The renal safety of bowel preparations for colonoscopy: a comparative study of oral sodium phosphate solution and polyethylene glycol

Renal impairment after ileostomy formation: a frequent event with long-term consequences

AIM

High stoma output and dehydration is common following ileostomy formation. However, the impact of this on renal function, both in the short term and after ileostomy reversal, remains poorly defined. We aimed to assess the independent impact on kidney function of an ileostomy after rectal cancer surgery and subsequent reversibility after ileostomy closure.

METHODS

This retrospective single-site cohort study identified patients undergoing rectal cancer resection from 2003 to 2017, with or without a diverting ileostomy. Renal function was calculated preoperatively, before ileostomy closure, and 6 months after ileostomy reversal (or matched times for patients without ileostomy). Demographics, oncological treatments and nephrotoxic drug prescriptions were assessed. Outcome measures were deterioration from baseline renal function and development of moderate/severe chronic kidney disease (CKD ≥ 3). Multivariate analysis was performed to assess independent risk factors for postoperative renal impairment.

RESULTS

Five hundred and eighty-three of 1213 patients had an ileostomy. Postoperative renal impairment occurred more frequently in ileostomates (9.5% absolute increase in rate of CKD ≥ 3; P < 0.0001) vs no change in patients without an ileostomy (P = 0.757). Multivariate analysis identified ileostomy formation, age, anastomotic leak and renin-angiotensin system inhibitors as independently associated with postoperative renal decline. Despite stoma closure, ileostomates remained at increased risk of progression to new or worse CKD [74/438 (16.9%)] compared to patients without an ileostomy [36/437 (8.2%), P = 0.0001, OR 2.264 (1.49-3.46)].

CONCLUSIONS

Ileostomy formation is independently associated with kidney injury, with an increased risk persisting after stoma closure. Strategies to protect against kidney injury may be important in higher risk patients (elderly, receiving renin-angiotensin system antihypertensives, or following anastomotic leakage).

Risk of Renal Injury After the Use of Polyethylene Glycol for Outpatient Colonoscopy: A Prospective Observational Study

GOAL

The goal of this study was to estimate the risk of renal injury after the use of 3-L polyethylene glycol (PEG) before outpatient colonoscopy.

BACKGROUND

Population-based studies showed that the use of PEG was associated with renal injury, but this association has not been confirmed by prospective study.

STUDY

Patients ≥40 years of age with an estimated glomerular filtration rate ≥30 mL/min were screened for enrollment. Laboratory data were collected before, during, and after the colonoscopies. Patients with a ≥30% increase in baseline serum creatinine levels were followed until a peak level was detected. Renal injury included acute renal dysfunction (ARD) and acute kidney injury (AKI), defined as a 30% to 49% increase and ≥50% increase in creatinine levels compared with the baseline, respectively.

RESULTS

A total of 1163 patients (mean age, 55.7 y) completed the study. Baseline and first postcolonoscopy laboratory data were obtained an average of 17.0 days before and 17.3 days after the colonoscopies were performed, respectively. Renal injury was identified in 32 patients; 26 patients (2.2%) had ARD, and 6 patients (0.5%) had AKI. All patients with renal injury recovered fully during follow-up. In the subgroup analysis, the use of nonsteroidal anti-inflammatory drugs (NSAIDs) before colonoscopy was statistically associated with the development of AKI (odds ratio, 6.5; 95% confidence interval, 1.2-35.5; P=0.03).

CONCLUSIONS

This prospective study showed that the use of PEG was associated with a small risk of renal injury. NSAIDs use was statistically associated with AKI in the context of colonoscopy for which PEG was used for bowel preparation.

A comparative review of use of sulphate and phosphate salts for colonoscopy preparations and their potential for nephrotoxicity

