|CASE SERIES AND BRIEF REVIEW
|Year : 2013 | Volume
| Issue : 2 | Page : 137-141
Enterolithiasis: An unusual cause of small intestinal obstruction
Basant M Singhal, Sunil Kaval, Pradeep Kumar, Chandra P Singh
Department of Surgery, Lala Lajpat Rai Memorial Medical College, Garh Road, Meerut, Uttar Pradesh, India
|Date of Web Publication||13-Dec-2013|
Basant M Singhal
Department of Surgery, Lala Lajpat Rai Memorial Medical College, Garh Road, Meerut - 250 004, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Small bowel obstruction is a common condition, encountered in the emergency room of the surgery department. Uncommon causes include gallstone ileus, worm infestation, internal hernias, mesentric ischemia, trichobezoars or phytobezoars, Crohn's disease, postoperative strictures, and diverticulosis. Even more uncommon is primary enterolithiasis. Enterolith, the enterogenous foreign bodies, are rare clinical and radiological entities. True enteroliths are formed due to precipitation and deposition of substances from alimentary chime. Primary enterolithiasis is a rare entity, occurring in association with pathological conditions that lead to hypomotility and stasis, like Crohn's disease, small intestine diverticulae, traumatic or postoperative strictures of ileum, ulcerative colitis and blind loops. Primary enterolithiasis may be asymptomatic or may present with sub-acute or acute intestinal obstruction, but specific radiological diagnosis of primary enterolithiasis is uncommon. Definitive treatment of enterolithiasis with small intestinal obstruction is essentially surgical. The options at laparotomy are manual lysis of the calculus without enterotomy or removal by enterotomy. Bowel resection is indicated in cases with definitive bowel pathology. We are presenting five cases of enterolithiasis, which we encountered in the Surgery Department of L.L.R.M. Medical College, Meerut from January 2006 to December 2012. Clinical presentation, diagnosis, investigations and treatment have been discussed along with a review of literature.
Keywords: Enterolithiasis, intestinal obstruction, small bowel obstruction
|How to cite this article:|
Singhal BM, Kaval S, Kumar P, Singh CP. Enterolithiasis: An unusual cause of small intestinal obstruction. Arch Int Surg 2013;3:137-41
| Introduction|| |
Enterolith, the enterogenous foreign bodies, are rare clinical and radiological entities in humans, although they are very common in animals such as horses.  These were first described by Pfahler and Stamm in 1915, but enterolith causing ileus similar to gallstone ileus was first reported by Philips in 1921. , Enteroliths are stones primarily formed in the gastrointestinal tract. Primary enterolith are formed in the small intestine, while secondary enteroliths are formed in the associated organs like gall bladder.  Primary entroliths can be grouped into false and true types. , False enteroliths are fecoliths, varnish stains, almond pits, fruit skin, oat stones, phytobezoars or trichobezoars, and foreign bodies that clump together and intestinal content deposit around them. On the other hand, true enteroliths are formed de novo as a result of precipitation and deposition of substances from the alimentary chime. , Primary enterolithiasis mostly occurs in association with pathological conditions leading to hypomotility and stasis. ,, Various pathologies associated with enterolithiasis are Crohn's disease, small intestine diverticulae, traumatic or postoperative strictures of ileum, ulcerative colitis, and blind loops. Uncommon conditions reported to cause enterolithiasis are Meckel's diverticulum, intestinal tuberculosis, afferent loops following partial gastrectomy, carcinoid tumors, eosinophilic enteritis, nontropical sprue, and duplication of alimentary tract. ,,,,,,,,,,, According to Ruiz et al., a genetic substrate predisposing to this uncommon entity is possible. 
Proximal small intestine enteroliths show a predominance of unconjugated bile acids, while those in the distal small intestine are mainly composed of salts of calcium. It is postulated that proximal small intestine and its diverticulae provide a more acidic environment necessary for choleic acid precipitation, leading to the formation of biliary primary enteroliths.  In distal small bowel, the milieu is more alkaline, which may be accentuated by age-related hypochlorhydria or prolonged use of proton pump inhibitors. Pathological conditions causing hypo-motility or stasis, along with alkaline pH shift favor precipitation of calcium salts, leading to the formation of calcium stones that are mostly radio opaque. ,, Hofman and Mysels postulated that small bowel dyskinesia lead to deconjugation of bile acid due to bacterial overgrowth, which subsequently precipitate with choleric acid in the small bowel.  Often, these enteroliths have a central nidus of bacterial or cellular debris or a fruit stone.  In the West, where tuberculosis is rare, the common underlying cause is intestinal diverticuli and less commonly the Crohn's disease. Enteroliths composed of predominantly uric acid and ammonium magnesium phosphate have also been reported.  We have reported here 5 patients with primary enterolithiasis presenting as acute intestinal obstruction, with a brief review of their clinical presentation, diagnosis, and management.
