ABSTRACT
Internal hernia is an uncommon cause of small bowel obstruction, especially in children and adolescents without previous abdominal surgery. Among its subtypes, transmesenteric hernia through a mesenteric defect is rare but clinically important because it may cause closed-loop obstruction, bowel ischemia, and strangulation. Early diagnosis and timely surgical treatment are therefore essential. A previously healthy 15-year-old boy was transferred to our emergency department with left upper quadrant abdominal pain and vomiting for 2 days. His vital signs were stable, and physical examination showed mild left upper quadrant tenderness without abdominal distension. Abdominal computed tomography revealed two transition points in the mid-abdomen and dilatation of the left-sided small bowel loops, suggesting closed-loop obstruction. Emergency laparoscopic exploration showed two segments of small bowel herniated through a defect in the jejunal mesentery. Although laparoscopic reduction was attempted first, marked bowel dilatation and the small size of the mesenteric defect prevented safe reduction. The procedure was therefore converted to open surgery through a periumbilical incision. The incarcerated bowel loops were carefully reduced, and the mesenteric defect was closed with interrupted sutures. The patient developed mild postoperative ileus, which resolved with conservative treatment. At the 1-year follow-up, he remained well, with no recurrence or postoperative sequelae. Transmesenteric internal hernia caused by a mesenteric defect should be considered in adolescents with small bowel obstruction, even when they have no history of abdominal surgery. Prompt surgical exploration and closure of the mesenteric defect may prevent bowel ischemia and strangulation and support favorable outcomes.
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Keywords: Internal hernia; Transmesenteric hernia; Intestinal obstruction; Child; Case reports
INTRODUCTION
Small bowel obstruction in children and adolescents is most often associated with postoperative adhesions, incarcerated hernia, intussusception, inflammatory bowel disease, or congenital anomalies. When there is no history of abdominal surgery, identifying the cause can be difficult, and uncommon etiologies should remain in the differential diagnosis. Internal hernia is a rare but potentially life-threatening cause of intestinal obstruction in which a viscus protrudes through a peritoneal or mesenteric aperture but remains within the abdominal cavity [
1-
3].
Transmesenteric internal hernia is a rare subtype that occurs when bowel passes through a congenital or acquired mesenteric defect [
4-
6]. Congenital mesenteric defects often remain undetected until bowel obstruction or strangulation occurs. Because herniated bowel loops can become tightly trapped within a narrow defect, closed-loop obstruction and bowel ischemia may develop rapidly. For this reason, early recognition and timely surgical intervention are critical [
7,
8]. Here, we report a rare case of transmesenteric internal hernia through a mesenteric defect in a previously healthy 15-year-old boy with no history of abdominal surgery.
CASE REPORT
Ethics statement
Written informed consent for publication of the case was obtained from the patient’s parents. This case report was prepared in accordance with the principles of the Declaration of Helsinki.
Patient information
A previously healthy 15-year-old boy was referred to our emergency department because intestinal obstruction was suspected. He had initially presented to a local medical center with a 2-day history of left upper quadrant (LUQ) abdominal pain and vomiting, after which he was transferred to our institution for further management. He had no history of abdominal surgery, trauma, significant medical illness, or relevant family history.
Clinical and diagnostic findings
On arrival, his vital signs were stable: blood pressure, 138/78 mmHg; heart rate, 77 beats/min; respiratory rate, 18 breaths/min; and body temperature, 36.8 °C. Physical examination showed mild LUQ tenderness without abdominal distension. Laboratory testing showed a white blood cell count of 9,130/mm³, hemoglobin level of 15.6 g/dL, platelet count of 183,000/mm³, and erythrocyte sedimentation rate of 10 mm/hr. The C-reactive protein level was mildly elevated at 0.62 mg/dL, whereas the remaining laboratory findings were within normal limits. Plain abdominal radiography showed dilatation of the small bowel in the left upper abdomen (
Fig. 1). Abdominal computed tomography (CT) demonstrated two transition points in the mid-abdomen, and dilatation of the left-sided small bowel loops suggested closed-loop obstruction (
Fig. 2). Although a small amount of ascites was present, there was no definite evidence of decreased bowel perfusion.
