Surgical procedures for obesity: normal anatomy and complications

Transcription

1 Surgical procedures for obesity: normal anatomy and complications Poster No.: C-1572 Congress: ECR 2012 Type: Scientific Exhibit Authors: J. Fernandez Jara, N. Alegre Bernal, J. Cubero Carralero, C. Cardenas Valencia, B. Corral Ramos, C. Poyo Calvo ; 1 2 Leganes/ES, Leganes /Madrid/ES Keywords: Ultrasound, Fluoroscopy, CT, Gastrointestinal tract, Anatomy, Abdomen, Surgery, Complications, Abscess, Obstruction / Occlusion, Volvulus DOI: /ecr2012/C-1572 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 46

2 Purpose BACKGROUND: Obesity is a growing problem worldwide. Obesity has been identified as one of the World Health Organisation s top 10 risks to health. The most practical means of classifying obesity is the body mass index (BMI). Overweight s defined as a BMI > 25 kg/m2 and obesity as a BMI > 30 kg/m2. There are currently 1 billion overweight and 300 million obese adults. Various statistics have been published regarding the percentage of morbidly obese individuals in the United States, but the general consensus is that approximately 5-7% of the adult population can be considered morbidly obese. Bariatric surgery has a clear role in the management of obesity. Surgical intervention is associated with increased life expectancy and economic benefits to society. Bariatric surgery has come to the forefront in the treatment of morbid obesity as a result of research-proven effectiveness and the frustrating failure of traditional conservative methods Surgery also has the ability to reduce, and in some cases resolve, much comorbidity such as hypertension, type 2 diabetes, and sleep apnea. Bariatric surgery is generally categorized into two main categories, restrictive and mal- absorptive. In restrictive procedures, gastric volume is reduced substantially to decrease caloric intake by promoting early satiety. In malabsorptive procedures, the gastrointestinal tract is surgically altered to induce malabsorption and hence decrease caloric intake. In addition, procedures may combine techniques. Diagnostic imaging test play an important role in the bariatric surgery postoperative period to asses for immediate complications, such as leakage, and in the longer term to investigate abdominal pain or weight gain. The increased of bariatric procedures performed means that radiologist have to be familiar with them. An understanding of the anatomy is required to identify early and late complications accurately and to prevent misinterpretation of normal findings. We present the normal anatomy as well as the complications associated with the 6 bariatric procedures used in our hospital from 2001 to present day was performed. We Page 2 of 46

3 have divided surgical procedures in purely surgical procedures and minimally invasive procedures, which are the followings (Fig. 1) : 1. PURELY SURGICAL PROCEDURES Open Roux-In-Y Gastric Bypass Tubular Gastrectomy Laparoscopic gastric bypass Vertical-Banded Gastroplasty 2. MINIMALLY INVASIVE PROCEDURES Laparoscopic Adjustable Gastric Banding Gastric Balloon PURPOSE: Diagnostic approach to the most appropriate imaging studies. To illustrate normal anatomy after surgical procedures for morbid obesity. To review early and late complications that occurs after these procedures. Images for this section: Page 3 of 46

4 Fig. 1: TYPES OF SURGICAL PROCEDURES Page 4 of 46

5 Methods and Materials An observational and retrospective study, including all consecutive patients (n=199) who underwent any of the surgical procedures for obesity between 2001 and 2011, was performed in our hospital Data were obtained from surgical and radiology reports as well as an administrative database. Demographic information (sex, age, BMI and risk factors: hypertension, diabetes or sleep apnea syndrome), type of surgical procedures (Open Roux-In-Y Gastric Bypass, Tubular Gastrectomy, Laparoscopic gastric bypass, Vertical-Banded Gastroplasty, Laparoscopic Adjustable Gastric Banding, Gastric Balloon), complications (early or late), mortality and technique reconversion were reviewed. Regarding risk factors, we considered the presence or absence of risk factors, when patients presented with hypertension and / or diabetes and / or sleep apnea syndrome. Complications (early and late) were analyzed independently in each surgical technique. Patients with Gastric Balloon were not included in the demographic analysis, because all of them were converted into other surgical procedure. The gastric balloon is placed in patients in our hospital since 2005 in selected patients in a randomized study. It is introduced 6 months before performing another type of surgical procedure to reduce weight before it. Patients who underwent any technique reconversion (11 patients) were also not included in the demographic analysis, because the same patient underwent two different techniques. In our centre there is a preoperative protocol that included imaging tests (US and fluoroscopy). The distribution of patients according to surgical technique is shown in Table 6 & Fig. 2. The variables were collected in Excel spreadsheets and analyzed and processed using SPSS Statistics 19. Page 5 of 46