Background and study aims  Colonoscopy is a widely used diagnostic procedure which requires prior cleansing of the bowel. Many different bowel cleansing preparations have been developed, all of which have specific advantages and disadvantages. This review compares two low-volume high-osmolarity bowel cleansing preparations, oral phosphate salts and oral sulphate salts, with a particular focus on risk of nephrotoxicity. Patients and methods  An electronic search of the Medline database was performed using the search terms "(phosphates OR sulfates) AND cathartics [MeSH Term] AND kidney" restricted to humans with a cut-off date of December 31, 2016. Results  Introduction of oral phosphate salts offered the advantage of low intake volume and low risk of bowel irritation compared to previous options. However, phosphate salts have been associated with renal toxicity (acute phosphate nephropathy [APN]), thought to arise due to perturbations of calcium and phosphate homeostasis as a consequence of increases in serum phosphate. This results in high concentrations of calcium phosphate in the distal tubule and collecting ducts of the kidney, where it may precipitate. Although APN is rare, it may lead to permanent kidney damage. For this reason, phosphate salts are contraindicated in vulnerable patient groups. As an alternative to phosphate salts, oral sulphate salts have recently been introduced. Because sulphate absorption from the intestinal tract is saturable, serum sulphate concentrations increase only minimally after ingestion. Furthermore, excretion of sulphate in the kidney is not accompanied by calcium excretion and urine calcium levels are unchanged. For these theoretical reasons, use of sulphate salts as bowel cleansing solutions is not expected to lead to calcium precipitation in the nephron. Conclusions  Oral phosphate salts are no longer recommended for routine use as bowel cleansing preparations as they carry significant risk of kidney damage and a safer alternative is available in the form of oral sulphate solutions. To date, use of sulphate salts has not been associated with elevations in serum creatinine or other markers of renal impairment, nor with clinical manifestations of kidney injury. Nonetheless, experience with sulphate salts in everyday practice is limited and physicians should be vigilant in detecting potential safety issues.

Systematic review and meta-analysis: is bowel preparation still necessary in small bowel capsule endoscopy?

INTRODUCTION

Optimal bowel preparation for small bowel capsule endoscopy(SBCE) is controversial. This meta-analysis aimed to investigate the effects of laxatives in SBCE.

METHODS

A comprehensive literature search was conducted for studies investigating the use of laxatives in SBCE. The primary outcome was diagnostic yield(DY) for SB findings; secondary outcomes SB visualization quality(SBVQ) and completion rate(CR). Pooled odds ratios(ORs) with 95% confidence intervals(CIs) and number needed to treat(NNT) were calculated.

RESULTS

Forty studies (4380 patients with laxatives, 2185 without) were included. Laxative use did not improve DY of SB findings overall (OR 1.11 (95%CI 0.85-1.44)) or for significant SB findings (OR 1.10 (95%CI 0.76-1.60)). However, SBVQ improved with the use of laxatives (OR 1.60 (95%CI 1.08-2.06)), NNT 14. The OR for completed SBCE was 1.30 (95%CI 0.95-1.78). Patients given polyethylene glycol(PEG) had lower DY than sodium phosphate(NaP). SBVQ improved more with NaP (NNT 7) than PEG (NNT 53).

CONCLUSIONS

Laxatives do not significantly improve DY or CR in SBCE, but do improve SBQV. The use of laxatives may be beneficial in patients likely to have subtle findings. There are significant differences in methodology/definitions between studies, hence the need for standardized visualization scoring and recording of SBCE findings.

Optimizing bowel preparation for colonoscopy: a guide to enhance quality of visualization

Colonoscopy is an important screening and therapeutic modality for colorectal cancer. Unlike other screening tests, colonoscopy is dependent on pre-procedure bowel preparation. If the bowel preparation is poor, significant pathology may be missed. Many factors are known to improve bowel preparation. This review will highlight those factors that may optimize the bowel preparation, including choice of bowel preparation, grading or scoring of the bowel preparation, special factors that influence preparation, and diet prior to colonoscopy that affects bowel preparation. The aim of the review is to offer suggestions and guide endoscopists on how to optimize the bowel preparation for the patients undergoing colonoscopy.

Acute Phosphate Nephropathy with Diffuse Tubular Injury Despite Limited Calcium Phosphate Deposition

An 86-year-old woman developed acute kidney injury after colonoscopy. A renal biopsy showed diffuse tubular injury with minimal calcium phosphate deposits (CPDs), which were thought to be caused by an oral sodium phosphate bowel purgative before colonoscopy. According to these findings, she was diagnosed with acute phosphate nephropathy (APhN). In contrast to previous reports of diffuse tubular injury associated with tubular CPDs in APhN, this case demonstrated diffuse tubular injury despite a limited distribution of CPDs, suggesting that calcium phosphate can cause tubular injury without deposition. This case thus supports the hypothesis that urinary calcium phosphate crystals may cause tubular injury via other mechanisms, including inflammatory cytokines.

