An estimated 100,000 surgical cases result in the creation of a stoma annually, of which approximately 40,000 are ileostomies.1., 2., 3. Given the truncation of the gastrointestinal (GI) tract and loss of the colon, ileocecal valve, and “ileal brake”, ileostomy patients are high risk for impaired sodium and water gastrointestinal absorption.4 Unsurprisingly, such alterations can lead to serious complications such as electrolyte derangements, dehydration, and acute kidney injury.

Though the definition of high-ileostomy output is debatable, it is typically recognized that a total ileostomy output exceeding 1.4 L per day has a potential of leading to such complications.5,6 An estimated 20–30% of ileostomy patients experience high output in the early postoperative period which imparts increases in morbidity, healthcare resource utilization, and length of inpatient stay.7., 8., 9. The goal of this article is to highlight the pathophysiology and causes of high ileostomy output and discuss management strategies to help optimize care for this vulnerable patient population.

The average gastrointestinal tract secretes approximately 9–10 L of fluid per day, which is a combination of oral intake in addition to gastric, pancreaticobiliary, and small bowel secretions. Approximately 85–90% of nutrient absorption and up to 6–7 L of fluid reabsorption occurs within the small bowel daily leaving 1.5–2 L of fluid to be reabsorbed by the colon. Thus, in the setting of an ileostomy it is reasonable to expect output ranging between 1 and 1.5 L/day in the early postoperative period before the small bowel adapts to its new anatomy.10 Such high output is less likely to be observed in patients with a colostomy, with exception of some very proximal colostomies. Generally, higher rates of ostomy output can be observed as stoma location moves proximally due to less absorptive surface area and faster small bowel transit times.

Small bowel length is highly variable, but generally averages to be around 300 cm in length in adults and roughly correlates with body size. The total amount of ileum resected affects both ostomy output as well as the adaptive capability of the remnant small bowel.11,12 Surface area losses also decrease the concentration gradient across the luminal surface, which in turn affects sodium and water balances due to disruption in cellular transport mechanisms responsible for enterocyte electrolyte reabsorption.10 The ileum also aids in reabsorption by providing a “braking” mechanism in which small intestine transit time is slowed through a neurohormonal process after meal consumption, which combined with the delayed emptying of intestinal contents into the colon by the ileocecal valve, ultimately leads to enhanced nutrient and hydration absorption within the ileum.4 Loss of this mechanism following resection and creation of an ileostomy thus can lead to faster small bowel transit times, and increased fluid losses which is proportional to the amount of ileum resected. Studies have also shown than when over 100 cm of ileum is resected, bile salt reabsorption is decreased, which lead to steatorrhea and fat malabsorption.13

The process of intestinal adaptation following surgical resection is a compensatory mechanism which involves hyperplasia of the villous mucosa, modification of gut-specific hormone levels (i.e., growth hormone, glucagon-like peptide-2, insulin-like growth factor, and epidermal growth factor), and alterations in the microbiome to improve its absorptive capacity. Though there is not a consensus definition of what constitutes a “high output” ileostomy, the proposed definition is > 1.4 L of daily output which is likely to lead to complications such as dehydration, hyponatremia, hypomagnesemia, acute kidney injury, and eventually possible malnutrition.8,14,15

In the days to weeks following surgery, prior to adaptation, ileostomy output matches the expected physiologic fluid excretion which is approximately 1–1.5 L per day. The amount of time it takes for the small bowel to adapt after surgery is variable. Adaptation can take weeks to months and can be influenced by factors such as length of small bowel resected, amount of oral intake, perioperative medications (e.g. opioids and medications that alter the renin-angiotensin-aldosterone system), and co-morbidities (age, body mass index [BMI], and diabetes).14,15 The presence of active inflammatory processes that impair mucosal healing; such as small bowel Crohn's disease, autoimmune enteropathies, radiation enteritis, or small bowel malignances (i.e. lymphoma, neuroendocrine tumors, etc.) can also impair adaptation. Other reported factors contributing to impaired intestinal adaptation in the perioperative period include alterations in the adrenal axis leading to adrenal insufficiency and reflexive gastric hyperacid secretion following intestinal resection.16., 17., 18.

