Step by Step Manual of Laparoscopic Surgery: Laparoscopic Hernia Surgery (Volume 4) JS Rajkumar, Neha Shah
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Endoscopic Anatomy of Inguinal RegionChapter 1

 
INTRODUCTION
It is very important to clearly understand the surgical anatomy of the inguinal region for a safe and successful outcome of laparoscopic hernia repairs.
The laparoscopic view of the groin anatomy is very different from the open one. In laparoscopic hernia repair, we go through a posterior approach while we are used to the anterior approach in open hernia repairs. Changing to a laparoscopic approach requires proper knowledge of anatomy. Certain structures like ilioinguinal nerve, inguinal ligament, pubic tubercle and lacunar ligament are clearly visible in open approach and not so in laparoscopy. Conversely, structures like Cooper's ligament and iliopubic tract that are not visible in the open approach are clearly visible with the laparoscopic approach.
In laparoscopic repair, we are targeting the point of origin of the hernia and not the point of presentation. So laparoscopy deals with all the potential sites at risk for hernia in the groin, i.e. it takes care of direct, indirect, femoral and obturator hernias. However, this is a three-dimensional view, with a two-dimensional handycam.
Importance of the Kessler's triangle: The Kessler's triangle is the one between the inguinal ligament and the upper edge of the intersections of the internal oblique, the transversus abdominis muscle and its upper aponeurosis to the rectus sheath. Thus the triangle is medially bounded by the lateral border of the rectus sheath, inferiorly bounded by the inguinal ligament and laterally bounded by the internal oblique transverse section. It is said that when there is a larger Kessler's triangle due to higher intersections of internal oblique and transverses the muscle into the rectus sheath, there is a larger space available for the muscles to occlude the triangle when they contract. This incomplete occlusion is set to be an important anatomical factor in the etiology of inguinal hernia. This triangle is not to be confused with Hasselbach's triangle (see below).2
 
HESSELBACH'S TRIANGLE
Frank Hesselbach and Kasper gave an original description of inguinal triangle called Hesselbach's triangle (Fig. 1.1).
Following are the boundaries:
  • Superolateral boundary—inferior epigastric vessels
  • Medially—rectus sheath (lower third)
  • Inferiorly—inguinal ligament (medial third)
 
MYOPECTINEAL ORIFICE OF FRUCHAUD
In 1956, Henry Fruchaud postulated that all groin hernias essentially originate in a single weak area, which he called the myopectineal orifice. This is funnel-like, and potential space formed superiorly by the internal oblique and transversus abdominis, inferiorly by the superior pubic ramus, medially by the rectus muscle sheath and laterally by the iliopsoas. This entire myopectineal orifice is divided by the iliopubic tract and the inguinal ligament into an inguinal defect (superiorly) and a femoral defect (inferiorly).
This oval, funnel-like potential orifice is formed of the following structures:
  • Superiorly: Internal oblique and transversus abdominis muscles
  • Inferiorly: Pecten pubis
  • Medially: Rectus muscle sheath
  • Laterally: Iliopsoas muscle
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Fig. 1.1: Hesselbach's triangle.
3Proper exposure of this orifice is essential to do a proper inguinal hernia repair. The whole orifice is divided by the iliopubic tract into superior and inferior compartments, with the inferior epigastric artery bisecting the superior compartment. Thus, direct and indirect hernias are visualized in the superior compartment and femoral hernias in the inferior compartment (Fig. 1.2).
The superomedial compartment of the myopectineal orifice corresponds to the original Hesselbach's triangle. Covering the complete myopectineal orifice is the anatomical fundamental of laparoscopic hernioplasty.
From the large posterior myopectineal orifice, the inguinal canal funnels forward into a narrow anterior wall, explaining the need for a larger mesh for posterior cover and a much smaller mesh for anterior cover. (15 × 12 cm in laparoscopic repair as it is posterior repair against 6 × 10 cm in open repair of hernia as it is anterior repair).
 
Peritoneal Landmarks from the Inside
 
Median Umbilical Ligament
This ligament is present in the midline and runs from the bladder to umbilicus. It represents the obliterated allantoic duct, and the lower part is the site of the rare urachal cyst.
 
