Ileostomy
Executive Summary
An ileostomy is a surgical procedure that creates an opening (stoma) by bringing the ileum, a part of the small intestine, through the abdominal wall. Its primary purpose is to divert stool from its usual route, allowing it to be evacuated from the body directly from the small bowel. Ileostomies can be temporary or permanent and are categorized as either a loop or an end ileostomy, depending on the clinical indication. Key reasons for the procedure include protecting a distal bowel anastomosis after surgery, managing conditions requiring the removal of the entire colon (such as colorectal cancer or inflammatory bowel disease), and relieving bowel obstructions.
While there are no absolute contraindications, factors like a short mesentery or extensive carcinomatosis can present relative challenges. The surgical technique is meticulous, emphasizing proper pre-operative site marking through the rectus abdominis muscle to prevent future hernias and ensure patient accessibility. Post-operative management is critical, with a high incidence of potential complications (affecting up to 20% of patients) ranging from stoma ischemia and stenosis to high-output dehydration and electrolyte imbalances. Successful patient outcomes hinge on a coordinated, interprofessional team approach, with surgeons, stoma nurses, and mental health consultants playing vital roles in procedural execution, patient education, and psychological support.
I. Definition and Purpose of Ileostomy
An ileostomy is a surgically-created opening, known as a stoma, where the lumen of the ileum (the final section of the small intestine) is brought through the anterior abdominal wall. This procedure reroutes the gastrointestinal tract, allowing stool to be evacuated directly from the ileum into an external appliance (stoma bag), thereby bypassing the colon and anus.
Key Characteristics:
Location: Typically formed on the right side of the abdomen.
Output: The effluent is consistent with small bowel content—loose or porridge-like, as it has not passed through the large bowel where water is absorbed to solidify stool.
Volume: Daily output typically ranges from 200 to 700 ml.
The procedure is considered a life-saving or life-improving adjunct to major surgery, enabling patients to maintain their usual activities of daily living.
II. Types of Ileostomy
Ileostomies are broadly classified by their construction and intended duration.
Loop Ileostomy
A loop ileostomy is created by bringing a loop of the distal ileum out to the skin. It is characterized by two lumens opening into the stoma bag.
Proximal Limb: The active, functioning opening that evacuates stool.
Distal Limb: Acts as a mucous fistula, draining secretions from the inactive portion of the bowel. It does not decompress the colon if the ileocecal valve is competent.
Purpose: Primarily used as a temporary measure to divert the fecal stream and protect a newly created distal anastomosis (e.g., after a segmental colonic resection) from contamination, reducing the risk of an anastomotic leak.
Duration: It is typically reversed 3 to 6 months later to restore bowel continuity once the distal anastomosis has healed. A stoma rod is often used for support during creation.
End Ileostomy
An end ileostomy is formed when the proximal end of the ileum is brought through the abdominal wall, with no distal bowel segment attached.
Construction: There is only one functioning lumen.
Purpose: This type is usually permanent and is performed following the complete removal of the colon (colectomy).
III. Clinical Rationale
Indications
The primary goal of an ileostomy is to divert stool away from the colon. Specific indications include:
Protecting a Distal Anastomosis: To defunction the bowel and reduce the risk of leakage at a downstream surgical connection.
Post-Colectomy Management: To provide a means of stool evacuation after the entire colon has been removed due to conditions such as:
Colorectal cancer
Crohn’s disease
Ulcerative colitis
Familial adenomatous polyposis
Relief of Bowel Obstruction: To decompress the bowel proximal to an obstruction.
Contraindications
There are no absolute contraindications to forming an ileostomy. However, relative contraindications and technical challenges include:
Short Mesentery: Prevents the ileum from reaching the abdominal wall without tension, a condition more common in obese patients.
Carcinomatosis: Widespread cancer that can prevent full mobilization of the ileum.
IV. Surgical Procedure: Creation
The creation of an ileostomy is a detailed process involving careful pre-operative planning and precise surgical technique.
Pre-Operative Preparation
Preparation involves both physical and psychological elements, with stoma nurses playing an invaluable role.
