TYPES OF WALL HERNIAS
The diagnosis of abdominal hernia is clinically established,
however Multislice computed tomography (MSCT) is very useful for identifying and classifying them.
Types of Wall hernias
- Direct inguinal
- Indirect inguinal
- Femoral
- Obturator
- Ventral
Umbilical
Paraumbilical
Epigastric
Hypogastric
Lateral or paramedian.
Spigelian
TYPES OF WALL HERNIAS
Direct inguinal hernias:
They appear through the Hesselbach hole,
above the inguinal and medial ligament to the inferior epigastric vessels.
They are acquired secondarily to a weakness of the transverse fascia in the triangle of Hesselbach and their incidence increases with age.
They are more frequent in men.
Indirect inguinal hernias
They are the most frequent and,
by definition,
they have a lateral and superior location to the inferior epigastric vessels,
lateral to the triangle of Hesselbach and protrude through the inner inguinal ring to enter the inguinal canal.
They are more frequent than direct inguinal hernias.
Femoral hernias
They are uncommon.
They occur when the peritoneal content is introduced into the femoral canal next to the femoral vessels.
They are located medial to the femoral vein and posterior to the inguinal ligament.
The herniated sac goes lateral to the inguinal duct,
between the insertion of the external oblique muscle into the upper pubic branch and the upper pubic branch itself.
They are more frequent in women and on the right side.
Obturator hernias
They are rare,
less than 1%,
and typical of elderly and,
on many occasions,
multiparous women,
as they are associated with weakness of the pelvic floor.
The herniated content is located between the pectineus muscle and the external obturator,
and,
less frequently,
between the external and internal obturators.
They have a high risk of strangulation.
Ventral hernias
This group includes anterior and lateral abdominal wall hernias.
Incarceration and strangulation are frequent complications.
They are subdivided into:
- Umbilical hernias: They are the most frequent,
usually small and in women.
- Paraumbilical hernias: Large defects through the linea alba in the navel area.
- Epigastric hernias.
- Hypogastric hernias.
- They can also be caused by lateral or paramedial defects.
- Spigelian hernias are produced by weakness of the aponeurosis of the internal oblique and the transverse,
allowing the herniation of peritoneal content.
Lumbar hernias
They occur due defects of the lumbar musculature or posterior fascia,
between the last ribs and iliac crest.
They usually appear after surgery or trauma.
Incisional hernias or eventrations
They are a complication of abdominal surgery and appear in up to 28% of patients.
They may occur in any surgical incision during the first few months after surgery,
including laparoscopic trocars orifices.
They are more frequent in vertical incisions than in horizontal ones.
Risk factors for their development are: advanced age,
obesity,
post-surgical infections,
COPD,
ascites,
malignant tumors and malnutrition.
Parastomal hernias are considered a subtype of incisional hernia.
Since 2007,
the European Hernia Society classifies them according to their size (less than 4 cm,
between 4 and 10 cm and more than 10 cm) and their location (midline and lateral).
Figure 3
ABDOMINAL WALL REPAIR MESHES
In the last 25 years,
biomaterials have been developed in order to repair abdominal wall defects,
resulting in a change of the surgical procedures of repair of the hernias and eventrations of the abdominal wall.
The emergence of highly biocompatible materials,
mainly represented by polypropylene,
polyester and modified Teflon in the form of expanded Polytetrafluoroethylene (PTFE),
has allowed the development of these implants.
- Some of the requirements to be met by the ideal prosthetic material are:
- Good tissue integration.
- Good behavior when in contact with the peritoneum.
- Good mechanical postimplant resistance.
- Flexibility,
to prevent erosions in larger structures,
maintain their integrity and offer some possibility of permanence.
- It must be inert to prevent further inflammatory response.
- Porousness to favor drainage of the exudate and fibroblast growth.
TYPES:
They can be classified according to:
THE CHARACTERISTICS OF THE MATERIAL:
- Non-absorbable (polypropylene,
polyester)
- Absorbable (polyglycolic acid [Dexon ®],
Polyglactin [Vicryl ®]
PLACE OF MESH PLACEMENT
- Extraperitoneal
- Intraperitoneal
FORM OF MANUFACTURING
- Reticulated
- Laminar
- Composite
GENERAL COMPLICATIONS OF ABDOMINAL WALL REPAIR MESHES
The post-surgical complications of the most frequent abdominal meshes are:
- Hernia recurrence
- Liquid collections (Bruises/Seromas)
- Complications related to the loops (enterocutaneous fistulas,
intestinal obstruction)
- Mesh-related complications (infection,
fragmentation,
folding,)
- Heterotopic ossification of the wall.
- Chronic infection forcing the removal of the mesh
- Incisional hernia
- Chronic pain
In the case of preaponeurotic meshes,
a greater incidence of early post-surgical seroma has been proven.
VISIBLE MESH FEATURES
Visible meshes have the characteristic of having fine ferrous particles (Fe3O4) integrated in the dark fibers of the mesh,
generating local magnetic gradients between the mesh and the environment.
In suitable MRI sequences,
these fibers appear in the form of small artifacts by paramagnetic susceptibility,
which are better identified in gradient echo sequences (GRE) than in fast spin echo sequences (TSE).
