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Intussusception in Children: Current Concepts in Diagnosis and Enema Reduction

¹ Section of Pediatric Radiology, Department of Diagnostic Radiology, Hospital Universitario Infantil 12 de Octubre, Carretera de Andalucía Km 5,400, 28041 Madrid, Spain (G.d.P., J.C.A., R.C., M.R., U.d.l.C., U.L.P.)
² Department of Diagnostic Radiology, Hospital Universitario de la Princesa, Madrid, Spain (D.T.)

View larger version (141K): [in a new window]   Figure 1.  Target sign. Plain radiograph shows a round soft-tissue mass in the right upper quadrant. The mass contains a ringlike area of lucency.

View larger version (125K): [in a new window]   Figure 2.  Meniscus sign. Plain radiograph shows the meniscus sign: a rounded soft-tissue mass (the intussusceptum) protruding into the gas-filled transverse colon.

View larger version (95K): [in a new window]   Figure 3a.  Meniscus and coiled spring signs. (a) Image from a barium enema study shows the meniscus sign in the contrast material–filled distal colon. (b) Image from a barium enema study performed after partial reduction of the intussusception shows the coiled spring sign. Contrast material outlines the facing mucosal surfaces of the intussuscipiens and the intussusceptum. (c) Image from a barium enema study performed after complete reduction of the intussusception shows barium flowing freely into the ileum.

View larger version (94K): [in a new window]   Figure 3b.  Meniscus and coiled spring signs. (a) Image from a barium enema study shows the meniscus sign in the contrast material–filled distal colon. (b) Image from a barium enema study performed after partial reduction of the intussusception shows the coiled spring sign. Contrast material outlines the facing mucosal surfaces of the intussuscipiens and the intussusceptum. (c) Image from a barium enema study performed after complete reduction of the intussusception shows barium flowing freely into the ileum.

View larger version (87K): [in a new window]   Figure 3c.  Meniscus and coiled spring signs. (a) Image from a barium enema study shows the meniscus sign in the contrast material–filled distal colon. (b) Image from a barium enema study performed after partial reduction of the intussusception shows the coiled spring sign. Contrast material outlines the facing mucosal surfaces of the intussuscipiens and the intussusceptum. (c) Image from a barium enema study performed after complete reduction of the intussusception shows barium flowing freely into the ileum.

View larger version (42K): [in a new window]   Figure 4.  Structure of an intussusception. Diagram shows a longitudinal view and three axial views of an intussusception; three bowel loops and the mesentery can be seen. The intussuscipiens (A) contains the two limbs of the intussusceptum: the everted returning limb (B), which is edematous, and the central entering limb (C), which is located at the center of the intussusception with the accompanying mesentery (M). The mesentery contains some lymph nodes (L). MS = contacting mucosal surfaces of the intussuscipiens and everted limb, S = contacting serosal surfaces of the everted limb and central limb.

View larger version (116K): [in a new window]   Figure 5a.  Structure of an intussusception. Axial US scans and corresponding pathologic specimens from pigs with intussusception show the doughnut sign: a hypoechoic outer ring formed by the everted limb of the intussusceptum (B) and the intussuscipiens (A) and a center that varies with the section level. C = central limb of the intussusceptum. (Reprinted, with permission, from reference 17.) (a, b) US scan (a) and pathologic specimen (b) obtained at the apex of an intussusception (section 1 in Fig 4) show a hypoechoic center, which represents the central limb of the intussusceptum with no mesentery present. Note the multilayered appearance, which is due to the demonstration of the five layers of the three bowel loops involved. (c, d) US scan (c) and pathologic specimen (d) obtained at the base of the intussusception (section 2 in Fig 4) show a hyperechoic, crescent-shaped center. This appearance occurs when the mesentery encloses the central limb of the intussusceptum (the crescent-in-doughnut sign). (e, f) US scan (e) and pathologic specimen (f) obtained at a different level of the base (section 3 in Fig 4) show an additional hypoechoic area in the hyperechoic, crescent-shaped center. This additional hypoechoic area represents a lymph node (L).