Several other factors can still cause high ileostomy output even after intestinal adaptation has occurred. In addition to osmotic diarrhea secondary to dietary consumption of poorly absorbed carbohydrates, infectious etiologies such as intra-abdominal abscess, occult partial bowel obstruction, small intestine bacterial overgrowth, and infectious enteritis from either bacterial or viral processes should always be considered in the acute setting.19

Other perioperative risk factors associated with dehydration include age (>65 years old), obesity, ileal pouch anal anastomosis creation, renal insufficiency, high American Society of Anesthesiologists (ASA) class, postoperative complications, discharge to skilled nursing facility, and shortened hospital stay. Clostridioides difficile, even absent a colon, can cause a profoundly morbid enteritis which can trigger voluminous ileostomy outputs.20,21 Stool studies including a 48–72 h fecal fat content assessment can often help elucidate fat malabsorption, which can be secondary to causes such as bile salt deficiency, pancreatic exocrine insufficiency, small intestine bacterial overgrowth, or mucosal inflammation.

Partial small bowel obstruction can develop from adhesive or structuring small bowel disease and lead to hypersecretory states and high stoma outputs.22 Other mechanical causes of a high output ileostomy include entero-enteric fistulas, lymphatic obstruction, and resolving ileus (either post-operative vs. medication-induced).

Although no uniformly accepted number exists, between 600 and 1400 ml per day is “normal” ileostomy output. This definition anchors on patients’ ability to balance ileostomy output with normal oral fluid intake without supplemental hydration. Typically, ileostomy output will change over time. As oral intake increases after surgery, stoma output is expected to rise. On the other hand, higher stoma outputs would be slowly counterbalanced by adaptive increases in small bowel absorption and patients’ learned ability to manage their output with dietary and medical means.23,24

The most important part of assessing an ileostomy patient is accurate volumetric measurements of ileostomy outputs. While patients tend to recall the number of times a stoma appliance is emptied per day, this measure may be problematic since the actual volume of each emptying varies between patients. Strict input and output recording should be instituted for accurate assessment. Stoma output measurements help to identify fluctuations in stoma output and provide valuable insight into potentially intervenable issues. For example, high nocturnal stoma output may indicate a patient who is consuming too large of a meal at bedtime. In addition to total volume, the consistency of ileostomy effluent should be noted. Generally, “apple sauce” consistency ileostomy output tends to be normal whereas consistently thin watery effluent may indicate concerningly high outputs. Light green translucent ileostomy effluent may be intraluminal edema associated with a partial bowel obstruction or ileus.

Subjective symptoms such as fatigue, weakness, thirst, and muscle cramps should also be assessed when evaluating a patient with an ileostomy. Thorough evaluation of dehydration includes assessments of vital signs, skin turgor, pallor, moisture of mucous membranes, and weight. Physical exam should also include an evaluation of the stoma to assess for signs of stricture, prolapse, or peristomal herniation and should include direct visualization (without appliance). Some advocate “digitizing” the stoma by passing a lubricated finger through the stomal os to exclude a food bolus obstruction or stomal narrowing. Digitization must be performed carefully (if at all) in ileostomies since a digit can perforate the ileostomy's narrow lumen. Laboratory studies should include measuring renal function (blood urea nitrogen and creatinine), as well as serum electrolytes. Urine output can be an especially useful measure of overall hydration, while urine electrolyte measures are less reliable.25,26

Understanding a patient's oral intake is essential in elucidating causes of high ileostomy output. Ileostomy patients are generally recommended to consume 1.5–2 L of fluids daily to maintain hydration. Fluids that are high in processed sugar, non-absorbable sugar substrates, and sugar-based alcohols should be minimized. Examples of these hypertonic fluids include (but are not limited to) soda, fruit juice, ice cream, syrup, and nutritional supplementation drinks. Excessive intake of hypertonic fluids can cause shifts in the osmotic gradient leading to luminal excretion of water and increased ostomy output. Conversely, consuming over 500–1000 ml per day of hypotonic fluids such as water, coffee, tea, and alcohol can lead to shifts in sodium excretion into the small bowel lumen which can also result in high ileostomy output.27 Fluids that are isoosmolar and contain a balance of glucose-saline with a sodium concentration of at least 90 mmol/L are recommended to maintain adequate hydration for ileostomy patients. An example of this is the formula commonly referred to as “St. Mark's solution” (3.5 gm NaCl, 2.5 gm NaHCO3, 20 gm Glucose, 1 L Water). Notably, most over-the-counter sport drinks contain too much glucose or potassium, which shift these solutions more towards hypertonicity, and can exacerbate ostomy output when consumed in excess. In one randomized controlled study where new ileostomy patients were either provided with prophylactic oral rehydration solution (at least 1 L per day) or no intervention, the treatment arm had a 0% re-admission rate for high ileostomy output associated dehydration compared to a 24% re-admission rate within the control arm by 40 postoperative days.28

