Ultrasonographic findings identifying the faecal-impacted appendix: differential findings with acute appendicitis

doi:10.1259/bjr/80553348

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Ultrasonographic findings identifying the faecal-impacted appendix: differential findings with acute appendicitis

N H Park, MD ¹ C S Park, MD ¹ E J Lee, MD ¹ M S Kim, MD ¹ J A Ryu, MD ¹ J M Bae, MD ² and J S Song, MD ³

¹ Department of Diagnostic Radiology, Myongji Hospital, Kwandong University, College of Medicine, ² Department of Preventive Medicine, Cheju National University, College of Medicine, ³ Department of Pathology, Myongji Hospital, Kwandong University, College of Medicine, Korea

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Figure 1. Pathologically confirmed faecal-impacted normal appendix. (a) Longitudinal and (b) transverse sonograms of the appendix show a distended lumen containing heterogeneous echogenic material implying faecal material (long arrow in b). Preservation of the inner hypoechoic mucosal lining (short arrows in b) is also noted. (c) Longitudinal image shows intraluminal faecal material (blue arrows) and a well-preserved abundant lymphoid mucosal layer without inflammatory cell infiltration (white arrows).

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Figure 2. A 10-year-old-boy with primary mesenteric lymphadenitis. (a,b) A normal hypoechoic mucosal layer (long arrows in a) and echogenic lumen–mucosa interface (short arrows in a) are well delineated without disruption. (b) The outer transverse diameter of the appendix is approximately 8.2 mm. No evidence of peri-appendiceal infiltration is seen. Pathology confirmed lymphoid hyperplasia with faecal impaction.

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Figure 3. A 4-year-old boy presenting with acute gastroenteritis and mesenteric lymphadenopathy. (a) Heterogeneous faecal material is noted in the appendix. The outer transverse diameter of the appendix is 6.7 mm. The normal wall layers of the appendix are preserved, including a thick hypoechoic mucosal layer (long arrows); no peri-appendiceal fat infiltration is seen, but scanty free fluid is seen in the peri-appendiceal area (short arrow). (b) Another 5-year-old boy with a faecal-impacted appendix; no demonstrably increased blood flow in the appendiceal wall is seen on colour Doppler study.

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Figure 4. A 9-year-old boy with mesenteric lymphadenitis (follow-up study). (a) A normal appendix without faecal impaction (initial examination). (b) Follow-up 18 days after the initial examination. Faecal impaction with a small echogenic faecolith (longest arrow) is seen. The normal echogenic mucosa–lumen interface (short arrows) and hypoechoic mucosal layer (long arrows) are preserved. The outer transverse diameter of the appendix is 6.7 mm. (c) Follow-up 19 days after the initial examination. Faecal impaction with a small echogenic faecolith is also noted. The outer transverse diameter of the appendix is 6.5 mm.

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Figure 5. Comparison between(a) faecal-impacted appendix and (b) acute appendicitis. Longitudinal ultrasonography image shows the heterogeneous echogenic feacal material impacted in the appendix and well-delineated hypoechoic inner mucosal layer (arrows). Longitudinal ultrasonography image shows the inner hypochoic mucosal layer, which is indistinguishable from hypoechoic intraluminal pus. A focally disrupted echogenic submucosal layer (short arrows) and echogenic inflamed peri-appendiceal fat infiltration (long arrows) are also noted.