View larger version (157K): [in a new window]   Figure 5b.  Structure of an intussusception. Axial US scans and corresponding pathologic specimens from pigs with intussusception show the doughnut sign: a hypoechoic outer ring formed by the everted limb of the intussusceptum (B) and the intussuscipiens (A) and a center that varies with the section level. C = central limb of the intussusceptum. (Reprinted, with permission, from reference 17.) (a, b) US scan (a) and pathologic specimen (b) obtained at the apex of an intussusception (section 1 in Fig 4) show a hypoechoic center, which represents the central limb of the intussusceptum with no mesentery present. Note the multilayered appearance, which is due to the demonstration of the five layers of the three bowel loops involved. (c, d) US scan (c) and pathologic specimen (d) obtained at the base of the intussusception (section 2 in Fig 4) show a hyperechoic, crescent-shaped center. This appearance occurs when the mesentery encloses the central limb of the intussusceptum (the crescent-in-doughnut sign). (e, f) US scan (e) and pathologic specimen (f) obtained at a different level of the base (section 3 in Fig 4) show an additional hypoechoic area in the hyperechoic, crescent-shaped center. This additional hypoechoic area represents a lymph node (L).

View larger version (106K): [in a new window]   Figure 5c.  Structure of an intussusception. Axial US scans and corresponding pathologic specimens from pigs with intussusception show the doughnut sign: a hypoechoic outer ring formed by the everted limb of the intussusceptum (B) and the intussuscipiens (A) and a center that varies with the section level. C = central limb of the intussusceptum. (Reprinted, with permission, from reference 17.) (a, b) US scan (a) and pathologic specimen (b) obtained at the apex of an intussusception (section 1 in Fig 4) show a hypoechoic center, which represents the central limb of the intussusceptum with no mesentery present. Note the multilayered appearance, which is due to the demonstration of the five layers of the three bowel loops involved. (c, d) US scan (c) and pathologic specimen (d) obtained at the base of the intussusception (section 2 in Fig 4) show a hyperechoic, crescent-shaped center. This appearance occurs when the mesentery encloses the central limb of the intussusceptum (the crescent-in-doughnut sign). (e, f) US scan (e) and pathologic specimen (f) obtained at a different level of the base (section 3 in Fig 4) show an additional hypoechoic area in the hyperechoic, crescent-shaped center. This additional hypoechoic area represents a lymph node (L).

View larger version (153K): [in a new window]   Figure 5d.  Structure of an intussusception. Axial US scans and corresponding pathologic specimens from pigs with intussusception show the doughnut sign: a hypoechoic outer ring formed by the everted limb of the intussusceptum (B) and the intussuscipiens (A) and a center that varies with the section level. C = central limb of the intussusceptum. (Reprinted, with permission, from reference 17.) (a, b) US scan (a) and pathologic specimen (b) obtained at the apex of an intussusception (section 1 in Fig 4) show a hypoechoic center, which represents the central limb of the intussusceptum with no mesentery present. Note the multilayered appearance, which is due to the demonstration of the five layers of the three bowel loops involved. (c, d) US scan (c) and pathologic specimen (d) obtained at the base of the intussusception (section 2 in Fig 4) show a hyperechoic, crescent-shaped center. This appearance occurs when the mesentery encloses the central limb of the intussusceptum (the crescent-in-doughnut sign). (e, f) US scan (e) and pathologic specimen (f) obtained at a different level of the base (section 3 in Fig 4) show an additional hypoechoic area in the hyperechoic, crescent-shaped center. This additional hypoechoic area represents a lymph node (L).

View larger version (153K): [in a new window]   Figure 5e.  Structure of an intussusception. Axial US scans and corresponding pathologic specimens from pigs with intussusception show the doughnut sign: a hypoechoic outer ring formed by the everted limb of the intussusceptum (B) and the intussuscipiens (A) and a center that varies with the section level. C = central limb of the intussusceptum. (Reprinted, with permission, from reference 17.) (a, b) US scan (a) and pathologic specimen (b) obtained at the apex of an intussusception (section 1 in Fig 4) show a hypoechoic center, which represents the central limb of the intussusceptum with no mesentery present. Note the multilayered appearance, which is due to the demonstration of the five layers of the three bowel loops involved. (c, d) US scan (c) and pathologic specimen (d) obtained at the base of the intussusception (section 2 in Fig 4) show a hyperechoic, crescent-shaped center. This appearance occurs when the mesentery encloses the central limb of the intussusceptum (the crescent-in-doughnut sign). (e, f) US scan (e) and pathologic specimen (f) obtained at a different level of the base (section 3 in Fig 4) show an additional hypoechoic area in the hyperechoic, crescent-shaped center. This additional hypoechoic area represents a lymph node (L).

