Diagnostics

Internal hernia associated with Meckel’s diverticulum in 2 pediatric patients

Sheung-Fat Ko MD^a,?, Miao-Ming Tiao MD^b, Fu-Chen Huang MD^b, Chie-Song Hsieh MD^c, Chung-Cheng Huang MD, Shu-Hang Ng MD^a,

Yung-Liang Wan MD^a, Tze-Yu Lee MD^a

^aDepartment of Radiology, College of Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center,

Chang Gung University, Kaohsiung, Kaohsiung Hsien 833, Taiwan

^bDepartment of Pediatrics, College of Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center,

Chang Gung University, Kaohsiung 833, Taiwan

^cDepartment of Pediatric Surgery, College of Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University, Kaohsiung 833, Taiwan

Received 5 June 2007; revised 5 July 2007; accepted 10 July 2007

Abstract We report 2 Pediatric cases of Small bowel obstruction due to a Meckel’s diverticulum complicated with internal hernia. Abdominal multidetector computed tomograms with multiple planar reconstructions revealed a bridge-like lesion with inconspicuous mucosal folds in the right lower quadrant formed by adhesion of the tip of Meckel’s diverticulum with the adjacent mesentery, with ileal loops converging at the “bridge” and engorged mesenteric vessels. These 2 cases highlight the feasibility of Multidetector computed tomography, especially in the ED, in revealing this unusual etiology of small bowel obstruction.

(C) 2008

Introduction

Meckel’s diverticulum (MD) is a common congenital anomaly of the gastrointestinal tract, occurring in 1% to 3% of the population [1,2]. Symptomatic MD usually occurs in children younger than 10 years old, especially in the first 2 years of life, and commonly presents with gastrointestinal bleeding and intussusception. In contrast, symptomatic MD usually causes intestinal obstruction and symptoms of inflammation in adult patients [1-8]. Meckel’s diverticulum complicated with internal hernia

* Corresponding author. Tel.: +886 7 7317123 2579; fax: +886 7

7318762.

E-mail address: [email protected] (S.-F. Ko).

leading to small bowel obstruction (SBO) is rare [3-8]. This report describes 2 unusual pediatric cases of acute SBO due to MD with focal mesenteric adhesion which formed a bridge-like lesion provoking internal hernia of the ileal loops. We gave emphasis on the multidetector computed tomographic (MDCT) features which may offer an appropriate preoperative diagnosis and early surgery.

Case reports

Case 1

A 2-year-old previously healthy boy visited our ED owing to nonbilious vomiting and progressive abdominal distension

0735-6757/$ - see front matter (C) 2008 doi:10.1016/j.ajem.2007.07.009

for 2 days. Physical examination revealed a soft but distended abdomen and decreased bowel sounds. The laboratory findings showed a low white blood cell count (3.1 x 10³ per cubic millimeter), an abnormal leukocyte differential count (segments, 10%; bands, 16%; monocytes, 19%), and an elevated C-reactive protein level (168.7 mg/ L). Plain abdominal radiograph showed gaseous distension of the small bowel. abdominal sonography performed by the ED pediatrician showed fluid-filled dilated small bowel loops. Subsequently, the patient underwent express abdominal MDCT (Aquilion 64 CFX, Toshiba Medical Systems Corporation, Tochigiken, Japan). Because of vomiting and abdominal distension, no oral contrast

agent was administered and intravenous enhanced MDCT showed diffuse dilatation of small intestinal loops with fluid retention. A bridge-like lesion with inconspicuous mucosal folds in the right lower quadrant was demon- strated, with dilated ileal loops converging at the “bridge.” Multidetector computed tomography also depicted engorged mesenteric vessels, in which some had thrombi (Fig. 1). Volvulus and strangulation of the ileum were initially impressed. Emergency surgery revealed an MD 20 cm away from the ileocecal valve, with its tip adhering to the adjacent mesentery forming a bridge-like lesion underneath which internal hernia of the ileal loops occurred with strangulation. Engorged mesenteric vessels

