Richter hernia in the Space of Retzius – An uncommon hernia in an unusual location

A 64-year-old male presented to the emergency department with worsening epigastric pain described as sharp and non-radiating. The patient had first noticed the pain two days prior with associated  transient bulge in the right groin. He stated that pain was worse with heavy lifting. Pertinent history included endovascular aortic repair (EVAR) of an abdominal aortic aneurysm. Laboratory values including lactate and lipase were unremarkable at presentation.

Contrast-enhanced computed tomography of the abdomen and pelvis was performed on a 256-detector scanner (Philips, Germany) as a portal venous phase after 100 milliliters of Omnipaque (Wipro GE Healthcare Pvt. Ltd, Shanghai, China) intravenous contrast was administered. Initial findings reported by the overnight teleradiologist included focal small bowel thickening near the right inguinal canal with associated hyperemia and adjacent fluid (Figure 1). Proximal dilatation of the remainder of the small bowel loops was noted. Upon further review by the daytime attending radiologist, a thin fat plane was noted on coronal reconstructions separating the small bowel-adjacent fluid in the space of Retzius from the right inguinal canal (Figure 2). Involvement of only the antimesenteric border of the involved loop of small bowel was noted on sagittal reconstructions (Figure 3).

Background

A Richter hernia is defined as a protrusion or strangulation of a portion of the bowel’s antimesenteric border through a small defect of the abdominal wall [1].

Clinical Perspective

The most common location is the femoral canal and as such there is a greater incidence in women. Richter hernias can also occur in the inguinal canal and with increasing popularity of minimally invasive surgical techniques, incisional hernias are increasing in prevalence. The space of Retzius is a rare site for small bowel hernia as the parietal peritoneum creates a continuous barrier from the anterior abdominal wall, draping across the dome of the urinary bladder, extending posteriorly to the proximal two-thirds of the rectum. Only a handful of such cases have been reported in the literature [2].  Patients tend to present in their seventh to ninth decades of life [3].

Since this hernia by definition is not a complete obstruction, presenting symptoms are vague and nonspecific. The subsequent delay in presentation of a patient can lead to dramatic complications [1,3]. Untreated incarceration of the intestine may result in reduced bloody supply and eventual gangrene [3]. Imaging including ultrasound and computed tomography (CT) plays a central role in diagnosing Richter hernias, their location, and assessing timing of surgery.

Imaging Perspective

A Richter hernia will appear as a protrusion of only the antimesenteric portion of a loop of bowel through a defect on computed tomography.  CT offers more precise spatial resolution to identify the herniated portion of bowel that ultrasound can miss and can assess for bowel viability [4]. The advantages of ultrasound include identification of a fascial defect [5].

Based on the imaging findings and patient history, we believe that the patient suffered an inadvertent injury of the parietal peritoneum during the vascular cut down portion of his endovascular aortic repair (EVAR). As shown in Figure 4, the loop of small bowel partially traversed this parietal peritoneal defect into the space of Retzius and became incarcerated.

Outcome

Clinically stable patients with viable bowel can undergo elective repair. Strangulated hernias should be managed emergently to minimize morbidity and mortality. Complications include chronic incarceration leading to enterocutaneous fistulas or gangrene and subsequent perforation [3]. In the presented case, the surgery team emergently took the patient to the operating room. A Richter hernia was confirmed in the right aspect of the space of Retzius in the vicinity of postsurgical changes related to vascular cut down from prior EVAR. The bowel appeared incarcerated and non-viable. A subsequent partial small bowel resection was performed and the peritoneal defect was closed with sutures. The patient tolerated the procedure well and was discharged home after two days. The patient stated he was tolerating his diet and having regular bowel movements at his follow-up appointment 3 weeks following surgery.     

Take-Home Message/Teaching Points

In conclusion, a Richter hernia in the space of Retzius is an extremely rare presentation but vital to recognize. Definitive repair of a Richter hernia is especially important given its associated nonspecific symptoms which can lead to insidious complications.

Written informed patient consent for publication has been obtained.