Duodenal Switch Gastric Bypass Surgery for Morbid Obesity: Imaging of Postsurgical Anatomy and Postoperative Gastrointestinal Complications

Transcription

1 Gastrointestinal Imaging Clinical Observations Mitchell et al. Gastric ypass Surgery for Morbid Obesity Gastrointestinal Imaging Clinical Observations Myrosia T. Mitchell 1 Joseph M. Carabetta 2 Rajshri N. Shah 3 Moira. O Riordan 4,5 runas E. Gasparaitis 3 John C. lverdy 6 Mitchell MT, Carabetta JM, Shah RN, O Riordan M, Gasparaitis E, lverdy JC Keywords: bariatric surgery, CT, fluoroscopy, gastrointestinal complications DOI: /JR Received October 13, 2008; accepted after revision June 19, Presented at the 2007 annual meeting of the merican Roentgen Ray Society, Orlando, FL. 1 Radiology Imaging Consultants, 4444 W 95th St., Oak Lawn, IL ddress correspondence to M. T. Mitchell. 2 Department of Radiology, Northwestern University, 3 Department of Radiology, University of Chicago, 4 Department of Internal Medicine, University of Chicago, 5 Present address: Department of Radiology, University of California, San Francisco, C. 6 Department of Surgery, University of Chicago, JR 2009; 193: X/09/ merican Roentgen Ray Society Duodenal Switch Gastric ypass Surgery for Morbid Obesity: Imaging of Postsurgical natomy and Postoperative Gastrointestinal Complications OJECTIVE. The purpose of our study was to evaluate the normal postsurgical findings and appearance of gastrointestinal tract complications in patients who have undergone biliopancreatic diversion with duodenal switch bariatric surgery. We performed a 4-year retrospective review of 218 patients who underwent duodenal switch surgery. CONCLUSION. The most common complications of duodenal switch surgery were bowel obstruction, followed by ventral hernias and anastomotic leaks. Only 2% of cases required repeat surgery for management. T he prevalence of obesity, currently defined as a body mass index (MI) greater than 30 kg/m 2 has dramatically increased over the past 50 years [1]. Whereas traditional conservative methods for weight loss in the morbidly obese frequently fail, bariatric surgery is now recognized as a research-proven, effective treatment of morbid obesity, currently defined as a MI of 35 kg/m 2 or greater with serious comorbidity or a MI of 40 kg/m 2 regardless of the presence of comorbidity [1, 2]. In addition, bariatric surgery, when indicated, is the most cost-effective treatment of morbid obesity [3]. Since the 1950s, bariatric surgery has been based on restrictive techniques that create a small stomach or malabsorptive bypass techniques that avoid transit of food through the absorptive small bowel. The current most commonly used surgical technique in the United States is the Roux-en-Y gastric bypass procedure, accounting for an estimated 88% of bariatric surgeries performed in 2002 [1]. The biliopancreatic diversion with a duodenal switch bariatric surgical procedure, sometimes referred to more simply as the duodenal switch, was developed by Hess and Hess [4] and by Marceau et al. [5] in the 1990s. The restrictive component consists of a pylorus-sparing vertical or sleeve gastrectomy that excludes 70 80% of the stomach at the greater curvature. The duodenum, jejunum, and proximal ileum are excluded from the stomach and form the biliary limb. The ileum is transected approximately 350 cm from the ileocecal valve to create a 250-cm alimentary limb and a 75- to 100-cm common channel. The alimentary limb is brought up in antecolic fashion and is anastomosed to the pylorus. Thus, the malabsorptive component is the dominant factor in weight loss because the patient has only 250 cm of small bowel available for food absorption (Fig. 1). lthough the duodenal switch provides superior weight loss in the superobese patient (MI > 50 kg/m 2 ) compared with Roux-en- Y [6], its use among bariatric surgeons has been limited because patients, physicians, and insurers often view it as experimental and unsafe [3]. lthough the imaging findings and complications of Roux-en-Y have been well described in the radiology literature [1], to our knowledge, no detailed studies have been published for duodenal switch. The purpose of our study was to identify the normal radiographic findings in this procedure and the findings in the gastrointestinal complications that may occur. Materials and Methods Patients This study was performed with institutional review board approval and was compliant with HIP. The need for patient informed consent in this retrospective review was waived. Our institution keeps a research database of all patients who undergo gastric bypass surgery. We performed a 4-year retrospective review of this database and identified 218 patients who had undergone duodenal switch. Indications for selection 1576 JR:193, December 2009

