A Rare Case of Small Bowel Obstruction in a 15-Year-Old Girl: Internal Hernia Associated with Meckel’s Diverticulum

Introduction

Pediatric small bowel obstruction (SBO) is a common surgical emergency [1]. Adult patients with SBO have a relatively narrow list of differentials, but SBO in children can be due to various etiologies, including congenital, infectious, inflammatory, or iatrogenic causes, and rarely a Meckel’s diverticulum, as in our case.

Most cases of Meckel’s diverticulum are asymptomatic, and the estimated risk of developing lifetime complications of Meckel’s diverticulum is around 4% [2]. Children who are symptomatic commonly present with bowel obstruction (about 40%) [3].

As SBO in children usually presents with nonspecific symptoms like abdominal pain and abdominal distension and vomiting, imaging plays a vital role in the prompt diagnosis of SBO and can determine its cause, extent, and location. Computed tomography (CT) has been shown to have a high sensitivity, specificity, and accuracy in diagnosis and revealing the level of small bowel obstruction in children, especially in children older than 2 years [4].

This case report is of a 15-year-old girl presenting as an emergency with vomiting and small bowel obstruction due to an internal hernia associated with Meckel’s diverticulum.

Case Report

A 15-year-old girl presented to the Children’s Emergency (CE) department in our institution with a 2-day history of vague generalized abdominal discomfort associated with multiple episodes of non-bilious non-bloody vomiting. Her vital signs at the time of the initial presentation were within normal limits and her abdomen was soft and non-tender. The initial diagnosis was thought to be that of gastroenteritis and she was given medication to relieve her symptoms. Her symptoms improved and she was subsequently discharged on the same day with the presumptive diagnosis of gastroenteritis.

The following day, the child returned to the CE with persistent vomiting, and new subjective descriptions of bloatedness and reduced bowel movements. Physical examination at this point revealed mild distension of the abdomen with associated mild generalized tenderness. The tenderness was not localized to the right iliac fossa and there was no evidence of guarding. Her vital signs demonstrated mild tachycardia but were otherwise normal. At this point, appendicitis and bowel obstruction were considered as differential diagnoses for her evolving abdominal pain.

Abdominal radiographs were performed, which showed multiple dilated small bowel loops centrally with fluid levels (Figure 1).

Blood tests at this point demonstrated neutrophilia and leukocytosis but were otherwise normal.

The presumptive diagnosis was that of SBO. She was admitted under the care of the Pediatric Surgery (PAS) department and initially managed with intravenous (IV) fluid resuscitation. She was kept nil per os in case surgery was required. At this point in time, the cause and level of the small bowel obstruction was unclear, and a CT scan with intravenous contrast was performed to investigate the cause and to delineate the level of obstruction.

The CT scan demonstrated multiple fluid-filled small bowel loops centered in the central abdomen with fluid levels within, in keeping with SBO. The dilated small bowel loops were seen to taper towards the right iliac fossa with transition points (Figure 2). There was also prominent eccentric fat stranding noted along the adjacent lateral conal fascia and along the antemesentric border of the bowel loops at the right iliac fossa, with no overt mesenteric congestion.

We noted a cluster of non-dilated small bowel loops at the region of the terminal ileum, with a loop of dilated small bowel with a “C”-shaped configuration (Figure 3). This loop was seen to demonstrate a distinctly different mucosal appearance and thickness to the rest of the adjacent dilated small bowel, with suggestion of a blind-ending appearance, which raised the possibility of an underlying Meckel’s diverticulum.

The appendix was not well demonstrated on the scan. There were also multiple small-volume nodes at the right iliac fossa and throughout the mesentery measuring up to 0.5 cm in short axis diameter, which were likely reactive lymph nodes. No pneumatosis, pneumoperitoneum, significant bowel wall thickening, or bowel wall edema were demonstrated. A small amount of hypodense pelvic ascites was also seen.

Overall, the CT scan findings and clinical presentation were suggestive of SBO with an etiology of either Meckel’s diverticulum or appendicitis. However, as the cause of the obstruction was not definite, we recommended that the patient undergo a diagnostic laparoscopy under general anesthesia.

Upon entering the peritoneum, a Meckel’s diverticulum was identified. The tip of the Meckel’s diverticulum was adherent to part of the small bowel mesentery, forming a 2-cm internal hernia defect. A loop of proximal ileum was seen herniating through this defect, resulting in proximal intestinal dilatation (Figure 4). There was straw-colored ascitic fluid without any pus seen. The appendix and bilateral ovaries were normal. A laparoscopy-assisted transumbilical Meckel’s diverticulectomy (LATUM) was subsequently performed (Figure 4C). The Meckel’s diverticulum was excised with a wedge of normal ileum, and an interrupted handsewn anastomosis was performed using polydioxanone (PDS) 5/0 sutures. The patient subsequently recovered without incident and had restoration of bowel function by the 2nd postoperative day. She was discharged on the 4th postoperative day.

