Alimentary Pharmacology & Therapeutics Systematic review: the adverse effects of sodium phosphate enema J. MENDOZA, J. LEGIDO, S. RUBIO & J. P. GISBERT Department of Gastroenterology, Hospital Universitario de La Princesa, Madrid, Spain Correspondence to: Dr J. P. Gisbert, Playa de Mojacar 29, Urb, Bonanza, 28669 Boadilla del Monte, Madrid, Spain. E-mail: gisbert@meditex.es Publication data Submitted 21 March 2007 First decision 13 April 2007 Resubmitted 18 April 2007 Accepted 18 April 2007 SUMMARY Background Sodium-phosphate enemas are widely used to treat constipation, and are rarely associated with side effects. Aim A systematic review of the literature was conducted to identify the most common adverse effects of sodium-phosphate enemas and associated risk factors. Methods A systematic search was conducted in Internet (MEDLINE), and the Cochrane Library, from January 1957 to March 2007. Results A total of 761 references were identified initially, and 39 relevant papers were finally selected. The most common therapeutic indications included constipation (63%). Sixty-eight per cent of the patients having adverse effects had associated conditions, the most common being gastrointestinal motility disorders, cardiological diseases and renal failure. Virtually, all side effects were due to water and electrolyte disturbances. Most patients were under 18 years of age (66%) or older than 65 years (25%). A total of 12 deaths were found. Conclusion The main side effects caused by sodium phosphate enemas are water and electrolyte disturbances. The main risk factors are extreme age and associated comorbidity. Aliment Pharmacol Ther 26, 9–20 ª 2007 The Authors Journal compilation ª 2007 Blackwell Publishing Ltd doi:10.1111/j.1365-2036.2007.03354.x 9 10 J . M E N D O Z A et al. INTRODUCTION Monosodium or disodium phosphate enemas are used for the treatment of acute and chronic constipation, and also for colon cleaning as preparation for endoscopic and surgical procedures, in both children and adults.1–3 Phosphate enemas contain sodium acid phosphate and sodium phosphate, which have an osmotic activity. This activity could increase the water content and the volume of the stool, which will follow to a rectal distension. It is thought that this induces defecation with stimulation of rectal motility. Generally, the effect is limited to 5–10 min, which lowers the effect of phosphate toxicity as it is evacuated with the stool. These products have been widely used for many years, and have been associated with minimal adverse effects in the general population. However, there are reports in the literature of some clinical cases with severe side effects, even leading to death. If defecation does not take place, pooling of the fluid in the bowel can result in large amounts of water in the gut, causing dehydration. On the other hand, if phosphate is retained in the gut lumen can potentially be absorbed, and sudden and severe hypernatraemia and hyperphosphataemia may result.4 Manufacturers propose a careful use of the product in young children (<2 years) and in the elderly population, specially if associated comorbidity as renal disease or impaired intestinal motility exists. Nevertheless, there is a lack of information of the real risk of phosphate enemas. We therefore considered it necessary to conduct a systematic review to know what are exactly the most common side effects, their frequency, their severity and the profile of patients with a high risk of experiencing such complications. METHODS We performed a literature search in Internet in the MEDLINE database (from January 1957 to March 2007). The clinical trials register (Cochrane Controlled Trials Register) of the Cochrane Library (number 1, 2007) was also reviewed. The following descriptors or key words were used (in all search fields): ‘phosphate enema or sodium phosphate enema’ or ‘phosphatebased enema’ or (phosphate AND enema) or (fleet AND enema) or ‘sodium phosphate laxatives’ or ‘sodium phosphate catharsis’ or ‘sodium phosphate cathartic’. No restriction by language or by type of publication was introduced. Literature references included in the papers meeting the selection criteria were also reviewed. We selected the articles referring to secondary effects because of the administration of phosphatebased enemas. Data from the articles about anorectal or traumatic injuries were not examined because of the different ethiopathological approach. To analyse the results, we performed a subanalysis according to the age criteria of the manufacturer’s recommendations (children under 2 years, children under 18 years, adults and elderly (above 65 years), to perform a more comprehensive analysis. In articles evaluating the side effects of sodium phosphate enemas, data were collected