This study was conducted at the radiology department of a specialized hospital in the period from December 2014 to March 2018. The study cohort primarily included all patients who underwent laparoscopic gastric bypass and sleeve gastrectomy operated at the bariatric surgery department for treating their morbid obesity (BMI > = 35 kg/m2) with obesity-related serious comorbidities (ex. DM, HTN) or BMI > 40 with or without comorbidities. These patients were referred for the diagnostic evaluation of their postoperative complaints in the early and late postoperative periods. Thorough history taking, clinical review, and laboratory investigations were done to rule out nutritional/functional causes of abdominal pain. An upper gastrointestinal imaging (UGI) was performed for all patients. This was followed by CT scans and right upper quadrant ultrasound (when the gallbladder is present). Exclusion criteria included 47 patients who had undergone other surgical techniques or had been operated by a different team, those proved to have functional or biliary causes of abdominal symptoms as shown by ultrasound, those with contraindications to radiation exposure or iodinated contrast media and those exceeding the weight limit of the examination table (300 kg maximum weight capacity). Included patients (a total 129) were interviewed and a protocol was filled with identification of hospital number, name, age, gender, time of surgery, and history of allergy to the iodinated contrast media or drugs.
An upper gastrointestinal contrast-enhanced study (UGIS) was first performed for all patients. The choice of contrast medium whether gastrografin or barium was determined by the time of presentation of the patient and his complain. For patients presenting in the early postoperative period (first 30 days after surgery) gastrografin meal was done unless there is any suspicion of aspiration or a fistulous communication to tracheobronchial tree due to the risk of gastrografin-associated pneumonitis. For patients presenting later, barium meal was done unless there is any fear of communication to the mediastinum or to the peritoneal cavity, gastrografin was used instead because of barium’s risk of massive peritonitis or mediastinitis. The patients were asked to fast for 6 h prior to the study. Scout images were obtained to detect free or loculated extraluminal gas as well as radiopaque staple lines that otherwise could be mistaken for small leaks during the fluoroscopic examination. Under fluoroscopic screening the patient was asked to swallow the bolus of the contrast and imaging was performed in the supine and supine left posterior oblique position, screening down the esophagus into the gastric pouch. If leakage was demonstrated across the staple line in RYGB or along the resection line in sleeve gastrectomy the examination was stopped. If no leakage was noticed, rotation from left lateral to RAO to supine until opacification of the duodenum then jejunal loops occurs. In RYGB, the CM is followed from the pouch into the Roux limb via the gastrojejunal anastomosis. The time taken for complete passage of the contrast through the gastric pouch was calculated (gastric emptying time) and the free passage through the bowel loops was assessed.
For computed tomography, a consent form was delivered to all patients and thoroughly explained. The MDCTs were conducted using 128-MDCT scanner (Toshiba Aquilion) with detector configuration of 128 × 0.5 mm, rotation time of 0.35 s, 120 kV, and 93 mAs. Axial slices were obtained from the diaphragmatic domes to the lower end of symphysis pubis. Unenhanced scan is performed to detect hemorrhage followed by contrast-enhanced scan after the intravenous injection of Omnipaque at a dose of 150 ml, with mechanical pump injectors at 2–3 ml/s in the arterial, portal, and equilibrium phases. The arterial phase is used mainly to identify active bleeding and the portovenous phase to identify an abscess. On suspicion of dehiscence of sutures or perforation, a sequence is then performed after oral intake of iohexol (Omnipaque 300 ®, Nycomed, Princeton, NJ, USA, diluted in mineral water for 30 min). The volume of administered oral contrast material will depend on the patient’s tolerance. Finally, the reconstructed image data set was networked to the workstation. Coronal and sagittal reconstruction was obtained at 2 mm slice thickness. All studies were reviewed by two radiologists with at least 15 years of experience in abdominal imaging.
All studies were reviewed by three radiologists with 8,15, and 20 years of experience in gastrointestinal radiology respectively.
