Clinical diagnosis
Case 257
【Discussion】
Meckel diverticulum is a remnant of vitelline duct between umbilicus and small intestine which is a main route for nutrients of fetus before formation of placenta. Vitelline duct is the same termed as yolk sac duct, umbilical-enteric duct or omphalo-enteric duct. It usually disappears at approximately two months after gestation. However, it fails to disappear, inducing formation of Meckel diverticulum with incidence of 2% (1).
It is known ‘rule of 2s’ to memorize the content of Meckel diverticulum: it occurs approximately 2% of infants, it measures 2 inches long and is located in the ileum 2 feet from Bauhin valve. It contains 2 type ectopic tissues of gastric or pancreatic, it is estimated approximately 15% of patients having ectopic tissues (2-5).
Meckel diverticulum causes asymptomatic most. Of the symptomatic causes, it causes bleeding in 20-30% usually occurring at infants or newborns originated from ulcer due to gastric or pancreatic cells secreting digestive enzymes of hydrochloric acid, pepsin or trypsin. Further, it causes small bowel obstruction (20-30%), diverticulitis (< 20%), umbilical anomalies and neoplasm (6).
Although Meckel diverticulum, a remnant of vitelline duct occurs in 2% of fetus, five forms are known: Meckel diverticulum itself, Meckel diverticulum attached to vitelline ligament (string), fibrous band (string), vitelline fistula, cyst plus vitelline ligament (fibrous band) (1, 2).
Meckel diverticulum causes small bowel obstruction when it herniated into inguinal foramen, femoral foramen or obturator foramen and incarcerated (7). Further, small bowel obstruction occurs when small bowel wound around vitelline ligament attached to Meckel diverticulum (6, 7).
In our case, small bowel obstruction was shown on non-enhanced CT. Small bowel coiled itself up at the occlusive site where sigmoid colon diverticulum attached which were mis-interpreted that sigmoid colon diverticulitis was the cause of adhesive ileus. However, contrast-enhanced CT demonstrated the low density area at the center of coil-up of small bowel corresponded to Meckel diverticulum. Namely, it was difficult to identify Meckel diverticulum on non-enhanced CT but possibly able to identify Meckel diverticulum on contrast-enhanced CT.
When small bowel obstruction is encountered and obstructive site is in the pelvis, vitelline ligament attached to Meckel diverticulum can be one of the responsible causes. It is important to identify the low density corresponded to Meckel diverticulum on enhance CT.
【Summary】
We presented a seventy eight-year-old female for abdominal pain. Non-enhanced CT showed small bowel ileus at the obstruction site in the pelvis where small bowel coiled itself up and enhanced CT showed the area with low density attached small bowel at the center of small bowel winding up. Laparotomy revealed small bowel obstruction due to Meckel diverticulum corresponded to the low density at the center of the occlusion site. It is borne in mind that there are five forms of Meckel diverticulum: Meckel diverticulum itself, Meckel diverticulum attached to vitelline ligament, vitelline ligament (fibrous band, string), vitelline fistula, cyst plus vitelline ligament (fibrous band). Vitelline ligament (fibrous band, string) attached to Meckel diverticulum can be the cause of small bowel obstruction.
【References】
1.Yahchouchy EK, et al. Meckel's diverticulum. J Am Coll Surg. 2001 May;192(5):658-62.
2.Sagar J, et al. Meckel's diverticulum: a systematic review. J R Soc Med. 2006 Oct;99(10):501-5. [PMC free article] [PubMed]
3.Park JJ, et al. Meckel diverticulum: the Mayo Clinic experience with 1476 patients (1950-2002). Ann Surg. 2005 Mar;241(3):529-33.
4.St-Vil D, et al. Meckel's diverticulum in children: a 20-year review. J Pediatr Surg. 1991 Nov;26(11):1289-92.
5.Elsayes KM, et al. Imaging manifestations of Meckel's diverticulum. AJR Am J Roentgenol. 2007 Jul;189(1):81-8.
6.Johnston AO. et al. "Complications of Meckel's diverticulum". British Journal of Surgery. 1976; 63: 453–454.
7.Wu Si-Y et al. Meckel's diverticulum incarcerated in a transmesocolic internal hernia. World J Gastroenterol . 2014 Oct 7;20(37):13615-9.
2022.2.15