View larger version (172K): [in a new window]   Figure 5f.  Structure of an intussusception. Axial US scans and corresponding pathologic specimens from pigs with intussusception show the doughnut sign: a hypoechoic outer ring formed by the everted limb of the intussusceptum (B) and the intussuscipiens (A) and a center that varies with the section level. C = central limb of the intussusceptum. (Reprinted, with permission, from reference 17.) (a, b) US scan (a) and pathologic specimen (b) obtained at the apex of an intussusception (section 1 in Fig 4) show a hypoechoic center, which represents the central limb of the intussusceptum with no mesentery present. Note the multilayered appearance, which is due to the demonstration of the five layers of the three bowel loops involved. (c, d) US scan (c) and pathologic specimen (d) obtained at the base of the intussusception (section 2 in Fig 4) show a hyperechoic, crescent-shaped center. This appearance occurs when the mesentery encloses the central limb of the intussusceptum (the crescent-in-doughnut sign). (e, f) US scan (e) and pathologic specimen (f) obtained at a different level of the base (section 3 in Fig 4) show an additional hypoechoic area in the hyperechoic, crescent-shaped center. This additional hypoechoic area represents a lymph node (L).

View larger version (166K): [in a new window]   Figure 6a.  Variable appearance of intussusception on axial US scans. C = central limb of the intussusceptum. (a) US scan obtained at the apex of an intussusception shows a hypoechoic outer ring separated from a hypoechoic center by a thin hyperechoic ring, which likely represents the opposed serosal surfaces of the intussusceptum (cf Figs 4 [section 1], 5a, 5b). G = gallbladder. (b) US scan obtained near the apex shows multiple concentric rings (a hypoechoic ring surrounding a hyperechoic ring, which surrounds another hypoechoic ring). The hyperechoic central ring is probably formed by the addition of the hyperechoic opposed submucosal and serosal surfaces of the intussusceptum. (c) US scan obtained at the base of an intussusception shows the central limb of the intussusceptum eccentrically surrounded by the hyperechoic mesentery (M), a situation that produces the crescent-in-doughnut sign (cf Figs 4 [section 2], 5c, 5d).

View larger version (175K): [in a new window]   Figure 6b.  Variable appearance of intussusception on axial US scans. C = central limb of the intussusceptum. (a) US scan obtained at the apex of an intussusception shows a hypoechoic outer ring separated from a hypoechoic center by a thin hyperechoic ring, which likely represents the opposed serosal surfaces of the intussusceptum (cf Figs 4 [section 1], 5a, 5b). G = gallbladder. (b) US scan obtained near the apex shows multiple concentric rings (a hypoechoic ring surrounding a hyperechoic ring, which surrounds another hypoechoic ring). The hyperechoic central ring is probably formed by the addition of the hyperechoic opposed submucosal and serosal surfaces of the intussusceptum. (c) US scan obtained at the base of an intussusception shows the central limb of the intussusceptum eccentrically surrounded by the hyperechoic mesentery (M), a situation that produces the crescent-in-doughnut sign (cf Figs 4 [section 2], 5c, 5d).

View larger version (179K): [in a new window]   Figure 6c.  Variable appearance of intussusception on axial US scans. C = central limb of the intussusceptum. (a) US scan obtained at the apex of an intussusception shows a hypoechoic outer ring separated from a hypoechoic center by a thin hyperechoic ring, which likely represents the opposed serosal surfaces of the intussusceptum (cf Figs 4 [section 1], 5a, 5b). G = gallbladder. (b) US scan obtained near the apex shows multiple concentric rings (a hypoechoic ring surrounding a hyperechoic ring, which surrounds another hypoechoic ring). The hyperechoic central ring is probably formed by the addition of the hyperechoic opposed submucosal and serosal surfaces of the intussusceptum. (c) US scan obtained at the base of an intussusception shows the central limb of the intussusceptum eccentrically surrounded by the hyperechoic mesentery (M), a situation that produces the crescent-in-doughnut sign (cf Figs 4 [section 2], 5c, 5d).

View larger version (165K): [in a new window]   Figure 7a.  Variable appearance of intussusception on longitudinal US scans. C = central limb of the intussusceptum, M = mesentery. (a) US scan obtained in the strict longitudinal plane of an intussusception slightly away from the apex shows the sandwich sign. The outer hypoechoic bands (arrows) represent the everted limb of the intussusceptum beside the intussuscipiens. The two hyperechoic bands represent the mesentery. The central hypoechoic band represents the central limb of the intussusceptum. (b) US scan obtained at the apex of an intussusception shows the hayfork sign, which differs from the sandwich sign in that the mesentery thins as it approaches the apex. The three hypoechoic prongs of the hayfork represent the involved bowel loops separated by the hyperechoic mesentery. L = lymph node. (c) US scan shows the pseudokidney sign. The mesentery is demonstrated on one side of the central limb of the intussusceptum.