on the number of patients, sex, age, comorbidity, indication for use, number of units administered, deaths and their cause when they were due to use of enemas. Data extraction was conducted by two independent reviewers and discrepancies in the interpretation were resolved by consensus. RESULTS The search conducted initially identified a total of 773 literature references. After a first selection by reading their abstracts, 707 references were discarded; most of these (553) did not refer to the question in hand. A further large group (146 references) was discarded because they addressed about sodium phosphate cleaning solutions administered by the oral route. Finally, 20 articles on sodium phosphate enemas were not included because their side effects were not reported.5–23 The remaining 54 articles were comprehensively analysed. Eleven of these were clinical trials, and seven of such trials compared several cleaning methods for performing endoscopy (sodium phosphate enemas, oral laxative sachets) and secondarily analysed adverse effects.2, 3, 24–27 The remaining four clinical trials evaluated water and electrolyte disturbances after enema administration.28–31 Of the remaining 43 references, we found conclusive data in 39 references, all of them case reports and letters to the editor.32–70 We also found four references to enema-induced anorectal injuries.71–74 All the cases revealed a damage in the anorectal tissue, mainly because of a harmful application. Because of the differential cause of damage, these cases were not considered as adverse effects ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd S Y S T E M A T I C R E V I E W : A D V E R S E E F F E C T S O F S O D I U M P H O S P H A T E E N E M A 11 but as a consequence of a harmful application and they were not considered in the review. Out of these 39 references,32–70 the occurrence of side effects after administration of sodium phosphate enemas was reported in 44 patients. Twenty-two of these patients (50%) were women and 22 men (50%). Mean age of patients was 26 years (range, 6 weeks to 96 years). Therapeutic indications Therapeutic indications included constipation in 28 patients (64%)33, 37–39, 41, 42, 44–50, 52, 54–70 and preparation for diagnostic test (barium enema or colonoscopy) or surgery in six patients (14%).32, 36, 39, 57, 64, 69 No mention was made of the indication in all other cases (10 patients, 23%).34, 35, 38, 40, 43, 51, 53 Units administered Units administered were difficult to assess, as dosage was not given for all patients. Dosage was stated in a total of 40 cases32, 33, 35–44, 46–56, 58–70 (91%), but many of these data were incomplete or inadequate (not exact dosage, type of enema or frequency of administration). The exact dosage and frequency when it was given are in Tables 1–5. The maximum number of enemas received by a patient was 8,62 but the time interval over which they were administered was not stated. The maximum frequency found in all analysed studies was six enemas over 6 h.69 Comorbidity Regarding past medical history, 38 patients (86%) had prior diseases,33, 36–44, 46, 47, 49–70 as summarized below. The most common associated diseases were gastrointestinal conditions, found in a total of 18 patients (41%), the most frequent was Hirschprung disease was reported in six cases.40, 44, 59 Neurological diseases were reported in eight cases (18%) and cardiological diseases occurred in five patients (11%). Chronic renal failure was reported in six patients (14%).53, 56, 58, 67, 68 Other conditions found are included in the Tables 1–5. Side effects The side effects mainly included metabolic disturbances, particularly hyperphosphataemia, hypocalcaemia, ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd hypernatraemia, hypokalaemia and metabolic acidosis. Tetany resulting from the hypocalcaemia-induced was reported in 17 cases (34%),37, 39, 40, 43, 47, 48, 52– 56, 58, 62, 65, 69 being the most frequent complication (the remaining complications can be consulted in Tables 1–5). Age The results in all patients were stratified by age, forming groups of patients under 18 years of age and adults (over 18 years of age). In turn, separate analyses were made in each group of patients <2 years old (in those under 18 years) and patients older than 65 years (in the adult group). Paediatric age (0–18 years) A total of 29 case reports, representing 66% of all reported cases, were identified. Patients aged 2 years or less (15 cases, 34% of all cases analysed)32–44 and patients older than 2 years (14 cases, 32%)38, 40, 45–56 were separately analysed. Within the latter group, it should be noted that almost all patients had ages ranging from 1 to 5 years, we only found one case of a child older than 5 years. Children under 2 years of