Colorectal cancer screening and surveillance in the elderly: updates and controversies

Colorectal cancer is common worldwide, and the elderly are disproportionately affected. Increasing age is a risk factor for the development of precancerous adenomas and colorectal cancer, thus raising the issue of screening and surveillance in older patients. Elderly patients are a diverse and heterogeneous group, and special considerations such as comorbid medical conditions, functional status and cognitive ability play a role in deciding on the utility of screening and surveillance. Colorectal cancer screening can be beneficial to patients, but at certain ages and under some circumstances the harm of screening outweighs the benefits. Increasing adverse events, poorer bowel preparation and more incomplete examinations are observed in older patients undergoing colonoscopy for diagnostic, screening and surveillance purposes. Decisions regarding screening, surveillance and treatment for colorectal cancer require a multidisciplinary approach that accounts not only for the patient’s age but also for their overall health, preferences and functional status. This review provides an update and examines the challenges surrounding colorectal cancer diagnosis, screening, and treatment in the elderly.

Case of inappropriate ADH syndrome: Hyponatremia due to polyethylene glycol bowel preparation

Colonoscopic screening has been reported to reduce deaths from colorectal cancer. Adequate bowel preparation is essential for this and safety is an important issue in choosing the methods. Polyethylene glycol (PEG) is regarded as a safe method for cleansing, especially compared with oral sodium phosphate. Here, we present a case of hyponatremia caused by the syndrome of inappropriate antidiuretic hormone (ADH) syndrome after PEG precolonoscopic cleansing resulting in generalized tonic-clonic seizures. A 62-year-old women had ingested PEG for precolonoscopic bowel cleansing. While waiting for the colonoscopy, she developed a stuporous mentality and generalized tonic-clonic seizures, which did not correlate with brain magnetic resonance imaging. Her serum sodium level was 113 mEq per liter and laboratory analyses were consistent with inappropriate ADH syndrome. Her thyroid and adrenal functions were normal. There were no malignancies, infections, respiratory disorders or central nervous disorders and she had no history of taking either diuretics or other medications, which might have caused inappropriate ADH syndrome. She was treated with 3% hypertonic saline and showed a complete neurological recovery as her sodium levels recovered. Follow-up visits showed the patient to have a normal sodium level without neurologic deficits. This case shows that inappropriate ADH syndrome can be caused by PEG preparation, which implies that physicians have to be aware of the possible side effects of this colonic cleansing approach and mindful of the possible ensuing symptoms.

Sodium phosphate does not increase risk for acute kidney injury after routine colonoscopy, compared with polyethylene glycol

BACKGROUND & AIMS

Oral sodium phosphate (OSP) is a common bowel purgative administered before colonoscopy; the Food and Drug Administration has warned against its use because of concerns about acute kidney injury (AKI) from the absorbed phosphate and dystrophic calcification. However, it is not clear if OSP is associated with AKI in the general population or in high-risk subgroups undergoing colonoscopy. We estimated the risk of AKI among patients undergoing a screening colonoscopy using OSP vs polyethylene glycol (PEG) for bowel cleansing in a large, US-based claims database.

METHODS

We used an insurance database to identify a cohort of patients ages 50 to 75 years who underwent screening colonoscopies as outpatients from January 2000 through November 2008 (before the Food and Drug Administration warning), receiving OSP (n = 121,266) or PEG (n = 429,430) within 30 days beforehand, without prior use of either drug. We collected data from patients for 6 months afterward to identify those who developed AKI or renal failure, or received dialysis. Adjusted and propensity score-matched hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models. We investigated the effects in subgroups with higher AKI risk (patients with chronic kidney disease, kidney stones, hypertension, or diabetes, or using antihypertensive or nonsteroidal anti-inflammatory drugs).

RESULTS

AKI occurred in 0.2% of OSP users and in 0.3% of PEG users (adjusted HR, 0.86; 95% CI, 0.75-0.99). OSP users matched well with PEG users, producing similar estimates (HR, 0.85; 95% CI, 0.72-1.01). We did not observe a consistent increase in the risk of AKI or other outcomes in any subgroups analyzed.

CONCLUSIONS

In a large database analysis, we did not associate administration of OSP before colonoscopy with increased risk of postprocedure AKI, even in high-risk clinical subgroups.

