CT findings on abdomen CT
Case 121
【Progress】Although clinical data and CT findings about small bowel necrosis were not obtained at that time, our clinicians thought surgical management should be done for this situation as soon as possible. Unfortunately, our surgeon was doing surgical management for other patient which was scheduled to take long time. Then, she was transferred to the emergent hospital where surgical management could be supplied at once.
【Discussion】
The function of appendix has been accepted as a remnant in the process of human evolution, being possibly non-functioning because removal of appendix does not cause harmful affect on human body. However, it is reported that individuals without appendix are more susceptible to recur clostridium difficile colitis four times more (1-3). Then, it is considered that appendix is a safe house or a reservoir after bacterial colitis. Namely, when bacterial colitis is infected, diarrhea flows away the harmful bacteria in the entire colon except appendix and the beneficial bacteria reserved in appendix proliferate and cover the whole colon, returning the healthy flora (1-3).
The base of the appendix is situated 2 cm beneath ileo-colic valve (Bauhin’s valve). The position of appendix is corresponded to McBurney’s point on the skin surface. The length of the appendix is approximately 10 cm long (< 26cm) (4-6). The appendix gets blood supply from the vessel protected in mesoappendix connected to mesentery. The position of appendix varies but is most common in retro-cecum with the incidence of approximately 60% followed by medio-inferior cecum (4-6).
Internal hernia after appendectomy usually occurs along with the surgical suture line (5, 6). When appendix situates at retro-cecum, the small bowel can herniate after appendectomy into the retro-cecum and/or retro-ascending colon. Then, it is important to interpret the relation of the position between herniated small bowel and the cecum or ascending colon In our case, small bowels of the herniated content situated behind the cecum and the ascending colon, implying the typical case of internal hernia after appendectomy.
In our patient, CT showed small mesentery fan sign, beak sign, feces sign, closed (cluster) loop sign, and whirl sign. These findings are usually adjacent to each other. Small mesentery fan sign implies mesentery gate of the herniated small bowel and the pivot of the fan implies the hernia gate. The herniated mesentery is often associated with edema due to obstruction of lymphatic channel and/or portal vein. Beak sign implies the occlusive point of small bowel. Both mesentery and small bowel are obstructed together almost at the same position, the hernia gate. It is easier to find out the small mesentery fan sign than beak sign. Closed (Clustered) loop sign implies the herniated small bowel. When the internal herniation space is larger, the configuration of the herniated small bowel looks like a closed loop and when the herniated space is narrow, the configuration of the herniated small bowel looks like a clustered loop. Irrespective closed loop or clustered loop, the small bowel wall thickens with edema. Feces sign is usually found in the oral-sided small bowel from the occlusion point, implying the contents of the small bowel do not move to anal side. Namely, feces sign indicates the occlusion point exists nearby. Whirl sign implies torsion of the mesentery and most often in strangulation ileus but that does not always mean irreversible strangulation ileus. We had previously experienced a case of ileus with whirl sign which was diagnosed as strangulation ileus but several days later, it returned to the original healthy position.
【Summary】
We present a ninety six-year-old female suffering from persistent abdominal pain. She had undergone appendectomy and ovariectomy approximately 50 years ago. CT showed small mesentery fan sign, beak sign, feces sign, closed loop sign and whirl sign. Closed loop situated at retro-cecum and ascending colon which was compatible with post-appendectomy internal hernia. We should keep in mind that ; small mesentery fan sign implies mesentery of the herniated small bowel and the pivot of the fan implies the hernia gate; Beak sign implies the occlusive point of small bowel at the hernia gate; Closed (Clustered) loop sign implies the herniated small bowel; Feces sign is usually found in the oral-sided small bowel from the occlusion point, implying the contents of the small bowel do not move to anal side: Whirl sign implies torsion of the mesentery and most often in strangulation ileus. Further, the function of appendix is a safe house or a reservoir after bacterial colitis. Furthermore, the position of appendix is most common in retro-cecum with the incidence of approximately 60% followed by medio-inferior cecum.
【References】
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5.Gordon R, et al. Residual appendix producing small-bowel obstruction after laparoscopic appendectomy. Can J Surg. 2004; 47: 217–218.
6.Rajan M, et al. Staple line as a cause of unusual early internal hernia after appendectomy. Int J Surg. 2014;12 :S159-61. doi: 10.1016/j.ijsu.2014.05.021. Epub 2014 May 22.
2018.9.19