Fig. 1 Case 1. A, Plain abdominal radiograph shows dilated small bowel gas. B, Axial CT scan shows a bridge-like lesion with enhanced mucosal folds in the right lower quadrant (white arrows) with converging ileal loops and mesenteric vessels (open arrows), and thrombi in several mesenteric veins (black arrows). C and D, Consecutive coronal CT reconstructions offer panoramic demonstrations of diffuse dilatation of the small intestinal loops with fluid retention, a bridge-like lesion with enhanced mucosal folds (white arrow), converging bowel loops and mesenteric vessels (open arrows), and thrombosed mesenteric veins (black arrows).

and some thrombotic mesenteric veins were also noted. Manual decompression, lysis of the adhesions, and resection of the MD and gangrenous small bowel with an end-to-end ileal anastomosis were performed. Pathology showed an MD without gastric tissue and segmental small Bowel necrosis. The patient recovered uneventfully and was discharged 1 week later.

Case 2

A 7-year-old previously healthy boy visited our ED because of sudden-onset postprandial vomiting and severe right paraumbilical abdominal pain for 6 hours. On physical examination, diffuse abdominal tenderness without rebound pain and hypoactive bowel sounds was revealed. Laboratory tests revealed a high white blood cell count (19.4 x 10³ per cubic millimeter) with 91% segmented leukocytes. Plain

Fig. 2 Case 2. Consecutive axial CT scans, (A) and (B), show a bridge-like lesion with enhanced mucosal folds in the right lower quadrant (white arrows) with ileal loops and mesenteric vessels (open arrows) converging at the “bridge.” Note the presence of ascites and dilated small loops with mild bowel wall edema.

abdominal radiograph showed mildly gaseous dilatation of the small bowel. Abdominal sonography performed by the ED pediatrician showed fluid-filled dilated small bowel loops and ascites. Because of vomiting and abdominal pain, only very small amount of oral contrast agent could be tolerated and thus we decided to skip it and express intravenous enhanced abdominal MDCT was performed. Multidetector computed tomography disclosed dilatation of small intestinal loops with fluid retention, bowel wall edema in the lower abdomen, and a small amount of ascites, suggestive of SBO with Bowel ischemia. There was a bridge-like lesion with inconspicuous mucosal folds in the right lower quadrant with ileal loops converging at the “bridge” (Fig. 2). Meckel’s diverticulum with internal hernia of the ileum and strangulated with ischemia was suspected. Emergency surgery confirmed the presence of an MD 65 cm from the ileocecal valve with a fibrotic band adhering its tip to the adjacent mesentery and internal hernia through the space underneath the MD with strangulation. Resection of the MD and gangrenous distal ileum with end- to-end anastomosis of the ileum to the proximal Ascending colon was performed. Pathology showed an MD without gastric tissue and hemorrhagic necrosis of the resected ileal loops. The patient was discharged 11 days later without any complications.

Discussion

Small bowel obstruction is a commonly encountered problem in the ED. In a retrospective review of 289 patients and 314 operations for SBO, adhesions (49%) and neoplasms (16.2%) were the most common causes. Hernia was the third most commonly encountered etiology, accounting for 15% of the cases [9]. However, only 0.5% to 4.1% of cases of intestinal obstruction have been ascribed to internal hernia caused by entrapment of the Small intestine through a normal or abnormal peritoneal or mesenteric aperture [10,11].

Meckel’s diverticulum is a remnant of the omphalome- senteric duct with clinical features which are usually described by “the rule of 2s”: present in approximately 2% of population but only 2% of cases are symptomatic; half of these patients are less than 2 years of age; it is commonly located 2 ft from the ileocecal valve; and the diverticulum is typically 2 in long. Meckel’s diverticulum classically presents with painless or minimally painful Rectal bleeding in children less than 5 years of age [1,2]. Meckel’s diverticulum may cause abdominal pain and distension due to intestinal obstruction induced by coexisting intussuscep- tion, volvulus, adhesions, diverticulitis, foreign body impaction, inversion into the intestinal lumen, neoplasm, or inclusion of the MD in a hernia [1,2]. Meckel’s diverticulum complicated with internal hernia presenting as an SBO is exceedingly rare [3-7].