2 Gastric ypass Surgery for Morbid Obesity Fig. 1 Schematic drawing shows postsurgical anatomy for duodenal switch surgery. of duodenal switch over other bariatric procedures were MI greater than 50 kg/m 2, MI greater than 35 kg/m 2 and severe major medical comorbidity (e.g., severe dyslipidemia), failed Roux-en- Y, or failed gastric banding. Duodenal switch was also performed if the patient specifically requested the procedure. The patient population consisted of 182 women and 36 men, ranging from 19 to 62 years old, with preoperative MI ranging from 39 to 75 kg/m 2. ll cases were begun laparoscopically. Conversion to an open duodenal switch was performed if technical difficulties, such as adhesions, were encountered. Of these patients, 175 underwent laparoscopic duodenal switch and 43 had an open duodenal switch. There were no significant differences in findings between the laparoscopic and open patients. Imaging t our institution, routine postoperative imaging is not performed in bariatric patients. Imaging is requested when a patient develops clinical signs or symptoms suspicious for postsurgical complications of leak or obstruction. Specifically, these indications include fever, nausea, vomiting, pain disproportionate to the procedure, worsening pain, unexplained tachycardia, and unexplained elevation of WC count. Fluoroscopic examinations were performed with either a D-340 Siregraph remote radiofrequency unit or a Sireskop SD conventional radiofrequency unit (both units, Siemens Healthcare). Most examinations were performed with ml of watersoluble oral contrast material (diatrizoate meglumine and diatrizoate sodium, Gastrografin, racco Diagnostics) as tolerated by the patient. Late postoperative studies in patients without suspicion of peritoneal leaks were usually performed with medium-density barium contrast material. CT was performed on either a CTI helical scanner (GE Healthcare) or a rilliance CT scanner (Philips Healthcare). Examinations were performed with water-soluble oral contrast material as tolerated by the patient up to 100 ml in the immediate postoperative period and up to 1,000 ml in the later postoperative period and with IV contrast material (iohexol, Omnipaque 350, GE Healthcare) up to 150 ml based on patient weight. None of these patients were candidates for MRI because of body habitus. Image nalysis Two fellowship-trained attending gastrointestinal radiologists reviewed by consensus all gastrointestinal imaging studies performed in these patients to identify the normal imaging findings in duodenal switch and the findings in gastrointestinal tract complications that were diagnosed by imaging. The medical records of these patients were reviewed for clinical course and treatment. Surgical pathologic correlation was obtained when available. Results Normal Imaging Findings Normal contrast-enhanced fluoroscopy and CT examinations in duodenal switch showed a gastric pouch that is narrower than a normal stomach but is the same length along the lesser curvature (Fig. 2). The suture line may be visible laterally and gastric mucosal folds may be seen. The pouch terminates at an intact pylorus. The proximal gastroenteric anastomosis is in the right upper quadrant. The alimentary Fig. 2 Normal contrast fluoroscopy findings in duodenal switch surgery., Upper gastrointestinal image in 37-year-old woman after duodenal switch surgery 8 months previously shows gastric pouch as narrow tube length of lesser curvature of normal stomach (arrowheads). The gastroesophageal junction (thin arrow) is at diaphragm as expected. limentary limb descends in right abdomen (thick arrow)., Spot image of distal pouch from upper gastrointestinal examination in 50-year-old woman after duodenal switch surgery 1 year previously shows pylorus is intact (arrow) and is anastomosed end-to-side to alimentary limb (arrowheads). It is important to differentiate normal pylorus from true gastric outlet stenosis. C, Overhead view from small-bowel series in same patient as shows elongated gastric pouch (straight arrow), considerably shortened length of small bowel lying mainly in right abdomen (arrowheads), and opacification of right colon (curved arrow). Normal transit times to colon are short, usually minutes. C JR:193, December