While there is no specific diet that is recommended for patients with an ileostomy, American Society of Parenteral and Enteral Nutrition (ASPEN) guidelines recommend that ileostomy patients receive a diet that is low in fiber and high in complex carbohydrates and protein. The recommended diet helps with overall energy requirements in addition to keeping osmolality low to help prevent increased ileostomy output.29 Absorbent foods such as bananas, white bread, pasta, rice, peanut butter, and potatoes can be very helpful in the early postoperative period following ileostomy creation. Patients are also told to avoid spicy foods. Minimization of ingestion of nuts, seeds, and fruits/vegetables with skins is often recommended to prevent fibrous food bolus blockages at the level of the stoma. Overall, keeping reasonable balance between intake of solids and fluids can also be helpful to avoid dehydration.

The recommended caloric intake in these patients is 25–30 kcal/Kg/day with 1.5–2 gs of protein per day. Vitamins (e.g. B12, folate, thiamine) and micronutrients (e.g. iron, zinc, and copper) are supplemented as needed.29,30 Using a diet recall diary can be a helpful tool to further elucidate potential dietary contributors to high ileostomy output. Per ASPEN guidelines, total parenteral nutrition (TPN) is typically not indicated in patients with ileostomies as they theoretically have sufficient absorptive capacity within the remnant small bowel provided no other small bowel has been resected. TPN does play a select role in managing high ileostomy outputs, particularly for malnourished postoperative patients who are unable to tolerate adequate caloric intake.

When dietary measures fail to keep ileostomy outputs manageable, the patient may require pharmacologic treatment to slow small bowel transit time and prevent hyperexcretion of intestinal fluids. Though low fiber intake is typically recommended in ileostomy patients, soluble fiber such as psyllium leads to increased output viscosity.31 Taken as powder or wafers, psyllium thickens ileostomy effluent by absorbing water. Psyllium is generally well tolerated by patients, although it provides only moderate decreases in ileostomy output.

Gastric hyperacid secretion following intestinal resection is a common cause of high ileostomy output, thus proton pump inhibitors (PPIs) play a significant role in decreasing ileostomy output volume. Case reports have also shown the beneficial effects with even empiric treatment of high ileostomy output with PPIs.32 We typically recommend pantoprazole 40 mg twice daily, taken at least 30 min prior to meals, for patients with high ileostomy output to reduce gastric acid hyperexcretion. To ensure maximal absorption; either liquid suspension or granule packet formulations are preferred in this population. One caveat to note is the potential for development of hypomagnesemia with PPI use, thus close monitoring of electrolytes is necessary.

If additional measures are needed, anti-motility agents such as loperamide (Imodium®) and diphenoxylate-atropine (Lomotil®) can be used. These agents are mu-opioid receptor antagonists that act by reducing small bowel transit time at the level of the bowel's myenteric plexus. This helps to increase fluid retention and aids in better absorption of electrolytes by reducing stoma output. The effectiveness of loperamide has been demonstrated in randomized controlled studies and has shown the ability to reduce ostomy output by 22–30% when using the maximum effective dose of 16 mg per day (typically divided into 4 mg four times per day)33., 34., 35. Some authors report using up to 24 mg of loperamide daily to control high ileostomy outputs (and up to 400 mg daily in some extremely refractory cases) although these doses currently exceed FDA recommended dosing.36,37 Loperamide is also straightforward to obtain by patients, as it does not require a prescription. Diphenoxylate-atropine is an effective medication for high output ileostomy, but can be associated with anticholinergic side effects in a number of patients from the atropine component.38 Medications most commonly used to prevent and treat high output ileostomies are listed in Table 1.

