material was drained.

Drainage of purulent material confirmed the diagnosis of abscess. Initially, the patient had a satisfactory clinical improvement with decreasing fever and a lower WBC. However, 1 week after tube placement, tube output had increased and his WBC rose to 23.4 × 10³/μL. The patient was referred to the interventional radiology service to check the drainage catheter.

Evaluation of the cavity was then performed by injection of contrast material through the draining tube (Figs. 8G and 8H).

The diagnosis is colonic perforation during pelvic abscess drainage.

The mortality rate of an undrained pelvic abscess treated with antibiotics is approximately 50–80%. Antibiotics and surgical drainage have been the standard treatment for large pelvic abscesses (> 3 cm), although some, such as tuboovarian abscesses, have been known to respond well to antibiotic therapy alone.

Percutaneous drainage of pelvic abscesses has gained acceptance as a safe and effective therapy in the management of large, well-defined pelvic abscesses. Jeffrey et al. [25] reported a 90% cure rate for this type of abscess with antibiotic therapy and percutaneous drainage alone, eliminating the need for surgery. For the remaining abscesses that eventually require surgical intervention, percutaneous drainage has been proven to be an excellent method in critically ill patients by reducing sepsis and providing anatomic information via abscessograms. This process improves surgical results and, in some instances, reduces the extent and number of subsequent surgeries needed. On the other hand, extensive, poorly defined abscesses are still treated initially with surgical intervention.

Figures 8A, 8B, and 8C are selected axial contrast-enhanced CT images of the abdomen at the level of the L5–S1 vertebrae. A well-defined fluid–air collection is seen between the psoas muscle and abdominal bowel loops. The fluid collection is completely surrounded by bowel loops. No contrast material is seen in the collection. The collection is well defined and surrounded by an enhancing wall. The surrounding mesentery shows inflammatory changes. This image is suggestive of periappendiceal abscess, although other causes, such as Crohn's disease and Meckel's diverticulitis, should be considered in the differential diagnosis. Figures 8D, 8E, and 8F, unenhanced axial CT images after drainage catheter placement, show the fluid collection has decreased in size. A high suspicion exists that the colon was traversed during drainage. Figures 8G and 8H are selected images obtained during the fluoroscopic abscessogram that show communication of the abscess cavity with the ascending colon.

Abscess complicates 2–3% of cases of appendicitis. Contrast-enhanced CT of the abdomen is the imaging technique recommended in the evaluation of adult patients in whom there is a clinical suspicion of a complicated appendicitis, especially if a mass is palpated in the abdomen. CT helps with the diagnosis, differentiating an abscess from phlegmonous thickening of the omentum and bowel loops. It also helps characterize more accurately the abscess extension and its fistulous communications, which are important for management considerations. The presence of air or oral contrast material in the abscess cavity suggests enteric communication.

Why did this patient have a complication?—It is not uncommon for pelvic abscesses to have fistulas. Pelvic abscesses are commonly caused by appendicitis, diverticulitis, trauma (surgical) to the gastrointestinal tract, and Crohn's disease. For this reason, the inflammatory cavity usually lies next to the diseased bowel that produced it, eroding it and creating the communication. Approximately 46% of periappendiceal abscesses have enteric fistulas [25].

Another possible cause of the complication, which is uncommon, is accidental catheter insertion through a bowel loop. Careful examination of the CT scan reveals loops of bowel surrounding the fluid collection. Some operators argue that if abscess drainage is performed under sonographic guidance, it is possible to “push away” the surrounding loops and access the cavity directly without traversing the bowel. In this case, however, it seems traversing the colon did occur and facilitated the creation of a fistula to the colon (Figs. 8G and 8H).

What is the management?—Drainage of small uncomplicated abscesses might take as little as 4–5 days. If a fistula is suspected, the abscess should be drained for 3 or 4 days before the abscessogram is obtained to avoid inducing bacteremia or sepsis. Larger and complicated abscesses usually take 3–4 weeks before the drain can be withdrawn.

Most lower enteric fistulas show a low output, draining less than 100 mL/day. These are best managed by placing the draining catheter as close as possible to the communication track without leaving the most dependent portion of the abscess undrained. If a second catheter is needed, it should be placed. Patients are usually followed up with abscessograms every 1–2 weeks as outpatients as soon as they are clinically able leave the hospital.

High-output fistulas require more drainage time (perhaps as long as 12 weeks) to heal and are associated with lower cure rates. Total parenteral nutrition should be started. A large-bore catheter should be placed, preferably in the fistula, occluding the track with subsequent smaller-bore catheter replacements that are slowly retracted to allow healing.

If the fistula was produced by the insertion of the drainage catheter through a bowel loop, the catheter must be kept in place at least for 1–2 weeks to allow track maturation. Then, as with high-output fistulas, the catheter can be progressively removed and replaced with smaller-bore catheters in the upcoming sessions. In this particular case, a drainage catheter was advanced into the ascending colon (Figs. 8I and 8J). Three to 4 weeks later, progressive catheter removal and downsize was done; the fistula healed completely 6 weeks after the initial drain.