Small bowel obstruction due to intra-abdominal hernia: New thoughts on diagnosis and treatment

Abstract

Internal herniation (IH) refers to the movement of intra-abdominal organs or tissues out of their original position through normal or abnormal orifices and fissures in the peritoneum or mesentery and into an anatomic space within the abdominal cavity. Although the incidence of small bowel obstruction (SBO) caused by IH is very low (approximately 0.2% to 0.9%), its incidence may be increased in certain specific populations or in postoperative patients. Recently Kaw et al shared their 13-year experience of managing IHs in a tertiary care hospital in India. This retrospective study analyzed and determined the clinico-demographic profiles, radiological and operative findings and postoperative course of patients with IH and the association with SBO. The results provide valuable insights into early diagnosis and establishment of a timely treatment regimen for this condition and emphasize the importance of combining rapid imaging evaluation with the traditional therapeutic approach of laparoscopic surgery, thus providing a novel perspective on the diagnosis and treatment of SBO caused by IH.

Key Words: Internal herniation; Small bowel obstruction; Patient; Differential diagnosis; Imaging evaluation; Conservative measures

Core Tip: Despite the low incidence of small bowel obstruction caused by internal herniation (IH), Kaw et al showed that there is still a need for IH as a differential diagnosis of intestinal bowel obstruction. Contrast-enhanced computed tomography combined with the traditional treatment method of laparoscopic surgery is an effective means of early diagnosis and reduces unnecessary investigations.

INTRODUCTION

Internal herniation (IH) is defined as the entry of intra-abdominal organs or tissues from their original position into an anatomical space in the abdominal cavity through a normal or abnormal orifice or fissure in the peritoneum or mesentery that leaves its original position[1]. With a low incidence of IH (about 0.2%-0.9%), lack of specific symptoms and signs, and is mostly independent of gender and age, making its preoperative diagnosis challenging[2]. When intra-abdominal organs or tissues protrude through the defective portion of the abdominal wall, they may compress or distort the bowel. Bowel obstruction occurs because excess gas and fluid accumulated in the abdominal cavity cannot pass smoothly through the bowel in the obstructed area[3]. Although rare, IH remains an important cause of small bowel obstruction (SBO). In addition, SBO caused by IH is prone to the complication of intestinal strangulation and is associated with a high morbidity and mortality rate, making early diagnosis and surgical treatment are crucial[4-8].

For SBO caused by IH, the predominant treatment options include surgical treatment, placement of supportive devices, medication, and conservative management[7,9-11]. The choice of treatment largely depends on the patient’s specific condition, the severity of the disease and the judgment of the physician. Therefore, for SBO caused by IH, it is very important to consult a physician in time and accept medical guidance and advice. On the other hand, for high-risk or postoperative patients, research on strategies to prevent the occurrence of IH-such as improving specific surgical techniques and developing postoperative management programs-is ongoing[12-14]. These studies continue to advance the understanding and management of SBO associated with IH, which in turn improves the prognosis of patients.

ETIOLOGY OF SBO CAUSED BY IH

An intra-abdominal hernia formed through a congenital foramen in the abdominal cavity is also known as a congenital IH (CIH). A CIH forms because of pores that exist within the embryo itself during development or those that arise from developmental anomalies. Types of CIH include: Para-duodenal hernia, omental foramen hernia (Winslow’s foramen hernia), transomental hernia, transmigratory mesenteric hernia, periaqueductal hernia, and peri-sigmoid hernia[15,16]. Meanwhile, an acquired IH (AIH) is an intra-abdominal hernia formed by the passage of abdominal contents (mostly the small bowel) through an acquired foramen formed in the abdominal cavity due to abdominal trauma and surgery[17,18]. Most of the intra-abdominal hernias that occur in patients undergoing abdominal surgery are IHs formed by intestinal adhesion bundles. There are relatively rare clinically and prone to forming strangulated intestinal obstructions, which represent a serious surgical emergency[19,20].

Numerous etiologic factors underlie the pathogenesis of SBO caused by IH. First, an intra-abdominal organ or peritoneal membrane prolapses through a weak point in the abdominal wall or a natural opening, forming a sac-like protrusion. If the intra-abdominal hernia becomes trapped or twisted, it can compress or block the small intestine in the abdominal cavity, leading to SBO. Second, congenital abdominal wall defects, surgical incisions, or trauma can lead to displacement of organs or tissues within the abdominal cavity and the formation of an IH, including inguinal hernias, umbilical hernias, and hernia-through-abdomen lesions. Furthermore, muscle weakness or laxity-including abdominal muscle laxity, abdominal wall muscle dysfunction, and severe obesity in the elderly, among others-is a common cause of SBO due to internal hernia. In addition, conditions such as peritonitis, gastrointestinal tumors, and inflammatory bowel disease may also lead to an IH and cause SBO. It is important to note that some behavioral habits, such as prolonged forceful defecation, weight lifting, or strenuous exercise, may also increase the risk of IH leading to SBO[21,22].

