Intestinal Segments and Urinary Diversion: Difference between revisions

*'''<span style="color:#0000ff">LSD ORGASMIC (9):</span>'''  

** '''<span style="color:#0000ff">L</span><span style="color:#ff0000">ytes'''

*** '''Factors that influence the amount of solute and type of absorption are:'''

***# '''Segment of bowel used'''

***# '''Surface area of the bowel'''

***# '''Amount of time the urine is exposed to the bowel'''

***# '''Concentration of solutes in the urine'''

***# '''Renal function'''

***# '''pH of the fluid'''

*** '''Stomach conduit'''

**** '''Electrolyte imbalances rarely occur in patients with normal renal function. However, hypochloremic, hypokalemic metabolic alkalosis''' '''can occur in patients with concomitant renal failure.'''

***** Symptoms of this include lethargy, respiratory insufficiency, seizures, and ventricular arrhythmias may occur.

***** '''Patients are usually successfully treated with an H2 blocker to reduce proton secretion by the gastric segment and rehydration.'''

*** '''Jejunal conduit'''

**** '''Hypochloremic, hyperkalemic, hyponatremic metabolic acidosis can occur.'''  

***** Symptoms of this include lethargy, nausea, vomiting, dehydration, muscle weakness, and elevated temperature.

***** '''May be exacerbated by administration of hyperalimentation solutions'''.

***** The severity of the syndrome depends on the location of the segment of jejunum that is used. The more proximal the segment, the more likely the syndrome is to develop.

***** '''Treatment is rehydration with sodium chloride and correction of the acidosis with sodium bicarbonate'''.

****** Provided that renal function is normal, the hyperkalemia is corrected by renal secretion.

****** '''A thiazide diuretic may be helpful to correct the hyperkalemia''' '''(recall side effects of thiazides: 3 hypers and 3 hypos: hyperglycemia, hyperlipidemia, and hyperuricemia with hypokalemia, hypocitraturia, and hypomagnesuria with metabolic alkalosis).'''

****** After restoration of normal electrolyte balance, long-term therapy involves oral supplements with sodium chloride and a thiazide diuretic, if needed.

*** '''Ileum or colon conduit'''

**** '''Hyperchloremic metabolic acidosis can occur.'''

***** Symptoms of this include lethargy, easy fatigability, anorexia, weight loss, and polydipsia.

***** '''The mechanism of hyperchloremic metabolic acidosis is a result of the ionized transport of ammonium'''

**** '''Treatment involves alkalizing agents or blockers of chloride transport.'''

***** '''≈16% of patients with ileal conduits will develop metabolic acidosis requiring treatment.'''

***** '''Alkalinization with oral sodium bicarbonate is effective in restoring normal acid-base balance.'''

***** '''Potassium citrate, sodium citrate, and citric acid solution (Polycitra) may be used instead if excessive sodium administration is a problem because of cardiac or renal disease and if potassium supplementation is desirable or at least not harmful.'''

*** '''Hypokalemia and total-body depletion of potassium may occur''' in patients with urinary intestinal diversion [though hyperkalemia with jejunal conduit].

**** '''More common in patients with ureterosigmoidostomies'''

**** '''In treating these patients, if the hypokalemia is associated with severe hyperchloremic metabolic acidosis, treatment must involve both replacement of potassium and correction of the acidosis with bicarbonate'''

** '''<span style="color:#ff0000">Altered </span><span style="color:#0000ff">S</span><span style="color:#ff0000">ensorium'''

*** '''May occur as a consequence of magnesium deficiency, drug intoxication, or abnormalities in ammonia metabolism'''

*** '''Ammoniagenic coma in patients with urinary intestinal diversion is most commonly associated with decreased liver function.'''

**** '''Ammonium excreted by the kidneys is reabsorbed by the intestinal segment,''' and then returned to the liver via the portal circulation. The liver metabolizes ammonium to urea via the ornithine cycle.

**** '''The liver usually adapts to the excess ammonia and rapidly metabolizes it; hepatic dysfunctionmay therefore result in ammoniagenic coma.'''

***** Ammoniagenic coma can occur in patients with normal hepatic function.

****** Systemic bacteremia, with endotoxin production, inhibits hepatic function and may precipitate this clinical entity. Urinary tract infections with urea-splitting organisms may also overload the ability of the liver to clear the ammonia.

****** If this syndrome occurs in a patient suspected of having near normal hepatic function, systemic bacteremia or urinary obstruction should be suspected.

**** '''Prompt urinary drainage''' with treatment of the offending urinary pathogens along with systemic antibiotics '''and the administration of oral neomycin or lactulose to reduce absorption of ammonia in the gastrointestinal tract are the key components to patient management.'''

** '''<span style="color:#ff0000">Abnormal </span><span style="color:#0000ff">D</span><span style="color:#ff0000">rug metabolism'''

*** '''Drug intoxication can occur in patients with urinary intestinal diversion. Drugs more likely to be problematic are those absorbed by the gastrointestinal tract and excreted unchanged by the kidney.''' Thus, the excreted drug is re-exposed to the intestinal segment, which then reabsorbs it, and toxic serum levels develop. '''This has been reported with phenytoin, methotrexate, lithium and theophylline.'''