Colorectal cancer of the elderly

OPINION STATEMENT

Colorectal cancer (CRC) disproportionately affects the elderly. Older age is a strong risk factor for both the development of precancerous adenomas and CRC, thus raising the issue of screening and surveillance in older patients. However, screening and surveillance decisions in the elderly can be complex and challenging. Elderly patients are a diverse and heterogeneous group and special considerations such as co-morbid medical conditions, functional status, and cognitive ability play a role in one's decisions regarding the utility of screening and surveillance. Such considerations also play a role in factors related to screening modalities, such as colonoscopy, as well as CRC treatment options and regimens. This review addresses many of the unique factors associated with CRC of the elderly and critically examines many of the controversies and challenges surrounding CRC in older patients.

Colorectal cancer and the elderly

Colorectal cancer and precancerous adenomas disproportionately affect the elderly, necessitating the need for screening and surveillance in this group. However, screening and surveillance decisions in the elderly can be challenging. Special considerations such as comorbid medical conditions, functional status, and cognitive ability play a role in one's decisions regarding the utility of screening and surveillance as well as the success and safety of various screening modalities. This article explores the evidence for screening and surveillance in the elderly, and addresses key challenges unique to this population.

Provider acceptance, safety, and effectiveness of a computer-based decision tool for colonoscopy preparation

PURPOSE

To assess provider acceptance of recommendations by a decision tool that scans the electronic medical record and determines whether sodium phosphate may be taken. In addition, to determine decision tool effects on a composite outcome of colonoscopies canceled, rescheduled, aborted, or repeated sooner than recommended due to preparation (prep) quality; prep quality; colonoscopy duration; and patient satisfaction with and tolerance of the preparation.

METHODS

We used 4 alternating 4-week periods to compare the decision tool with usual care for outpatient colonoscopy. All decision tool decisions were reviewed in real-time by gastroenterology nurses and/or physicians. Patients completed a survey about the prep process. Endoscopists blindly rated prep quality. Colonoscopy duration and findings were recorded.

RESULTS

Of 354 persons in the decision tool group, 4 prep decisions were overridden because of patient preference or prior prep failure, but none for medical reasons. Sodium phosphate was used more frequently in the decision tool group (73% vs. 41%; P < 0.01). There was no difference between the decision tool and usual care groups in the composite outcome (26% vs. 30%, respectively; P = 0.29), acceptable prep quality (62% vs. 56%; P = 0.22), colonoscopy duration (28 vs. 30 min; P = 0.17), patient satisfaction (P = 0.38), or preparation tolerance (P = 0.37).

CONCLUSIONS

An electronic medical record-based decision tool can safely and effectively tailor the prep for colonoscopy and may improve colonoscopy efficiency and patient satisfaction.

LIMITATIONS

This study was performed at a single VA medical center and endoscopy unit, relies on the presence of relevant medical conditions and laboratory data in the electronic medical record, and had a higher than expected use of sodium phosphate during usual care.

Severe hypocalcaemia and hyperphosphataemia caused by oral sodium phosphate fleet solution in a haemodialysis patient after parathyroidectomy

We report a case with severe electrolyte disturbance after the use of oral sodium phosphate solution (OSPS). A 69-year-old patient on haemodialysis received 45 mL of OSPS for bowel preparation. He had symptomatic hypocalcaemia with a serum calcium level of 0.95 mmol/L and serum phosphate level of 4.73 mmol/L. He was treated with haemodialysis and intravenous calcium supplementation. This patient had total parathyroidectomy recently leading to the absence of parathyroid hormone response. OSPS has been reported to cause life-threatening electrolyte disturbance especially in patients with renal failure. We suggest the use of safer alternatives for bowel preparations in renal failure patients.

Colorectal cancer screening and surveillance in the elderly patient

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in the United States. Older age is associated with a rise in colorectal cancer and adenomas, necessitating the need for CRC screening in older patients. However, decisions about CRC screening and surveillance in older adults are often difficult and challenging. The decision requires an individualized assessment that incorporates factors unique to performing colonoscopy in older adults in order to weigh the risks and benefits for each patient according to their overall health and preferences. This review addresses the factors unique to colorectal cancer and performing colonoscopy in older adults that are relevant in weighing the risks and benefits of screening and surveillance in this population.