6 Images for this section: Table 6: TYPES OF SURGICAL PROCEDURES Fig. 2: GRAPHIC - TYPES OF SURGICAL PROCEDURES Page 6 of 46

7 Results Study populations demographics are shown in Table 1. Mortality was very low, only 3 patients died (1.65%). Two of the patients underwent a laparoscopic gastric bypass: a 47 year old man with hypertension and diabetes and a 2 2 BMI of 49 kg/m and a 60 year old woman with hypertension and a BMI of 43 kg/m. The other patient was a 55 year old man with hypertension and sleep apnea syndrome, with 2 a BMI of 56 kg/m who underwent an open Roux-In-Y gastric bypass. All patients with Gastric Balloon were converted into other surgical procedure (5 into tubular gastrectomy, 10 into laparoscopic gastric bypass and 3 of them are not yet operated). Of the remaining patients 11 were converted into other surgical procedure. The reconversion technique most frequently used was tubular gastrectomy (6 patients). The results are shown in Table patients (39.7%) had complications that are analyzed independently below in each surgical technique. A. PURELY SURGICAL PROCEDURES 1. OPEN ROUX-IN-Y GASTRIC BYPASS Technique and Normal anatomy: Originally introduced by Griffen et al. in 1977, The Roux-In-Y gastric bypass is now the most commonly performed bariatric procedure. Several variations are used, but the general procedure involves the formation of a gastric pouch (15-30 ml) that is surgical removed from the rest of the stomach, called the remnant stomach. Formation of the pouch can involve anatomic separation by physically dividing the pouch from the remnant or by simply functional division with the application of staples (as we do in our institution). After this, the jejunum is divided approximately cm distal from the ligament of Treitz, mobilized from the mesentery, and brought up to create a side-to-side gastrojejunostomy with the gastric pouch. This anastomosed jejunal loop is called as the Roux limb or Page 7 of 46

8 efferent limb and is placed retrocolic through an opening created in the transverse mesocolon. Typically, a small afferent or "blind" loop is present as a result of the sideto-side approach. To complete the operation, a jejunojejunostomy is created approximately cm distal from the gastrojejunostomy and all mesenteric defects are closed (Fig. 3) The Roux-In-Y gastric bypass is a mixed procedure, taking advantage of both restrictive and malabsorptive components. Varying length of the efferent limb will increase or decrease he malabsorptive component. Radiological evaluation: Initial imaging is should be performed on postoperative day 1 with a Gastrografin (meglumine diatrizoate, Bracco Diagnostic) fluoroscopy study to asses for leak proximally at the gastrojejunostomy and distally at the jejunojejunostomy. The normal postoperative fluoroscopic anatomy is presented in Fig. 4 A. CT is used when fluoroscopic examination is not resolving and when obstruction or an intraabdominal abscess is suspected. Normal postoperative findings at CT are shown in Fig. 4 B & C. It is normal to see retrograde flow of oral contrast material into the afferent limb and gastric remnant. We can also see gastric fluid or air in the remnant stomach as well. Our Hospital: In our hospital Laparoscopic Roux-In-Y gastric bypass is more used. Only 3 patients of our study underwent Open Roux-In-Y gastric bypass. 3 women of 48, 54 and 62 year old, 2 with BMI of 50, 46.6 and 44 kg/m respectively. The firs two had arterial hypertension and the other one did not have any associated risk factors. The 48 year old woman was a technique reconversion patient from Vertical-Banded Gastroplasty. Complications: Page 8 of 46

9 Two of the patients had complications. The 48 year old woman had a wound infection and the 62 year old woman developed an abdominal wall and intraabdominal infected collections (Fig. 5 A and B). 2. TUBULAR GASTRECTOMY Technique and Normal anatomy: It involves removal of the gastric fundus and greater curvature, creating a tubular gastric conduit. It is a restrictive technique that involves reducing the stomach capacity. The surgical technique scheme is shown in Fig. 6. Radiological evaluation: Initial imaging is should be performed on postoperative day 1 with a Gastrografin (meglumine diatrizoate, Bracco Diagnostic) fluoroscopy study to asses for leaks. Normal postoperative fluoroscopy and CT are shown in Fig 7 A & B. Our Hospital: 25 morbid obese patients (12.5% of the study population) were operated with this technique (19 women and 6 men). Age (years): y/o (Mean: 46 ± 10.8 SD) 2 2 BMI (Kg/m ): kg/m (Mean: 46.7 ± 7.4 SD) Risk factors: 15 patients (60%) (Arterial Hypertension: 15 patients; Diabetes: 4 patients; Sleep Apnea Syndrome: 5 patients). Complications: Only 4 of the 25 patients had complications. Two of then had a hemoperitoneum, one a wound infection and the other one had first an intraabdominal collection and later Page 9 of 46