View larger version (169K): [in a new window]   Figure 7b.  Variable appearance of intussusception on longitudinal US scans. C = central limb of the intussusceptum, M = mesentery. (a) US scan obtained in the strict longitudinal plane of an intussusception slightly away from the apex shows the sandwich sign. The outer hypoechoic bands (arrows) represent the everted limb of the intussusceptum beside the intussuscipiens. The two hyperechoic bands represent the mesentery. The central hypoechoic band represents the central limb of the intussusceptum. (b) US scan obtained at the apex of an intussusception shows the hayfork sign, which differs from the sandwich sign in that the mesentery thins as it approaches the apex. The three hypoechoic prongs of the hayfork represent the involved bowel loops separated by the hyperechoic mesentery. L = lymph node. (c) US scan shows the pseudokidney sign. The mesentery is demonstrated on one side of the central limb of the intussusceptum.

View larger version (168K): [in a new window]   Figure 7c.  Variable appearance of intussusception on longitudinal US scans. C = central limb of the intussusceptum, M = mesentery. (a) US scan obtained in the strict longitudinal plane of an intussusception slightly away from the apex shows the sandwich sign. The outer hypoechoic bands (arrows) represent the everted limb of the intussusceptum beside the intussuscipiens. The two hyperechoic bands represent the mesentery. The central hypoechoic band represents the central limb of the intussusceptum. (b) US scan obtained at the apex of an intussusception shows the hayfork sign, which differs from the sandwich sign in that the mesentery thins as it approaches the apex. The three hypoechoic prongs of the hayfork represent the involved bowel loops separated by the hyperechoic mesentery. L = lymph node. (c) US scan shows the pseudokidney sign. The mesentery is demonstrated on one side of the central limb of the intussusceptum.

View larger version (175K): [in a new window]   Figure 8a.  Variant forms of the outer ring. (a) Axial US scan shows an outer ring (arrowheads) that is hyperechoic relative to the adjacent liver (L). This appearance was seen when the child had an attack of colicky pain. (b) Axial US scan shows alternating hyperechoic and hypoechoic bands (arrows) produced by the layers of the bowel wall of the intussuscipiens and the everted limb of the intussusceptum (multilayered image). (c) Axial US scan shows a band of hyperechoic dots between the thin intussuscipiens (A) and the everted limb of the intussusceptum (B). Arrowheads indicate the outer ring.

View larger version (176K): [in a new window]   Figure 8b.  Variant forms of the outer ring. (a) Axial US scan shows an outer ring (arrowheads) that is hyperechoic relative to the adjacent liver (L). This appearance was seen when the child had an attack of colicky pain. (b) Axial US scan shows alternating hyperechoic and hypoechoic bands (arrows) produced by the layers of the bowel wall of the intussuscipiens and the everted limb of the intussusceptum (multilayered image). (c) Axial US scan shows a band of hyperechoic dots between the thin intussuscipiens (A) and the everted limb of the intussusceptum (B). Arrowheads indicate the outer ring.

View larger version (182K): [in a new window]   Figure 8c.  Variant forms of the outer ring. (a) Axial US scan shows an outer ring (arrowheads) that is hyperechoic relative to the adjacent liver (L). This appearance was seen when the child had an attack of colicky pain. (b) Axial US scan shows alternating hyperechoic and hypoechoic bands (arrows) produced by the layers of the bowel wall of the intussuscipiens and the everted limb of the intussusceptum (multilayered image). (c) Axial US scan shows a band of hyperechoic dots between the thin intussuscipiens (A) and the everted limb of the intussusceptum (B). Arrowheads indicate the outer ring.

View larger version (156K): [in a new window]   Figure 9a.  Variant forms of the mesenteric crescent. C = central limb of the intussusceptum. (a) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of two oval mesenteric lymph nodes (L) (cf Figs 4 [section 3], 5e, 5f). (b) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of the cecoappendiceal complex (arrow). (c) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of the appendix (arrow) and vessels, which appear as hypoechoic dots.

View larger version (164K): [in a new window]   Figure 9b.  Variant forms of the mesenteric crescent. C = central limb of the intussusceptum. (a) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of two oval mesenteric lymph nodes (L) (cf Figs 4 [section 3], 5e, 5f). (b) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of the cecoappendiceal complex (arrow). (c) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of the appendix (arrow) and vessels, which appear as hypoechoic dots.

View larger version (155K): [in a new window]   Figure 9c.  Variant forms of the mesenteric crescent. C = central limb of the intussusceptum. (a) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of two oval mesenteric lymph nodes (L) (cf Figs 4 [section 3], 5e, 5f). (b) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of the cecoappendiceal complex (arrow). (c) Axial US scan obtained at the base of an intussusception shows the crescent-in-doughnut sign altered by inclusion of the appendix (arrow) and vessels, which appear as hypoechoic dots.