3 Mitchell et al. limb has an ileal-fold pattern and descends in the right abdomen. The common limb ends at the ileocecal valve. lthough it is not possible to directly measure limb lengths by imaging, the alimentary limb subjectively appears about twice as long as the common limb if the distal anastomosis can be identified, corresponding with the surgically determined lengths of 250 cm for the alimentary limb and cm for the common limb. The biliary limb is unopacified by oral contrast material. Normal transit times to the colon were short, in the range of minutes. Complications detailed list of gastrointestinal complications that could be diagnosed radiographically is provided in Table 1. owel obstruction was the most common complication, seen in 16% of cases (n = 34). Obstructions most often involved the gastric pouch (n = 22), with approximately two thirds at the level of the proximal anastomosis and the rest in the midbody. Distal anastomotic obstructions accounted for 32% of obstructions (n = 11) and more often involved the biliary limb (n = 8) than the alimentary limb (n = 3). bout 35% of bowel obstructions occurred within 1 week of surgery (n = 12) and were due to postsurgical edema of the proximal anastomosis or the alimentary limb that caused luminal narrowing and aperistalsis. ll of these cases resolved spontaneously with bowel rest; nasogastric tube decompression was added if needed. Fig year-old woman after duodenal switch surgery 1 year previously and lysis of adhesions 1 month previously who underwent upper gastrointestinal examination for persistent nausea and vomiting. Spot image of gastric pouch shows severe stenosis in midportion of pouch (arrow). More caudal indentation (arrowhead) was peristaltic wave. t surgery, fibrotic stricture was identified and repaired. The remaining cases of bowel obstruction occurred from 3 weeks to 4 years postoperatively. Later gastric pouch obstructions were due to prolonged postsurgical edema, which also resolved with bowel rest or were due to stenosis from fibrosis (Fig. 3), which was treated with balloon dilatation. Later distal postoperative obstructions were due to adhesions, TLE 1: Postsurgical Gastrointestinal Complications of Duodenal Switch Complication Type of Procedure Laparoscopy (n = 175) Open (n = 43) ll Patients (n = 218) No. of Cases No. of Cases No. of Cases owel obstruction 25 (14) 9 (21) 34 (16) Gastric body or outlet a 22 (65) iliary limb 8 (24) limentary limb 3 (9) Unknown b 1 (3) Hernia 10 (6) 8 (19) 18 (8) Ventral or incisional c 12 (6) Internal 2 (1) Hiatal (symptomatic) 3 (1) nastomotic leak 5 (3) 5 (12) 10 (5) Gastric staple line 7 (3) Proximal gastroenteric anastomosis 2 (1) Distal enteric anastomosis 1 (1) Enteric fistula 1 (0.5) 2 (5) 3 (1) Note Data in parentheses are percentages calculated as percent of cases in each group of patients and are rounded to the nearest whole number. Percentages do not add up to 100 because some patients had more than one complication. a One patient had three separate episodes of gastric obstruction. Two patients each had two separate episodes of gastric outlet obstruction. b proximal small bowel obstruction was identified by CT without a discrete point of obstruction delineated. The obstruction resolved spontaneously. c One patient had two ventral or incisional hernias. Fig year-old woman after duodenal switch surgery 6 months previously who presented with nausea and vomiting., Coronal CT image shows moderate dilatation of unopacified biliary limb (arrowheads). Colon is normal caliber. limentary limb was opacified by enteric contrast and was mildly dilated on coronal images obtained more anteriorly (not shown), compatible with partial small-bowel obstruction of common limb., xial CT image through lower abdomen shows cause of obstruction to be ventral hernia (arrowheads) containing edematous distal small bowel. This was surgically repaired JR:193, December 2009

4 Gastric ypass Surgery for Morbid Obesity Fig year-old man after duodenal switch surgery 1 year previously who presented with persistent draining cutaneous wound. Upper gastrointestinal examination image shows contrast opacification of enterocutaneous fistula (long arrow) extending from featureless segment of alimentary limb (arrowheads) to cutaneous surface (short arrow). Featureless mucosa raises possibility of bowel ischemia contributing to development of fistula. more common in the open procedure group, and all were managed conservatively with nasogastric tube decompression in this cohort. Remote postoperative obstructions occurring months to years after surgery were usually due to distal anastomotic strictures, again managed conservatively with endoscopic balloon