Medial Umbilical Ligament
This ligament represents obliterated umbilical artery on each side and can be traced down to the internal iliac artery.
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Fig. 1.2: External view of myopectineal orifice of Fruchaud.
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Lateral Umbilical Ligament
It is a peritoneal fold which is raised by the inferior epigastric artery and its two veins, and it courses around medial border of internal inguinal ring and passes upwards into the posterior abdominal wall.
 
FOSSAE
As far as the fossae are concerned, there are three of them that every laparoscopic hernia surgeon should know (Fig. 1.3).
 
Supravesical Fossa
The infraumbilical area between the median and medial umbilical ligaments is called supravesical fossa. This is the site of origin of the supravesical hernia.
 
Medial Umbilical Fossa
The infraumbilical area between the medial and lateral umbilical ligaments is called medial umbilical fossae. This is the site of origin of direct inguinal hernias above the iliopubic tract and femoral hernia below the iliopubic tract.
 
Lateral Umbilical Fossa
The infraumbilical area lateral to the lateral umbilical ligament. This is the site for the origin of the indirect inguinal hernia.
 
PREPERITONEAL SPACE (Fig. 1.4)
This is a very important space to understand as all the repairs and mesh placement are done in this space.
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Fig. 1.3: Laparoscopic view of normal pelvic anatomy on the right side (before peritoneal reflection).Keys: A, median umbilical ligament; B, medial umbilical ligament; C, lateral umbilical ligament; D, supravesical fossa; E, medial fossa; F, lateral fossa.
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Fig. 1.4: Preperitoneal space.
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Bilaminar Transversalis Fascia (of Gallaudet)
The current understanding of the transversalis fascia is of a two layered or bilaminar structure. The superficial layer is a membranous layer and the deep layer is a fatty layer. The superficial layer is closely opposed to the posterior aspect of the rectus abdominis muscle in the posterior rectus sheath. The posterior fatty layer is closely adherent to the underlying peritoneum.
The orientation of the two layers of the transversalis fascia is identical to the two layers of the superficial facia of the anterior abdominal wall as if Camper's and Scarpa's fasciae are reflected inwards.
Both layers are inserted into the Cooper's ligament inferiorly. Condensation of the transversalis fascia forms three important structures: (1) interfoveolar ligament, (2) medial margin of internal ring and (3) iliopubic tract.
 
Iliopubic Tract (Fig. 1.5)
It is the thickened lateral extension of the transversalis fascia which runs from the superior pubic ramus to the iliopectineal arch and the anterior superior iliac spine.
It forms a strong aponeurotic band only in 28–30% of patients. Its significance in laparoscopic hernia repair is to identify it as it forms the superior border of triangle of pain. No diathermy or tackers are to be used in this triangle.
This continues anteriorly with the forepart of the inguinal ligament, but the tract is distinct in structure and separate from the inguinal ligament. It is anterior to the Cooper's ligament and inferior epigastric artery, and posterior to the inguinal ligament.
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Fig. 1.5: Iliopubic tract.
7This separates the internal ring from the femoral canal and is visualized laparoscopically as a fibrous white tract. Its significance in hernia repair is that it forms superior boundary for the triangle of pain.
The spaces of the inguinal canal visualized by laparoscopy are divided into six groups: (1) superomedially by the space of Retzius, (2) superiorly by the space of Bogros, (3) laterally by the space of Dulucq, (4) inferomedially by the corona mortis, (5) inferiorly by the triangle of doom and (6) laterally by the triangle of pain.
 
Iliopectineal Arch
It is a thickened structure covering the iliac muscles and arches from anterior superior iliac spine inferiorly to the iliopubic eminence. It gives origin to portion of the internal oblique and transversus abdominis muscle as well as inguinal ligament.
 
Space of Retzius (Fig. 1.6)
This is the prevesical space that lies deep to the supravesical fossa and medial umbilical fossa and contains loose connective tissue. Fat dissection of the space is mandatory in a transabdominal preperitoneal (TAPP) or totally extraperitoneal (TEP) techniques to enable the medial border of the mesh to adequately overlap the medial edge of the defect.
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Fig. 1.6: Space of Retzius.
8Important structures in this plane are:
  • Vascular: External iliac artery and vein with its branches, i.e. deep circumflex iliac and inferior epigastric vessels.
  • Nerves: Lateral femoral cutaneous nerve, genitofemoral, femoral, ilioinguinal, iliohypogastric and sympathetic plexus.
  • Lymphatics: External iliac group of lymph nodes and associated deep lymphatics.
  • Normal and aberrant obturator vessels.
  • Accessory pudendal vessels (10%).
 
