CASE 10617 Published on 15.01.2013

Gallstone ileus due to a radiolucent stone

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Yuranga Weerakkody¹, James Rippey², Wei Ling Ooi³, Siva Thirumalai⁴

(1) FRANZCR
(2) MBBS, DDU, FACEM
(3) MBChB
(4) MRCSEd, MS - General Surgery

Department of Radiology, SCGH,
NMAHS, 6009 Perth, Australia

Patient

80 years, male

Categories

Area of Interest Abdomen, Adrenals ; Imaging Technique CT, Image manipulation / Reconstruction

Procedure Education ; Special Focus Pathology ;

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Clinical History

80-year-old patient with vague abdominal discomfort and no bowel evacuation for 2 days. On examination he had a distended abdomen with generalised abdominal tenderness but no guarding. A provisional clinical diagnosis of bowel obstruction was made. He was then evaluated with a CT scan followed by a targeted ultrasound scan.

Imaging Findings

The CT scan demonstrates moderate small bowel dilatation continuing through to distal small bowel with a transition point in the right iliac fossa. At this point, there is a subtle crescenteric ring suggesting a radiolucent stone (figures 1b,2a and 3a). Images of the gallbladder fossa show an absent gallbladder contour as well as a juxta-duodenal free air locule indicative of a cholecysto-duodenal fistula (figures 1d,2a-b and 3b). A further adjacent iso-attenuating stone with a faint calcific rim is appreciated at the gallbladder neck (figures 1c,2c and 3c). A subsequent targeted ultrasound scan over the right iliac fossa shows a hypo-echoic shadowing stone confirming the suspected CT abnormality. The patient later underwent a laparotomy which demonstrated a gallstone lodged at the ileum with collapsed distal small bowel (figure 5). Both the obstructing ileal stone and gallbladder neck stone were removed by an enterotomy and cholecystostomy respectively (figure 6 - removed gallstones).

Discussion

A gallstone ileus refers to a mechanical obstruction from a distally impacted gallstone which has eroded through to bowel. It is an uncommon (0.3–0.5%) complication of cholelithiasis [1] and may be responsible of 1-4% of all bowel obstructions [4, 6]. There is a recognised increased female predilection with ratios ranging between 3-16:1.

Intestinal obstruction can result when a stone enters the gastrointestinal tract. This usually occurs through a cholecysto-enteric fistula where the commonest site is between the gallbladder and the duodenum. Once within the intestinal tract, the gallstone may be either vomited, passed spontaneously through to the rectum, or impact and cause obstruction.

While stone impaction can occur anywhere along the gastrointestinal tract, it typically occurs at the terminal ileum (narrowest portion of the small bowel).

Clinical features for gallstone ileus are often non-specific and more than a third of patients may not have biliary symptoms [10]. Some patients may present with abdominal pain and / or vomiting where the median duration of symptoms of usually range around 3 days [5].

Described CT features of gallstone ileus include [1, 8].
1. Presence of small bowel obstruction/bowel dilatation
2. Direct visualisation of an ectopic gallstone - which can be totally calcified, rim-calcified or radiolucent
3. An abnormal gallbladder morphology with presence of air within, air-fluid levels, or fluid accumulation with an irregular +/- thickened wall
4. Direct identification of a bilio-digestive (usually cholecysto-enteric) fistula
5. Pneumobilia
6. Pericholecystic or focal free fluid.

The first four features were presence in this case.
CT may be of particular use in identification of an ectopic gallstone at the transition point between dilated and decompressed bowel [9] and can also be useful for pre-operative planning [10].

Diagnosis of gallstone ileus at times be challenging on imaging especially if the stone is radiolucent. The presence of ancillary signs such as additional similarly radiolucent stones within the gallbladder and visualisation of a cholecysto-enteric fistula may aid towards the diagnosis. There are some occasions where the stone may not even be detectable at all on CT and this can be particularly the case with radiolucent calculi.

Surgical intervention is the mainstay of treatment [4] and usually comprises of either an enterolithotomy alone or enterolithotomy with cholecystectomy and fistula closure or cholecystostomy and removal of stone [7]. Early recognition of a mechanical cause will expedite surgical treatment.

This case highlights typical imaging features of a gallstone ileus secondary to a radiolucent gallstone.

Differential Diagnosis List

Gallstone ileus secondary to a radiolucent stone

Small bowel obstruction secondary to an adhesion

Ogilvie syndrome

Small bowel obstruction with a concurrent unrelated cholecysto-duodenal fistula.