| Patients and Methods|| |
Between January 2006 and December 2012, five patients presented with mechanical small bowel obstruction due to enterolithiasis to the General Surgery Department of L.L.R.M. Medical College, Meerut. There age and sex distribution is shown in [Table 1].
|Table 1: Age/sex incidence, management in patients with enterolithiasis (n-5)|
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| Case Reports|| |
A 65-year-old farmer presented with a history of recurrent colicky abdominal pain for 15 days followed by progressively increasing distention of the abdomen, vomiting, and constipation for 24 h. There was no history suggestive of abdominal tuberculosis. Clinical examination and abdominal X-ray were suggestive of acute small bowel obstruction. The patient was resuscitated. On exploration, there was obstruction in distal ileum 20 cm from the ileo - caecal junction by a large hard enterolith of about 3-cm diameter, which could not be broken and therefore removed by enterotomy [Figure 1] and [Figure 2]. Postoperative recovery was uneventful and the patient was discharged on the 8 th postoperative day.
A 50-year-old man presented with features of acute small intestinal obstruction for 2 days. The patient had a prior history of abdominal tuberculosis with complete treatment 10 years back. On clinical evaluation of the abdomen, there was gross distension and tenderness. Plain X-ray of the abdomen and gastrograffin study revealed small intestinal obstruction in the distal ileum. At exploration, there was no bowel pathology or stricture. The mechanical obstruction was due to a large hard enterolith (4-cm diameter) 40 cm from the ileo - caecal junction, which could be extracted only by enterotomy. Bowel activity returned in 48 h, and the postoperative period was uneventful except a minor wound infection; the patient was discharged on the 8 th postoperative day.
A 67-year-old female presented with sub-acute obstruction for 3 months. There was a history of cholecystectomy 20 years back and a history of abdominal tuberculosis 40 years back with complete anti-tubercular treatment for 1 year. At the time of admission, there was moderate distention of the abdomen with exaggerated bowel sounds. On ultrasound and X-ray, signs of small bowel obstruction were detected. On contrast study, there was an abrupt cut-off in the mid ileum with gross dilation of the ileum and jejunum proximal to it. The patient was managed conservatively at another hospital for 2 days before presenting to our department. Exploratory laparotomy was undertaken and there was obstruction in ileum approximately 100 cm from the ileo - caecal junction due to two hard enteroliths (approx 2-2.5 cm diameter), which were broken down by finger pressure and milked into the cecum. Bowel activity returned in 36 h, recovery was uneventful, and the patient was discharged on the 9 th postoperative day.
A 35-year-old female presented with abdominal pain for 2 days and features of peritonitis. On ultrasound and abdominal X-ray, there was free gas and fluid in the abdomen. The patient was Hbs Ag positive, but she had no history of abdominal tuberculosis. Following abdominal examination a diagnosis of acute peritonitis was made. At exploration, the peritoneal cavity had fecal contamination due to pressure necrosis in distal ileum approximately 40 cm from the ileo - caecal junction by a large hard enterolith (4 cm diameter) and a smaller enterolith (2 cm diameter) was present proximal to it. The enteroliths were removed and ileostomy was done as bowel was very edematous and the patient was hemodynamically unstable due to gross sepsis. Post operatively, the patient was kept on ionotopic support for 24 h and the bowel activity returned in 48 h. The postoperative period was uneventful, and the patient was discharged on the 10 th postoperative day. Ileostomy was closed after 3 months.
A 45-year-old male presented with sub-acute obstruction for 15 days. Plain X-ray of the abdomen and contrast study was suggestive of mechanical cause of small bowel obstruction in the proximal ileum. On exploration, there was obstruction in the ileum at approximately 90 cm from the ileo - caecal junction due to two hard enteroliths (approx 1.5-2.5 cm in diameter), which were broken down by finger pressure and milked into the cecum. The rest of the bowel was normal. Bowel activity returned in 48 h, postoperative recovery was uneventful, and the patient was discharged on the 8 th postoperative day.
In all cases, there was no preoperative or intraoperative evidence of biliary pathology. At exploration, no associated bowel pathology, diverticulae, or stricture was identified in any patient. Chemical analysis of the extracted enteroliths is presented in [Table 2].
| Discussion|| |
Primary enterolithiasis may be asymptomatic or may present with sub-acute or acute intestinal obstruction. ,,, Gall stone ileus is more common in elderly patients, average age being 70 years and it accounts for 25% of non-strangulated sub-acute intestinal obstructions in those over 65 years of age. , On the contrary, fewer than 100 reported cases of primary enterolithiasis causing small intestinal obstruction have been reported. , Presenting features may vary from uncomplicated recurrent intestinal obstruction to complications like ulceration with malaena, perforation, or gangrene of bowel. ,,,, In our cases, the age ranged from 35 years to 67 years with a mean age of 52.4 years, which is much lower than the age reported by most of the investigators for gall stone ileus and enterolithiasis.  Clinical presentation in our series varied from sub-acute to acute intestinal obstruction and even perforation with peritonitis in 1 patient. None of these patients presented with a recent or a past history of malena or GI bleed.
