Ultrasound imaging for inguinal hernia: a pictorial review

Abstract

Inguinal hernia is the most prevalent type of abdominal wall hernia. Indirect inguinal hernia is twice as common as direct inguinal hernia. Computed tomography and magnetic resonance imaging can be used to evaluate inguinal hernia, but these modalities are greatly limited by their cost and availability. Ultrasonography has emerged as the most convenient imaging tool for diagnosing inguinal hernia due to its advantages, such as portability and absence of radiation. The present pictorial review presents an overview on the use of ultrasonography in the evaluation of inguinal hernia with a particular emphasis on the regional anatomy, relevant scanning tips, identification of subtypes, postoperative follow-up, and diagnosis of pathologies mimicking inguinal hernia.

Keywords: Groin; Hernia recurrence; Hernia repair; Inguinal hernia; Ultrasonography.

Fig. 1.. Illustration of direct and indirect inguinal hernia.

Schematic drawing demonstrates the structures relevant to the occurrence of inguinal hernia. EIA, external iliac artery; GF, genital branch of the genitofemoral nerve; IC, inguinal canal; IEA, inferior epigastric artery; IH, inguinal hernia; IL, inguinal ligament; ILN, ilioinguinal nerve; RAB, rectus abdominis muscle; SC, spermatid cord.

Fig. 2.. Ultrasonography of the normal inguinal canal.

A. The transducer is placed next to the lateral edge of the rectus abdominis muscle (RAB). B. The transducer is gradually moved from the superior-medial to inferior-lateral aspects to visualize the inferior epigastric artery (red arrows in A-C) approaching the external iliac artery (EIA). C. The transducer is then pivoted 90° to see the inguinal canal (yellow dashed region) on its short axis. D. Once the short axis of the inguinal canal is located, the transducer can be redirected parallel to the inguinal ligament to identify the inguinal canal in the long axis. White arrowheads indicate vas deferens. EAO, external abdominal oblique muscle; V, testicular vessels; F, fat.

Fig. 3.. Ultrasonography in a man with indirect inguinal hernia.

A. The transducer was placed in the long-axis view to visualize the hernia sac, the inside of which contained peritoneal fat and bowels (asterisks in A and B). B. The transducer was placed in the short-axis view to visualize the hernia sac. White arrowheads and red arrowhead indicate spermatid cord and testicular vessel, respectively.

Fig. 4.. Ultrasonography in another man with indirect inguinal hernia.

A. The transducer was placed in the short-axis view to visualize the hernia sac, the inside of which contained peritoneal fat and bowels (asterisks in A and B). B. The transducer was placed in the long-axis view to visualize the hernia sac. The deep inguinal ring (black arrow) could be visualized at the cranial side of the hernia sac. White arrowheads indicate spermatid cord.

Fig. 5.. The Valsalva maneuver for provoking indirect inguinal hernia.

A. Ultrasonography of the inguinal canal (arrowheads in A and B) was obtained in the resting supine position. B. Ultrasonography was obtained during the Valsalva maneuver, demonstrating a hernia sac with peritoneal fat and bowels (asterisks) protruding along the inguinal canal.

Fig. 6.. Ultrasonography in a woman with indirect inguinal hernia.

A. Ultrasonography of the inguinal canal was obtained at the level of the deep inguinal ring. B. Ultrasonography of the inguinal canal was obtained at the middle portion of the inguinal ligament. C. Ultrasonography of the inguinal canal was obtained at its maximally dilated part. D. Ultrasonography of the inguinal canal was obtained at the superficial inguinal ring. EIA, external iliac artery. White arrowheads, round ligament; white arrows, inguinal ligament; large asterisks, hernia sac with peritoneal fat and bowel; small asterisk, fluid.

Fig. 7.. Ultrasonography of bladder hernia.

Ultrasonography reveals an anechoic compressible cyst (asterisk) beside the external iliac artery (EIA), with a tract extending to the bladder (arrowhead). ILA, iliacus muscle; PUB, pubic bone.

Fig. 8.. Ultrasonography of fluid accumulation inside the canal of Nuck in a woman.

A. Ultrasonography reveals a very large myoma (arrowheads). B. Ultrasonography demonstrates an accidental finding of fluid accumulation (asterisk) inside the canal of Nuck. Black arrow indicates round ligament. RAB, rectus abdominis muscle.

Fig. 9.. Ultrasonography of a very large hydrocele in a man.