10 developed several leaks and the presence of fistulas; these complications are shown in Fig 8 A, B & C. 3. LAPAROSCOPIC GASTRIC BYPASS Technique and Normal anatomy: Technique and normal anatomy is explained in Open Roux-In-Y gastric bypass (Fig 3). Radiological evaluation: Postoperative imaging is the same as in Open Roux-In-Y gastric bypass and normal fluoroscopy and normal CT findings are shown in Fig 4 A, B & C. Our Hospital: 90 morbid obese patients (45.2% of the study population) were operated with this technique (67 women and 23 men). It is the most used surgical procedure for obesity and it is more used than Open laparoscopic bypass (1.5%). Age (years): y/o (Mean: 42.4 ± 10.5 SD) 2 2 BMI (Kg/m ): kg/m (Mean: 48.9 ± 6.3 SD) Risk factors: 53 patients (58.9%) (Arterial Hypertension: 50 patients; Diabetes: 13 patients; Sleep Apnea Syndrome: 16 patients). Complications 49/90 (54%) patients had complications. The list of complications that were diagnosed are provided in Table 3. Wound infection was the most common complication seen in 33.3 % (n=30), which is an early and minor complication. Some examples of these complications are shown in Figures from 9 to 17. Page 10 of 46

11 4. VERTICAL-BANDED GASTROPLASTY Technique and Normal anatomy: The vertical banded Gastroplasty, as described by Mason in 1982, creates early satiety by surgically forming a small gastric pouch with a restricted outlet. A staple line is created along the upper lesser curvature to form a pouch of 50 ml or less capacity between the gastroesophageal junction and the remainder of the stomach. The outlet of the pouch is restricted by a silicone ring, which creates a stoma of mm in diameter (Fig. 18). Radiological evaluation: Initial postoperative imaging is performed with fluoroscopy to assess for contrast extravasation, staple line competence, and gastric pouch size; and for unhindered passage of orally administered contrast material through the surgically created stoma. Normal postoperative fluoroscopic anatomy is shown in Fig. 19. Our Hospital: This technique was performed only in to two of our patients. 2 women of 62 and 54 year 2 old, with BMI of 44 and 46.6 kg/m respectively. The first one did not have any associated risk factors, and the other one had arterial hypertension. Complications: None of these 2 women had complications but one of them, the one with 54 y/o underwent a reconversion technique into an Open Roux-In-Y Gastric Bypass. B. MINIMALLY INVASIVE PROCEDURES 1. LAPAROSCOPIC ADJUSTABLE GASTRIC BANDING Technique and Normal anatomy: Purely restrictive bariatric procedure with decreased of gastric volume and therefore early satiety. Also with decreased caloric intake. Page 11 of 46

12 Only adjustable and reversible bariatric technique. Minimally invasive (laparoscopic): reduced hospitalization time, shorter recovery period, lower rates of mortality and surgical complications, low risk of malnutrition. The technique consists of placing a silicone inflatable band around the upper stomach, dividing it into two parts: the small proximal gastric bag ("pouch") and the distal gastric remnant (Fig. 20) Both sides communicate through a stoma adjustable. The band is sutured with the serosa of the anterior stomach wall, preventing slippage. The band is connected to a silicone catheter which itself is connected to a subcutaneous access port located in the abdominal wall. Through the aspiration or injection of saline through the port will increase or decrease the size of the band and adjust the diameter of the stoma. Radiological evaluation: Fluoroscopy should be performed before and after the procedure. Technique: Patient elevated, 25-45º. Lateral dynamic Gastric view while the contrast passes through the stoma. Postprocedure fluoroscopy - Recommended measures (Fig. 21 A & B): - Proximal gastric "pouch": 3 to 4 cm of largest diameter being distended with barium. - Stoma: 3 to 4 mm. - Contrast of the proximal "pouch" should be emptied after 15 to 20 minutes after administration. Recommended postprocedure radiological control (Fig. 22 A & B): - Radiological assessment 24 hrs. after surgery (Oral contrast): position of the band, rule out perforation. We should not measure or adjust the stoma because of post-surgical gastric mucosa inflammation. - Radiological control 6-8 weeks (barium): Measurement and adjustment of the stoma: 3-4mm. 3 to 3.5 ml injection of saline. Page 12 of 46

