Continent Catheterizable Reservoir Made From Ileum
MOHAMED A. GHONEIM
A substantial number of techniques have been described for the creation of continent cutaneous urinary reservoirs. For construction of such systems, three elements are required: a low-pressure compliant reservoir, an antirefluxive ureterointestinal anastomosis, and a continent stoma that allows easy catheterization.
To create a reservoir with high capacity at low pressure, various segments of bowel have been utilized: the ileum, the ileocolonic region, the ascending colon, and the transverse colon. Regardless of the selected bowel segment, detubularization and double folding are basic prerequisites to achieve this goal.
A reliable antirefluxive ureterointestinal anastomosis is necessary, since bacteriuria is a constant feature in these systems and results from intermittent catheterization. The technique employed should provide a unidirectional but nonobstructed flow. The antirefluxing mechanism should not be at the expense of a higher incidence of obstructive complications.
Hinman (1) classified continent outlets into four categories according to the mechanism of their action. These included an antiperistaltic ileal segment (2); imbricated or tapered ileal segments resulting in passive tubular resistance (3); outlets using the pressure equilibration principle, including an ileal spout valve (4), flutter valve (5), inkwell hydraulic valve, intussusception nipple (6), or ileal servomechanism sphincter (7); and flap valves, which are created by the incorporation of tubular structures within the wall of the reservoir, such as the appendix (8), fallopian tubes (9), parts of ileum (10), or tubularized cecal segments (11). Multiplicity of techniques implies that none is optimal. Many of the previously mentioned techniques rely on an inert or even unphysiologic mechanism, and problems and malfunctions soon appear.
INDICATIONS FOR SURGERY
Any patient who requires bladder replacement is a potential candidate for this operation. The indications of continent cutaneous urinary diversion include the following:
Pelvic malignancies: in patients for whom cystectomy is indicated for bladder cancer or those requiring an anterior pelvic exenteration for other pelvic malignancies
Benign indications: These include neuropathic bladders when conservative measures fail, extensive urethral strictures with damaged urethral sphincter, contracted bladders with compromised urinary continence, complex urinary fistulas affecting the sphincteric mechanism, and some cases of bladder exstrophy with failed attempts of primary repair.
Urinary conversion: conversion from other types of urinary diversion, such as ileal conduits in young healthy patients, for patients who develop isolated urethral recurrence following radical cystectomy and orthotopic bladder substitution, and in some cases of ureterosigmoidostomy suffering from intractable metabolic acidosis
PATIENT SELECTION AND EVALUATION
Suitable candidates should have reasonable manual dexterity. Motivation to carry out clean intermittent catheterization at regular intervals is necessary. Furthermore, a good prognosis might be expected if the indication to diversion was a pelvic malignancy. Patients who are unfit for prolonged surgery and those with a history of previous bowel resection, short bowel syndrome, or heavily irradiated bowel are among the contraindications for this procedure. Patients with impaired renal function (serum creatinine equal to or >1.8 mg per dL and/or creatinine clearance equal to or <40 mL per minute) are unsuitable candidates since metabolic acidosis would be inevitable.
Alternative techniques of urinary diversion should be discussed with the patient when orthotopic bladder substitution or continent cutaneous reservoirs are contraindicated or unfeasible. These include conduit diversion and anal sphincter-controlled bladder substitutes. The potential postoperative complications, changes in future lifestyle, and long-term sequelae should be clearly explained to the patients.
Since the small bowel is utilized, no specific preparation is necessary. The only requirement is fasting overnight with administration of intravenous fluids to ensure good hydration. Patients with histories of thromboembolic disease or varicose veins should receive a prophylactic dose of heparin (5,000 U subcutaneously) the night before the operation and every 12 hours thereafter until ambulation. Compression leg stockings are also advised. Although the intention is to use a concealed umbilical stoma, a stoma therapist should examine the patient and determine a suitable site for an abdominal stoma. A parenteral broad-spectrum antibiotic is given just before induction of anesthesia and continued postoperatively for 3 days.
The patient is put in the supine position with a Trendelenburg tilt. Slight flexion of the knees will further help in the relaxation of the abdominal muscles, facilitate retraction, and provide wider exposure. If total urethrectomy is planned, the patient is put in a slight lithotomy position for access to the perineum. The surgical area to be sterilized and draped extends from the lower chest down to the upper thighs.