Amyand's hernia - incidental finding on CT scan

Clinical History

A 52-year-old male patient presented with left flank pain. Ultrasound screening showed mild hydronephrosis in the left kidney. Laboratory markers were unremarkable. Plain Computed Tomography of the abdomen was performed for suspected left ureteric calculus. Incidental finding of a right inguinal hernia containing the appendix was observed. Follow-up was unavailable as the patient was not willing to undergo surgery.

Imaging Findings

Plain CT scan of abdomen was performed with multiplanar reconstruction. Mild hydronephrosis in the left kidney was observed with no evidence of radio-dense calculus in the left ureter. Right inguinal hernia was found with thin-walled gas-containing tubular structure within the hernia sac. No inflammatory changes like fat stranding or fluid collection were seen in the hernia sac. Incidental diagnosis of right inguinal hernia containing appendix was made.

Discussion

Amyand’s hernia is defined as the presence of the vermiform appendix in an inguinal hernia sac. Appendix within a hernia sac can be normal or inflamed. Incidence of normal appendix in an inguinal hernia varies from 0.5% to 1.1%. However, appendicitis is seen in only 0.1% of these cases. [1] This rare entity was first described by Claudius Amyand in 1735 who performed surgery on an 11-year-old boy presenting with fecal fistula in the groin. [2]

Inflammation of the appendix within a hernia sac is caused by extra-luminal obstruction due to pressure on the hernia neck. [3] Retention of appendix in the hernia sac is caused by adhesion within the sac. [4] Complications like strangulation and incarceration occur rarely. Perforation and periappendicular abscess in an inguinal hernia sac is also rare. Acute appendicitis within Amyand’s hernia could be life-threatening unless treated promptly. [5] Intra-operative detection of Amyand’s hernia is common in these clinical scenarios. Preoperative diagnosis is uncommon in complicated cases which require immediate surgery.

Imaging plays an important role in the preoperative diagnosis of Amyand’s hernia. Computed tomography with multi planar reconstruction is helpful for detection of Amyand’s hernia and its complications. Contents of inguinal hernia can be easily identified with CT scan.

Different classifications of Amyand’s hernia were proposed, such as Nyhus Classification [6] and Losanoff and Basson Classification [7]. Nyhus Classification emphasizes anatomical criteria of the size of the deep inguinal ring and the status of the floor of the inguinal canal. Losanoff and Basson Classification describes four types depending on complicating intra-abdominal pathology and proposes appropriate surgical management. Preoperative imaging is crucial for surgical planning and decision. There are different opinions about surgical management of Amyand’s hernia. Appendectomy with hernia repair should be done in case of inflamed appendix in a hernia sac. When normal the appendix is found in a hernia sac, the appendix can be removed as this may prevent future complication. Standardized guidelines for management of Amyand’s hernia have not been established yet. But individualized and appropriate approach should be applied according to clinical setting [8].

Amyand's hernia is a rare variety of hernia, with complication leading to a diagnostic dilemma for the clinician. Pre-operative imaging, especially CT scan, helps with surgical decision making. The best course of action should be individualized according to the clinical scenario.

Differential Diagnosis List

Final Diagnosis

Amyand's hernia

URL:	https://eurorad.org/case/14663
DOI:	10.1594/EURORAD/CASE.14663
ISSN:	1563-4086