Clinical History
A 82-year-old woman with a history of cystectomy and ileal conduit urinary diversion for urothelial bladder carcinoma presented to the emergency department with diffuse abdominal pain and inability to pass stool or gas for 48 hours.
Imaging Findings
A contrast-enhanced abdominal computed tomography (CT) examination was performed. The study demonstrated parietal herniation of the antimesenteric wall of an ileal small bowel loop, passing through the wall defect created for the ileal conduit urinary diversion stoma in the right iliac fossa. The hernia showed signs of obstruction with dilated upstream small bowel loops, air-fluid levels, and a flat efferent ileal loop. A small amount of free fluid was associated but no direct sign of bowel wall ischaemia (Fig 1a-c).
Discussion
Richter hernia was first described in 1778 by August Gottlob Richter (1782-1812) [1]. It is a subtype of abdominal hernia where only part of the bowel's circumference is entrapped in the hernia defect, typically the antimesenteric wall [1]. Up to 5–15% of strangulated hernias are Richter hernias. As in the here presented case, their incidence is higher at sites of laparoscopic port insertion [1, 2]. The most commonly entrapped bowel structure is the terminal ileum, however, any part of the bowel may be implicated in Richter hernia. Most patients presenting the pathology are 60-80 years old [3], and there is a female preponderance of 57% [4].
Early in the disease course, Richter hernia's clinical picture may be misleading. It presents less often with early bowel obstruction than classic abdominal wall hernia, even if incarcerated, and patients rather exhibit aspecific complaints like local pain, fullness, or malaise. Richter hernia may be detected only after prolonged strangulation with wall gangrene, perforation, or even enterocutaneous fistula. At the time of presentation, patients may present abdominal distention and show local inflammation and swelling at the site of the hernia [4]. The most common site for nonincisional Richter hernia is in the femoral ring in 36-88% [1], where it can easily be mistaken for an enlarged lymph node. Accurate diagnosis of Richter's hernia can be challenging and requires a high index of suspicion. A history of laparoscopic surgery may be the key to early diagnosis. If a Richter hernia is suspected, attempts of manual reduction should be avoided prior to prompt operative intervention with direct inspection and evaluation of the viability of the intestine [5].
Richter hernia can be diagnosed on CT scans as a bowel loop positioned only partially within the abdominal wall. Also ultrasound may identify the parietal defect, as well as the part of the bowel that enters into the hernia sac [6].
As early surgery is often not performed for the aforementioned reasons, Richter hernia is associated with a high mortality of 17% [1].
The unusual and interesting aspect of our case consists in the fact that the incarcerated Richter hernia caused early intestinal obstruction without bowel necrosis. The patient was treated by surgery with repair of the hernia defect and without the need for bowel resection.
Differential Diagnosis List
Incarcerated parastomal Richter hernia
Abdominal wall abscess
Parietal emphysema
Classic abdominal wall hernia
Final Diagnosis
Incarcerated parastomal Richter hernia
