Residency · Residency · General Surgery

Inguinal Hernia: Anatomy and Open Repair

Overview

Inguinal hernias are the most common type of abdominal wall hernia, with a lifetime risk of 27% in males and 3% in females. Mastery of inguinal canal anatomy and open repair techniques is a foundational competency for the general surgery resident. The Lichtenstein tension-free mesh repair is the most widely performed open technique worldwide.

Surgical Anatomy

Inguinal Canal

The inguinal canal is an oblique passage through the anterior abdominal wall, approximately 4 cm long, extending from the deep (internal) inguinal ring to the superficial (external) inguinal ring. The anterior wall is formed by the external oblique aponeurosis along its entire length, with the internal oblique contributing laterally. The posterior wall (floor) consists of the transversalis fascia along its entire length, with the conjoint tendon (fused internal oblique and transversus abdominis aponeurosis) contributing medially. The roof is formed by the arching fibers of the internal oblique and transversus abdominis. The inferior wall consists of the inguinal ligament (Poupart ligament) and the lacunar ligament medially.

Key Landmarks

The deep (internal) inguinal ring is an opening in the transversalis fascia, located lateral to the inferior epigastric vessels, and transmits the spermatic cord or round ligament. The superficial (external) inguinal ring is an opening in the external oblique aponeurosis, just lateral to the pubic tubercle. Hesselbach triangle is bounded by the inferior epigastric vessels laterally, the rectus sheath medially, and the inguinal ligament inferiorly, and is the site through which direct hernias emerge. The myopectineal orifice of Fruchaud encompasses the entire area of potential groin herniation, bounded by the internal oblique and transversus abdominis superiorly, rectus muscle medially, iliopsoas and Cooper ligament inferiorly, and the iliopsoas laterally.

Spermatic Cord Contents

The spermatic cord contents follow the "rule of 3s": three arteries (testicular artery from the aorta, artery of the vas from the inferior vesical, and cremasteric artery from the inferior epigastric), three fascial layers (external spermatic fascia from the external oblique, cremasteric fascia from the internal oblique, and internal spermatic fascia from the transversalis fascia), and three other structures (vas deferens, pampiniform plexus of veins, and genital branch of the genitofemoral nerve), along with lymphatics and sympathetic fibers.

Critical Nerves

Three nerves are critical to identify and protect during inguinal hernia repair. The ilioinguinal nerve (L1) runs on the surface of the cord beneath the external oblique and provides sensory innervation to the medial thigh, mons pubis, and labia or scrotum. The iliohypogastric nerve (L1) runs between the internal oblique and transversus abdominis and provides sensation to the suprapubic region. The genital branch of the genitofemoral nerve (L1-L2) enters the inguinal canal through the deep ring, provides motor innervation to the cremaster, and carries sensation from the scrotum or labia.

Classification

Indirect inguinal hernias exit through the deep inguinal ring, lateral to the inferior epigastric vessels. They follow the spermatic cord and may extend into the scrotum (complete) or remain within the canal (incomplete). They are congenital in etiology, arising from a patent processus vaginalis, and represent the most common type of inguinal hernia in both sexes and all age groups.

Direct inguinal hernias protrude through the posterior wall of the inguinal canal within Hesselbach triangle, medial to the inferior epigastric vessels. They are acquired, resulting from weakness of the transversalis fascia due to chronic elevated intra-abdominal pressure. Direct hernias rarely enter the scrotum and have a lower incidence of incarceration and strangulation.

A pantaloon hernia is a combined direct and indirect hernia straddling the inferior epigastric vessels. A sliding hernia occurs when a visceral organ (sigmoid colon, cecum, or bladder) forms part of the hernia sac wall and must be recognized intraoperatively to avoid organ injury.

Open Repair Techniques

Lichtenstein Tension-Free Mesh Repair

The Lichtenstein repair is the most commonly performed open technique. The skin incision is made 2 cm above and parallel to the inguinal ligament from the pubic tubercle to the deep ring. The external oblique aponeurosis is opened, and the ilioinguinal and iliohypogastric nerves are identified and protected. The spermatic cord is mobilized, and the hernia sac is identified -- an indirect sac lies anterolateral within the cord and is dissected, reduced, or ligated and excised, while a direct hernia is reduced by inverting the attenuated transversalis fascia. Polypropylene mesh is placed on the posterior wall with the medial tail overlapping the pubic tubercle by 1 to 2 cm (secured to periosteum or rectus sheath). The inferior edge is sutured to the inguinal ligament with a continuous non-absorbable suture. The mesh is split laterally to accommodate the spermatic cord in a keyhole fashion, with the superior tail overlapping the inferior tail and sutured to create a snug new deep ring. The superior edge is secured to the internal oblique or conjoint tendon with interrupted sutures. The external oblique is then closed over the cord. The Lichtenstein repair achieves a recurrence rate below 1 to 2%, though chronic pain occurs in 10 to 12%.

Shouldice Repair

The Shouldice repair is a pure tissue repair involving multi-layered imbrication of the transversalis fascia and conjoint tendon using a four-layer continuous suture technique. Layers 1 and 2 address the transversalis fascia, while layers 3 and 4 secure the internal oblique and conjoint tendon to the inguinal ligament. The Shouldice Hospital reports recurrence rates below 1%, though results elsewhere are typically 5 to 10%. This repair is reserved for young patients, clean fields where mesh is contraindicated, and specialized centers.

