Imaging diagnosis
Case 120
【Progress】Her abdominal pain was getting relieved after admission. Two days later, laboratory test revealed marked decrease of values of amylase and lipase. However, she was still under inspection without getting food at the time of Day 5 in her hospital stay.
【Discussion】
Billroth I, Billroth II and Roux-en-Y are supplied as surgical procedures of partial gastrectomy for gastric cancer. Billroth I is gastroduodenostomy, and Billroth II and Roux-en-Y are gastrojejunostomy. Billroth II is the procedure that closure of the resected end of duodenum is associated with end-to-side suture between the residual stomach and the first jejunum (1-6). Meanwhile, Roux-en-Y is the procedure that closure of the resected end of duodenum is associated with two anastomosis; end-to-end suture between the residual stomach and the second jejunum: side-to-side suture between the first jejunum and the second jejunum. Roux-en-Y procedure is more preferred than both of Billroth I and II because of the less incidence of reflux of bile and pancreatic juice due to the long distance of the afferent and efferent limbs (1-6).
However, the incidence of internal hernial is known to happen more in Roux-en-Y than both of Billroth I and II (1-6). Roux-en-Y procedure has two methods. When the second jejunum runs anterior to transverse colon, it is called “ante-colic” and when the second jejunum runs posterior to transverse colon, it is called “retro-colic”. In case of retro-colic, a pore is formed in mesocolon for passage of the second jejunum. Then, in case of retro-colic, there are three possible sites for internal hernia; mesocolon defect, interspace between mesocolon of the transverse colon and mesentery of the second jejunum, which is called Petersen defect, and interspace between mesentery of the first jejunum and the mesentery of the second jejunum, which is called jejuno-jejunostomy defect (1-6). In case of antero-colic which is usually adopted by endoscopic laparotomy, there are two possible sites of internal hernia: Petersen defect and jejuno-jejunostomy defect (1-6). Our patient illness history revealed Roux-en-Y was performed for advanced gastric cancer and coronal image of abdomen CT showed retro-colic type anastomosis.
Of the internal hernias after Roux-en-Y management, Peterson hernia is the most common and occurs peculiarly in Roux-en-Y management. It occurs irrespective of ante-colic and retro-colic. The closure of this space or the long second jejunum limb more than 50 cm are known to prevent Peterson hernia (1-6). CT findings are imperative to diagnose internal hernia (7). In short, small fan sign that means that herniated small-type mesentery with superior mesenteric vessels sometimes associated mesenteric edema and ascites (chyle ascites), indicating hernia gate with strangulated mesentery. Clustered loop sign or closed loop sign implies internal-herniated small intestine with edematous thick wall due to congestion or ischemia (1, 7). Feces sign means the dilated small intestine in which contains contents with air bubble like colon stool, indicating the obstructed non-flow segment of small intestine. Whirl sign indicates rotation or strangulation of the mesentery associated with small bowels. Coronal image of abdomen CT is more critical rather than axial or sagittal images to visualize these configurations because the space of coronal image is the largest. Enhanced CT is also important to check ischemia of the herniated bowel in comparing the contrast medium concentration of vessels and the herniated bowel wall to those of the non-herniated bowel (1, 7). In our case, abdomen CT showed small fan sign, clustered (closed) loop sign, feces sign and whirl sign, but almost the same concentration of contrast medium of herniated bowel wall and its mesentery vessels as non-herniated bowel and its mesentery, indicating no status of necrosis. There are possible sites of the internal hernias; Peterson hernia occur in the right lower abdomen, jejuno-jejunostomy hernia in left lower abdomen and mesocolon hernia in the upper abdomen above transverse colon. Internal hernia in our patient was shown in abdomen CT in right lower abdomen, not contradictory with Peterson hernia.
When intraluminal pressure of afferent loop is elevated by ileus, pancreatitis can occur. In our case, the first symptom was abdominal pain and laboratory test revealed high values of amylase, which might be caused by Peterson hernia.
【Summary】
We present a seventy six-year-old female suffering from abdominal pain, and high values of amylase and lipase in laboratory test. She previously received Roux-en-Y management for advanced gastric cancer. Abdomen CT showed internal hernia in the right lower abdomen with edematous small fan sign, feces sign, clustered (closed) loop sign and whirl sign, although enhanced CT using contrast medium showed no ischemic damage to the herniated small bowel. We should keep in mind that of the three defects after Roux-en-Y anastomosis, Peterson hernia occurs most often between an interspace of mesocolon and mesentery of the second jejunum, irrespective of ante-colic or retro-colic approach. Further, small fan sign indicates internal hernia which sometimes associates with mesentery edema, clustered (closed) loop sign does edematous bowel inside the internal hernia, feces sign does obstructive small bowel with least flow of the contents inside, whirl sign does torsion or strangulation of mesentery and small bowel.
【References】
1.Massimiliano Fabozzi, et al. Intestinal infarction by internal hernia in Petersen’s space after laparoscopic gastric bypass. World J Gastroenterol. 2014 Nov 21; 20(43): 16349–16354.
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7.Lockhart ME, et al. Internal Hernia After Gastric Bypass: Sensitivity and Specificity of Seven CT Signs with Surgical Correlation and Controls. A. m J Roentgenol. 2007;188:745–750. [PubMed]
2018.9.12