In the setting of SBO, identification of a laminated enterolith with a lucent center in the right lower quadrant on Plain radiography has been described as a suggestive radiographic feature for MD [1]. Without an enterolith, as in our cases, diagnosis of MD is indeed difficult. Barium studies may reveal an MD as a blind-end saccular or tubular lesion on the antimesenteric site of the ileum or a triradiate fold pattern at the junction of the diverticulum and the ileum [1,2]. However, in the obstructed or strangulated small bowel, barium filling of the MD is hampered. In addition, barium studies of SBO are time consuming and the barium column may be diluted by intraluminal fluid obscuring the detail of the obstruction site [12]. Angiography is useful for identify- ing MD but is usually reserved for survey of intestinal hemorrhage rather than intestinal obstruction [1,2,6].

Meckel’s diverticulum may appear on sonogram as a round or tubular cystic lesion, with an outer hypoechoic layer corresponding to the muscularis propria and an inner hyperechoic layer corresponding to the mucosa and submucosal layers of the intestine. However, it may mimic a dilated bowel loop or a duplication cyst [1]. Sonography is useful for evaluating SBO with an accuracy of about 89%. However, less than 20% of underlying etiologies of SBO can be definitively recognized [13]. In both of our cases, the MDs were missed on sonograms owing to obscuration by fluid-filled dilated bowel loops. Color Doppler sonography may reveal hyperemia or an anomalous vessel in the inflamed MD, but the differential considerations encompass appendicitis, a perforated neoplasm, inflammatory bowel disease, and Pelvic inflammatory disease [1].

Although CT has been reported to have high reliability in diagnosing SBO, accurate identification of MD as the cause of intestinal obstruction is difficult [1,12]. On CT, MD typically manifests as a blind-end tubular segment or diverticular sac in the lower abdomen, containing fluid, enterolith, or fecal-like intraluminal content. However, most MDs may be obscured by coexistent intussusception, volvulus, diverticulitis or foreign body impaction, and SBO [1,7,8]. On the other hand, internal hernia is a rare cause of SBO and usually involves the paraduodenal, periceal, foramen of Winslow, transmesenteric, or transme- socolic regions [10,11]. Diagnosis of internal hernia with CT remains difficult, although some suggestive CT features have been reported, including clustering of bowel loops; stretched, crowded, and engorged mesenteric vessels; and evidence of SBO [10,11]. Recently, MDCT with high spatial resolution and isotropic multiplanar reconstruction images has become widely available. It has offered clear demonstration of MD as a blind-end loop included in a paracolic internal hernia or the inguinal canal (Littre hernia) [7,8]. In both of our cases, the multiplanar capability of MDCT clearly depicted the characteristic features of a bridge-like lesion with incon- spicuous mucosal folds in the right lower quadrant with ileal loops and/or mesenteric vessels converging at the “bridge.” To our knowledge, this is the first report on MDCT diagnosis of SBO due to internal hernia through a bridge-like lesion

formed by adhesion of the distal MD tip to the adjacent mesentery. Furthermore, significant associated findings, including mesenteric vein engorgement and thrombosis, CT signs of bowel ischemia such as ascites and bowel wall edema, were also clearly depicted and this information was crucial to prompt early surgery [9-11].