age Nine boys (60%) and six girls (40%) were found under the age of 2. As regards associated comorbidity, an underlying disease was found in 11 cases (73%). Indications for prescription included constipation in six cases (40%)33, 37, 40 and colon preparation for surgery in another three patients (20%).32, 36, 39 All cases seen in infants under 2 years of age showed metabolic disturbances. Finally, a case was identified in a newborn that had bone mineralization disturbances probable because of repeated enema used by his anorexic mother during pregnancy34 (Table 1). Children aged 2–18 years Seven males (50%) and seven females (50%) were found between the ages of 2–18. Twelve of these patients (86%) had associated comorbidity (Table 2). The most common group of conditions were gastrointestinal motility disorders, found in six patients (43%).38, 40, 47, 49, 50, 54 12 J . M E N D O Z A et al. Table 1. Adverse effects reported in patients under 2 year of age Author ⁄ year No. of units administered Sex Age Associated condition Indication Male 1 year No 1 Ismail et al. (2000)41 Walton et al. (2000)33 Male Male 1.5 years 6 weeks Asthma, epilepsy Premature birth Preparation for surgery Constipation Constipation Craig et al. (1994)42 Rimersberger et al. (1992)34 Female Female 2 years Newborn VATER syndrome No Constipation – McCabe et al. (1991)43 Female 2 years – Wason et al. (1989)35 Martin et al. (1987)36 Female Male 5 months 11 months Reedy et al. (1983)37 Male 1 year Cat cry syndrome, heart failure No Intestinal reconstruction due to imperforate anus Muscle dystrophy 2 Multiple, administered to mother during pregnancy 1 (90 mL) Gómez et al. (1981)44 Davis et al. (1977)38 Honig et al. (1975)39 Male Female Male 1.3 years 4 months 5 months Moseley et al. (1968)40 Male Moseley et al. (1968)40 Moseley et al. (1968)40 Everman et al. (2003) 32 1 1 ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd – Preparation for surgery 1 (adult) 4 (adult) Constipation 1 Constipation Constipation Preparation for surgery – 2 1 60-mL fleet enema 8 months Hirschprung Constipation Intestinal reconstruction due to imperforate anus Hirschprung Male 7 months Hirschprung – ½ adult enema Female 2 years Hirschprung – ½ adult enema 2 every 12 h Disturbances induced Death Water-electrolyte disturbances, acute respiratory failure Water-electrolyte disturbances Water-electrolyte disturbances, acute renal failure Water-electrolyte disturbances Bone mineralization disturbances No Water-electrolyte disturbances, tetany Water-electrolyte disturbances Water-electrolyte disturbances Water-electrolyte disturbances, tetany, fever Water-electrolyte disturbances Water-electrolyte disturbances Water-electrolyte disturbances, tetany, fever Water-electrolyte disturbances, tetany Water-electrolyte disturbances, tetany Water-electrolyte disturbances, tetany, QT prolongation Yes Yes No No No No Yes No No No No No No No Author ⁄ year Sex Age (years) Associated condition Indication No. of units administered Butani et al. (2005)56 Male 11 Constipation 2 paediatric enemas 4 Neurogenic bladder, end-stage renal failure Spinal muscular atrophy Marrafa et al. (2004)55 Female Constipation Male 3 No Constipation 2 adults enemas within 4 h – Melvin et al. (2002)45 Ballesteros et al. (2001)46 Helikson et al. (1997)47 Male Female 3 3 Lymphoma, liver transplantation Anorectal malformation Constipation Constipation 1 (80 mL) 3 (adult) Franch et al. (1995)48 Female 4 No Constipation 1 (250 mL) Hunter et al. (1993)49 Female 4 Constipation Constipation Edmonson et al. (1990)50 Male 4 Constipation Constipation 2.5 enemas 3 times weekly 3 (adult) Forman et al. (1979)51 Sotos et al. (1977)52 Female Female 3 3 Gaucher Myelomeningocele – Constipation 2 2 Davis et al. (1977)38 Oxnard et al. (1974)53 Male Male 3 5 – – 1 1 (adult) Swerdlow et al. (1974)54 Male 3 Constipation Chronic renal failure, congenital urinary obstruction Pyloric stenosis Constipation Moseley et al. (1968)40 Female 3 Hirschprung – 1 (undiluted Fosfosoda) – Disturbances induced Death Water-electrolyte disturbances, tetany, QT prolongation Water-electrolyte disturbances, tetany, QT prolongation Water-electrolyte disturbances, intravascular haemolysis Water-electrolyte disturbances Water-electrolyte disturbances, tetany Water-electrolyte disturbances, tetany Water-electrolyte disturbances, abdominal distention Water-electrolyte disturbances, QT prolongation Water-electrolyte disturbances Water-electrolyte disturbances, tetany Neurological disturbances Water-electrolyte disturbances, tetany, QT prolongation Water-electrolyte disturbances, tetany Water-electrolyte disturbances, tetany, QT prolongation No No No Yes No No No No No No No No No No S Y S T E M A T I C R E V I E W : A D V E R S E E F F E C T S O F S O D I U