In all our patients, plain abdominal X-ray and contrast studies were suggestive of small intestinal obstruction, but specific shadows were not identified, and specific diagnosis of enterolithiasis was made only at abdominal exploration. Low calcium content revealed by chemical analysis might be the reason for non-identification of these enteroliths. Although specific radiological diagnosis of primary enteroliths is uncommon, several radiological features suggestive of enterolithiasis have been described. Most important ones are typical dense rim with pale core in oval, round, or rectangular shadows, "Coin-end-on" appearance of the shadows, wide mobility of radio opaque shadows in relation to the fixed structures in successive plain radiographs of abdomen, and wide separation in one with closeting together in other radiographs.  Accurate diagnosis of sub-acute intestinal obstruction by enterolith may require water-soluble contrast study combined with cross-sectional imaging modality like computed tomography (CT) scan.  If calcified enterolith can be visualized, being a rare entity, it should be included in differential diagnosis of intra-abdominal calcification with appendicolith, teratoma, and calcified lymph nodes.  Differentiation from gallstone ileus is difficult as both diseases have a chronic course with superimposed acute small intestinal obstruction. However, pneumobillia on plain abdominal film suggests gallstone ileus, and the diagnosis of enterolith can be established only after documenting the normalcy of the gallbladder by ultrasound or CT scan. 
Most of the published articles have reported enterolithiasis leading to distal small bowel obstruction in association with Crohn's disease, jejunal diverticuli, and Meckel's diverticulum. ,,,,,, In our cases, congenital or acquired bowel diverticulae or any other pathology was not present. Perez et al., and Shetty and Sridhar have also reported absence of any intestinal pathology in patients having small bowel obstruction due to a calcified enterolith. , Quazi et al., have reported a large uric acid containing enterolith without any bowel pathology.  Other intestinal pathologies reported to be commonly associated with primary enterolithiasis, are intestinal tuberculosis, strictures, and blind loops. ,,,, In our series, two cases (40%) had history of treated abdominal tuberculosis, however, on exploration, they did not have any evidence of active disease or its squeal like bowel hypertrophy, stricture, or bands. It is interesting to note that although intestinal tuberculosis is fairly common in India and is associated with multiple strictures of small intestine, providing ideal conditions for enterolithiasis, surprisingly, its occurrence seems to be rare. Low dietary calcium intake along with high phytate content may be the reason for the low incidence in such patients. , This might also explain the very low incidence of enteroliths in South Indian population as they have a comparatively lower intake of milk and milk products. 
Chemical analysis of stones extracted in our case series identifies the organic material and food residues as major components (64-70.78%), while second major component was calcium salts (14.45-27.72%). In all of our cases, enteroliths were present in the distal small intestine where alkaline pH favor precipitation of calcium salts, which, along with food fibers, lead to the formation of these enteroliths. Bile salts and biliary pigments were present in small quantity, which rules out gallstone ileus in all cases. Other ingredients present in small amounts included fatty acids, cholesterol, and ammonium magnesium phosphate (Struvite). In neonates, it has been postulated that both the prolonged stasis of the meconium, which is high in calcium, and the change of pH due to mixing of urine, causes precipitation of the calcium salt in intestine.  Intra-luminal calcification of meconium has been reported in association with several pathological conditions such as imperforate anus,  persistent cloaca,  multiple gastrointestinal atresias,  small bowel stenosis,  total colonic aganglionosis (Hirschsprung disease),  and functional ileal obstruction. 
Definitive treatment of enterolithiasis with small intestinal obstruction is surgical. The consensus management policy at laparotomy is to first attempt manual lysis of the calculus without enterotomy and then milking the smaller parts into the proximal colon, from where they pass through the rectum. ,,, If this is not possible, then enterolith removal by enterotomy from proximal less edematous part of small intestine should be done. Bowel resection with primary anastomosis is indicated in cases with inflammation, perforation, necrotic bowel diverticulosis over a limited part of the bowel, congenital diverticuli, and congenital reduplication of the gut. ,,, In the presence of associated strictures, stricture-plasty may be done for small solitary stricture, but for long or multiple strictures and associated complications, resection of the affected bowel is indicated.
| Conclusion|| |
Enterolithiasis is an uncommon cause of intestinal obstruction and can occur in patients of all age groups. It should be considered when plain abdominal radiograph shows multiple radio opaque shadows in a patient with mechanical small bowel obstruction. It can be differentiated from gallstone ileus by documenting the absence of biliary pathology by ultrasound or CT scan. Enterolithiasis may occur in the absence of any bowel pathology. The treatment is essentially surgical for relieving obstruction as well as for confirmation of diagnosis. Associated pathologies like stricture or diverticulae, if present, will need resection at the time of exploration.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]