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Axial Torsion of Meckel's Diverticulum Causing Small Bowel Obstruction in Adult: A Case Report

Meckel’s diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract that occurs in 2–3% of the population (1). The MD results from incomplete obliteration of the proximal most portion of the omphalomesenteric duct within 5 to 7 weeks of fetal development (2). Gastrointestinal bleeding due to ectopic gastric mucosa of MD causing ileal peptic ulceration is the most common complication in childhood. In adults, the more common complication is bowel obstruction caused by either intussusception or small bowel volvulus around a fibrotic band or patent omphalomesenteric duct anchored to the anterior abdominal wall. Other common complications include acute inflammation leading to perforation and hemorrhage. More rare complications include perforation of MD with foreign bodies, vesicodiverticular fistulae, strangulation in Littre’s hernia, or primary neoplasms. Torsion of MD, one of the rarest complications, is the result of axial twisting around its base (3). Pre-operative diagnosis of MD as a cause of small bowel obstruction is difficult, because the diagnosis can be made only if the diverticulum is delineated at the site of obstruction. In many cases, computed tomography (CT) features are similar to those of small bowel obstruction secondary to postoperative adhesions. Imaging features and risk factors of small bowel obstruction secondary to MD suggest the diagnosis. Herein, we reported a rare case of MD with axial torsion; furthermore, we briefly reviewed the relevant literature. Axial Torsion of Meckel’s Diverticulum Causing Small Bowel Obstruction in Adult: A Case Report 성인에서 발생한 멕켈 게실의 급성 염전에 의한 소장 폐색: 증례 보고


INTRODUCTION
Meckel's diverticulum (MD) is the most common congenital anomaly of the gastrointestinal tract that occurs in 2-3% of the population (1). The MD results from incomplete obliteration of the proximal most portion of the omphalomesenteric duct within 5 to 7 weeks of fetal development (2). Gastrointestinal bleeding due to ectopic gastric mucosa of MD causing ileal peptic ulceration is the most common complication in childhood. In adults, the more common complication is bowel obstruction caused by either intussusception or small bowel volvulus around a fibrotic band or patent omphalomesenteric duct anchored to the anterior abdominal wall.
Other common complications include acute inflammation leading to perforation and hemorrhage. More rare complications include perforation of MD with foreign bodies, vesicodiverticular fistulae, strangulation in Littre' s hernia, or primary neoplasms.
Torsion of MD, one of the rarest complications, is the result of axial twisting around its base (3).
Pre-operative diagnosis of MD as a cause of small bowel obstruction is difficult, because the diagnosis can be made only if the diverticulum is delineated at the site of obstruction. In many cases, computed tomography (CT) features are similar to those of small bowel obstruction secondary to postoperative adhesions. Imaging features and risk factors of small bowel obstruction secondary to MD suggest the diagnosis.
Herein, we reported a rare case of MD with axial torsion; furthermore, we briefly reviewed the relevant literature. Meckel's diverticulum (MD) is the most common congenital abnormality of the gastrointestinal tract that is prevalent in 2-3% of the population. The lifetime risk of complications is estimated at 4%. Small bowel obstruction is the second most common complication of MD. Among the causes of bowel obstruction, axial torsion of MD is the rarest complication. Urgent surgical treatment is needed in cases of small bowel obstruction associated with torsion of MD. Pre-operative diagnosis of MD as a cause of small bowel obstruction is difficult, because the diagnosis can be made only if the diverticulum is delineated at the site of obstruction. We reported a case of axial torsion of MD with necrosis that caused proximal small bowel perforation in a 21-year-old male. A. Consecutive axial images (order is marked by number 1 through 4) from contrast-enhanced computed tomography demonstrate a tubular structure (arrow in 1) connected with distal ileum and axial torsion of its neck (arrows in 2 and 3). Air-fluid level is observed in the lumen of tubular structure with pneumatosis of its wall (arrows in 4). Note the dilated adjacent small bowel loops. B. On coronal reformatted image, the artery suggesting vitellointestinal artery (arrowheads) originates from ileal branch of superior mesenteric artery (arrow) and supplies the MD in distal ileum. C. Coronal reformatted image demonstrates an approximately 4.8 × 5.5 × 17.8 cm sized tubular structure, which is connected to distal ileum extending into pelvic cavity with blind-end (arrow). D. The surgical specimen is an about 20 cm-length of infarcted MD (arrows), which is connected to distal ileum (thick arrows) with gangrenous change. There is no fibrous band attached to the distal end of MD. The patient underwent emergent laparoscopy assisted exploration. Intra-operatively, axial torsion and gangrenous diverticulum was detected at the antimesenteric border of distal ileum (about 180 cm from IC valve) (Fig. 1D). There were also a few perforated foci at the ileal loops, proximal to the diverticulum.

Index terms
Hence, laparoscopy assisted diverticulectomy of a 20 × 4 cm sized MD and primary repair of small bowel was performed. The patient recovered uneventfully and was discharged on the 5th postoperative day. Several risk factors are suggested; fibrous band of remnant omphalomesenteric duct, the size and length of MD and primary neoplasm arising within MD. Fibrous band that is the partially obliterated omphalomesenteric duct, increases the chance of torsion (4,5). Other reported risk factors are the diverticular length and width of the diverticular sac; longer and wider diverticular sac frequently results in complications such as perforation or small bowel obstruction (5,7,8). Particularly, a narrow neck connecting the diverticulum and the ileum, increases the risk of torsion (5,8). In addition, primary neoplasm arising within MD is another risk factor. Although primary neoplasm of MD is rare, it is a potential risk factor. Benign as well as malignant tumors may increase the risk of torsion (5).

DISCUSSION
Diverticular torsion occurred, despite the absence of fibrous band that connects diverticulum to umbilicus in our patient. Diverticular torsion occurred because our patient had a very large diverticulum with relatively narrow neck.
In conclusion, tracing of vitellointestinal artery supplying obstructive ileal loops might suggest the diagnosis of MD in the setting of small bowel obstruction. Furthermore, blind-ended tubular structure that is connected to ileum at the level of small bowel obstruction is indicative of the diagnosis. Several factors such as a fibrous band of remnant omphalomesenteric duct, the width and length of MD with narrow neck and primary neoplasm arising within MD increase the risk of torsion.