M P H O S P H A T E E N E M A 13 ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd Table 2. Adverse effects reported in patients older than 2 years and younger than 18 years 4 in 48 h Constipation No 2 Male Young et al. (1968)59 21 Male Haskell et al. (1985)58 58 Male Pitcher et al. (1997)57 64 Polycystic renal disease, chronic renal failure Hirschprung – Preparation for colonoscopy Constipation No Yes Extensive calcifications, liver enzymes elevation, multiorgan failure and shock Water-electrolyte disturbances, shock, multiorgan failure Water-electrolyte disturbances, tetany Water-electrolyte disturbances 3 (in several days) Female Eckstein et al. (2006)60 64 Kidney transplantation, hyperpathiroidism, gastrectomy Rectal neoplasm Constipation Yes Death Associated condition Age (years) Sex Author ⁄ year Table 3. Adverse effects reported in patients aged 18–65 years Indication No. of units administered Disturbances induced 14 J . M E N D O Z A et al. The indication for enema was constipation in 10 cases (71%),45–50, 52, 54–56 while no data on indication was found in the remaining four patients (35%).38, 40, 51, 53 All patients experienced the previously reported water and electrolyte disturbances. Other conditions included tetany in seven cases (50%)40, 47, 52–56 and QT interval prolongation in five cases (36%).40, 50, 53, 55, 56 One death (7%) was identified in this group, in a male with a significant comorbidity (gastrointestinal lymphoma and liver transplantation).46 Adults aged 18–65 years. In the adult group, a total of 15 cases with adverse effects were found. Four of these occurred in patients under 65 years of age,57–60 and 11 in patients over 65 years of age.61–70 The mean age in patients aged 18–65 years who experienced adverse effects was 52 years. They all had comorbidity of a different severity. Water and electrolyte disturbances occurred in all cases. We found two deaths in this group57, 60 (Table 3). Adults over 65 years of age Finally, 11 clinical cases, eight females and three males with a mean age of 81 years (range: 70–96 years), were found among patients older than 65 years. They all had comorbid conditions. The most common associated conditions were heart diseases, reported in six patients (55%).61–64, 67, 68 Indications included constipation in nine cases (73%)61–63, 65–68, 70 and preparation for colonoscopy or barium enema in two patients (27%).64, 69 As regards the dosage given, seven patients (64%) received three or more units,61–63, 65, 66, 69, 70 and a maximum of eight doses were received by a single patient.62 All patients experienced water and electrolyte disturbances (Table 4). Six patients over 65 years of age died (55%).61–63, 67, 70 Five of these patients (45%) had been given three or more doses,61–63, 70 and the remaining patient had significant associated comorbidity (acute pulmonary oedema, heart failure and chronic renal failure).67 Mortality Among all aforementioned studies, a total of 12 deaths (27%) were found, six in males and six in females.33, 36, 41, 46, 57, 60–63, 67, 70 Eleven of such deaths ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd Author ⁄ year Sex Age (years) Associated condition Indication No. of units administered Farah et al. (2005)70 Male 70 Spondyloartropathy Constipation Tan et al. (2002)61 Tan et al. (2002)61 Martinez Velasco et al. (1998)62 Knobel et al. (1996)63 Female Female Female 73 82 86 Heart failure – Atrial fibrillation Constipation Constipation Constipation 4 enemas within 12 h (133 ml each) 3 3 8 Female 87 Constipation 4 in 48 h Sutters et al. (1996)64 Male 71 Preparation for colonoscopy 2 Korzets et al. (1992)65 Female 77 Ischaemic heart disease, high blood pressure, megacolon Chronic obstructive pulmonary disease, high blood pressure, supraventricular tachycardia Urinary incontinence Constipation 6 in 12 h Aradhye et al. (1991)66 Female 96 Dementia, gastrostomy Constipation 2 Spinrad et al. (1989)67 Female 91 Constipation 1 Biberstein et al. (1985)68 Male 81 Constipation Rohack et al. (1985)69 Female 77 Heart failure, acute pulmonary oedema, chronic renal failure Chronic renal failure, atrial fibrillation, atherosclerosis Diverticulitis Barium enema preparation Disturbances induced Death Water-electrolyte disturbances, cardiac arrest Water-electrolyte disturbances Water-electrolyte disturbances Water-electrolyte disturbances, tetany Water-electrolyte disturbances, coma, and respiratory failure Water-electrolyte disturbances Yes Water-electrolyte disturbances, confusion, QT prolongation, and tetany Water-electrolyte disturbances, lethargy Water-electrolyte disturbances No 1 Water-electrolyte disturbances, QT prolongation No 6 in 6 h Water-electrolyte disturbances, coma, tetany, and fever No Yes Yes Yes Yes No No Yes S Y S T E