dilatation, or to hernias. The second most common gastrointestinal tract complication was hernia formation (excluding hiatal hernias), seen in 7% of patients (n = 15). Nearly all of these were ventral hernias (n = 13), usually through one of the surgical incision sites (Fig. 4). One ventral hernia occurred acutely 3 days postoperatively. The other hernias were late complications, occurring 5 months to nearly 3 years after surgery. These were managed with nasogastric decompression. Two of these were internal hernias, one consisting of bowel herniating through a surgical mesocolic defect and the other of bowel incarcerated between limbs of the distal anastomosis. These were managed surgically. nastomotic leaks occurred in 5% of patients (n = 10). Most of these leaks were from the gastric staple line (n = 7) (Fig. 5), with a few from the proximal gastroenteric anastomosis (n = 2) and from the distal enteric anastomosis (n = 1). Leaks tended to present early in the postoperative course, with more than half presenting in the first 2 weeks (n = 6) and only two presenting after 1 month. Smaller leaks often resolved with conservative therapy. Larger leaks and persistent small leaks were treated with percutaneous Fig year-old woman after duodenal switch 2 years previously with late complication of gastric staple line leak and abscess., Upper gastrointestinal examination performed with water-soluble contrast material shows extravasation of contrast material (arrow) from proximal aspect of gastric staple line and extending to lateral fluid loculation (arrowheads), compatible with abscess., Coronal CT image shows staple line leak (arrow) extending from gastric pouch to fluid loculation (arrowheads). drainage because these leaks could lead to abscess or fistula formation. Rare complications were fistulas (n = 3) and symptomatic hiatal hernias (n = 3). Fistulas were late complications of anastomotic leaks, with two enterocutaneous and one enteropleural (Fig. 6). The symptomatic hiatal hernias presented with either reflux symptoms or atypical phrenic pain simulating cardiac symptoms (Fig. 7). In some of the patients, these were shown only on CT. The symptoms resolved with surgical repair of the hiatal hernias. Discussion Technical Considerations for Imaging oth dynamic fluoroscopic imaging and CT are useful tools in evaluation of the bariatric Fig year-old woman after duodenal switch surgery 2.5 years previously who presented with postprandial left hemithoracic and cervical pain., Upper gastrointestinal examination shows probable protrusion of gastric staple line (arrows) above diaphragm (arrowheads)., Coronal CT reformation image clearly shows portion of gastric staple line (arrow) above diaphragm, confirming presence of hiatal hernia. Relationship of staple line relative to diaphragm can be difficult to delineate with only axial images. Patient s symptoms resolved with repair of hernia. JR:193, December

5 Mitchell et al. patient. Initial evaluation is usually done with a modified upper gastrointestinal examination. Digital equipment is essential because analog equipment is unable to adequately penetrate in these patients. We use modified generator curves that start at a higher kilovoltage and ramp up more quickly to maximum kilovoltage for improved image quality and decreased artifacts in these patients. Water-soluble oral contrast material is administered in patient-controlled boluses during fluoroscopic observation, and spot images of the anatomy are obtained. Given the large size of these patients, overhead views tend to be of limited use. Optimally, patients should be imaged upright and supine as well as in frontal, lateral, and oblique projections. In reality, many patients can be imaged only in a standing upright projection because of their physical limitations and the technical constraints of the imaging equipment. Hiatal hernias were difficult to diagnose and sometimes occult at upper gastrointestinal examination for this reason and also because scatter artifact often obscured the gastric mucosa and gastric suture lines. CT is performed if further information is needed, particularly in patients with more severe obstructive symptoms and in those in whom abscess is suspected. CT is feasible in these patients as long as they do not exceed the table weight limit of 200 kg [7]. We use 140 kvp in these very large patients and a manually increased current, usually in the range of m. We use oral and IV contrast material as indicated by the clinical question. Clinical spects Duodenal switch is considered technically more complex than the