Final Diagnosis

Gallstone ileus secondary to a radiolucent stone

References

[1] Lassandro F, Romano S, Ragozzino A, Rossi G, Valente T, Ferrara I, Romano L, Grassi R (2005) Role of helical CT in diagnosis of gallstone ileus and related conditions. AJR - American Journal of Roentgenology 185(5):1159-65 (PMID: 16247126)

[2] Yu CY, Lin CC, Shyu RY, Hsieh CB, Wu HS, Tyan YS, Hwang JI, Liou CH, Chang WC, Chen CY. (2005) Value of CT in the diagnosis and management of gallstone ileus. World Journal Gastroenterology 14;11(14):2142-7 (PMID: 15810081)

[3] Lassandro F, Gagliardi N, Scuderi M, Pinto A, Gatta G, Mazzeo R. (2004) Gallstone ileus analysis of radiological findings in 27 patients. European Journal of Radiology 50(1):23-9 (PMID: 15093232)

[4] Chou JW, Hsu CH, Liao KF, Lai HC, Cheng KS, Peng CY, Yang MD, Chen YF (2007) Gallstone ileus: report of two cases and review of the literature. World Journal of Gastroenterology 28;13(8):1295-8 (PMID: 17451220)

[5] Ayantunde AA, Agrawal A. (2007) Gallstone ileus: diagnosis and management. World Journal of Surgery 31 6):1292-7. Epub 2007 Apr 15 (PMID: 17436117)

[6] Kirchmayr W, Mühlmann G, Zitt M, Bodner J, Weiss H, Klaus A. (2005) Gallstone ileus: rare and still controversial. Australian and New Zealand Journal of Surgery 75(4):234-8 (PMID: 15839973)

[7] Tan YM, Wong WK, Ooi LL (2004) A comparison of two surgical strategies for the emergency treatment of gallstone ileus. Singapore Medical Journal 45(2):69-72 (PMID: 14985844)

[8] Reimann AJ, Yeh BM, Breiman RS, Joe BN, Qayyum A, Coakley FV. (1994) Gallstone ileus demonstrated by CT. Journal of computer assisted tomography 18(2):262-5 (PMID: 8126278)

[9] Reimann AJ, Yeh BM, Breiman RS, Joe BN, Qayyum A, Coakley FV. (2004) Atypical cases of gallstone ileus evaluated with multidetector computed tomography. Journal of computer assisted tomography 28(4):523-7 (PMID: 15232385)

[10] Delabrousse E, Bartholomot B, Sohm O, Wallerand H, Kastler B. (2000) Gallstone ileus: CT findings. European Radiology 10(6):938-40. (PMID: 10879707)

Case information

URL:	https://eurorad.org/case/10617
DOI:	10.1594/EURORAD/CASE.10617
ISSN:	1563-4086

Figure 1

CT abdomen - axial images

Axial CT image demonstrates multiple dilated small bowel loops in keeping with a small bowel obstruction.

Axial CT image demonstrates multiple small bowel loops. There is a subtle cresenteric ring (arrowed) involving one of the loops at a transition point in the iliac fossa suggestive of a radiolucent stone

Axial CT image at the level of the gallbladder demonstrates a further impacted radiolucent gallstone at the gallbladder neck (arrowed)

Axial CT image demonstrates an extra colonic air locule (arrowed) suggesting the point of erosion (cholecysto-duodenal fistula) of the obstructing right iliac stone causing the ileus. This is adjacent to the impacted gallbladder neck stone

Figure 2

CT abdomen - coronal images

Coronal CT image suggest the presence of a radiolucent stone (arrowed) at a transition point in the right iliac fossa as well as a separate small free air locule adjacent to the gallbladder (also arrowed)

Coronal CT image showing communication between the free air locule and the D2 duodenal segment suggesting the entry site (cholecysto-duodenal fistula) of the right iliac fossa gallstone causing the ileus.

Coronal CT image demonstrates a further radiolucent gallstone with a calcific rim at the gallbladder neck

Figure 3

CT abdomen - sagittal images

Sagittal CT image demonstrates a radiolucent rounded gallstone within a distal small bowel loop at transition point in the iliac fossa (arrowed). Associated background small bowel dilatation also shown

Sagittal CT image demonstrates a free air locule adjacent to the gallbladder (arrowed)

Sagittal image demonstrates a further separate radiolucent gallstone (similar in attenuation to the right illiac fossa stone) with rim calcification which is located at the gallbladder neck (arrowed)

Figure 4

Ultrasound

Targeted ultrasound scan of the right iliac fossa demonstrates a hypoechoic shadowing rounded calculus corresponding to the suspected position on the preceding CT.

Figure 5

Intra-operative photgraph

Intra-operative photograph confirms moderately dilated small bowel with a calibre change in the right iliac fossa corresponding to the transition point on the CT scan.

Figure 6

Post operative specimen photograph