M A T I C R E V I E W : A D V E R S E E F F E C T S O F S O D I U M P H O S P H A T E E N E M A 15 ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd Table 4. Adverse effects reported in patients over 65 years of age 16 J . M E N D O Z A et al. Table 5. Dead patients ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd Author ⁄ year Sex Age Associated condition Indication No of units administered Cause of death Eckstein et al. (2006)60 Female 64 years Constipation 3 (in several days) Farah et al. (2005)70 Male 70 years Kidney transplantation, hyperpathiroidism, gastrectomy Spondylortopathy Constipation Tan et al. (2002)61 Female 73 years Heart failure Constipation 4 enemas within 12 h (133 ml each) 3 Tan et al. (2002)61 Ballesteros Garcı́a et al. (2001)46 Ismail et al. (2000)41 Walton et al. (2000)33 Female Male 82 years 3 years Constipation Constipation 3 1 (80 mL) Male Male 17 months 6 weeks No Lymphoma, liver transplantation Asthma, epilepsy Premature birth Extensive calcifications, liver enzymes elevation, multiorgan failure and shock Water-electrolyte disturbances, cardiac arrest Pneumonia. Water-electrolyte disturbances Water-electrolyte disturbances Water-electrolyte disturbances Constipation Constipation 1 1 Martinez Velasco et al. (1998)62 Pitcher et al. (1997)57 Female 86 years Atrial fibrillation Constipation 8 Water-electrolyte disturbances Water-electrolyte disturbances, acute renal failure Water-electrolyte disturbances Male 64 years Rectal neoplasm – Water-electrolyte disturbances Knobel et al. (1996)63 Female 87 years 4 Water-electrolyte disturbances Spinard et al. (1989)67 Female 91 years Constipation 1 Water-electrolyte disturbances Martin et al. (1987)36 Male 11 months High blood pressure, ischaemic heart disease Heart failure, acute pulmonary oedema, chronic renal failure Imperforate anus, colostomy Preparation for colonoscopy Constipation Preparation for surgery 4 Water-electrolyte disturbances S Y S T E M A T I C R E V I E W : A D V E R S E E F F E C T S O F S O D I U M P H O S P H A T E E N E M A 17 (92%) were due to water and electrolyte disturbances secondary to administration of sodium phosphate enemas. Age of dead patients ranged from 11 months36 to 91 years.67 Virtually, all dead patients were at the extreme ages of life. Four deaths (30%)33, 36, 41, 46 occurred among patients under 18 years of age. In the group of patients over 18 years of age, a total of six deaths (55%)57, 60–63, 67, 70 occurred in patients aged 64–91 years. Among adult patients aged 18– 65 years, death was only reported in two clinical cases (Table 5). The subgroup of adults who died included six women (75%)60–62, 67 and two men.57, 70 All patients under 18 years of age who died were males.33, 36, 41, 46 All dead patients except 1 (92%)61 had associated comorbidity in all age groups studied. (Table 5). DISCUSSION Sodium phosphate enemas are products widely used in both in-patient and out-patient settings. The most common indication is for symptomatic treatment of constipation, and to a lesser extent in preparation for colonoscopy or surgery. There are no accurate data about worldwide prescription of these products. According to the manufacturer (Casen ⁄ Fleet), more than 5 00 000 000 U have been sold up to now, which can give us an approximate idea of the widespread use of these products. No randomized clinical trials, meta-analysis or systematic reviews exist in the literature to answer the question of safeness or adverse effects of these products. The side effects are minimal, and literature reports only refer to the most severe cases, such as water and electrolyte disturbances that may even be fatal in some cases. There are various randomized clinical trials comparing the tolerability and efficacy for colon cleaning of several preparation methods for endoscopic procedures. Such trials assessed the side effects of phosphate enemas that were considered to be mild and with no clinical impact. In a US study3 conducted on 157 patients, nausea (6–18%), vomiting (0–7%) and abdominal pain (8–9%) were reported, while abdominal distention occurred in 90% of subjects receiving one enema and in 98% of patients when two enemas were administered. Atkin et al.2 found similar results in an analysis of 721 patients receiving a sodium phosphate enema. It should not be forgotten that sodium phosphate enemas are widely used, and our review only found a ª 2007 The Authors, Aliment Pharmacol Ther 26, 9–20 Journal compilation ª 2007 Blackwell Publishing Ltd minimum number of patients with side effects. Specifically, the review conducted found 46 reports of side effects of different severity, which would represent a minimal proportion of side effects if we take into account the widespread use of enemas. Nevertheless, these