Roux-en-Y procedure. t our institution, it is the preferred procedure for superobese patients because it shows statistically greater weight loss and decrease in MI compared with Roux-en-Y as well as a significantly greater likelihood of successful weight loss, defined as achieving at least 50% of excess body weight [6]. Patients who undergo the duodenal switch procedure at our institution are followed postoperatively by both the surgeon and by a dietitian for diet advancement and nutritional supplementation as needed. In the future, this procedure may increase in popularity for treatment of the superobese. Postoperative Complications The rate of clinically significant complications from duodenal switch is probably comparable to Roux-en-Y [6]. In our series, the overall incidence of gastrointestinal complications diagnosed radiographically was approximately 20%, with obstructions accounting for the majority of duodenal switch complications. This value of 20% is high because it includes many transient, self-limited gastric obstructions related to postsurgical edema. Most of the other complications were managed conservatively or with limited interventional or endoscopic management, whereas only 2% of cases required repeat surgery. nastomotic leaks were less common than obstruction. This may be due to the larger capacity of the pouch or the presence of a pylorus creating a feeling of satiety that decreases the likelihood of overdistention of the pouch by food. The frequency of leaks in our series was similar to that reported by other investigators [8]. Complications of ventral hernia, internal hernia, abscess, enterocutaneous fistula, and symptomatic hiatal hernia were infrequent. Hiatal hernias were symptomatic because the gastric pouch in duodenal switch contains parietal cells causing acid reflux. In duodenal switch patients who present with pain, nausea, vomiting, or food intolerance in whom other causes for these symptoms have been excluded, identification of a hiatal hernia should be considered a significant finding. We did not encounter any complications of misconstruction in our series. These are complications that are seen more often with revisions of Roux-en-Y procedures than with the primary surgery [9]. We suspect that these are more likely to occur with alimentary and biliary limbs of similar length that are more easily confused intraoperatively. In conclusion, the duodenal switch gastric bypass procedure is a relatively new bariatric procedure that has been shown to be more effective for weight loss in the superobese patient. In contradistinction to Rouxen-Y, it relies more on the malabsorptive component than the restrictive component. oth contrast fluoroscopy and CT are useful diagnostic techniques. The more common complications in our series were bowel obstructions, hernias, and anastomotic leaks, most of which were managed without surgical intervention. thorough understanding of expected postoperative anatomy is essential in evaluation of these patients. cknowledgment We thank Lydia Johns, senior research associate in the Department of Surgery at the University of Chicago, for the medical illustrations. References 1. Chandler RC, Srinivas G, Chintapelli KN, et al. Imaging in bariatric surgery: a guide to postsurgical anatomy and common complications. JR 2008; 190: National Institutes of Health. Obesity Education Initiative. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report. National Institutes of Health; National Heart, Lung, and lood Institute; 1998 (NIH publication no ). ob_gdlns.pdf. ccessed ugust 19, lverdy JC, Prachand V, Flanagan, et al. ariatric surgery: a history of empiricism, a future in science. J Gastrointent Surg 2009; 13: Hess DS, Hess DW. iliopancreatic diversion with a duodenal switch. Obes Surg 1998; 8: Marceau P, iron S, ourque R, et al. iliopancreatic diversion with a new type of gastrectomy. Obes Surg 1993; 3: Prachand VN, DaVee RT, lverdy JC. Duodenal switch provides superior weight loss in the superobese (MI > 50 kg/m 2 ) compared with gastric bypass. nn Surg 2006; 244: Vannier M, Johnson P, Dachman, Mitchell M, aron R. Multidetector CT of massively obese patients. (abstr) In: Proceedings of the Radiological Society of North merica. Chicago, IL: Radiological Society of North merica, 2005:237(P): Serra C, altasar, Perez N, et al. Total gastrectomy for complications of the duodenal switch, with reversal. Obes Surg 2006; 16: Mitchell MT, Pizzitola VJ, Knuttinen MG, Robinson T, Gasparaitis E. typical complications of gastric bypass surgery. Eur Radiol 2005; 53: JR:193, December 2009