13 - Radiological control 3rd year: Position of the band, measurement and adjustment of the stoma, rule out any complications Our Hospital: 61 morbid obese patients (30% of the study population) were operated with this technique (50 women and 11 men). Age (years): (Mean: 41.3 ± 11.7 SD) 2 BMI (Kg/m ): (Mean: 43.9 ± 6.1 SD) Risk factors: 31 patients (50.8%) (Arterial Hypertension: 23 patients; Diabetes: 7 patients; Sleep Apnea Syndrome: 5 patients). Complications (Table 4 & 5): 24/61 (39%) patients had complications. The list of complications that were diagnosed are provided in Table 5. The most common complications were: port rotation and inversion in 9.8 % (n=6) and leak from port-tubing connection that was seen in 8.2 % (n=5). Some examples of these complications are shown in Figures from 23 to % (n=9) of the patients (3 with complications and 6 of them without complications) underwent technique reconversion (6 underwent Tubular Gastrectomy and 3 Laparoscopic gastric bypass). 2. GASTRIC BALLOON Technique and Normal anatomy: It represents an endoscopic device for temporary treatment of obesity, completely reversible and repeatable, initially developed from observing the effects naturally caused by bezoars. It consists of positioning a balloon in the gastric lumen under endoscopic control, filled with between 400 and 700 ml of saline solution and methylene blue (Fig. 29). Page 13 of 46

14 It's leaved for a maximum period of 6 months, allowing a weight reduction of about kg. Radiological evaluation: In patients treated with Gastric Balloon radiologist must remember that fluoroscopy studies requires patience because the transit through the stomach is markedly delayed: often orthostatic view is insufficient to prove a duodenum opacization and supine acquisitions, specially if patient is asked to lay on the right side, are useful to rule out a complete contrast distribution inside gastric lumen and real dimensions of the balloon. The device radiologically appears as a rounded radiolucent structure filling almost the entire stomach (Fig. 30 A & B). It must be located in the corpus and in the fundus, the latter often showing a thin gastric bubble. A well-positioned device must not occupy the antrum with contrast transit obstruction. Our Hospital: In our institution Gastric Balloon is placed since 2005 in some patients included in a randomized study. Gastric Balloon is introduced 6 months before performing another type of surgical procedure to reduce weight before it. 5 patients underwent Tubular Gastrectomy after Gastric Balloon, 10 patients underwent Laparoscopic gastric bypass and 3 of the patients have not been operated yet. 18 morbid obese patients (9% of the study population) underwent this technique (11 women and 7 men). Age (years): y/o (Mean: 38.8 ± 9.9 SD) 2 2 BMI (Kg/m ): kg/m (Mean: 45.8 ± 3.6 SD) Risk factors: 8 patients (44.4%) (Arterial Hypertension: 6 patients; Diabetes: 0 patients; Sleep Apnea Syndrome: 5 patients). Complications: There were no complications in patients with Gastric Balloon. Page 14 of 46

15 Images for this section: Table 1: STUDY POPULATION DEMOGRAPHICS Table 2: TECHNIQUE RECONVERSION Page 15 of 46

16 Fig. 3: Normal Roux-In-Y Gastric Bypass. Diagram shows gastric pouch (I), gastrojejunal anastomosis (II), excluded gastric remnant (III), efferent limb (IV), afferent limb (V), and jejunojejunal anastomotic (VI). Page 16 of 46

17 Fig. 4: Normal Roux-In-Y Gastric Bypass. A. Fluoroscopic image B. & C. Axial contrastenhanced CT image. Gastric pouch (I), gastrojejunal anastomosis (II), excluded gastric remnant (III), efferent limb (IV), afferent limb (V), and jejunojejunal anastomotic (VI). Page 17 of 46

18 Fig. 5: A. Coronal and B. Sagittal contrast-enhanced CT images show an abdominal wall (arrow) and intraabdominal infected (*) collections in a 62 y/ o women who underwent open Roux-In-Y gastric bypass. Page 18 of 46

19 Fig. 6: Normal Tubular Gastrectomy. Diagram shows gastric remnant (I), and removed stomach part (II). Page 19 of 46

20 Fig. 7: Normal Tubular Gastrectomy. A. Fluoroscopic image B. Curve reconstruction contrast-enhanced CT image. Page 20 of 46