Given the suspicion of closed-loop obstruction, emergency surgical exploration was performed. Laparoscopy revealed two segments of small bowel herniated through a mesenteric defect (
Fig. 3A). Reduction was initially attempted laparoscopically, but marked bowel dilatation and the relatively small defect prevented safe reduction. The operation was therefore converted to open surgery through a periumbilical incision. A 4-cm defect was identified in the jejunal mesentery (
Fig. 3B). Two segments of small bowel, located approximately 70 cm and 100 cm proximal to the ileocecal valve, had herniated through the defect. After careful reduction, the color of the herniated bowel loops gradually improved, and there was no evidence of irreversible ischemia or necrosis. Bowel resection was therefore not required. The defect was closed with interrupted 3-0 black silk sutures, and no other intra-abdominal abnormalities were identified.
Oral intake was started on postoperative day 5; however, the patient subsequently developed mild postoperative ileus, which resolved with conservative management. He was discharged on postoperative day 17 in stable condition without further complications. At the 1-year follow-up, he remained asymptomatic, with no evidence of recurrent obstruction or other postoperative sequelae.
DISCUSSION
Transmesenteric hernias often occur in patients without prior laparotomy and are frequently diagnosed only after acute intestinal obstruction or strangulation has developed. In the present case, the patient’s adolescent age and lack of abdominal surgery, trauma, intra-abdominal infection, or inflammatory disease supported the presumption that the mesenteric defect was congenital. Transmesenteric hernias can progress rapidly to bowel ischemia because the herniated bowel may become tightly incarcerated within a relatively small mesenteric defect.
The clinical presentation of transmesenteric internal hernia is nonspecific. Patients may have abdominal pain, vomiting, abdominal distension, or signs of peritonitis when bowel ischemia or perforation develops [
9]. In the present case, the patient had abdominal pain and vomiting but remained hemodynamically stable and had no signs of peritoneal irritation. Laboratory findings were also largely unremarkable. These features suggest that clinical examination and laboratory testing alone may be insufficient to exclude closed-loop obstruction or early strangulation.
Fujita et al. [
10] emphasized the diagnostic value of serial plain abdominal radiographs in patients with suspected internal hernia. They suggested that internal hernia should be considered when similar intestinal gas patterns persist on radiographs obtained several hours apart. In patients with small bowel obstruction, comma-shaped or coffee bean-shaped gas patterns may indicate strangulated obstruction. When these findings are present, prompt additional evaluation, including CT, or immediate surgical intervention should be considered.
CT is useful for diagnosing internal hernia and assessing bowel viability [
11,
12]. In this case, CT showed two transition points with small-bowel dilatation; these findings were suggestive of closed-loop obstruction. Although no definite bowel-wall perfusion defect was identified, the combination of closed-loop obstruction and ascites supported urgent surgical exploration.
Surgical treatment consists of reducing the herniated bowel, assessing bowel viability, resecting nonviable bowel when necessary, and closing the mesenteric defect to prevent recurrence [
9]. Although laparoscopy can be useful in selected patients, conversion to open surgery may be necessary when severe bowel dilatation, a small mesenteric defect, or difficulty with safe reduction limits the laparoscopic approach. In the present case, laparoscopic reduction was unsuccessful because of severe bowel dilatation and a narrow mesenteric defect. After conversion, the herniated bowel was successfully reduced, bowel viability improved, and bowel resection was avoided.
This case highlights several clinically important points. First, transmesenteric internal hernia should remain in the differential diagnosis of small bowel obstruction in adolescents with no history of abdominal surgery. Second, CT findings suggestive of closed-loop obstruction should prompt urgent surgical evaluation, even when physical examination and laboratory findings are not alarming. Third, early surgical intervention may prevent bowel necrosis and preserve intestinal continuity.
In conclusion, transmesenteric internal hernia through a mesenteric defect is a rare but important cause of small bowel obstruction in adolescents with no history of abdominal surgery. Because clinical manifestations and laboratory findings may be nonspecific, CT plays a key role in identifying closed-loop obstruction. Prompt exploration permits assessment and restoration of bowel viability, while closure of the defect reduces the risk of recurrence. In this patient, timely intervention allowed reduction without bowel resection and was followed by a favorable long-term outcome.
NOTES
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Authors’ contributions
All the work was done by JP.
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Conflict of interest
None.
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Funding
None.
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Data availability
Not applicable.
Fig. 1.Plain abdominal radiograph showing small-bowel dilatation in the left upper abdomen.
Fig. 2.Abdominal computed tomography showing two transition points in the mid-abdomen (arrow) and dilatation of the left-sided small bowel loops, suggesting closed-loop obstruction.
Fig. 3.Intraoperative findings. (A) Two segments of small bowel herniated through the mesenteric defect (arrow). (B) A 4-cm defect was identified in the jejunal mesentery.
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