Space of Bogros
This is the preperitoneal space which actually forms the central aspect of the dissection under the peritoneum. This is continuous with the rectus space medially and continuous with Dulucq's space laterally. This is important because immediately anterior to the Bogros’ space is the inferior epigastric artery and the deep ring.
Important structures in this space are indicated in Figure 1.7.
 
Dulucq's Space
This space continues as a lateral extension of the Bogros’ space and extends laterally from the inferior epigastric artery right up to the iliopsoas below and lateral. Thus, from medial to lateral on the superior side, the surgeon while performing TAPP or TEP, will have to dissect the spaces of Retzius, Bogros and Dulucq in that order.
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Fig. 1.7: Space of Bogros.
9We personally tend to dissect out the space of Retzius first and then the space of Dulucq, and finally perform the dissection of the space of Bogros as the vital structures, namely the inferior epigastric artery, the vas and the testicular vessels run very close to this space.
Inferior epigastric artery is single, but the inferior epigastric vein is usually double, i.e. the two veins flank the inferior epigastric artery and joins the external iliac vein about 1 cm proximal to the inferior epigastric artery take off. Thus the inferior epigastric veins are a little more prone to injury than inferior epigastric artery. Some veins could pose a problem.
The deep venous circle of Bendavid is located in the space of Bogros as it is a circular network of deep inferior epigastric rectusial vein, retropubic and suprapubic veins. Care should be taken while dissecting out these small veins as hematoma could result in this situation.
 
OTHER VEINS
 
Iliopubic Vein
This vein courses deep into the iliopubic tract and joins the anterior pubic vein and could be injured dissecting out the iliopubic tract.
 
Rectorectal Vein of Bendavid
This vein runs along within the lower lateral fibers of the rectus and forms a venous anastomotic ring joining the iliopubic vein above the pubic crest.
 
Retropubic Vein
This vein is a small collateral branch of the anastomotic pubic vein and is observed on the inferior posterior aspect of the pubic ramus beneath the Cooper's ligament.
 
