Overview
Definition:
A diverting loop ileostomy is a type of ostomy where a loop of the small intestine (ileum) is brought to the skin surface, incised, and everted to create a stoma
Its primary purpose is to divert fecal stream away from a distal anastomosis or diseased segment of the bowel, allowing for healing or rest
It is typically a temporary diversion
The loop is constructed such that afferent (proximal) bowel carries fecal content and efferent (distal) bowel is either left intact to continue its normal function or may be closed or tapered.
Epidemiology:
Ileostomies, including diverting loops, are performed in a significant percentage of patients undergoing colorectal surgery, particularly those with low anterior resections for rectal cancer, inflammatory bowel disease, or complex abdominal infections
Incidence varies based on surgical indications, with rates higher in emergency procedures and for procedures involving distal bowel anastomosis
Factors like patient comorbidities and surgeon experience also influence rates.
Clinical Significance:
Diverting loop ileostomies are crucial for patient management in complex gastrointestinal surgery
They significantly reduce the risk of anastomotic leak, a potentially life-threatening complication, by decompressing the distal bowel and reducing the fecal load
Effective formation and management are vital for optimal patient outcomes, minimizing morbidity, and facilitating subsequent reversal
Understanding its formation is a core competency for surgical residents preparing for DNB and NEET SS examinations.
Indications
Primary Indications:
To protect a distal anastomosis (e.g., after low anterior resection, ileal pouch-anal anastomosis)
To defunctionalize a diseased segment of bowel (e.g., severe diverticulitis, toxic megacolon, Crohn's disease flares)
To manage intra-abdominal sepsis or abscesses where distal bowel continuity is compromised
To prevent contamination from a distal bowel injury.
Specific Scenarios:
Low anterior resection with high risk of anastomotic leak
Rectal prolapse repair
Severe radiation proctitis
Perforated diverticulitis with distal contamination
Crohn's disease affecting the distal ileum and colon requiring proximal diversion.
Contraindications:
Absolute contraindications are rare, but relative ones include severe malnutrition, active intra-abdominal sepsis without source control, and extensive adhesions that prevent adequate mobilization of the ileum
Patient refusal or inability to cope with stoma care is also a consideration.
Preoperative Preparation
Patient Assessment:
Thorough medical history and physical examination
Assessment of nutritional status, hydration, and comorbidities
Evaluation of abdominal scars from previous surgeries
Discussion of the procedure, risks, benefits, and alternatives, including stoma care and potential for reversal.
Stoma Site Marking:
Crucial step to ensure optimal stoma placement
Site should be in a flat, avascular area (typically within the rectus abdominis muscle), away from bony prominences, skin folds, previous scars, and the umbilicus
Ideally marked with patient standing, sitting, and lying down to assess for changes with position
Collaboration with an enterostomal therapy nurse is highly recommended.
Bowel Preparation:
Mechanical bowel preparation (laxatives, enemas) and/or oral antibiotics are typically administered to reduce bacterial load and improve visualization during surgery
Prophylactic intravenous antibiotics are administered prior to incision.
Procedure Steps
Exploration And Mobilization:
Abdominal cavity is explored to assess the extent of disease and confirm indications
A healthy loop of ileum, typically 15-20 cm proximal to the ileocecal valve, is identified and mobilized
Adequate length is crucial for creating a tension-free stoma
The mesentery of the chosen loop is carefully examined to ensure adequate vascularity and to avoid tension on the vascular pedicle.
Loop Creation And Exteriorization:
A small enterotomy is made in the transverse mesocolon (if a transverse loop colostomy) or through the greater omentum or rectus sheath (for ileostomy) to create a path for the ileal loop
The isolated loop is then gently pulled through this opening to the pre-marked stoma site
Care is taken to avoid twisting or kinking of the bowel loop.
Stoma Formation And Closure:
The efferent limb (distal segment) is usually returned to the abdomen and either oversewn and left in situ, or if planned for immediate closure, it may be stapled
The afferent limb (proximal segment) is then opened along its antimesenteric border for a length of 3-5 cm to create the stoma
The edges of the mucosa are sutured to the skin using absorbable sutures (e.g., 3-0 or 4-0 Vicryl or PDS) to form the everted stoma
A protective stoma appliance is applied immediately.