Intermediate bioelectrolyte changes after phospho-soda or polyethylene glycol precolonoscopic laxatives in a population undergoing health examinations

BACKGROUND

Colonoscopy is a common procedure for diagnosing and screening colon cancer and other bowel-related diseases. Many studies have pointed out that using phospho-soda as a bowel preparation can cause obvious electrolyte abnormalities or acute kidney injury. Nonetheless, there are few studies related to its prevalence and risk factors in the population undergoing health examinations. Our aim was to compare the biochemical and electrolyte changes after using two commonly used bowel preparation regimens in this population.

METHODS

In this retrospective study, we collected data about participants who, before a screening colonoscopy, used oral phospho-soda laxatives in 2006, and those who used polyethylene glycol-based laxatives in 2005. Several serum biochemical and electrolyte profiles were compared between the two groups. Additional risk factors of hyperphosphatemia, a well-known side effect of phospho-soda, were also derived.

RESULTS

We enrolled a total of 2270 participants (1321 in 2005; 1449 in 2006). The basic demographic data of the two groups were not statistically different. Nonetheless, between the two groups, some serum biochemical and electrolytic data differed significantly: in those using oral phospho-soda laxatives, we found a higher prevalence of hyperuricemia, hypocalcemia, hypokalemia, hypernatremia and hyperphosphatemia. Further analyses showed that using oral phospho-soda laxatives was a risk factor for hyperphosphatemia; conversely, being male was a protective factor.

CONCLUSION

Oral phospho-soda laxatives indeed influence the biochemical and electrolyte profiles of persons undergoing health examinations. One should be careful when interpreting bioelectrolytic data while using phospho-soda as a bowel preparation.

Polyethylene glycol vs. sodium phosphate for bowel preparation: a treatment arm meta-analysis of randomized controlled trials

Background

Results of meta-analyses of randomized trials comparing PEG and NaP are inconsistent and have not included trials comparing either or both preps to less traditional ones.

AIM: To perform a meta-analysis by treatment arm.

Methods

Using MEDLINE and EMBASE, we identified English-language trials published from 1990 to 2008 that included PEG and/or NaP, and aggregated them by treatment arm into: 4 liter (L) PEG; 2 L PEG; split-dose PEG; two 45 ml doses of NaP +/- adjunctive medication; and NaP tablets. We compared prep quality and the proportion completing the prep.

Results

Among 71 trials (patient N = 10,201), excellent prep quality was present in 34% (CI, 26-41%) for 4 L PEG alone; 39% (CI, 26-51%) for 2 L PEG; 37% (CI, 28-46%) for split-dose PEG; 42% (CI, 33-51%) for NaP solution; 44% (CI, 38-51%) for NaP with adjunctive meds; and 58% (CI, 49-67%) for NaP tablets. Patients receiving NaP were more likely to complete the prep (97% [CI, 96-98%] vs. 90% [CI, 87-92%] for 4L PEG alone); however, completion rates for 2L PEG (98%) and split dose PEG (95%) were similar to NaP.

Conclusions

NaP tablets resulted in better prep quality and higher completion rates compared to other regimens. In comparisons limited by sample size, split dose PEG was not statistically different from NaP solution for completion rate or prep quality.

Complications of colonoscopy: magnitude and management

Although complications of colonoscopy are rare, they are potentially serious and life threatening. In addition, less serious adverse events may occur frequently and may have an impact on a patient's willingness to undergo future procedures. This article reviews the magnitude of and risk factors for major and minor colonoscopy complications, discusses management of complications, and suggests ways to design quality improvement programs to reduce the risk of complications.

The safety of osmotically acting cathartics in colonic cleansing

Efficient cleansing of the colon before a colonoscopy or a radiological examination is essential. The osmotically acting cathartics (those given the Anatomical Therapeutic Chemical code A06AD) currently used for this purpose comprise products based on three main substances: sodium phosphate, combinations of polyethylene glycol and electrolyte lavage solutions (PEG-ELS), and magnesium citrate. All these preparations give adequate cleansing results and have similar profiles in terms of the frequency and type of mild to moderate adverse effects. However, serious adverse events, such as severe hyperphosphatemia and irreversible kidney damage owing to acute phosphate nephropathy, have been reported after use of sodium-phosphate-based products. The aim of this Review is to provide an update on the potential safety issues related to the use of osmotically acting cathartics, especially disturbances of renal function and water and electrolyte balance. The available evidence indicates that PEG-ELS-based products are the safest option. Magnesium-citrate-based, hypertonic products should be administered with caution to elderly individuals and patients who are prone to develop disturbances in water and electrolyte balance. Sodium-phosphate-based products can occasionally cause irreversible kidney damage and should not be routinely used in bowel-cleansing procedures.