Bassini and McVay Repairs

The Bassini repair is a single-layer repair suturing the conjoint tendon to the inguinal ligament. It has historical significance but carries a higher recurrence rate of 5 to 10% and is rarely performed today. The McVay (Cooper ligament) repair sutures the conjoint tendon to Cooper ligament medially, then transitions to the inguinal ligament laterally, and requires a relaxing incision in the anterior rectus sheath. It is the only open tissue repair that also addresses the femoral space but has a higher recurrence rate than mesh repair and is rarely used except in contaminated fields.

Mesh Considerations

Polypropylene (heavyweight, lightweight, or medium-weight) is the most commonly used mesh material. Lightweight mesh may produce less foreign body sensation and potentially less chronic pain, though some studies show higher early recurrence rates. Mesh should overlap the defect by at least 2 to 3 cm in all directions. Mesh infection occurs in approximately 1% of cases and usually requires explantation. Biologic mesh is reserved for contaminated fields and is rarely needed in elective inguinal hernia repair.

Incarceration and Strangulation

A reducible hernia allows its contents to be returned to the peritoneal cavity. An incarcerated (irreducible) hernia has trapped contents that may or may not have compromised blood supply. A strangulated hernia involves compromised blood supply to incarcerated contents and constitutes a surgical emergency.

Management begins with attempting manual reduction with sedation and analgesia (Trendelenburg position, ice, gentle sustained pressure). If reduction succeeds, semi-elective repair is performed within 24 to 48 hours. If the hernia is irreducible or strangulation is suspected (pain, erythema, fever, peritoneal signs), emergent surgery is indicated. Bowel viability must be assessed before returning contents to the abdomen. Mesh use in emergency or contaminated settings is controversial, and biologic mesh or tissue repair may be preferred.

Watchful Waiting

The WWHD trial demonstrated that watchful waiting is safe for minimally symptomatic inguinal hernias, though 68% of patients crossed over to surgery by 10 years due to increasing symptoms. The risk of acute incarceration or strangulation during observation is approximately 1.8 per 1,000 patient-years. Watchful waiting is appropriate for patients with minimal symptoms who accept ongoing monitoring.

<image>Detailed anatomical illustration of the inguinal canal showing anterior and posterior walls, the superficial and deep inguinal rings, Hesselbach triangle (bounded by inferior epigastric vessels laterally, rectus sheath medially, and inguinal ligament inferiorly), spermatic cord contents, and the course of the ilioinguinal, iliohypogastric, and genital branch of the genitofemoral nerve. Show both indirect hernia path (through the deep ring, lateral to epigastric vessels) and direct hernia path (through Hesselbach triangle, medial to epigastric vessels).</image>

<image>Step-by-step surgical illustration of the Lichtenstein tension-free mesh repair showing: (1) external oblique opened with nerve identification, (2) spermatic cord mobilized with indirect hernia sac dissected, (3) polypropylene mesh placement with medial tail overlapping the pubic tubercle, sutured to the inguinal ligament inferiorly, (4) mesh split to accommodate the cord with tails overlapping to create a snug new deep ring, and (5) final mesh configuration secured to the internal oblique superiorly.</image>

<image>Posterior (preperitoneal) view of the myopectineal orifice of Fruchaud showing the critical anatomical landmarks from the laparoscopic perspective: the direct space (medial), indirect space (lateral), and femoral space (inferior). Label Cooper ligament, iliopubic tract, inferior epigastric vessels, vas deferens, spermatic vessels, triangle of doom (external iliac vessels), and triangle of pain (lateral cutaneous nerve of thigh, femoral branch of genitofemoral nerve).</image>

Clinical Pearls

Indirect inguinal hernias are lateral to the inferior epigastric vessels while direct hernias are medial -- this distinction is critical but often only definitively made intraoperatively. The Lichtenstein tension-free mesh repair achieves a recurrence rate below 1 to 2% and is the most widely performed open technique. The ilioinguinal, iliohypogastric, and genital branch of the genitofemoral nerve must always be identified and protected to minimize chronic pain. If a nerve is encased in scar or mesh and cannot be preserved, intentional neurectomy is preferred over leaving a damaged nerve in situ. A sliding hernia with sigmoid colon, cecum, or bladder forming part of the sac wall must be recognized to avoid organ injury -- the sac should be reduced rather than excised. In emergency hernia repair with bowel compromise or contamination, tissue repair (Shouldice or McVay) or biologic mesh may be safer than synthetic mesh. The McVay repair is the only open tissue repair that also addresses the femoral space. Watchful waiting is acceptable for minimally symptomatic inguinal hernias, but most patients will eventually require surgery due to progressive symptoms.

References

• HerniaSurge Group. International guidelines for groin hernia management. Hernia. 2018;22(1):1-165.
• Lichtenstein IL, Shulman AG, Amid PK, Montllor MM. The tension-free hernioplasty. Am J Surg. 1989;157(2):188-193.
• Fitzgibbons RJ Jr, Giobbie-Hurder A, Gibbs JO, et al. Watchful waiting vs repair of inguinal hernia in minimally symptomatic men: a randomized clinical trial. JAMA. 2006;295(3):285-292.
• Amato B, Moja L, Panico S, et al. Shouldice technique versus other open techniques for inguinal hernia repair. Cochrane Database Syst Rev. 2012;(4):CD001543.

Read this lecture as Markdown