Patient Counseling: The surgeon and stoma nurses discuss the procedure, its implications, and stoma management. Psychological support is critical, and a mental health consultation may be beneficial.
Stoma Site Marking: This is a crucial step performed pre-operatively while the patient is awake in both sitting and supine positions. The ideal site is:
Through the rectus abdominis muscle to reduce parastomal hernia risk.
On the right side, at the lateral edge of the rectus muscle.
Visible and easily accessible to the patient.
Away from skin creases, scars, bony prominences (costal margin, iliac crest), the umbilicus, and belt lines.
Physical Preparation: May include shaving the abdomen, weight loss for elective patients to reduce tension on the mesentery, and optimizing diabetic control to improve wound healing.
Surgical Technique
Trephine Incision: A circular opening is created at the marked site.
A 2.5 to 3 cm circle of skin is excised.
Dissection proceeds through subcutaneous fat to the anterior rectus sheath.
A cruciate (cross-shaped) incision is made in the anterior sheath, and the rectus muscle fibers are split or retracted, taking care to avoid the epigastric vessels.
Another cruciate incision is made in the posterior sheath and peritoneum.
The defect is stretched to accommodate two fingers, ensuring enough room for the bowel.
Exteriorization of the Ileum: The selected segment of terminal ileum is passed through the trephine. The loop must be tension-free with an adequate blood supply.
Stoma Maturation (Loop Ileostomy):
A stoma rod is inserted through a mesenteric window to support the loop.
A transverse incision is made on the distal (efferent) limb.
The proximal (afferent) limb is everted using a Langenbeck retractor to create a "spout" that protrudes approximately 5 cm above the skin. This directs effluent away from the skin.
The stoma is matured in a "Brooke fashion" by placing sutures that take a full-thickness bite of the ileum edge, a seromuscular bite of the ileum at skin level, and a dermal bite to secure the everted bowel to the skin.
Stoma Maturation (End Ileostomy):
The stapled end of the ileum is brought through the trephine.
The staple line is excised.
The lumen is opened and matured circumferentially in the Brooke fashion to create a spout.
Common practice is to close any primary abdominal wounds before maturing the stoma to prevent fecal contamination.
V. Surgical Procedure: Closure (Reversal)
The closure of a loop ileostomy is performed to restore bowel continuity.
Procedural Steps:
Incision: A circular or diamond-shaped incision is made along the mucocutaneous junction of the stoma.
Dissection: The surgeon dissects through subcutaneous tissue and fascia, freeing the ileal loops from adhesions to the surrounding tissue. The loops are gently extracted from the peritoneal cavity.
Resection: The mucocutaneous junction and any fibrotic or nonviable tissue at the edges of the stoma are excised.
Reconstruction: An antiperistaltic, side-to-side anastomosis is created by stapling the antimesenteric sides of the ileum together with a linear stapler. The remaining enterotomies are then transected with the stapler.
Closure: The reconstructed bowel is returned to the peritoneal cavity. The fascial defect is closed with long-lasting absorbable sutures, and the skin is closed.
VI. Equipment and Patient Supplies
Surgical Instruments
A specific set of instruments is required for both creation and closure procedures.
Post-Operative Patient Supplies
Ongoing patient care requires specialized ostomy supplies for managing stoma output.
Stoma Bags/Pouches: Appliances that adhere to the skin around the stoma to collect effluent. Different designs exist, including pouches with a round tip for liquid stool (ileostomy) and a square tip for more formed stool (colostomy), as depicted in source imagery.
Adhesive Products: Sprays, powders, pastes, and rings to enhance the seal and protect the skin.
Maintenance Items: Adhesive removal spray, wet wipes, and waste disposal bags.
VII. Complications
Complications following stoma creation are experienced by approximately 20% of patients and can be classified as immediate, early, or late.
High output from an ileostomy can lead to significant fluid loss, causing dehydration and electrolyte disturbances, which requires careful monitoring, especially in patients with pre-existing renal impairment.