View larger version (169K): [in a new window]   Figure 10a.  Variant forms of the central limb of the intussusceptum. (a) Axial US scan shows a small amount of fluid (F) within the lumen of the central limb. (b) Axial US scan shows an intensely echogenic area (arrow) with acoustic shadowing. This appearance is due to gas passing through the lumen of the central limb.

View larger version (140K): [in a new window]   Figure 10b.  Variant forms of the central limb of the intussusceptum. (a) Axial US scan shows a small amount of fluid (F) within the lumen of the central limb. (b) Axial US scan shows an intensely echogenic area (arrow) with acoustic shadowing. This appearance is due to gas passing through the lumen of the central limb.

View larger version (162K): [in a new window]   Figure 11a.  Trapped peritoneal fluid. (a) Axial US scan shows the double-crescent-in-doughnut sign, which consists of the crescent-in-doughnut sign plus an echo-free crescent due to the trapped fluid (F). (b) Longitudinal US scan at the apex of the intussusception shows the intussusceptum filled with trapped fluid.

View larger version (166K): [in a new window]   Figure 11b.  Trapped peritoneal fluid. (a) Axial US scan shows the double-crescent-in-doughnut sign, which consists of the crescent-in-doughnut sign plus an echo-free crescent due to the trapped fluid (F). (b) Longitudinal US scan at the apex of the intussusception shows the intussusceptum filled with trapped fluid.

View larger version (126K): [in a new window]   Figure 12.  Free peritoneal fluid. Axial US scan shows a small amount of free peritoneal fluid (F) adjacent to an intussusception that demonstrates the multiple concentric ring sign. G = gallbladder.

View larger version (86K): [in a new window]   Figure 13a.  Use of Doppler US to evaluate intussusception. Doppler US scans obtained at the apex (a), middle (b), and base (c) of an intussusception clearly show blood flow within the intussusceptum (a, b) and mesentery (c). This intussusception could be reduced.

View larger version (76K): [in a new window]   Figure 13b.  Use of Doppler US to evaluate intussusception. Doppler US scans obtained at the apex (a), middle (b), and base (c) of an intussusception clearly show blood flow within the intussusceptum (a, b) and mesentery (c). This intussusception could be reduced.

View larger version (67K): [in a new window]   Figure 13c.  Use of Doppler US to evaluate intussusception. Doppler US scans obtained at the apex (a), middle (b), and base (c) of an intussusception clearly show blood flow within the intussusceptum (a, b) and mesentery (c). This intussusception could be reduced.

View larger version (127K): [in a new window]   Figure 14.  Barium enema therapy. Image from a barium enema study shows perforation with free spillage of barium into the peritoneal cavity. The dissection sign is also evident; the intussusceptum is outlined for several centimeters by barium in the colon.

View larger version (138K): [in a new window]   Figure 15a.  Air enema therapy. (a) Image obtained at the beginning of an air enema study shows the meniscus sign and a mass in the middle of the upper abdomen. (b) Image obtained after complete reduction shows gas passing freely into the small intestine.

View larger version (115K): [in a new window]   Figure 15b.  Air enema therapy. (a) Image obtained at the beginning of an air enema study shows the meniscus sign and a mass in the middle of the upper abdomen. (b) Image obtained after complete reduction shows gas passing freely into the small intestine.

View larger version (149K): [in a new window]   Figure 16a.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (143K): [in a new window]   Figure 16b.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (183K): [in a new window]   Figure 16c.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (132K): [in a new window]   Figure 16d.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (157K): [in a new window]   Figure 16e.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (163K): [in a new window]   Figure 16f.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (170K): [in a new window]   Figure 16g.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (159K): [in a new window]   Figure 16h.  US-guided saline enema therapy. (a) Longitudinal US scan shows the fluid outlining the intussusceptum in the transverse colon. This appearance is the US equivalent of the meniscus sign. (b – d) Longitudinal US scans show the enema pushing the intussusceptum into the ascending colon (b), into the ileocecal valve (c), and finally through the valve (d). Arrows in d = ileocecal valve. (e, f) Axial US scans show multiple bowel loops (e), including the terminal ileum (f), filled with fluid. This appearance indicates that complete reduction has been achieved. The thickened and collapsed terminal ileum must not be confused with a residual intussusception. Arrows in f = ileocecal valve. (g) Longitudinal US scan shows a thickened ileocecal valve (arrows). (h) Axial US scan shows the Mercedes-Benz sign, which is produced by the collapsed terminal ileum.

View larger version (30K): [in a new window]   Figure 17.  Management algorithm for cases with clinical suspicion of intussusception. In this approach, US is the principal imaging modality.