In our environment,
we use DynaMesh ®-CICAT meshes made out of polyvinylidene fluoride monofilament,
which is non-resorbable and biostable.
They count on partially-dyed green or black threads to facilitate their manipulation,
recognition and positioning of the mesh during surgery; in addition to allowing post-operative recognition of the mesh with MRI,
since they contain the ferric particles.
They have the characteristic of being placed preaponeuroticly outside the peritoneal cavity,
since they cannot be in contact with the intestinal loops.
VISIBLE MESH FEATURES
The structures of the lattice,
specially developed and the ideal size of the mesh DynaMesh ®-CICAT,
are optimally adapted to the dynamometry of the abdominal wall.
These marking bands of the mesh should be oriented toward a craniocaudal direction to ensure optimal mesh orientation as for the dynamometric properties of the abdominal wall.
Fig.
4
INDICATIONS FOR THE REPAIR WITH VISIBLE MESHES
The Preaponeurotic/extraperitoneal meshes have the same indications as the classic intraperitoneal prosthesis in the REPAIR OF HERNIAS AND EVENTRATIONS, especially large hernial defects and associated risk factors,
eventrations of lumbar location and close to bone reliefs (subcostal,
juxta-pubic and juxta-xiphoid) and multi-relapsing eventrations.
In recent years,
studies including several meta-analyses have demonstrated the safety and efficacy of preaponeurotic meshes in PROPHYLACTIC REPAIR in order to median laparotomy by improving parietal reinforcement and reducing incidence of incisional hernia,
without increasing the incidence of complications.
Other advantages of this prophylactic use are less surgical time and less time for hospitalization and recovery.
Fig. 4: Reference articles
MRI PROTOCOL
In our center,
we are conducting a prospective study on the use of prophylactic preaponeurotic meshes in patients with supra,
umbilical and infraumbilical (SUI) median laparotomy,
conducting a MRI study 6 weeks and a year after the surgery.
We have an MRI of 1.5 T GE Signa
We use single shot sequence (SSFSE) with suspended respiration as a locator.
We perform T1 echo gradient sequences (GRE) in the three planes of the space to assess the meshes use of the paramagnetic susceptibility in these sequences.
To finalize the study,
we performed T2 FSE sequence with respiratory synchronization for anatomical assessment and evaluation of possible complications.
In cases where hernia or eventration recurrence are identified,
film sequences can be added since they also provide information about the condition of the wall musculature
If the equipment allows it,
T1 3D acquisitions can be made to process the image (MIP) and carry out a quantitative analysis
MRI PROTOCOL
Fig. 15: Table of Contents
APPEARANCE OF THE MESHES IN THE DIFFERENT SEQUENCES
SSFSE BH
Fig. 16: Table of Contents
As locator,
we use sequences with very short acquisition time which combine the single-shot TSE mode with the Half Fourier (HF) acquisition and suspended respiration.
Fig. 5
In addition,
it allows us a quick vision the area of study and to prove the presence of liquid collections.
Fig. 6
EGT1
Fig. 17: Table of Contents
For a detailed study of the mesh implant,
T1-GRE sequences must be performed on the three planes which they allow,
thanks to the paramagnetic susceptibility of the mesh fibers containing iron particles,
to correctly evaluate the implant.
Fig. 7
This device or loss of signal in the area of influence of that paramagnetic substance gives us information about its placement,
disposition,
folding...
Fig. 8 y Fig. 9
The GRE T1 sequence in sagittal plane allows us to assess the craniocaudal disposition and length of the mesh and to detect contractions.
Fig. 10 ,
Fig. 11 and Fig. 12
Sometimes the mesh is placed horizontally in patients with supraumbilical laparotomy. These are specially-designed meshes to be placed this way,
with the same vertical design of the fibers as the vertical meshes.
Fig. 13 y Fig. 14
T2 FSE
Fig. 18: Table of Contents
To obtain more detailed information on the anatomy,
FSE T2 sequences with respiratory synchronization must be used.
They are more sensitive to inflammatory pathological changes,
although they require more study time.
We provide information on the presence of collections and/or bruises both intraperitoneal and in the abdominal wall.
Fig. 20
EG T2
In cases where it is especially important and complex to determine the position relation between the mesh and the anatomical structures,
the additional use of GRE T2 sequences that correctly represent both the mesh and the anatomy is recommended,
as well as being able to separate it from adjacent intestinal loops.
RADIOLOGICAL REPORT
In our center and in agreement with our surgeons,
the radiological report consists of a description of the type of incision performed (middle,
lateral,
horizontal laparotomy) and the presence or not of preaponeurotic mesh.
We must carry out measurements in the three planes of the space,
providing the maximum and minimum transverse and crown-rump diameters of the supraumbilical,
umbilical and infraumbilical region,
which in future controls will allow us to evaluate mesh contractions,
detachments,
displacements…
It is necessary to include/confirm the correct orientation of the fibers in the craniocaudally plane in both vertical and horizontal meshes.
It is also necessary to determine the presence of:
- Collections (seromas and/or bruises)
- Hernia recurrences
- Folding
Finally,
we must not forget that most of our patients are oncological and it is essential to review the findings of the FSE T2 axial acquisition.