Anatomy and pathology of inguinal canal Poster No.: C-1908 Congress: ECR 2014 Type: Educational Exhibit Authors: A. Llanes Rivada, M. Rausell Félix, A. M. Julve Parreño, M. J. Moreno, C. Soto Sarrión; Valencia/ES Keywords: Anatomy, Abdomen, Ultrasound, CT, MR, Education, Hernia, Neoplasia DOI: 10.1594/ecr2014/C-1908 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 17
Learning objectives The inguinal region is a complex area consisting of the intersection of multiple structures. Knowledge of anatomy and imaging findings of pathologies that we can identify in it we will facilitate its characterization and diagnosis. We propose to attend these objectives: -Review the anatomy of the inguinal canal. -Describe the imaging features of different pathologies of the inguinal canal diagnosed in our center. Background The inguinal canal (IC) is a diagonal passage in the lower anterior abdominal wall measuring approximately 4 cm in length that is lined by the aponeuroses of three muscles: the external oblique, internal oblique, and transversus abdominis muscles. The IC has openings at either end: the deep and superficial inguinal rings. The deep inguinal ring is an oval gap in the transversalis fascia and lies 1 cm superior to the inguinal ligament and lateral to the inferior epigastric vessels. The anterior wall is formed by the aponeurosis of the external oblique and internal oblique muscles, the posterior wall is formed mainly by the transversalis fascia and the conjoint tendon, the superior wall is formed by the internal oblique and transversus abdominis muscles and the inferior wall is formed by the superior surface of the inguinal ligament. The contents of the inguinal canal are different depending on gender. In males, the inguinal canal transmits the spermatic cord, which includes the vas deferens, the testicular artery, and the genital branch of the genitofemoral nerve, from the pelvic cavity Page 2 of 17
to the scrotum. In females, the inguinal canal transmits the round ligament of the uterus and the ilioinguinal nerve to the labia majora. The pathology in this location can be classified in two groups: Hernias and no hernia pathology (Figure 1). I. Hernias: Hernias usually develop from abnormalities that cause high intraabdominal pressures, resulting in nonclosure of the processus vaginalis. The risk factors are Marfan syndrome, elevated maternal estrogen levels and metabolic changes (collagen degeneration). The content of the sac is very variable: omental fat, small intestine, mobile segments of the colon (Figure 2), appendix (Figure 3), bladder (Figure 4), or Meckel's diverticulum (Littre's hernia). It is important to detect signs of complications. U.S may provide information on the herniated organs and repercussions in the peritoneal cavity. Signs of mechanical ileus and of decompensation with the presence of peritoneal fluid, the presence or absence of color Doppler signals in the hernial contents and the presence or absence of peristalsis in the herniated bowel loop may be detected. An important sign, with high specificity but limited sensitivity, of incarceration is fluid in the herniated bowel loop with bowel wall thickening and free fluid in the hernial sac. Inguinal hernias may be indirect or direct: a) Indirect inguinal hernia is the result of herniation of abdominal contents through the deep inguinal ring which can be extended to the scrotum or labia majora. b) Direct inguinal hernia originates medial to epigastric vessels and rarely complicated. II. Lesions of vascular origin. The pseudoaneurima is an accumulation of encapsulated blood, connected to the arterial lumen. In ultrasound we can see a hypoechoic mass with Doppler study shows a Page 3 of 17
characteristic pattern of flow (Figure 5). In CT and MRI after administration of contrast media in the arterial phase was observed with the lumen of the artery (Figure 6). A hematoma is a mass, elliptical or fusiform, which compresses or displaces the adjacent normal structures. Its radiographic appearance depends on the time of evolution. In the acute phase is anechoic, evolving to heterogeneous lesion with different echogenicities in the subacute and chronic phases. At CT, generally appear as hyperattenuating masses in the IC, with attenuation greater than 30 HU. At MR imaging, hematomas can have a variable appearance. At follow-up, hematomas usually resolve without therapy. III. Inflammatory or infectious processes. Multiple inflammatory or intra-abdominal infections or adjacent soft tissue may affect the inguinal region. Clinical findings include abdominal cramping, an irreducible groin mass, fever, and leukocytosis. The clinical symptoms can be less localizing, resulting in delayed diagnosis. The sonographic appearance is variable. At CT, abscesses are low attenuation masses with ring enhancement (Figure 7). At MR imaging, abscesses typically have low signal intensity on T1-weighted images and high signal intensity on T2-weighted images and can exhibit a thin rim of peripheral enhancement IV. Tumors. Primary tumors can originate in any structure: connective tissue, muscle, fat, nerves, blood vessels and lymphoid tissue. The most common benign tumor is a lipoma. Other benign tumors include leiomyoma, desmoid and neurofibroma. Most primary malignant tumors are sarcomas (Figure 8, 9 and 10). Liposarcoma is the most common of them and often manifest as a palpable, painless, slow-growing softtissue mass. Dedifferentiation of liposarcomas manifests as heterogeneously enhancing nonfatty components with calcification. Page 4 of 17
The metastases can affect the inguinal region by direct extension or distant V. Other entities. Cryptorchidia: Arrest of the normal process of testicular descent from the abdominal cavity to the scrotum (Figure 11). Images for this section: Fig. 1 Page 5 of 17
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Findings and procedure details Were reviewed the imaging studies of patients with pathology of the inguinal canal diagnosed in our hospital in the last 3 years. The explorations were performed with: the SIEMENS SONOLINE Antares ultrasound platform. The multidetector CT scanners: Sensation 16, Siemens and a 64-channel scanner (Brilliance 64; Philips Medical Systems) and the MRI on 1.5-T Siemens scanners. Conclusion Knowledge of anatomy and the imaging features of the inguinal region facilitate the characterization and diagnosis of masses in this complex area. The results of the review of cases diagnosed in our center of the inguinal canal pathology consistent with those described in the literature. Benign pathology is more common than malignant. The most common diagnosis in general are hernias and in malignant pathologies, sarcomas. Personal information References 1. Cherian PT, Parnell AP. Radiologic anatomy of the inguinofemoral region: insights from MDCT. AJR 2007 Oct;189(4):W177-83. 2. StandringS, Ellis H, Healy JC, Johnson D, Williams A. Inguinal canal. In: Standring S, ed. Gray's anatomy: the anatomical basis of clinical practice. 39th ed. Edinburgh, Scotland: Elsevier Churchill Livingstone, 2005; 1109-111. Page 16 of 17
3. Yang DM, Kim HC, Lim JW, Jin W, Ryu CW, Kim GY, Cho H.Sonographic findings of groin masses. J Ultrasound Med. 2007 May;26(5):605-14. 5. ShadboltCL, Heinze SB, Dietrich RB. Imaging of groin masses: inguinal anatomy and pathologic conditions revisited. RadioGraphics2001; 21(spec issue): S261-S271. 6. MurpheyMD, Arcara LK, Fanburg-Smith J. Imaging of musculoskeletal liposarcoma with radiologic-pathologic correlation. RadioGraphics2005; 25: 1371-1395. Page 17 of 17