*** Patients receiving chemotherapy who have intestine interposed in the urinary tract have increased toxic effects of chemotherapeutic agents. '''Although chemotherapy is usually well tolerated by patients with conduits, toxicity has been documented in a patient with an ileal conduit.'''

**** In patients with continent diversions who are receiving chemotherapy, consideration should be given to draining the pouch while the toxic drugs are being administered.

** '''<span style="color:#0000ff">O</span><span style="color:#ff0000">steomalacia'''

*** Osteomalacia or renal rickets occurs when mineralized bone is reduced and the osteoid component becomes excessive.

*** Osteomalacia in urinary intestinal diversion may be caused by:

**** Persistent acidosis

**** Vitamin D resistance

**** Excessive calcium loss by the kidney

*** Treatment involves correction of the acidosis and dietary supplementation of calcium

*** '''Patients who develop osteomalacia report lethargy, joint pain, especially in the weight-bearing joints, and proximal myopathy'''

** '''<span style="color:#0000ff">R</span><span style="color:#ff0000">enal function deterioration'''

*** '''≈20% of patients experience significant and progressive renal function deterioration independent of the type of urinary diversion'''

**** '''Incidence for both sepsis and renal failure are greater in patients with ureterosigmoidostomy than in those with conduits'''

***** '''Most common cause of death in patients with ureterosigmoidostomy for > 15 years is acquired renal disease'''

*** '''Renal function necessary for urinary intestinal diversion'''

**** The amount of renal function required to effectively blunt the reabsorption of urinary solutes by the intestinal segment and to prevent serious metabolic side effects '''depends on the type of urinary intestinal diversion constructed (i.e., the amount of bowel to be used and the length of time the urine is exposed to the intestinal mucosa).'''

***** '''A greater degree of renal function is necessary for continent diversions than for short conduit diversions.'''

**** '''eGFR cut-off for continent diversion''' varies by source:

***** Chapter 97: > 40ml/min

***** Chapter 99: >35 – 40 mL/min

***** '''2019 AUA MIBC Guidelines: > 45 mL/min'''

****** '''A patient with serum creatinine > 2 mg/dL (177 µmol/L) may be considered for a continent diversion if:'''

******# '''Able to achieve a urine ≤ pH of 5.8 after an ammonium chloride load'''

******# '''Able to achieve urine osmolality ≥ 600 mOsm/kg in response to water deprivation'''

******# '''GFR > 35 mL/min'''

******# '''Minimal protein in the urine'''

*** '''Because urea and creatinine are reabsorbed by both the ileum and the colon, serum concentrations of urea and creatinine do not necessarily accurately reflect renal function'''

**** '''Fractional excretion of sodium most accurately measures renal function in a patient with a urinary diversion.'''

** '''<span style="color:#0000ff">G</span><span style="color:#ff0000">rowth retardation'''

*** Conduits have detrimental effect on linear growth and development. Patients are more susceptible to fractures and to complications after orthopedic procedures.

** '''<span style="color:#0000ff">A</span><span style="color:#ff0000">cidosis/</span><span style="color:#0000ff">A</span><span style="color:#ff0000">lkalosis'''

*** '''The ability to establish a hyperchloremic metabolic acidosis appears to be retained by most segments of ileum and colon over time.'''

** '''<span style="color:#0000ff">S</span><span style="color:#ff0000">tones'''

*** '''Risk factors for stone formation with urinary diversion'''

***# Persistent infection, associated with the development of '''magnesium ammonium phosphate stones.'''

***# Foreign body such as a staple or nonabsorbable suture, on which concretions form

***# Alterations in bowel mucosa may also serve as a nidus for stone formation

***# Alterations in intestinal mucus, particularly in the presence of infection or obstruction, may serve as a nidus or, more important, may interfere with emptying and thereby exacerbate infection and stone formation

** '''<span style="color:#0000ff">M</span><span style="color:#ff0000">alabsorption'''

*** '''In patients with a significant loss of ileum, there can be malabsorption of'''

***# '''Vitamin B12 resulting in anemia and neurologic abnormalities'''

***#* '''Since the liver stores enough vitamin B12 to supply the body’s requirement for 3-5 years without oral intake''', pathologic problems would not be expected to manifest themselves for many years

***# '''Bile salts resulting in''' mucosal irritation and '''diarrhea''' because the ileum is the major site of bile salt reabsorption.

***#* '''There are 3 mechanisms of diarrhea in a patient with ileal conduit:'''

***#*# '''Malabsorption of bile salts''' since the ileum is the major site of bile salt reabsorption

***#*# '''Malabsorption of fat''' from loss of “ileal break" and small intestinal bacterial overgrowth from loss of ileocecal valve

***#*## The ileal break is a mechanism whereby gut motility is reduced when lipids come in contact with the ileal mucosa so that increased absorption can occur. With the loss of ileum, the lipid does not result in decreased motility and is presented unmetabolized to the colon, which may cause '''fatty diarrhea.'''