Corona Mortis (Fig. 1.8)
The pubic branch of the inferior epigastric artery courses in a vertical fashion inferiorly, crossing the Cooper's ligament and anastomosing with the obturator artery. In 25–30% of individuals (can be as high as 70–80%), the pubic branch is large and can replace the obturator artery. This large arterial branch (aberrant obturator artery) can partially encircle the neck of a hernia sac and be injured in a femoral hernia repair. It could also be injured while exposing the Cooper's ligament by freeing it of areolar adipose connective tissue. Because of this possibility an enlarged pubic branch of the inferior epigastric artery has in the past been known as the—“corona mortis”. This danger of injury in this area is more significant of obturator veins.10
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Fig. 1.8: Corona mortis.
What are the four nerves and the places where they are most easily injured? What will happen to them?
  1. Lateral femoral cutaneous nerve: This nerve is the most commonly injured nerve during laparoscopic hernia repair.
    Course of the nerve: As it arises from L2-3, it emerges at the lateral edges of the psoas, and courses along the iliac fossa lateral to the iliac vessels. It passes below (or sometimes even through the fibers of) the inguinal ligament lying in a fibrous tunnel 1 cm medial to the anterior superior iliac spine. Its area of supply is the upper lateral aspect of thigh. Common site of injury in relation to the iliopubic tract is in the triangle of pain, resulting in the sequelae of pain and numbness in the upper lateral thigh called meralgia paresthetica or Bernhardt's syndrome.
  2. Genitofemoral nerve: The femoral branch of the genital femoral nerve is at risk of damage during laparoscopic hernia repair. The genital branch of genitofemoral nerve is more often injured in an open inguinal repair. Sometimes if extensive maneuvers are performed to the sac and the perisac tissues at the internal ring, the genital branch of the genitofemoral nerve could be injured. Nerve arises from L1-2, courses through the psoas major occupying the anteromedial aspect of the muscle, dividing into genital and femoral branches before reaching the internal inguinal ring. The genital branch pierces the iliopubic tract lateral to the deep ring and then enters the ring (within 5 mm of the upper border of the ring, and courses through the inguinal canal). This is the reason why when the peritoneum is opened in a TAPP; it is always opened at the point atleast 1 cm superior to the upper edge of the ring to avoid injury to the genital branch of the genital femoral nerve. The femoral branch courses beneath 11the inguinal ligament to the thigh. Area of supply of the genital branch is the cremaster, the spermatic fascia and tunica-vaginalis of the testes; it is also the efferent branch for the cremastric reflux, and in the female, it is sensory to the labium major. The femoral branch is the cutaneous branch to the skin over the femoral triangle and is the afferent branch for the cremasteric reflex.
    Common site of the entrapment is on the posterior abdominal wall especially if tackers or staplers are used well below the iliopubic tract. Post injury, it causes pain in the groin, scrotum and upper thigh. Tenderness is found along the internal ring and along the inguinal canal with hyperextension or external rotation of the hip, thus increasing the pain. The loss of cremasteric reflex indicates that either the genital, or the femoral branch or both have been injured during the operation.
  3. Femoral nerve: Usually the intermediate cutaneous branch of the anterior division of the femoral nerve is at risk during laparoscopic meshplasty although injury to the main trunk of the femoral nerve has also been described.
    Course of femoral nerve: Arising from L2-4, the femoral nerve emerges from the lateral aspect of the psoas muscle and travels, and courses below the inguinal ligament lateral to the femoral artery and outside the femoral sheath. Common site of injury is the posterior abdominal wall, well posterior to the ilioinguinal tract and little lateral to the genitofemoral nerve (medial to lateral are the genitofemoral nerve, the femoral nerve and then the lateral cutaneous nerve of the thigh). Post-injury pain could be the anteromedial aspect of the thigh with or without thigh paralgesia or paresthesia. Even a little hip extension causes pain. Later the quadriceps muscles weaken, and loss of patellar reflex could occur.
  4. Ilioinguinal nerve: This nerve is rarely involved in laparoscopic hernia repair. It is frequently involved in open inguinal hernioplasty. It is only injured if excessive pressure is applied during laparoscopic mesh fixation, compressing the muscles sufficiently to allow the tacker or the stapler to reach the deeply situated nerve.
    Course of ilioinguinal nerve: Arising from L1, travels retroperitoneally across the quadratus lumborum behind the kidney and then passes anterior to the iliac muscles, piercing the transversus abdominis near the anterior end of the iliac crest, and then piercing the internal oblique. It travels through the inguinal canal in an anterolateral position in the spermatic cord and exits through the superficial inguinal ring or the external oblique aponeurosis.
Area of supply:
  • Skin at the root of the penis
  • Anterior third of the scrotum
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  • Labium majora in female
  • Small area of thigh inferomedial to the inguinal ligament
  • Motor supply is the internal oblique before it reaches the inguinal canal.
    Common site of entrapment is medial to the anterosuperior iliac spine (only if excessive pressure is applied on the anterior abdominal wall during the mesh fixation).
Post-injury paresthesia in the lower abdomen, scrotum and upper medial thigh. Extension of hip increases the pain.
 
Triangle of Doom (Fig. 1.9)
The boundaries of triangle of doom, medially it is vas deferens, laterally it is gonadal vessels and posteriorly it is peritoneal edge. The contents are the external iliac vessels, deep circumflex vein, femoral nerve and genital branch of genitofemoral nerve. The point to be remembered is that the mesh should not be fixed in this region to avoid “doom” bleeding complication.
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Fig. 1.9: Triangle of doom.
 
Triangle of Pain (Fig. 1.10)
The boundaries of triangle of pain are the spermatic cord medially, iliac crest laterally and superiorly the iliopubic tract. The contents, from lateral to medial, of triangle of pain are lateral femoral cutaneous nerve, anterior femoral cutaneous nerve, femoral branch of genitofemoral nerve and femoral nerve.
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Fig. 1.10: Triangle of pain.
The point to be remembered is electrocautery should not be used in this region. Dulucq's fascia covers these nerves and one should try not to strip off during dissection to avoid neuropraxia.