KEY NOTES CHAPTER 7: THE TRUNK AND UROGENITAL SYSTEM - Open Abdomen.

Question 0

Draw the layers of the abdominal wall.

Answer 0

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Question 1

What are the layers of the abdominal wall?

Answer 1

∘ Skin
∘ Subcutaneous fat within Camper’s fascia
∘ Scarpa’s fascia (below the level of the umbilicus only)
∘ Sub-Scarpa’s fat
∘ Anterior rectus sheath centrally, aponeuroses of the oblique muscles laterally
∘ Muscles
∘ Posterior rectus sheath (above the arcuate line only)
∘ Transversalis fascia
∘ Preperitoneal fat
∘ Peritoneum.

Question 2

Describe the anatomy of the fascial layers in relation to the muscles on the anterior abdominal wall.

Answer 2

1 Longitudinally orientated, centrally placed muscles:
∘ Rectus abdominis (RA)
∘ Pyramidalis.
2 Flat, laterally placed muscles:
∘ External oblique (EO)
∘ Internal oblique (IO)
∘ Transversus abdominis (TA).

• Linea semilunaris: Aponeuroses of EO, IO & TA fuse lateral to RA. They divide into anterior and posterior laminae to enclose RA in a fascial (rectus) sheath.
• Linea alba: midline fusion of aponeuroses.

Arcuate line: ~ 1∕3 from umbilicus to pubic symphysis (ASIS level).
• Superior to arcuate line:
- Posterior rectus sheath = posterior leaf of IO and TA aponeurosis.
- Anterior rectus sheath = aponeurosis of EO and anterior leaf of IO aponeurosis.
• Below arcuate line: posterior lamina is deficient, all aponeuroses pass anterior to RA, and RA lies on transversals fascia.

Question 3

What is the nerve supply of the muscles?

Answer 3

Segmental nerve supply, T6/T7-T12.
EO: iliohypogastric nerve (T12, L1) also.
IO: iliohypogastric and ilioinguinal (L1) nerves also.
• All nerves run in neurovascular plane between IO and TA.

Question 4

What is the arterial supply of the anterior abdominal wall?

Answer 4

• Segmental intercostal and lumbar vessels
• Superior epigastric arteries
• Superficial and deep inferior epigastric arteries
• Superficial and deep circumflex iliac arteries
• Superficial external pudendal arteries.

Question 5

What is a laparostomy? When is it indicated?

Answer 5

Abdominal wall defect created by intentionally leaving an abdominal incision open.

Indications:
∘ Damage control surgery for trauma
∘ Intra-abdominal sepsis
∘ Excessive visceral oedema that precludes direct closure
∘ Abdominal wound dehiscence.
∘ Following decompression of abdominal compartment syndrome

Question 6

What classification of open abdomen are you aware of?

Answer 6

Björck et al.

Grade 1: Open abdomen without adherence between bowel and abdominal wall or fixity of the abdominal wall (lateralisation).

• A: clean
• B: contaminated.

Grade 2: Open abdomen with developing adherence/fixity.

• A: clean
• B: contaminated.

Grade 3: Open abdomen complicated by fistula formation.

Grade 4: Frozen open abdomen with adherent/fixed bowel that cannot be closed surgically,
with or without fistula.

Question 7

How is the open abdomen mananged?

Answer 7

Three phases:

1. Temporary abdominal closure
2. Patient optimisation
3. Definitive closure.

Question 8

What is the purpose and methods of temporary closure?

Answer 8

Purpose of temporary closure:
∘ Protect intestines
∘ Maintain a clean environment
∘ Avoid fluid and temperature loss.

Methods of temporary abdominal closure:

1. Skin-only closure using towel clips
2. Silo technique: non-adherent plastic sheets wrapped around intestines
3. Temporary mesh
4. Intraperitoneal packing
5. Negative pressure wound therapy
6. Various proprietary devices.

Question 9

How are patients optimised?

Answer 9

• Patients are often critically ill.
• Optimisation maximises chances of successful reconstruction.

• Summarised by the ‘SNAP’ principle:
∘ Sepsis control - both intra-abdominal infection and systemic inflammatory response.
∘ Nutrition - supplemental enteral or parenteral feeding.
∘ Anatomy - defining defect by pre-operative imaging.
∘ Planning - determining type and extent of reconstruction required.

Question 10

How can a laparostomy be closed definitively?

Answer 10

Small wounds: delayed primary closure or healing by secondary intention, or
Skin graft directly onto bowel / granulation tissue (to minimise protein losses).
Myofascial layer reconstruction: months later when patient is well, if unfit, manage with abdominal binder / corset.

Question 11

What are the methods of myofascial layer reconstruction?

Answer 11

1 Prosthetic
2 Bioprosthetic
3 Autologous.

Question 12

What are the different types of prosthetic reconstruction and what are the advantages and disadvantages?

Answer 12

• Meshed or non-meshed, absorbable or non-absorbable.

Meshed materials - allow continued drainage of the abdominal cavity.
• Granulation ingrowth and delayed skin grafting.
• Cover mesh with omentum and skin grafted.

• Absorbable meshes are associated with higher rates of fistula and late hernia compared to polypropylene meshes, e.g. Marlex®.

Question 13

What bioprosthetic reconstruction do you know of and what are the advantages?

Answer 13

ADM e.g. Permacol.
• Form fewer adhesions with bowel compared to prosthetic materials.
• Incorporate by regeneration and are replaced by native tissue, and are more resilient to infected wounds.
• Generally lose integrity when used as ‘bridge grafts’ for ventral hernias, with high
recurrence rates.

Question 14

What autologous reconstruction options are there for the abdominal wall?

Answer 14

Fascia lata (graft)
TFL 
Pedicled ALT (+/- fascia lata)
Muscle flaps (local or distant)
Components separation
Tissue expansion

Question 15

Name some muscle flaps for abdominal reconstruction.

Answer 15

∘ RA, transposition or turnover.
∘ EO, for upper abdominal defects.
∘ IO, for lower abdominal defects.
∘ Latissimus dorsi, rectus femoris, vastus lateralis and gracilis pedicled or free.

Question 16

What is components separation?

Answer 16

Technique described by Ramirez that allows greater advancement of myofascial layers towards the midline for direct closure.

Releasing incisions are made in the deep fasciae:
1 EO aponeurosis is divided from rectus sheath JUST LATERAL TO LINEA SEMILUNARIS.
2 RA is separated from posterior rectus sheath by incising MEDIAL EDGE OF THE SHEATH and freeing muscle.

Allows bilateral advancement of rectus muscles and anterior rectus sheath:

• 5 cm in the epigastrium
• 20 cm at the umbilicus
• 6 cm in the suprapubic region.

Question 17

Draw the components separation technique.

Answer 17

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Question 18

Which plane should the tissue expander be placed?

Answer 18

• between EO and IO or between IO and TA.

Question 19

What post-operative complications may be encountered?

Answer 19

∘ Wound dehiscence
∘ Enterocutaneous fistula
∘ Hernia
∘ Infected prosthetic mesh - usually requires removal
∘ Seroma.

Question 20

Describe the algorithm for reconstructing a partial abdominal defect.

Answer 20

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Question 21

Describe the algorithm for reconstructing a complete abdominal defect.

Answer 21

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