Mesenteric Defect Closure:
The mesenteric defect or opening created for the loop is meticulously closed with sutures (e.g., 3-0 silk or permanent sutures) to prevent internal herniation, a common and serious complication
The abdomen is then closed in layers.
Postoperative Care
Stoma Management:
Regular monitoring of stoma viability (color, edema, bleeding)
Edema is expected initially and should subside
Accurate measurement of stoma output and characteristics
Appropriate stoma appliance changes and skin care to prevent peristomal skin irritation
Patient and family education on stoma care is paramount.
Fluid And Electrolyte Balance:
Ileostomies can produce significant fluid losses (up to 1-2 liters per day or more)
Intravenous fluid resuscitation and electrolyte monitoring are essential, especially in the early postoperative period
Gradual transition to oral fluids and diet is guided by stoma output and patient tolerance.
Pain Management And Monitoring:
Adequate analgesia is provided
Patients are monitored for signs of surgical site infection, bowel obstruction, anastomotic leak (if applicable), and stoma-related complications
Early mobilization is encouraged.
Nutritional Support:
Dietary adjustments are made based on tolerance
High-fiber foods may need to be introduced gradually
Nutritional supplementation may be required in cases of prolonged ileostomy output or malabsorption.
Complications
Early Complications:
Stoma ischemia or necrosis: Due to compromised blood supply
Stoma retraction: Stoma retracts below skin level, leading to leakage
Stoma stenosis: Narrowing of the stoma opening
Wound infection: Infection at the surgical site
Bleeding from the stoma site
Internal herniation: Bowel protrudes through an unrepaired mesenteric defect.
Late Complications:
Parastomal hernia: Hernia sac forms adjacent to the stoma
Adhesures and bowel obstruction: Scar tissue causing blockage
Recurrent Crohn's disease at the stoma site
Skin irritation or breakdown: Due to leakage or improper appliance use
Stoma prolapse: Eversion of the bowel loop out of the stoma
Fistula formation.
Prevention Strategies:
Meticulous stoma site selection and marking
Adequate mobilization of the ileal loop
Tension-free exteriorization and mesenteric defect closure
Careful handling of bowel and mesentery during surgery
Prompt recognition and management of stoma edema
Educating patients on avoiding heavy lifting and abdominal strain to reduce hernia risk.
Prognosis
Factors Affecting Prognosis:
The prognosis is generally good for temporary diverting loop ileostomies, as reversal is often successful
Factors influencing long-term outcomes include the underlying pathology for which the ileostomy was created, development of complications such as parastomal hernias or adhesions, and the patient's overall health status.
Outcomes With Reversal:
Successful reversal rates are high, typically over 90%, for temporary ileostomies created for low anterior resections
However, complications related to the reversal surgery itself, such as ileus or anastomotic leak, can occur
The functional outcome after reversal depends on the extent of prior bowel surgery and the health of the remaining bowel.
Follow Up:
Follow-up involves monitoring for stoma complications, signs of obstruction, and assessing readiness for reversal
Post-reversal follow-up focuses on bowel function, wound healing, and any long-term sequelae related to the initial surgery or stoma
Regular review by a surgical team and potentially an enterostomal therapist is important.
Key Points
Exam Focus:
Understand the indications for temporary diversion
Master the steps of loop ileostomy formation, including stoma site marking and mesenteric defect closure
Be aware of early and late complications, especially internal and parastomal hernias
Recognize the importance of stoma care and patient education.
Clinical Pearls:
Always use a measuring tape to assess the length of the loop needed
Ensure adequate length to avoid tension
Close the mesenteric defect meticulously to prevent internal herniation
Consider patient's body habitus and potential for weight changes when marking the stoma site
Educate patients on the difference between the afferent and efferent limbs, and the importance of pouch adherence.
Common Mistakes:
Inadequate stoma site selection leading to appliance issues or parastomal hernia
Insufficient loop length causing tension and ischemia
Incomplete closure of the mesenteric defect leading to internal herniation
Overly aggressive opening of the bowel to create a stoma, leading to excessive retraction or stenosis
Poor stoma care education resulting in peristomal skin problems.