Since small bowel transit time increases immediately after meals, we recommend loperamide and diphenoxylate-atropine are consumed approximately 30 min before meals (three times daily) and immediately before bedtime to optimize intestinal absorption and reduce stoma output. Scheduling these medications, as opposed to using them as needed, is more effective at adequately controlling high ileostomy output. Codeine phosphate dosed between 15 and 60 mg every 4 h (maximum dose of 360 mg per day) can be added to loperamide and diphenoxylate-atropine if high ileostomy outputs persist, however codeine has a higher potential for abuse and has a less desirable side-effect profile.39 Alternatively, tincture of opium contains liquid morphine in various concentrations and can also supplement loperamide and diphenoxylate-atropine. Tincture of opium tastes extremely bitter and can be difficult for patients to dose since formulations vary in concentration. Moreover, opium tincture is currently restricted by many United States insurance plans and commercial availability of the drug has been limited by regional supply chain problems.40

Somatostatin analogues such as octreotide and larazotide work by slowing small bowel transit time and limiting the volume of gastrointestinal secretions. Their effectiveness in controlling high-ileostomy output when conventional measures have failed has been demonstrated in several case studies and placebo-controlled trials.41., 42., 43. Insurance approval for such medications can often be difficult to obtain. Moreover, this class of medications is known to cause biliary stasis, cholelithiasis, and cholecystitis and has the potential for exacerbating fat malabsorption via suppressed pancreatic enzyme production.44

Select patients with chronically high ileostomy outputs that are refractory to all other treatments can consider starting a glucagon-like peptide 2 (GLP-2) analogue such as teduglutide (Gattex®). Typically dosed at 0.05 mg/kg once daily subcutaneously, teduglutide helps increase the absorptive capacity of the remnant small bowel by causing hypertrophy of the small bowel villi, thus increasing absorptive surface area to aid fluid and nutrient absorption and reducing small bowel transit time. Teduglutide is effective for patients with less than 200 cm of remaining small bowel.45 At this time, however, teduglutide is only approved for patients that have failed conventional therapies and require TPN and/or parenteral fluids at least three times per week for longer than one year. Teduglutide is contraindicated in patients with active inflammatory bowel disease, malignancy, polyps, and bowel obstruction (including small bowel strictures). Teduglutide can cause villous hypertrophy that could potentially cause narrowing at the level of the stoma. Though the teduglutide experience in non-short bowel syndrome ileostomy patients is limited, one successful case report highlighted its use for a high output ileostomy that caused frequent hospitalizations.46

In some cases, chronically high ileostomy output is caused by mechanical issues such as intrinsic strictures, entero-enteric fistulas, adhesive bowel disease, or a parastomal hernia. Although surgery may be necessary in some cases, the surgeon should approach these situations extremely cautiously since most causes of high output ileostomy are transient and non-surgical. Surgically correctable causes of high ileostomy output are rare and work-up should first focus on the plethora of non-surgical etiologies. In special cases, when functional colon remains inside the patient with a persistently high output ileostomy, stoma reversal is the best long-term solution for appropriate patients.47., 48., 49.

Comprehensive “Ileostomy pathways” were first reported by Nagle et al. in 2012, and showed a reduction in re-admission rates for high ileostomy outputs from 15.5% to 0% in the first 7 postoperative months compared to a historical controls.50 Since the introduction of the pathway, similar programs were developed at other institutions.3,51,52 Typically, ileostomy pathways start with preoperative patient education focusing on teaching the patient stoma output goals along with dehydration recognition and treatment measures. Preoperative instruction is reinforced during the inpatient postoperative period as the patient is proctored to care for their own stoma while recording their stoma output (rather than relying on nursing). All patients receive dietary education regarding their ileostomy while bowel slowing medications are aggressively titrated on an as-needed basis. Once discharge criteria are met, ileostomy pathway patients have close outpatient follow-up with scheduled phone calls and early in-person outpatient follow-up. Several studies examining several ileostomy pathways have shown variable decreases in dehydration related re-admissions, however some studies have shown lesser impressive results.53,54

“Smart stomas” are electronically integrated stoma appliances that can measure volume and electrolyte composition of stomal affluent. These devices have been promoted as an early warning system that allows patients and their care teams to intervene before high output related dehydration is evident.54 These proprietary devices offer promise in monitoring and potentially intervening against high output ileostomies, however more studies are required before these costly devices can be universally recommended for all ileostomy patients of variable health and technology literacy.