Meta-analysis: randomized controlled trials of 4-L polyethylene glycol and sodium phosphate solution as bowel preparation for colonoscopy

BACKGROUND

Randomized controlled trials (RCTs) comparing polyethylene glycol (PEG) with sodium phosphate (NaP) are inconsistent.

AIM

To compare the efficacy of and tolerance to PEG vs. NaP for bowel preparation.

METHODS

We used MEDLINE and EMBASE to identify English-language RCTs published between 1990 and 2008 comparing 4-L PEG with two 45 mL doses of NaP in adults undergoing elective colonoscopy. We calculated the pooled odds ratios (ORs) for preparation quality and proportion of subjects completing the preparation.

RESULTS

From 18 trials (n = 2792), subjects receiving NaP were more likely to have an excellent or good quality preparation than those receiving PEG (82% vs. 77%; OR = 1.43; 95% CI, 1.01-2.00). Among a subgroup of 10 trials in which prep quality was reported in greater detail, there were no differences in the proportions of excellent, good, fair or poor preparation quality. Among nine trials that assessed preparation completion rates, patients receiving NaP were more likely to complete the preparation than patients receiving 4-L PEG (3.9% vs. 9.8% respectively did not complete the preparation; OR = 0.40; CI, 0.17-0.88).

CONCLUSION

Among 18 head-to-head RCTs of NaP vs. 4-L PEG, NaP was more likely to be completed and to result in an excellent or good quality preparation.

A prospective assessment of renal impairment after preparation for colonoscopy: oral sodium phosphate appears to be safe in well-hydrated subjects with normal renal status

BACKGROUND

The outcome of colonoscopy is highly dependent upon the quality of bowel cleansing prior to the procedure. Oral sodium phosphate solutions (OSPS) or preparations containing polyethylene glycol (PEG) are generally employed. However, the safety of administering OSPS prior to colonoscopy has been questioned because of the potential for renal failure.

AIM

To compare rates of renal failure after OSPS and PEG in a randomized, prospective trial and to assess the quality of colonoscopy after these two bowel preparations.

METHODS

Subjects with eGFR >or= 60 ml/min/1.73 m(2) and expressed willingness to adhere to hydration recommendations were randomized to OSPS or PEG solutions. Renal function was assessed 1 week prior to, immediately prior to, and 1 week after colonoscopy.

RESULTS

No subject had acute kidney failure after OSPS or PEG. OSPS was associated with significant increases in the serum phosphate and sodium levels and significant decreases in the calcium and potassium levels. These values returned to normal limits in all subjects by 1 week after colonoscopy. The quality of colonic cleansing was superior after OSPS than after PEG (Ottawa score 2.5 +/- 2.2 vs. 3.5 +/- 2.3, respectively, P < 0.05). The detection of one or more adenomatous polyps was higher after OSPS than after PEG.

CONCLUSIONS

Renal failure was not detected after the use of OSPS for colonoscopy preparation in subjects with recently documented normal renal function who were able to consume the required amounts of water after each dose. However, based on the number of subjects studied, the theoretical risk of this complication is still between 0 and 6.3%. Thus, it is appreciated that only a very large prospective trial would have yielded a more accurate estimate of the likelihood of renal compromise after OSPS. Despite this caveat, OSPS has advantages over PEG in terms of the adequacy of colonic visualization and the number of polyps detected.

Change in renal function after sodium phosphate preparation for screening colonoscopy

AIM: To investigate the changes in renal function at 12-24 mo in patients following sodium phosphate (NaP) preparation for screening colonoscopy.

METHODS: We carried out a retrospective study on the results from patients who received health check-up services as part of an employer-provided wellness program performed between August 2006 and May 2008 and who were followed up for 12-24 mo. Prior to screening colonoscopy, 224 patients underwent bowel cleansing with NaP (NaP group) and 113 patients with polyethylene glycol (PEG group). The control group comprised 672 age-matched patients. We compared the changes in the creatinine levels and the glomerular filtration rates (GFRs) from baseline to 12-24 mo between the NaP, PEG, and control groups using two-way repeated measured analysis of variance. In addition, multivariate linear regression analysis was performed to assess the risk factors for a decreased GFR.

