Overview
Definition:
A parastomal hernia is the protrusion of abdominal contents through an abdominal wall defect adjacent to a surgically created stoma (colostomy or ileostomy)
Prophylactic mesh placement aims to reinforce the abdominal wall at the stoma site, thereby reducing the incidence of parastomal hernia formation.
Epidemiology:
Parastomal hernias are a common complication following ostomy creation, with reported incidence rates ranging from 2% to 50% depending on the stoma type, patient factors, and surgical technique
Ileostomies tend to have a higher incidence than colostomies
Risk factors include obesity, increased intra-abdominal pressure, poor tissue quality, and stoma site selection.
Clinical Significance:
Parastomal hernias can lead to significant morbidity, including pain, bowel obstruction, strangulation, stomal ischemia, and poor cosmesis
They often require reoperation, increasing healthcare costs and patient suffering
Prophylactic measures are crucial to improve long-term outcomes for patients undergoing ostomy surgery.
Indications For Prophylaxis
Patient Factors:
Patients with increased risk of hernia formation, such as those who are obese, have multiple comorbidities (e.g., diabetes, COPD), or have a history of previous abdominal surgery and hernia formation
Consider in younger patients likely to live longer with the stoma.
Stoma Type:
Especially considered for ileostomies due to higher intra-abdominal pressure and more frequent stool output, leading to increased strain on the abdominal wall
Also relevant for end colostomies.
Surgical Considerations:
When creating a stoma in a challenging anatomical location or in patients with compromised abdominal wall integrity
Prophylaxis may be considered in elective settings where optimal surgical conditions exist.
Surgical Technique:
Choice of mesh material (synthetic vs
biologic), fixation method (sutures, tacks), and placement (underlay, inlay, onlay) are critical considerations
Newer techniques like keyhole mesh or custom-made meshes are being explored.
Mesh Types And Placement
Mesh Materials:
Various synthetic meshes (polypropylene, ePTFE) and biologic meshes are available
Synthetic meshes offer strong reinforcement but carry a higher risk of infection and foreign body reaction
Biologic meshes are more expensive but may reduce infection risk, though they have less tensile strength and may be associated with recurrence.
Placement Techniques:
The "keyhole" technique, where a pre-cut mesh has a central aperture through which the bowel is exteriorized, is a common approach
Other methods include placing a mesh inlay or underlay around the stoma site
The mesh should ideally be placed in a retromuscular or preperitoneal plane for optimal support.
Fixation Methods:
Secure fixation of the mesh to the abdominal wall is essential to prevent migration and displacement
This can be achieved using non-absorbable sutures, tacks, or fibrin glue, depending on the mesh type and anatomical location
Care must be taken to avoid bowel injury during fixation.
Surgical Procedure Steps
Preoperative Planning:
Careful site selection for the stoma is paramount
Preoperative marking of the stoma site is crucial
Patient counseling regarding potential risks and benefits of mesh prophylaxis is important.
Dissection And Mesh Preparation:
Dissection to create a suitable plane for mesh placement (e.g., rectus sheath or transversalis fascia)
The mesh is then prepared according to the chosen technique, often cut to create a keyhole aperture for the stoma.
Bowel Exteriorization And Mesh Placement:
The bowel is brought through the abdominal wall and the prepared mesh aperture
The mesh is then positioned and secured to the surrounding fascia and musculature, ensuring adequate coverage and tension-free closure.
Fascial Closure And Skin Closure:
Closure of the overlying fascia and subcutaneous tissues
Skin closure is performed in a standard fashion
Meticulous technique is vital to minimize tension on the stoma site and the mesh.
Complications Of Prophylaxis
Early Complications:
Mesh infection, seroma formation, wound dehiscence, bleeding, and early stoma-related complications like ischemia or retraction
These are more common with synthetic meshes and suboptimal surgical technique.
Late Complications:
Mesh migration, mesh erosion into the bowel lumen or other organs, chronic pain, hernia recurrence despite mesh placement, and adhesions leading to bowel obstruction
Biologic meshes may have a higher recurrence rate due to their inherent weakness.
Prevention Strategies:
Strict aseptic technique during surgery, judicious use of prophylactic antibiotics, careful selection of mesh material and fixation methods, meticulous surgical technique to avoid bowel injury, and proper patient selection for mesh prophylaxis are crucial preventive measures.
Evidence And Controversies
Evidence Base:
Randomized controlled trials and systematic reviews have shown a reduction in parastomal hernia incidence with prophylactic mesh placement, particularly for ileostomies
However, the long-term benefits and optimal techniques are still subjects of ongoing research.
Controversies:
Debate exists regarding the routine use of mesh for all ostomies versus selective use in high-risk patients
Cost-effectiveness, long-term safety of different mesh types, and the potential for mesh-related complications are areas of concern
Standardization of techniques and outcomes reporting is needed.
Future Directions:
Development of novel, bioabsorbable meshes with superior mechanical properties, advanced fixation techniques to minimize complications, and improved patient selection algorithms are areas for future research and clinical application.
Key Points
Exam Focus:
Understand the incidence, risk factors, and complications of parastomal hernias
Differentiate between prophylactic mesh techniques and their indications
Know the types of meshes used and their pros/cons
Be familiar with the surgical steps and potential complications of mesh placement.
Clinical Pearls:
Always consider stoma site selection carefully
For ileostomies, prophylactic mesh is increasingly favored
Meticulous surgical technique is paramount to minimize complications
Educate patients about the possibility of parastomal hernia development even with prophylaxis.
Common Mistakes:
Failure to adequately secure the mesh, leading to migration
Incorrect placement of the mesh, resulting in inadequate support
Injury to the bowel during mesh fixation
Over-reliance on mesh without addressing patient-specific risk factors for hernia development.