Histology samples confirmed a Meckel’s diverticulum with ec-topic gastric mucosa. Notably, the patient did not have any antecedent history of recurrent abdominal pain or painless per-rectal bleeding prior to her presentation with mechanical small bowel obstruction.

Discussion

Meckel’s diverticulum is a congenital intestinal diverticulum that arises from the incomplete obliteration of the omphalomesenteric duct during embryonic development and is the most common congenital malformation of the gastrointestinal tract, with an estimated prevalence of about 2% and average age of symptomatic presentation of about 2.5 years [5,6].

Complications that can arise from a Meckel’s diverticulum include: painless lower gastrointestinal bleeding (LGIB) due to acid secretion from ectopic gastric mucosa lining the diverticulum, SBO due to incarceration of the diverticulum, perforation from inflammation secondary to Meckel’s diverticulitis, or the diverticulum can also act as a lead point for intussusception [6]. There can also be a fibrous band attached to the Meckel’s diverticulum, which can result in small bowel obstruction [6]. In our patient, the abnormal attachment of the Meckel’s diverticulum to the small bowel mesentery, likely from a remnant fibrous or adhesion band, resulted in an internal hernia and subsequently small bowel obstruction, which is a rare complication [7].

The most sensitive test for Meckel’s diverticulum is a Meckel radionuclide scan, which uses 99mTc-Na-pertechnetate to locate ectopic gastric mucosa, with sensitivity up to 90% in children [6,8]. If there is LGIB, CT angiography can also detect contrast extravasation. The definitive treatment of symptomatic treatment of Meckel’s Diverticulum is surgical excision [9].

There are several patterns in which SBO can arise from a Meckel’s diverticulum, including distal ileal obstruction due to bowel torsion around an omphalomesenteric band, secondary to intussusception of a Meckel’s diverticulum, or extension of the Meckel’s diverticulum into a hernia sac (Littre’s hernia). Internal herniation by the Meckel’s diverticulum causing SBO is rare, and several cases of internal herniation due to adhesion of inflamed end of the Meckel’s diverticulum to the corresponding base of mesentery have been reported by Papaziogas et al [10] and Lin et al [11]. Additionally, Pandove et al reported a case of an adhesion band extending from the tip of the diverticulum to the adjacent mesentery, in addition to internal herniation of bowel into a sac formed by unusual mesentery of the Meckel’s diverticulum and the adhesion band [12]. In a case reported by Zhang et al, the tip of the diverticulum was densely adhered to the adjoining mesentery, forming a narrow ring through which small intestine had drilled through, resulting in gangrene of the herniated small bowel [13]. These patients also presented with symptoms of vomiting and abdominal pain, similar to ours.

In our patient, the tip of the Meckel’s diverticulum was adherent to part of the small bowel mesentery, forming a 2-cm internal hernia defect through which a loop of proximal ileum had herniated, causing SBO. The noteworthy aspect of our case is the clear demonstration of the mesenteric window on surgical exploration, which was not well demonstrated in the CT study.

On CT, an uncomplicated Meckel’s diverticulum can be difficult to differentiate from background small bowel, and even when symptomatic and inflamed, it can mimic a single enlarged bowel loop, making accurate diagnosis difficult. The diverticulum usually appears as a round or tubular blind-ending structure that communicates with the small bowel, with accompanying mural wall thickening and enhancement and surrounding inflammatory changes [8]. Non-enhancement of the diverticular wall suggests gangrene and impending rupture. In our case, the distinctly different mural thickness of the diverticulum aided in diagnosis.

However, Meckel’s diverticulum as a cause of pediatric SBO remains an extremely difficult pre-operative diagnosis to make accurately, but should always be considered as a possible etiology, especially if there are supporting imaging findings. If there is delay in diagnosis or treatment, SBO can lead to bowel necrosis [14] or other complications, which can be life-threatening. Prompt surgical resection of the Meckel’s diverticulum is therefore essential for treatment in SBO patients.

Conclusions

Meckel’s diverticulum causing an internal hernia is a rare manifestation of pediatric SBO with nonspecific signs and symptoms and remains a challenging imaging diagnosis, but should always be considered as an etiology. Early diagnosis and prompt intervention will improve clinical outcomes and avoid complications.