***#*# '''Loss of ileocecal valve'''

***#*#* '''May result in reflux of large concentrations of bacteria into the ileum,''' resulting in small intestinal bacterial overgrowth which may cause nutritional abnormalities that involve '''interference with fatty acid reabsorption and bile salt interaction.'''

***#** '''With the lack of absorption of fats and bile salts, these are presented to the colon and result in diarrhea.'''

*** '''Loss of a significant portion of jejunum may result in malabsorption of fat, calcium, and folic acid'''

*** '''Loss of the colon may result in diarrhea because of lack of fluid and electrolyte absorption, loss of bicarbonate'''

** '''<span style="color:#0000ff">I</span><span style="color:#ff0000">nfections'''

*** An increased incidence of bacteriuria, bacteremia, and septic episodes occurs in patients with bowel interposition.

*** '''≈75% of ileal conduit urine specimens are infected.''' Many of these patients, however, show no untoward effects and seem to do well with chronic bacteriuria.

**** Deterioration of the upper tracts is more likely when the culture becomes dominant for Proteus or Pseudomonas. '''Thus patients with relatively pure cultures of Proteus or Pseudomonas should be treated, whereas those with mixed cultures may, in general, be observed, provided they are not symptomatic.'''

*** '''Pouchitis'''

**** '''Not uncommon, especially in the early postoperative period when mucous accumulation can be high.'''

**** '''A simple program of mechanical irrigation can decrease the incidence of infections, though asymptomatic colonization may not decrease'''

*** '''Pyocystis'''

**** '''Ooccurs in ≈20% of patients who undergo supravesical diversion.'''

**** '''Patients typically have a malodorous discharge and may develop sepsis.'''

**** '''If conservative measures, such as routine bladder irrigations fail, vaginal vesicostomy (creation of a large vesico-vaginal fistula), is an effective method of preventing pyocystis in women. This is an especially good alternative for an elderly or high risk patient. Cystectomy is an effective treatment for pyocystis and would likely be required if the patient was a male'''

** '''<span style="color:#0000ff">C</span><span style="color:#ff0000">ancer'''

*** '''Bladder cancer after augmentation presents:'''

**** '''At a younger age''' than is typical for bladder malignancies

**** '''With atypical symptoms''' such as vague abdominal pain, urosepsis or increased frequency of urinary tract infection (UTI), difficult catheterization, and renal failure.

**** '''With atypical signs''' such as new hydronephrosis and bladder wall thickening.

**** '''Advanced disease'''

**** '''Usually with a minimum 10-year lag time between augmentation and presentation of bladder malignancy.'''

**** '''Most of the tumors are adenocarcinomas,''' but can also be adenomatous polyps, sarcomas, and urothelial carcinoma

*** The incidence of cancer development in patients with ureterosigmoidostomy varies between 6-29%, mean 11%. '''Because its incidence is significant in patients with ureterosigmoidostomies, they should have routine colonoscopies on a scheduled periodic basis.''' Case reports of tumors developing in patients with ileal conduits, colon conduits, bladder augmentations, rectal bladder, neobladders, and ileal ureters have been described. '''When ureterointestinal anastomoses are defunctionalized, there remains a risk of adenocarcinoma in the defunctionalized diversion. Therefore, they should be excised rather than merely ligated and left in situ'''

* '''False-positive pregnancy test'''

** '''Male and female patients with urinary diverison can have false positive urinary pregnancy tests,''' possibly due to the mucous produced§

* Ruptured augmented bladder

** Up to 50% of cystogram studies in cases of a ruptured augmented bladder may be negative for the injury; therefore, a negative cystogram does not rule out a bladder rupture.

** Confirmation of suspected perforation of an augmented bladder is best achieved by performing a CT cystogram with a minimum of 300 ml of contrast placed in the bladder with a CT phase taken with the bladder distended and emptied.

** '''Volume-pressure considerations'''

*** '''By splitting most segments, the volume increases by ≈50%.''' The goal in reconfiguring the bowel is to achieve a spheric storage vessel. This configuration has the most volume for the least surface area.

*** '''Over time, the volume capacity of segments increases'''. This occurs only if they are frequently filled. Their volume decreases with time if they are nonfunctional

** '''Motor activity'''

*** It has been suggested that splitting the bowel on its antimesenteric border discoordinates motor activity and thereby causes a lesser intraluminal pressure. However, the literature is contradictory with respect to the effect of detubularization on segments of ileum and colon used to construct storage vessels for continent diversions.

*** Thus, '''reconfiguring bowel usually increases the volume, but its long-term effect on motor activity and wall tension is unclear at this time'''. Some patients with orthotopic bladders after a number of years of spontaneous voiding require intermittent catheterization. In these patients the bowel segment has become flaccid, and the ability of the patient to generate intraluminal pressure by a Valsalva maneuver is limited.