Ultrasonography reveals a very large anechoic cyst (asterisks) extending thorough the inguinal canal.

Fig. 10.. Ultrasonography in a patient with direct inguinal hernia.

A. Ultrasonography was obtained over Hesselbach’s triangle during the supine resting position. B. Ultrasonography was obtained over Hesselbach’s triangle during the Valsalva maneuver, showing the bowel contents protruding toward the abdominal wall. EAO, external abdominal oblique muscle; IAO, internal abdominal oblique muscle; RAB, rectus abdominis muscle. Black arrows, inferior epigastric artery; asterisks, herniation content (bowels); white arrow, indicating protrusion of the underlying bowels.

Fig. 11.. The mesh plug method for hernia repair in a male patient with indirect inguinal hernia.

A. Initially, the hernia sac was identified. B. The hernia sac was separated from the spermatid cord. C. The hernia sac was reduced back to the abdominal cavity. D. A cone-shaped mesh was prepared for plugging. E. The mesh was plugged through the deep inguinal ring. F. After being plugged, the mesh was fixed on the abdominal wall. G. Finally, a patch of mesh was placed to enforce the posterior wall. The series of figures are reprinted from Huang CS (2021). In: Yeh CC, ed. NTU surgery core course [14], with permission of National Taiwan University College of Medicine.

Fig. 12.. Ultrasonography of a hematoma after a hernia repair.

A. Ultrasonography was obtained over the inguinal region using the B mode, revealing a circular hypoechoic structure with multiple intralesional septa. B. Ultrasonography was obtained over the inguinal region using the power Doppler imaging, showing an increase in peripheral vascularity of the lesion. White arrows, hematoma; white arrowheads, spermatid cord.

Fig. 13.. Ultrasonography of recurrence after surgical repair for indirect inguinal hernia.

A. Ultrasonography was obtained in the short-axis view of the inguinal canal. B. Ultrasonography was obtained in the long-axis view of the inguinal canal. Asterisks indicate hernia sac with peritoneal fat.

Fig. 14.. Another patient with recurrence after surgical repair for indirect inguinal hernia.

Ultrasonography reveals a dilated inguinal canal with presence of peritoneal fat and collapsed bowels (asterisks).

Fig. 15.. Ultrasonography for recurrence in a case with direct inguinal hernia after mesh placement.

A. The transducer was placed over the region where the mesh was implanted. B. Caudal to the level where the mesh was implanted, a bowel-containing hernia sac (asterisk) was visualized. RAB, rectus abdominis muscle.

Fig. 16.. Demonstration of ultrasound-guided ilioinguinal nerve block in a man.

A. The ilioinguinal nerve (arrowhead in A-D) was located between the internal abdominal oblique (IAO) and transverse abdominis (TRA) muscles at the level of the iliac crest. Red arrow indicates deep iliac circumflex artery. B. The transducer was moved medially to visualize the nerve emerging toward the undersurface of the aponeurosis (black arrows) of the external abdominal oblique muscle. C. The needle was inserted from the lateral aspect of the inguinal area to target the nerve. D. The injectate was distributed surrounding the nerve. ILA, iliacus muscle.

Fig. 17.. Ultrasonography of common pathologies mimicking inguinal hernia.

A. Ultrasonography reveals lymphadenopathy (arrow) at the inguinal region. B. Ultrasonography shows a very large lipoma (arrow) at the inguinal region. EIA, external iliac artery; SAR, sartorius muscle.

Fig. 18.. Ultrasonography of endometriosis in the inguinal region in a woman.

A. The transducer was placed along the inguinal ligament (white arrows in A and B) in its long axis. B. Ectopic endometrium (arrowhead) was shown by relocating the transducer more caudally. EIA, external iliac artery; ILA, iliacus muscle; PEC, pectineus muscle.

Fig. 19.. Power Doppler ultrasonography of ectopic endometrium in a woman.

The power Doppler ultrasonography reveals increased vascularity inside the ectopic endometrium (arrowhead). PEC, pectineus muscle.

Fig. 20.. Ultrasonography of ascites.

Ultrasonography reveals anechoic homogenous fluid collection with posterior enhancement caused by ascites (asterisks) in the panoramic view. Stars, peritoneal fat.

Fig. 21.. Ultrasonography of the protruding abdominal wall in a patient with sarcopenia.

A. Ultrasonography was obtained in the supine resting position. B. The lower abdominal wall protruded forward (arrow) in the standing position. RAB, rectus abdominis muscle.