In cases of Roux-en-Y gastric bypass
The anatomy of the postoperative gastric bypass was studied by analyzing the volume of the gastric pouch, proximal aspect of the jejunum efferent loop, the jejunal afferent loop (blind loop), the excluded stomach, and the gastric area. The presence of complications was investigated such as (1) anastomotic leaks; most leaks are defined after oral administration of water-soluble contrast as blind-ending tracks or sealed-off collections abutting the anastomotic region or, less frequently, as free leaks into the peritoneal cavity. Most leaks occur at the gastrojejunal anastomosis [24, 25], less common sites of perforation include the gastric pouch, blind-ending jejunal stump, and jejunojejunostomy. Anastomotic leaks may extend as extraluminal collections in the left upper quadrant on upper GI studies or CT scans, sometimes continuing superiorly into the subphrenic space [15, 23,24,25, 32]. (2) gastrojejunal anastomotic strictures. They usually appear on UGIS as short segments of smooth narrowing at the gastrojejunal anastomosis . If obstruction is present, the gastric pouch may be dilated, and emptying of barium into the Roux limb may be delayed with no distension of the distal small intestine and colon. (3) Internal hernia, usually results from herniation of small bowel loops through a defect in the transverse mesocolon (for a retrocolic Roux limb), is a defect in the small bowel mesentery (for a jejunojejunal anastomosis), or a defect posterior to the Roux limb (i.e., Petersen defect). It should be suspected on both CT images and barium studies when a cluster of small bowel loops is seen in abnormal locations especially the left mid-abdomen or left upper quadrant above the transverse mesocolon often displacing other bowel and associated with migration of an anastomotic jejunojejunal suture line. This suture line is most often displaced from its typical location in the left mid-abdomen into the left upper quadrant, but it can also be displaced into the right mid-abdomen . One advantage of the barium study over CT is the ability to visualize changes in the configuration of the small bowel entering and exiting the hernia during the course of the examination with retention of barium within these loops [26, 33]. However, CT enables visualization of changes in the mesentery, such as stretching and rotation of vessels “swirl sign” and or engorgement of mesenteric vessels [33, 34]. (4) Intestinal obstruction may be caused by adhesions, internal hernias, anterior abdominal wall hernias, strictures at the jejunojejunal anastomosis, and, rarely, intussusceptions. (5) Intussusception typically occurs at or near the jejunojejunal anastomosis, with the staple line at this anastomosis presumably acting as the lead point for the intussusception . (6) Gastroesophageal spasm.
In cases of sleeve gastrectomy
UGSI and C.T images were assessed for the presence of the following: (1) intraoperative organ injury, e.g., splenic injury. (2) Gastric leaks along the staple line, the leak may be free or contained. A free leak was diagnosed if spillage of contrast was seen into the peritoneal cavity, whereas a contained leak was diagnosed on the extension of the contrast beyond the expected lumen. (3) Perigastric collection, hematoma, and hemoperitoneum. Acute hematoma has high attenuation values (40—60 HU) Chronic hematoma may be difficult to distinguish from other fluid collections. (4) Presence of vascular affection, e.g., portal, splenic, and mesenteric vascular occlusion. (5) Abscess formation secondary to leak identified as high-density intraperitoneal fluid collection with rim enhancement that contains both gas and fluid. The presence of contrast material within the abscess after oral ingestion of contrast material confirms its origin. (6) Fistula formation: gastrocutaneous and gastrobronchial fistula secondary to subphrenic infection complicating staple line leak. CT may demonstrate the fistula, subphrenic abscesses, associated pleural effusion, and lung infection. (7) Strictures; gastric strictures may occur early, within a few days, secondary to ischemia or edema, or may occur later, usually as a result of fibrosis. Focal strictures or long segments of narrowing may occur when scarring occurs along the greater curvature staple line and barium studies may reveal focal strictures or long segments of narrowing with delayed emptying of barium from the residual stomach. (8) dilatation of gastric pouch. Barium studies may reveal the widening of the gastric sleeve, which no longer has a tubular appearance. (9) Incisional hernia. (10) Hiatus hernia [15, 23, 32].
Data were analyzed using Statistical Program for Social Science (SPSS) version 20.0. Quantitative data were expressed as mean ± standard deviation (SD). The following tests were done: (1) independent samples t test of significance was used when comparing between two means. (2) A one-way analysis of variance (ANOVA) when comparing between more than two means. (3) Chi-square (χ2) test of significance was used in order to compare proportions between two qualitative parameters. Probability (P value) P value < 0.05 was considered significant. P value < 0.001 was considered as highly significant. P value > 0.05 was considered insignificant.