Overview of Surgical Ostomy for Fecal Diversion
Executive Summary
This document provides a comprehensive overview of surgical ostomy for fecal diversion, synthesizing current principles, techniques, and recommendations. An ostomy is a surgically created anastomosis between the gastrointestinal tract and the skin of the anterior abdominal wall, designed to divert the fecal stream. These procedures, classified primarily as ileostomies or colostomies, may be temporary to manage acute conditions or permanent when restoring intestinal continuity is not feasible. The overall number of fecal diversions appears to be declining.
Key takeaways include the critical importance of preoperative patient preparation. Comprehensive counseling by an ostomy nurse specialist significantly improves postoperative quality of life, and meticulous preoperative stoma site selection is essential for minimizing complications and optimizing patient self-care. For surgical approach, laparoscopy is preferred over open surgery for creating defunctioning stomas when clinically appropriate, as it is associated with reduced morbidity and faster recovery.
For temporary diversion, a diverting loop ileostomy is generally favored over a loop colostomy due to a more straightforward reversal process. The use of prophylactic mesh at the time of stoma creation to prevent parastomal hernias remains controversial; routine placement is not recommended. However, if mesh is used, a sublay position is preferred. Finally, the timing of ostomy reversal is critical, with procedures typically delayed until the patient's underlying condition has resolved and inflammation has subsided.
I. Fundamentals of Fecal Diversion
Definition and Purpose
An ostomy is defined as a purposeful anastomosis created between a segment of the gastrointestinal (GI) tract and the skin of the anterior abdominal wall. Its primary function is to divert the fecal stream. This procedure is indicated when restoring or maintaining intestinal continuity is contraindicated or not immediately feasible given the patient's clinical condition.
Indications for Ostomy Creation
Fecal diversions can be either temporary or permanent and are utilized to manage a wide range of pathologic conditions.
Temporary Diversion: May be required for managing conditions such as congenital anomalies, colon obstruction, inflammatory bowel disease, traumatic intestinal disruption, or gastrointestinal malignancy. It is also used to protect a high-risk or low colorectal or coloanal anastomosis.
Permanent Diversion: Necessary when the distal bowel, rectum, or anus must be permanently removed or bypassed, and the anorectal sphincter mechanism is no longer functional.
Classification of Fecal Diversions
Ostomies are classified according to the segment of the bowel used and the method of surgical construction.
Bowel Segment:
Ileostomy: Involves the distal small intestine (ileum).
Colostomy: Involves the large intestine (colon).
Surgical Construction:
Loop: A loop of bowel is brought through the abdominal wall.
End: The transected end of the bowel is brought through the abdominal wall.
Reservoir: An internal pouch is constructed for continence.
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II. Types of Ostomies and Surgical Techniques
A. Ileostomy
An ileostomy is performed to remove or bypass the entire colon and rectum. It can be constructed as a diverting loop, end stoma, or continent reservoir.
Diverting Loop Ileostomy: This is the preferred method for protecting a distal colorectal or coloanal anastomosis following a sphincter-saving rectal resection. A loop of the terminal ileum is brought through the abdominal wall and stabilized with a rod or bridge until the bowel granulates to the abdominal wall.
End-Ileostomy: This is a permanent ostomy required when the anorectal sphincter mechanism is removed along with the entire colon and rectum. The Brooke's technique is the accepted approach, which involves eversion of the bowel to create a protruding stoma (2 to 3 cm) that exposes the mucosa. This protrusion directs effluent into the pouching system, minimizing skin irritation.
Continent Ileostomy: A specialized permanent procedure performed by surgeons with expertise in this technique. It involves creating an internal pouch from detubularized ileum (e.g., Kock pouch) with a nipple valve for continence. The stoma is flush with the skin, and the patient intubates the reservoir regularly to drain its contents. The Barnett continent ileal reservoir (BCIR) is a modification that adds an ileal "collar" to improve continence. These procedures have a high reoperation rate and are contraindicated in patients with Crohn's disease.
B. Colostomy
A colostomy is performed when it is necessary to bypass or remove the distal colon, rectum, or anus.
Temporary Colostomy: Can be used for emergency decompression of an obstructed colon or to facilitate the healing of perianal sepsis (e.g., fistulas). However, for protecting a low-lying colorectal anastomosis, a diverting loop ileostomy is generally preferred due to easier reversal.
Colostomy for Decompression: Utilized in patients with obstructing lesions of the colon. Common types include:
Transverse loop colostomy: A loop of the transverse colon is brought through the abdominal wall.
Cecostomy: The anterior wall of the cecum is opened and sutured to the abdominal wall.
Sigmoid loop colostomy: Similar to a transverse loop but involves the sigmoid colon.
Colostomy for Fecal Diversion: Can be created in various ways to divert the fecal stream away from a distal site of inflammation or a fistula.
Loop Colostomy: A loop of colon with a proximal (afferent) and distal (efferent) limb is created.
End-loop Colostomy: The colon is divided, and the proximal end is matured as the stoma, while the distal end is placed in the subcutaneous space as a mucous fistula.
Double Barrel Stoma: The bowel is transected, and both the proximal (functional) and distal (mucous fistula) ends are brought up to the abdominal wall as separate stomas.
Hartmann's Procedure: The proximal end of the transected bowel is brought to the abdominal wall as an end-colostomy, while the distal stump is oversewn and left in the abdominal cavity.
Permanent Colostomy: Required when fecal diversion is permanent. This is often beneficial for older patients as it carries a lower risk for dehydration and electrolyte abnormalities compared with a permanent ileostomy.