The study by Kaw et al[23] showed that out of 7 (1.2%) patients diagnosed with IH, 4 had CIH and 3 had AIH, with a balanced male to female ratio. In the CIH group, the male to female ratio was also close. In terms of age, the age of onset of IH patients ranged from 26 to 64 years, with a median age of 33.5 years in the CIH group and 31 years in the AIH group. No significant features were shown in terms of gender as well as age factors. Therefore, early detection and diagnosis are key to preventing SBO caused by IH.

DIAGNOSIS AND TREATMENT OF SBO CAUSED BY IH

An accurate diagnosis of BO due to IH aid the development of an appropriate post-surgical rehabilitation program and reduces the complication rate. In terms of clinical manifestations, patients often experience abdominal pain, vomiting, bloating and constipation. Sudden, intermittent abdominal pain may suggest an IH. If an IH is suspected, the physician should carefully palpate and examine the patient's inguinal region for the presence of a bulge or prolapse. The patient may also be asked to cough or forcefully urinate to help confirm the presence of a prolapse in the groin area. Imaging is the most common means of confirming a diagnosis of IH. Furthermore, X-rays, while not as accurate as computed tomography (CT), can be used to initially assess for SBO. Furthermore, ultrasound can help the physician determine the location, size, and content of the IH and rule out other underlying conditions. CT scanning, which is the most effective tool for diagnosing IH. CT can show abnormal location, dilation, and interruption of the bowel, as well as abnormalities in the arrangement of the mesenteric blood vessels. However, the diagnostic results of CT still need to be distinguished from other causes of SBO such as adhesions and tumors[24,25].

A definitive diagnosis enables an early decision to be made on the need for surgical intervention: Once IH leading to SBO is diagnosed, prompt surgery can prevent serious complications such as intestinal necrosis. The use of laparoscopic techniques has made the treatment of IH more efficient, and there have been increasingly used in the management of IH. Laparoscopic surgery has the advantages of less trauma, quicker recovery, and shorter hospitalization compared with traditional open surgery, thus increasing the speed of patients’ postoperative recovery. In recent years, several new treatment methods have also been widely explored and studied, such as percutaneous endoscopic laparoscopic surgery and laparoscopic intraperitoneal surgery. These noninvasive or minimally invasive surgical approaches can reduce patient pain and complications as well as accelerate postoperative recovery[26,27]. The optimal choice of medication is also useful in treating SBO caused by IH. Antispasmodic medications can help relieve intestinal spasms and thus reduce the symptoms of obstruction, while analgesics (including acetaminophen and non-steroidal anti-inflammatory drugs) can relieve pain and discomfort caused by the intestinal obstruction; further, anti-nausea medications, such as omeprazole, may be administered in cases of severe vomiting or nausea. Conservative measures such as fasting and gastrointestinal decompression have also been used to reduce the symptoms of intestinal obstruction. Fasting avoids aggravating the bowel, while gastrointestinal decompression-which involves the insertion of a nasogastric tube to relieve pressure and insufflation of the gastrointestinal tract-can help to relieve discomfort. In some cases, gentle abdominal massage may help to promote bowel movements; and, in addition, some patients may be able to obtain symptomatic relief by changing position[28,29]. It is important to note that conservative treatment is usually indicated for milder forms of obstruction, or implemented while awaiting surgical evaluation. If there is a risk of severe IH or intestinal necrosis, surgery may be the only effective treatment.

The study by Kaw et al[23] found that close to one-third of patients did not have any preoperative diagnosis or suspicion of IH, and the majority of the patients had multiple symptomatic episodes with abdominal pain and distension being the most common complaints within a median duration of 1 year. Contrast-enhanced CT is the most reliable preoperative diagnostic method. For treatment, 3 patients underwent laparoscopy and 4 patients underwent laparotomy. Left paracolic duodenal hernia and trans mesenteric AIH occurred with an equal frequency of about 43% each. No recurrence was reported during the follow-up period. Overall, timely and accurate diagnosis of IH and appropriate treatment strategies can significantly improve the outcome and quality of life of patients with SBO.

CONCLUSION

There is an interplay between IH and SBO. The presence of IH increases the risk of compression and distortion of the bowel, which may induce SBO. Furthermore, surgery for IH itself may also lead to the development of SBO. This highlights the need for close attention to the development of associated intestinal symptoms and complications when diagnosing and treating IH in order to avoid the development of SBO caused by IH.