21 Fig. 8: A. Postoperative axial contrast-enhanced CT shows an intraabdominal collection (*) in a 52 y /o who underwent a tubular gastrectomy. B & C Fluoroscopic images in the same patient some days later show extraluminal oral contrast material extending to the perisplenic region (arrowheads) and the abdominal wall region (arrow) demonstrating the presence of multiple fistulas. Page 21 of 46

22 Table 3: COMPLICATIONS OF LAPAROSCOPIC GASTRIC BYPASS Page 22 of 46

23 Fig. 9: Dumping Syndrome. Contrast study demonstrated a premature emptying of the contrast medium from the stomach. Page 23 of 46

24 Fig. 10: Obstruction. A. Plain abdominal radiography shows fluid levels (arrow) in relation to intestinal obstruction that improved with conservative treatment B. Contrast study in a different patient demonstrate an occlusive crisis by stricture in the jejunojejunal anastomosis (*) (9 days after surgery). C. Coronal contrast-enhanced CT image of a pseudo-obstruction (*dilated loops; +collapsed loops), that resolved conservatively. Page 24 of 46

25 Fig. 11: A & B. Axial contrast-enhanced CT images show wound infection with cellulitis and myositis (arrows). Page 25 of 46

26 Fig. 12: Jejunojejunal anastomosis leak. Axial contras-enhanced CT images (A and B) show air bubbles near jejunojejunal anastomosis (arrow) and a intraabdominal collection (*) Page 26 of 46

27 Fig. 13: A & B. Axial contrast-enhanced CT images demonstrated an intraabdominal hematoma / hemoperitoneum (*) next to the gastric pouch (I). Page 27 of 46

28 Fig. 14: Gastrojejunal stricture. Contrast study demonstrates a narrowed gastro-jejunal anastomosis (arrow) with dilated gastric pouch Page 28 of 46

29 Fig. 15: Port site hernia. A. Sagittal contrast-enhanced CT image shows ventral hernia (arrow) B. Ultrasound image shows same patient s hernia (*). The patient came to the emergency department with a painful lump in the abdominal wall (ultrasonography was performed first) Fig. 16: Axial (A) and Sagittal (B) contrast-enhanced CT images demonstrate incarcerated port side hernia (arrow). Page 29 of 46

30 Fig. 17: Axial contrast-enhanced CT image show an abdominal wall infected collection in a patient with a laparoscopic gastric bypass that underwent an abdominoplasty, performed after weight loss. Page 30 of 46

31 Fig. 18: Normal Vertical-Banded Gastroplasty. Diagram shows gastric pouch (I) and the sillicone ring (II) Page 31 of 46

32 Fig. 19: Normal Vertical-Banded Gastroplasty. Fluoroscopic image shows gastric pouch (I) and the stoma creates by the sillicone ring (II). Page 32 of 46

33 Fig. 20: Normal Laparoscopic Adjustable Gastric Banding. Diagram shows gastric pouch (I), band (II), distal gastric remnant (III) and port (IV), which is place subcutaneously. Page 33 of 46

34 Fig. 21: Normal Laparoscopic Adjustable Gastric Banding. A & B. Plain Abdominal radiographies show access port (1), silicon catheter (2) and gastric band (3). Page 34 of 46

35 Fig. 22: A & B. Recommended postprocedure radiological control. Contrast studies show gastric pouch (arrowhead), stoma (arrow in A), esophagus (E), gastric remnant (S) and gastric band (arrow in B). Table 4: COMPLICATIONS OF LAPAROSCOPIC ADJUSTABLE GASTRIC BANDING Table 5: COMPLICATIONS OF LAPAROSCOPIC ADJUSTABLE GASTRIC BANDING Page 35 of 46

36 Fig. 23: A & B. Gastric pouch dilatation (measures: 50 x 42 mm.) Page 36 of 46

37 Fig. 24: Contrast image show persistence of stenosis in the gastric fundus after band removal because of band abscess and gastric perforation. Page 37 of 46