III. Preoperative Management and Planning
Thorough preoperative preparation is paramount for positive patient outcomes, addressing the significant physical, psychological, social, and economic burdens associated with living with an ostomy.
Patient Counseling and Education
Preoperative counseling by an ostomy nurse specialist has been shown to improve postoperative quality of life by helping patients adapt psychologically to the significant lifestyle changes. It is associated with decreased stoma-related postoperative complications and improved patient stoma proficiency. Involvement in ostomy support groups, such as the United Ostomy Association of America, also correlates with long-term positive outcomes.
Stoma Site Selection and Marking
Proper site selection is essential for minimizing postoperative complications and achieving a good quality of life.
Process: Site selection should be a collaborative process involving an enterostomal therapy nurse, the surgeon, and the patient. In urgent surgery where preoperative marking is not possible (occurring in 23% versus 46% of cases), an experienced surgeon should select the site.
Principles of Siting:
Location: The stoma should lie on either side of the abdominal midline, just lateral and inferior to the umbilicus, and placed through the rectus abdominis muscle for support.
Visibility & Accessibility: The patient must be able to see and access the stoma without difficulty. For patients with obesity, a higher placement may be necessary.
Clearance: The site must be at least 5 cm from all skin folds, creases, previous incisions, the umbilicus, and bony prominences to ensure a flat surface for appliance adherence.
Patient Factors: Considerations include the patient's natural clothing style (belt line), abdominal contour in sitting and standing positions, occupation, and any physical disabilities.
IV. Surgical Approaches and Construction
Role of Laparoscopy
The laparoscopic approach is a safe and effective alternative to laparotomy for creating loop ostomies.
Advantages: It provides an excellent view of the abdominal cavity and minimizes the risks and complications associated with an open procedure. Studies have shown that a laparoscopic approach leads to:
Lower postoperative morphine requirements (48 versus 90 mg).
Earlier return of bowel function (2.2 versus 3.6 days).
Earlier tolerance of a solid diet (3.6 versus 5.5 days).
Fewer postoperative complications.
Indications: It is the preferred approach for creating a defunctioning stoma, provided the likelihood of adhesions from previous surgeries is low.
Principles of Ostomy Construction
Bowel Mobilization: A segment of healthy, well-vascularized bowel of sufficient length must be selected to ensure a tension-free approximation to the skin.
Aperture Creation: The opening in the abdominal wall must be sized correctly. A large aperture increases the risk of a parastomal hernia, while a small aperture can lead to ischemia, stricture, or obstruction. The author prefers a 2 cm vertical incision in the anterior rectus fascia.
Stoma Maturation
End-Ostomy: An ileostomy should protrude 2 to 3 cm above the skin to allow effluent to empty directly into the appliance. A colostomy requires only 1 to 2 cm of protrusion due to its more solid output. Eversion of the stoma is achieved by placing full-thickness sutures from the bowel to the dermis.
Loop Ostomy: Can be performed as a defunctionalized distal limb or a double barrel ostomy. In a defunctionalized loop ostomy, the proximal functioning limb is everted and sutured to the skin, while the distal limb is not everted.
Double Barrel Ostomy: Both proximal and distal limbs are brought through the abdominal wall. The back wall can be kept intact or divided. If intact, both limbs are everted. If divided, they are matured separately like end-ostomies.
V. Prophylactic Mesh in Stoma Creation
The use of prosthetic mesh during stoma creation to prevent parastomal hernia is a subject of ongoing debate.
Clinical Evidence and Recommendations
The evidence regarding the efficacy of prophylactic mesh is conflicting, leading to a recommendation against its routine placement (Grade 2C).
Mesh Placement and Type
Placement Technique: If mesh is used, the sublay position (posterior to the rectus sheath) is the preferred technique. It is the most frequently used method and has been shown to significantly reduce the risk of parastomal hernia (rates of 0-22% with mesh versus 44-81% without). Onlay (anterior to the fascia) and intraperitoneal placements are less common.
Mesh Type: Prosthetic (synthetic) mesh is generally favored over biologic mesh due to lower cost and available data. Biologic mesh may be considered in contaminated fields or for patients with inflammatory bowel disease, who may be at higher risk of reoperation.
VI. Ostomy Reversal and Hernia Prevention
Timing of Reversal
The timing for closing a temporary ostomy depends on the type of stoma and the resolution of the patient's underlying medical condition.
Colostomy Closure: Reversal is delayed until the patient has fully recovered, and inflammation has subsided, which can take three months or more. Closure of a diverting loop colostomy may be performed within six to eight weeks if the distal anastomosis is healed.
Ileostomy Closure: Typically performed between eight weeks and three months after the initial procedure. Studies on early closure (8 to 17 days) found it reduced postoperative ileus but increased surgical site infection rates compared to late closure (after 57 days).
Hernia Prevention at the Reversal Site
An incisional hernia at the former stoma site is a common complication, occurring in approximately one-third of patients, with half of those requiring surgical repair.
Prophylactic Mesh at Closure: There is growing evidence to support placing mesh during ostomy reversal to prevent hernia formation.
The ROCSS multicenter trial found that reinforcing the abdominal wall with a biologic mesh at the time of stoma closure significantly reduced clinically detectable hernias at two years (12% versus 20%) without increasing complications.
A 2019 systematic review and meta-analysis also supported prophylactic mesh placement, associating it with lower rates of surgical site incisional hernia (7.8% versus 18.1%) and reoperations (8.1% versus 12.1%).
Recommendation: Evidence supports placing either synthetic or biologic mesh at the time of reversal to reduce the risk of incisional hernia. However, caution is advised, as high-risk patients were often excluded from these trials.
