Internal Hernia Through the Pars Flaccida: A Rare Intraoperative Finding

Introduction

Internal hernias are an uncommon but clinically important cause of small-bowel obstruction, with an overall incidence of less than 1%, and accounting for approximately 0.6% to 5.8% of all intestinal obstruction cases [1,2]. These hernias are defined by the protrusion of viscera through normal or abnormal peritoneal or mesenteric apertures while remaining within the peritoneal cavity [3,4]. While traditionally classified into several anatomical subtypes, herniation through the pars flaccida of the lesser omentum is an extremely rare variant that poses unique diagnostic and therapeutic challenges [5].

The pars flaccida, forming part of the hepatogastric ligament, is an anatomically complex region where iatrogenic defects can develop after upper-abdominal surgery [6]. Unlike more common internal hernias such as paraduodenal (53%), pericecal (13%), or transmesenteric (8%) variants, pars flaccida hernias have been only sporadically reported in the literature [1,7]. The rarity of this condition, combined with its nonspecific clinical presentation, makes preoperative diagnosis particularly challenging [8].

Recent studies have demonstrated an increasing incidence of internal hernias, largely attributed to the growing adoption of laparoscopic surgical procedures [9,10]. While much attention has focused on internal hernias following bariatric surgery, particularly Roux-en-Y gastric bypass, pars flaccida herniation presents distinct anatomical and technical considerations that warrant specific attention [11]. Diagnosis often remains challenging due to variable symptoms, ranging from intermittent mild digestive problems to acute intestinal obstruction [12]. While computed tomography (CT) has emerged as the primary diagnostic tool, the radiological features of pars flaccida hernias can be subtle and may not demonstrate the classical signs associated with other internal hernias, such as the “swirl sign” [13].

We present a case of successful laparoscopic management of an internal hernia through the pars flaccida, highlighting the diagnostic approach, operative technique, and specific considerations for minimally invasive repair. This report aims to contribute to the limited literature on this rare entity and provide practical insights for surgeons encountering similar cases.

Case Report

A 52-year-old woman presented with recurrent episodes of epigastric abdominal pain. Her past medical history was significant for gastroesophageal reflux disease, endometriosis, total thyroidectomy for papillary thyroid carcinoma, and rectosigmoid-invasive moderately differentiated adenocarcinoma (Stage IIIA – pT2N1aM0) diagnosed in 2017. She underwent laparoscopic low anterior resection with a colonic J-pouch creation followed by FOLFOX adjuvant chemotherapy. Starting December 2018, she developed intermittent bouts of diffuse abdominal pain, initially attributed to inflammatory bowel syndrome. These episodes continued through 2019 and increased in frequency by 2021. The patient described a consistent pain pattern that began in the right side of her abdomen, progressed to the umbilical region, and extended up to the sternum.

During a severe episode in 2021, she went to the emergency department and a CT of the abdomen and pelvis revealed a left-sided colon volvulus requiring decompression via flexible scope. Subsequently, she underwent robot-assisted left colectomy with colonic J-pouch resection, splenic flexure mobilization, coloanal anastomosis, and diverting loop ileostomy in 2021, with stoma reversal in 2022.

After stoma reversal, she continued to experience multiple episodes of epigastric abdominal pain and nausea. These episodes typically lasted approximately 1 hour and were characterized by severe nausea without vomiting. In September 2024, emergency department evaluation, including CT imaging, suggested malrotation of the small bowel with small bowel located in the left of the abdomen and large bowel in the right, as well as swirling of the small bowel, suggesting a volvulus, but no evidence of obstruction or bowel thickening.

The patient presented to our clinic in October 2024 with a long history of epigastric pain, nausea, and non-bloody, non-bilious emesis. Repeat CT imaging demonstrated abnormal positioning of small-bowel loops, with evidence of swirling, consistent with an internal hernia. Given her complex surgical history and recurrent symptoms, she was scheduled for diagnostic laparoscopy to investigate for internal hernia versus intermittent volvulus.

Discussion

POTENTIAL PITFALLS:

This systematic approach allows for safe and effective management of pars flaccida hernias while minimizing the risk of complications. The key to success lies in meticulous attention to anatomical details, careful tissue handling, and thorough inspection for additional defects.

A comprehensive literature review was conducted using the PubMed database to identify previously reported cases of internal hernias through the pars flaccida of the lesser omentum (also known as gastrohepatic or hepatogastric ligament) managed laparoscopically. The search strategy included combinations of the terms “internal hernia”, “pars flaccida”, “lesser omentum”, “gastrohepatic ligament”, and “hepatogastric ligament”. Table 1 summarizes the published cases identified through this search.

When comparing our case to the existing literature on pars flaccida hernias, several important distinctions emerge. Unlike the cases reported by Masubuchi et al [14] and Makutani et al [15], which occurred following colectomy procedures, our patient had undergone multiple colorectal surgeries, including low anterior resection, volvulus treatment, and subsequent coloanal anastomosis, creating a more complex surgical background. The technical approach described by Ugianskis [3] involved a 35-year-old man with BMI 21 following total colectomy, where the entire small intestine, including the duodenojejunal flexure, was herniated through the lesser omentum, requiring creation of a neo-lesser sac rather than primary closure due to the large defect size. In contrast, our case allowed for primary defect closure using non-absorbable sutures, similar to the approach described by Alves et al [16]. The presentation timeline also differed significantly – while Makutani et al [15] reported cases occurring 4 to 6 months after colectomy, and Masubuchi et al [14] described herniation 42 months after surgery, our patient developed symptoms years after her initial colorectal cancer surgery, with multiple intervening procedures. The laparoscopic approach we employed aligns with the minimally invasive techniques described across all published cases, though our identification of a secondary mesenteric defect requiring separate repair was unique among the reported literature and highlights the importance of comprehensive bowel examination in patients with complex surgical histories.

Our patient’s regular postoperative follow-up exam showed complete symptom resolution. At 8 months after laparoscopic repair, she underwent a CT scan, which found no acute abnormalities and demonstrated appropriate bowel positioning without evidence of hernia recurrence. She has remained asymptomatic throughout the follow-up period. While our current follow-up period of 8 months demonstrates early success of the laparoscopic approach, we acknowledge that longer-term follow-up data would further strengthen the evidence for durability of this repair technique. Given the rarity of pars flaccida hernias, accumulating long-term outcome data will be important for establishing the optimal management approach for this uncommon condition.

Conclusions

Internal hernias through the pars flaccida are a rare but clinically significant surgical condition that requires a high index of suspicion for diagnosis. Our case demonstrates that successful laparoscopic management is feasible with careful attention to anatomical details and systematic surgical technique. The key to successful repair lies in preoperative planning, strategic port placement, and thorough inspection for additional defects. This case highlights the importance of considering internal hernias in the differential diagnosis for patients with intermittent abdominal pain following previous surgery, even when initial imaging studies are inconclusive. Given the increasing number of laparoscopic procedures being performed, surgeons should maintain awareness of this potential complication and be familiar with the technical aspects of its repair.