Internal hernia (IH) is a rare culprit of small bowel obstruction (SBO) with an incidence of < 1%. It poses a considerable diagnostic challenge requiring a high index of suspicion to prevent misdiagnosis, improper treatment, and subsequent morbidity and mortality.

To determine the clinico-demographic profile, radiological and operative findings, and postoperative course of patients with IH and its association with SBO.

Medical records of 586 patients with features of SBO presenting at a tertiary care centre at Lucknow, India between September 2010 and August 2023 were reviewed.

Out of 586 patients, 7 (1.2%) were diagnosed with IH. Among these, 4 had congenital IH and 3 had acquired IH. The male-to-female ratio was 4:3. The median age at presentation was 32 years. Contrast-enhanced computed tomography (CECT) was the most reliable investigation for preoperative identification, demonstrating mesenteric whirling and clumped-up bowel loops. Left paraduodenal hernia and transmesenteric hernia occurred with an equal frequency (approximately 43% each). Intraoperatively, one patient was found to have bowel ischemia and one had associated malrotation of gut. During follow-up, no recurrences were reported.

IH, being a rare cause, must be considered as a differential diagnosis for SBO, especially in young patients in their 30s or with unexplained abdominal pain or discomfort post-surgery. A rapid imaging evaluation, preferably with CECT, is necessary to aid in an early diagnosis and prompt intervention, thereby reducing financial burden related to unnecessary investigations and preventing the morbidity and mortality associated with closed-loop obstruction and strangulation of the bowel.

Internal hernias are an uncommon cause of small bowel obstruction and present a challenging clinical diagnostic scenario. They result from the abnormal protrusion of an abdominal organ through a peritoneal defect and can cause intermittent obstructive symptoms, diffuse abdominal discomfort, and postprandial pain. Paraduodenal hernias comprise 53% of all internal hernias ¹ and occur due to failure of the fixation of either the left or transverse mesocolon to the posterior abdominal wall. Its relative rarity results in mortality between 20 and 50% ² because of delayed diagnosis and consequent obstruction, strangulation, and bowel ischemia. Our case series describes three patients before and after operative fixation of paraduodenal hernia. Only one of the three was identified by preoperative radiologist interpretation. Subsequent diagnosis and definitive treatment were completed by surgical staff to resolve undiagnosed undulating abdominal pain and obstructive-type symptoms. We further analyze left-sided paraduodenal hernias after laparoscopic and robotic repair to define common symptomatology, typical CT findings, and preferred laparoscopic repair techniques.

Paraduodenal hernias (PDH), also called mesocolic hernias, account for up to 53% of all internal hernias, but they cause only 0.2-0.9% of all cases of intestinal obstruction. This is the first systematic review of all reported cases so far, investigating their clinical presentation, radiological imaging, and treatment outcomes.

After a detailed search in PubMed and Medline, using the keywords "paraduodenal hernia", 115 studies matched our criteria. A review of these reports was conducted and the full texts were examined.

A total of 159 patients were included in our analysis, with 69.8% and 30.2% of them suffering from either a left or a right PDH, respectively. Mean age at diagnosis was 44.1 years, with a 2/1 male/female ratio. PDH were associated with non-specific symptoms and signs; abdominal pain being the most common. Computed tomography (CT) scan of the abdomen was the most frequently used diagnostic modality. Regardless of PDH localization, all patients were operated on, with approximately one-third of them undergoing a laparoscopic operation, which was associated with a significantly decreased morbidity rate as well as length of hospital stay, compared with the open repair.

PDH are not usually associated with specific symptoms and signs; thus, they constitute a diagnostic challenge, requiring a high level of knowledge and clinical suspicion. Undoubtedly, CT scan of the abdomen is the gold standard diagnostic tool. Their operative repair is mandatory, with the laparoscopic approach demonstrating significant advantages over the open repair, seeming to be the optimum treatment strategy.