38 Fig. 25: Pouch eccentric dilatation (7.6 cm.). Normal caliber stoma (3.6 cm.) Page 38 of 46

39 Fig. 26: Leak from port-tubing connection Page 39 of 46

40 Fig. 27: Band erosion into stomach (arrow). Radiological (A) and endoscopic (B) image. Page 40 of 46

41 Fig. 28: Gastric volvulus. Page 41 of 46

42 Fig. 29: Diagram shows normal Gastric Balloon. Page 42 of 46

43 Fig. 30: Fluoroscopic image and plain abdominal radiograph show normal Gastric Balloon (*) Page 43 of 46

44 Conclusion The alarming increase in the prevalence of morbid obesity has led to increase the number and variety of surgical procedures in obese subjects. Therefore it is important that the radiologist is familiar with normal postoperative anatomy in patients undergoing surgical procedures for morbid obesity, as well as possible complications. And thus knows what imaging technique used in each time and the obese patient-adapted. In our institution Laparoscopic gastric bypass is the most used surgical procedures for obesity followed by Laparoscopic adjustable gastric banding. We had few complications in our patients and the most common in all techniques were early and minor complications. Novel techniques such as laparoscopic adjustable gastric banding and gastric balloon, where fluoroscopy plays a key role, often cause a little account of major complications. References 1. Quigley S, Colledge J, Mukherjee S, et al. Bariatric surgery: A review of normal postoperative anatomy and complications. Clinical Radiology 2011; 66: Chandler R C, Srinivas G, Chintapalli K N, et al. Imaging in Bariatric surgery: A guide to postsurgical Anatomy and Common Complications. American Journal of Roentgenology 2008; 190: Mitchell M T, Carabetta J M, Shah R N, et al. Duodenal Switch Gastric Bypass Surgery for Morbid Obesity: Imaging of postsurgical Anatomy and Postoperative Gastrointestinal Complications. American Journal of Roentgenology 2009; 193: Buckley O, Ward E, Ryan A, et al. European obesity and the radiology department. What can we do to help? Eur Radiol 2009; 19: Smith T R and White A P. Narrowing of the Proimal Jejunal Limbs at Their passage throug the Transverse Mesocolon: A Potential Pitfall of Laparoscopic Roux-en-Y Gastric Bypass. American Journal of Roentgenology 2004; 183: Page 44 of 46

45 6. Carucci L R, Turner M A, Conklin R C, et al. Roux-en-Y Gastric Bypass Surgery for Morbid Obesity:Evaluation of Postoperative Extraluminal Leaks with Upper Gastrointestinal Series. Radiology 2006; 238: Hainaux B, Coppens E, Sattari A, et al. Laparoscopic adjustable silicone gasric banding: radiological appearance of a new surgical treatment for morbid obesity. Abdominal Imaging 1999; 24: Carucci L R, Turner M A and Shaylor S D. Internal Hernia Following Roux- en-y Gastric Bypass Surgery for Morbid Obesity: Evaluation of Radiographic Findings at Small-Bowel Examination. Radiology 2009; 251: Lockhart M E, Tessler F N, Canoon C L, et al. Internal Hernia After Gastric Bypass: Sesitivity and Specificity of Seven CT Signs with Surgical Correlation and Controls. American Journal of Roentgenology 2007; 188: Reddy S A, Yang C, McGinnis L A, et al. Diagnosis of Transmesocolic Internal Hernia as a Coplication of Retrocolic Gastric Bypass: CT Imaging Criteria. American Journal of Roentgenology 2007; 189: Maggard M A, Shugarman L R, Suttorp M, et al. Meta-Analysis: Surgical Treatment of Obesity. Annals of Internal Medicine 2005; 142: Scheirey C D, Scholz F J, Shah P C, et al. Radiology of the Laparoscopic Roux-enY Gastric Bypass Procedure: Conceptualiza- tion and Precise Inter- pretation of Results. Radiographics 2006; 26: Trenkner S W. Imaging of morbid obesity procedures and their complications. Abdominal Imaging 2009; 34: Yu J, Turner M A, Cho S-R, et al. Normal Anatomy and Complications after Gastric Bypass Surgery: Helical CT Findings. Radiology 2004; 231: Merkle E M, Hallowell P T, Crouse C, et al. Roux-en-Y Gastric Bypass for Clinically Severe Obesity: Normal Appearance and Spectrum of Complications at Imaging. Radiology 2005; 234: Page 45 of 46

46 16. Sandrasegaran K, Rajesh A, Lall C, et al. Gastrointestinal complications of bariatric Roux-en-Y gastric bypass surgery. Eur Radiol 2005; 15: Personal Information JAVIER FERNANDEZ JARA Servicio de Radiodiagnóstico Hospital Universitario Severo Ochoa Avenida Orellana s/n, Leganés (Madrid), SPAIN Page 46 of 46