data should be analysed with caution because of the possible publication bias incurred, as only a minority of side effects may be reported, and they are probably the most severe. As regards age distribution of patients reported as experiencing side effects, it should be noted that most of them were in the extreme age groups (older than 65 years and younger than 5 years, 25% and 64%, respectively). Only five cases were reported in patients aged from 5 to 65 years. It should therefore be inferred that extreme ages are associated with a greater frequency of side effects. Comorbid conditions were noted in 86% of cases, particularly including neurological, gastrointestinal and renal disorders. Such associated conditions could be related to the increased phosphate absorption shown in some clinical trials. Thus, in the Schumann et al. study28, high serum phosphorus levels were shown in patients with a longer enema retention time. There have been reports of several experimental studies in animals showing phosphorus absorption in the colonic mucosa,29, 30 that is dependent on luminal phosphorus levels. By contrast, other studies analysing water and electrolyte disturbances in patients who were prepared for colonoscopy using sodium phosphate enemas only showed a mild increase in serum phosphate levels that did not reach pathological ranges.26, 28 It could be hypothesized that the existence of increased blood phosphate levels in patients with gastrointestinal disorders could be due to an increased contact between enema contents and the intestinal wall, which would promote phosphorus and sodium absorption. The actual dosage administered to cases reported in the literature is difficult to assess, as neither the dose nor the composition of enemas are adequately reported in most publications. It should also be noted that formulations differ depending on the country.75 Moreover, some publications report outpatient administration of adult enemas to paediatric patients. Overdosage was reported in eight clinical cases, and up to eight enemas were administered to a 86-year-old patient.62 In this respect, it should be noted that most dead patients had been administered two or more enemas. An influence of the dose 18 J . M E N D O Z A et al. received on adverse effects and their severity is therefore likely. The side effects reported are related to water and electrolyte disturbances resulting from hyperphosphataemia, hypocalcaemia, hypernatraemia, and metabolic acidosis, because of the absorptive effect of enema components and to their inadequate elimination in some cases, such as patients with chronic renal failure. Therefore, an increased caution is required when enemas are administered to patients with this condition. It should be noted that virtually all deaths reported in the literature occurred in people with extreme ages and a significant comorbidity. Deaths were caused by water and electrolyte disturbances, by an episode of pneumonia and by an extensive calcification with subsequent multiorgan failure in a patient with renal transplantation and hyperparathyroidism. To sum up, age older than 65 years and under 5 years could be suggested as a potential risk factor for mortality, which could be related to an increase in associated conditions. REFERENCES 1 Harrington L, Schuh S. Complications of Fleet enema administration and suggested guidelines for use in the pediatric emergency department. Pediatr Emerg Care 1997; 13: 225–6. 2 Atkin WS, Hart A, Edwards R, et al. Single blind, randomised trial of efficacy and acceptability of oral picolax versus self administered phosphate enema in bowel preparation for flexible sigmoidoscopy screening. BMJ 2000; 320: 1504–8; discussion 1509. 3 Osgard E, Jackson JL, Strong J. A randomized trial comparing three methods of bowel preparation for flexible sigmoidoscopy. Am J Gastroenterol 1998; 93: 1126–30. 4 Bowers B. Evaluating the evidence for administering phosphate enemas. Br J Nurs 2006; 15: 378–81. 5 Laxatives for bowel clearing before investigations. Drug Ther Bull 2002; 40: 86–8. 6 Herman M, Shaw M, Loewen B. Comparison of three forms of bowel preparations for screening flexible sigmoidoscopy. Gastroenterol Nurs 2001; 24: 178–81. To summarize, it may be concluded that water and electrolyte disturbances are the reason for the main side effects occurring in patients administered sodium phosphate enemas. The main risk factors include chronic renal failure, diseases altering intestinal motility (neurological, morphological, etc.), and extreme ages of life. Adequate prescription is required in patients with such conditions, as use of sodium phosphate enemas are not risk-free, although the incidence of side effects is nevertheless very low. 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