early diagnosis and treatment are essential because of the high mortality rate (approximately 50%) associated with strangulated internal hernia [14]. Overlooking of internal hernia in pediatric patients may lead to abdominal cata- strophes, as such patients can deteriorate within hours and have a sudden cardiopulmonary arrest [15]. In the ED, routine workup of abdominal pain with initial plain radio- graphs followed by sonography, and eventually abdominal CT, may be time consuming. Furthermore, if the radiology protocol requires oral and intravenous contrast agent, it may take hours to complete. As CT is rapidly becoming an important tool in the workup of acute abdominal pain [15], such a time-consuming protocol may not be feasible. In our ED, for patient with suspected acute abdomen, after initial Abdominal radiographs, depending on the decision of the ED physicians, sonography is optional and is frequently skipped over to abdominal MDCT. However, abdominal pain and vomiting are common in patients with SBO and intake of large amount of oral contrast agent for abdominal MDCT is often hindered. Nevertheless, as seen in our patients, fluid retention in the dilated bowel loops could actually offer good contrast of the bowel lumen and, thus, oral contrast agent might not be absolutely necessary. On other hand, intrave- nous contrast agent was important for clear MDCT demonstration of mesenteric vessels, bowel wall details, and evaluation of the abdominal viscera. Above all, instead of following routine protocol, in our ED, after direct discussion with the radiologist in charge, the ED physicians can arrange express MDCT under close surveillance for patients with suspected critical conditions to avoid any delay. We believe that such an express arrangement is crucial for critical patients, especially in circumstances where rapid diagnosis and surgical treatment can be life saving, for instance, in children with internal hernias.

In summary, an accurate diagnosis of SBO due to MD complicated with internal hernia may be hinted by recognizing a bridge-like lesion in the right lower quadrant with ileal loops converging at the “bridge.” Our 2 cases highlight the feasibility of MDCT, especially in the ED, in revealing this unusual etiology of SBO, allowing early Surgical consultation.

References

1. Levy AD, Hobbs CM. Meckel diverticulum: radiologic features with pathologic correlation. Radiographics 2004;24:565-87.
2. McCollough M, Sharieff GQ. Abdominal Surgical emergencies in infants and young children. Emerg Med Clin North Am 2003;21: 909-35.
3. Murakami R, Sugizaki K, Kobayashi Y, Ogura J, Yamamoto K, Kurokawa A, et al. Strangulation of small bowel due to Meckel diverticulum: CT findings. Clin Imaging 1999;23:181-3.
4. Lee MC, Lin LH, Chen DF. Internal hernia caused by Meckel diverticulum in an infant: report of one case. Acta Paediatr Taiwan 2001;42:105-7.
5. Dalinka MK, Wunder JF, Wolfe RD. Internal hernia through the mesentery of a Meckel’s diverticulum. Radiology 1970;95:39-40.
6. Hawkins HB, Slavin Jr JD, Levin R, Spencer RP. Meckel’s diverticulum. Internal hernia and adhesions without gastrointestinal bleeding-ultrasound and scintigraphic findings. Clin Nucl Med 1996;21:938-40.
7. Sinha R. Bowel obstruction due to Littre hernia: CT diagnosis. Abdom

Imaging 2005;30:682-4.

1. Aggarwal BK, Rajan S, Aggarwal A, Gothi R, Sharma R, Tandon V. CT diagnosis of Meckel diverticulum in a paracolic internal hernia. Abdom Imaging 2005;30:56-9.
2. Mucha Jr P. Small intestinal obstruction. Surg Clin North Am 1987;67:

597-620.

1. Blachar A, Federle MP, Dodson SF. Internal hernia: clinical and imaging findings in 17 patients with emphasis on CT criteria. Radiology 2001;218:68-74.
2. Takeyama N, Gokan T, Ohgiya Y, Satoh S, Hashizume T, Hataya K, et al. CT of internal hernias. Radiographics 2005;25:997-1015.
3. Balthazar EJ. CT of Small-bowel obstruction. AJR Am J Roentgenol 1994;162:255-61.
4. Ko YT, Lim JH, Lee DH, Lee HW, Lim JW. Small bowel obstruction: sonographic evaluation. Radiology 1993;188:649-53.
5. Martin LC, Merkle EM, Thompson WM. Review of internal hernias: radiographic and clinical findings. AJR Am J Roentgenol 2006;186: 703-17.
6. Pershad J, Simmons GT, Chung D, Frye T, Marques MB. Two acute pediatric abdominal catastrophes from strangulated left paraduodenal hernias. Pediatr Emerg Care 1998;14:347-9.