Abdominal wall anatomy, incisions& ventral hernias -د.جمال مسعد

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Abdominal wall anatomy, incisions& ventral hernias

Anatomy of the anterior abdominal wall
Layers:
1. skin, then fat (camper’s fascia)
2. scarpa’s fascia, then more fat
3. external oblique muscle
4. internal oblique muscle
5. transverses abdominis muscle
6. fascia transversalis
7. preperitoneal fat
8. peritoneum
Rectus Abdominis
Its fibers run vertically between the pubic symphysis and the xiphoid process.
The right and left recti are separated medially by the linea alba.
The rectus sheath is formed by aponeurotic fibers of three lateral muscle layers; the external oblique aponeurosis forms the anterior layer, the internal oblique will split and contribute to both anterior and posterior layers, the transverses abdominis aponeurosis forms the posterior layer. Below the arcuate line the posterior layer is composed of the fascia transversalis.
• The arcuate line is located midway between the umbilicus and pubis. It is a landmark for the change in disposition of the aponeurotic fibers. Above the arcuate line, the posterior and anterior layers of the rectus sheath have equal thickness; below it, all aponeurotic fibers run anterior to the rectus abdominis which makes it a weak point liable to hernia (spigelian)
• Superior and inferior epigastric vessels travel in the posterior layer of the rectus sheath.
Linea Alba
- The linea Alba is a shallow groove that runs vertically in the median plane from the xiphoid to the pubis separating the right and left rectus abdominis muscles. Above the umbilicus it’s sheath like - decussation of fibers - extending about 2cm in both sides of the midline while below it, it’s a line ( i.e., weaker above the umbilicus) .

Incisions:
Most of them are done in the midline; [1] less time is needed to do the incision in the midline (abdominal trauma) [2] the least site to cause bleeding (for a patient with bleeding tendency)
- Midline incisions are more liable for hernia and less painful than others.
- There are vertical, transverse and oblique incisions.

- Vertical: According to its relation to the umbilicus:
1. Midline upper abdominal incision.
2. Midline lower abdominal incision.
3. Mid-midline incision (upper and lower).
4. Para median incision- the peritoneum is reached after retracting the muscles.

- Oblique:
1. Left hypochondrial incision (Kocher): to reach the liver, GB, deudenum. It is considered a bad one due to the major interruption of the abdominal wall musculature and cutting of 6th-9th intercostal nerves.
2. McBurney’s incision: in the right lower quadrant for an appendectomy through McBurney’s point (one third from the anterior superior iliac spine to the umbilicus).
3. Kidney transplant: in the lower quadrant.

-Transverse:
1. Pfannenstiel: low transverse abdominal incision with retraction of the rectus muscles laterally, mostly for gynecologic procedures.
2. Rocky-Davis: like McBurney’s incision except transverse.

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- One of the most important challenges facing surgery is post-op scaring.

- Scar formation  interruption of the normal anatomy weak point  hernia.

- Recent scars are purple in color, while old ones are white.

- To minimize the problem:
1. Shift from traditional surgeries (through incisions) to laparoscopic surgeries (through punctures).
2. In-utero surgeries.
The surgery is done after cutting the abdominal wall and opening the uterus… after delivery the newborn won’t have any scars due to the presence of certain growth factors (lacking in adults).
- Researches are being done to study the possibility of performing a “scarless surgery” by injecting the patient with certain inhibitory growth factors...







Hernia:
- Protrusion of a hollow viscus or a solid organ in a through a defect in the abdominal wall with a preformed sac.
- It comes through a weak point:
1. incisional hernia: through scars
2. umbilical: inside the umbilicus
3. periumbilical hernia: around (usually above)
4. spigelian hernia A.K.A spontaneous lateral ventral hernia: through spigelian fascia below the arcuate line
5. epigastric hernia: in the sheath-like part of linea alba A.K.A. fatty hernia of linea alba because its content is only fat
6. inguinal hernia (direct through fascia tranversalis within Hesselbach’s triangle, indirect through the internal oblique lateral to Hesselbach’s triangle)
7. Femoral hernia: through the femoral ring.





- Rare types:
1. sciatic hernia: through the sciatic foramen
2. Obturator hernia: through the obturator canal. Patients present with knee pain due to compression to the genicular branch of obturator nerve.
3. lumber hernia: through the lumber triangle:
Medial border: latissimus dorsi.
Lateral: external oblique.
Inferior: iliac crest.

- clinical evidence to diagnose a hernia:
1. Swelling that appears on straining and disappears on lying flat.
2. Comes through a defect known to be weak, either congenital or acquired.
3. Visible and palpable cough impulse.

- Complications:
1. Strangulation: incarcerated hernia with resulting irreversible ischemia and bowel necrosis due to venous obstruction.
2. Intestinal obstruction
3. infection







- Small bowel infarction: caused by arterial obstruction. The bowel will be ischemic, cold and pale, with lack of peristalsis.

- Small bowel strangulation: caused by venous obstruction. The bowel will be blue, swollen, congested with mucosal ulceration. It can’t be diagnosed clinically.

- Incarcerated: implies that the contents of the hernial sac are stuck inside by adhesions.

-Soft, reducible hernia tense, tender, no cough impulsedescribe it as incarcerated as it could be either strangulated (irreversible ischemia) or irreducible (reversible after decompression), you can be sure only after operating.

- The most common cause of intestinal obstruction in developed countries is adhesions while it’s hernia in underdeveloped countries.

-The most common cause of intestinal obstruction in children is hernia.


THE END