RESULTS: The baseline mean serum creatinine level in the NaP, PEG, and control groups was 1.12 ± 0.15, 1.12 ± 0.16, and 1.12 ± 0.15 mg/dL, which increased to 1.15 ± 0.15, 1.15 ± 0.18, and 1.15 ± 0.15 mg/dL, respectively, after 12-24 mo. The baseline mean GFR in the NaP, PEG, and control groups was 69.0 ± 7.7, 68.9 ± 8.0, and 69.6 ± 6.7 mL/min per 1.73 m², which decreased to 66.5 ± 7.8, 66.5 ± 8.3, and 67.4 ± 6.4 mL/min per 1.73 m², respectively, after 12-24 mo. The changes in serum creatinine levels and GFRs were not significantly between the NaP, PEG, and control groups (P = 0.992 and P = 0.233, respectively). Using multivariate linear regression analysis, only the baseline GFR was associated with the change in GFR (P < 0.001). Indeed, the bowel preparations were not associated with the change in GFR (P = 0.297).

CONCLUSION: NaP bowel preparation in subjects with normal renal function was not associated with renal injury, and NaP can thus be used safely for screening colonoscopy.

Clinical trial: the efficacy and safety of routine bowel cleansing agents for elective colonoscopy in persons with spinal cord injury - a randomized prospective single-blind study

BACKGROUND

As difficulty with evacuation is a common occurrence in individuals with spinal cord injury, preparation prior to colonoscopy may be suboptimal and, perhaps, more hazardous.

AIM

To assess the safety and efficacy of bowel cleansing regimens in persons with spinal cord injury.

METHODS

Randomized, prospective, single blind study comparing polyethylene glycol (PEG), oral sodium phosphosoda (OSPS) and combination of both for colonic preparation prior to colonoscopy in subjects with spinal cord injury.

RESULTS

Thirty six subjects with eGFR > or =60 mL/min/1.73 m(2) were randomized to PEG or OSPS or PEG+OSPS. Regardless of bowel preparation employed, >73% of subjects had unacceptable colonic cleansing. No subject in the OSPS preparation group demonstrated a decrease in eGFR or an increase in serum creatinine concentration from the baseline. OSPS and PEG+OSPS preparations caused a transient change in serum potassium, phosphate and calcium concentrations, but no change in electrolytes was noted in the PEG group.

CONCLUSIONS

Neither OSPS alone, PEG alone nor their combination was sufficient to prepare adequately the bowel for colonoscopy in most patients with spinal cord injury. However, administration of OSPS and/or PEG appears to be safe in the spinal cord injury population, provided adequate hydration is provided.

Acute phosphate nephropathy

Acute phosphate nephropathy (APhN) is a clinical pathological entity characterized by acute and subsequent chronic renal failure following exposure to oral sodium phosphate (OSP) bowel purgatives. Renal biopsy findings include acute and chronic tubular injury with prominent tubular and interstitial calcium phosphate deposits. Risk factors for APhN include older age, female gender, hypertension, chronic kidney disease (CKD), and treatment with angiotensin converting enzyme inhibitors, angiotensin receptor blockers, and diuretics. The pathomechanism of APhN involves hypovolemia-induced avid proximal salt and water reabsorption, delivery of a large phosphate load to the distal nephron, and precipitation of calcium phosphate in the distal tubule and collecting duct. To date, 37 cases of biopsy-proven APhN have been reported, and epidemiologic studies have produced inconsistent results regarding the incidence of acute kidney injury (AKI) following the use of OSP purgatives. OSP solution was withdrawn from the market in December of 2008, but OSP tablets, offered by prescription only, remain available. Prevention of APhN is best achieved by avoiding OSP in high-risk patients, aggressive hydration before, during, and after OSP administration, minimizing the dose of OSP, and maintaining a minimum of a 12 h interval between OSP administrations.

Colon cleansing before colonoscopy: does oral sodium phosphate solution still make sense?

Oral sodium phosphate (NaP) solution has been withdrawn from the market in the United States but remains available for over-the-counter purchase for bowel preparation for colonoscopy in Canada. The present review summarizes recent data regarding the renal toxicity of oral NaP as well as its efficacy and tolerability relative to other preparations. Given the availability of effective alternatives to NaP solution, its use for colonoscopy preparation in Canada should be limited. Candidate patients for oral NaP solution should be assessed for eligibility and preparation instructions should adhere to the current recommendations for maximizing the safety of oral NaP.

Randomized study comparing two regimens of oral sodium phosphates solution versus low-dose polyethylene glycol and bisacodyl

PURPOSE

Low-volume bowel preparation regimens for colonoscopy are reported to improve patient acceptance and compliance. We sought to compare the bowel cleansing efficacy, tolerability, and acceptability of three low-volume regimens: an oral sodium phosphates solution 45/45 ml (NaP-45/45), a reduced-dose oral sodium phosphates solution 45/30 ml (NaP-45/30), and polyethylene glycol plus bisacodyl (PEG-2L).

RESULTS

A total of 121 patients were evaluated (mean age 55.2 +/- 8.9 years). Bowel cleansings rated as excellent and good were significantly different among the groups: NaP-45/45 = 98%, NaP-45/30 = 88%, and PEG-2L = 76% (P < 0.04). Side effects were not significantly different except for greater thirst in the NaP-45/45 group (P = 0.001) and increased vomiting in females using PEG-2L (two-tailed interaction, P < 0.10). Willingness to retake the preparation was higher among the sodium phosphates regimens (88, 95, and 73%, respectively; P = 0.019).

CONCLUSIONS

Better cleansing and willingness to retake the regimen was achieved with the oral sodium phosphates solutions than with polyethylene glycol plus bisacodyl.

Prospective Comparison of Three Bowel Preparation Regimens: Fleet Phosphosoda, Two-Liter and Four-Liter Electrolyte Lavage Solutions

In an attempt to improve patients’ tolerance for colon cleaning, three bowel preparation regimens: 90-mL Fleet phosphosoda (FPS), 2-L electrolyte lavage solution plus 20 mg oral bisacodyl, and 4-L lavage, were compared for efficacy and safety. A total of 912 patients were prospectively nonrandomized into three study groups. In Group A, 304 patients were given 45-mL Fleet phosphosoda at 9 AM and 6 PM the day before colonoscopy. In Group B, 304 patients were given four tablets of 5 mg bisacodyl at 12 PM the day before colonoscopy followed by 2 L electrolyte lavage by mouth at 6:00 PM the evening before colonoscopy. In Group C, 304 patients were given 4 L electrolyte lavage at 6:00 PM the evening before colonoscopy. All patients were kept on a clear liquid diet the day before colonoscopy. The bowel cleanliness was accessed by one colonoscopist. One registered nurse accessed the ease of the patient. In Group A (FPS), every patient finished the 90-mL Fleet phosphosoda. Colon cleanliness was 95.1 per cent. In Group B (2 L), three patients (0.6%) could not finish the laxative. Colon cleanliness was 95.9 per cent. In Group C (4 L), 22 patients (7.3%) could not finish the laxative preparation. Colon cleanliness was 95.3 per cent. The study found these three regimens can achieve equally good results of bowel preparation; however, the small volume laxative (FPS) has been accepted favorably by patients.

Is bowel preparation before colonoscopy a risky business for the kidney?

Acute phosphate nephropathy after bowel preparation with oral sodium phosphate (OSP) for colonoscopy has emerged as an important clinical entity. In 2004, five cases of nephrocalcinosis and irreversible renal failure after bowel preparation with OSP were reported. More recently, several retrospective studies have shown that the incidence of acute kidney injury after OSP use is in the range of 1-4%, similar to the incidence of contrast nephropathy in the general population. The degree of renal failure is not generally as severe as in the first reported cases, but irreversible damage can still occur. Millions of people worldwide undergo screening colonoscopies for colon and rectal cancer after the age of 50, so careful patient selection and monitoring for possible complications is essential when OSP is used. In addition to educating patients about the possibility of renal damage, physicians should routinely watch for considerable weight loss during bowel preparation and correct the fluid deficit as needed. Carrying out a renal function panel, which includes serum phosphorus level, is prudent after colonoscopy. Alternative bowel cleansing agents are needed because calcium phosphate precipitation is inevitable after OSP use even in the normal kidney.