Trip Answers

Question answered:07/09/07 Warning! this question is over two years old.

Should oral laxatives be prescribed if there is a likelihood of small bowel obstruction?

 

The CKS quick reference guide to constipation notes:

 

“Stimulant laxatives.

 

- Prolonged use of high doses of stimulant laxatives (especially if fluid intake is inadequate) can lead to significant fluid and electrolyte imbalance…
- Do not use stimulant laxatives in people with intestinal obstruction. 

 

Faecal softeners

 

- Do not use oral docusate sodium in people with intestinal obstruction.

 

Bulk-forming laxatives.
- Do not use in people with intestinal obstruction, colonic atony, faecal impaction, or severe dehydration

 

Osmotic laxatives.

 

- Do not use osmotic laxatives in people with gastrointestinal obstruction.” [1]

 

What would be an appropriate plan if there are potential problems of using aperients in potential small bowel obstruction?
We found no guidance on how patients should be managed if laxatives cannot be used. Thus, we can only suggest discussing this case with a local specialist.

 

If an enema is administered and no bowel movement results, will this result in toxicity due to retaining the phosphate enema?

 

A search in the Medline database identified two cases of phosphate enema poisoning in children. The abstracts to these reports read:

 

“OBJECTIVE: To report a case of hypocalcaemic tetany occurring in a child secondary to two phosphate enemas administered for faecal retention, and review the literature of phosphate enema toxicity in children. CLINICAL FEATURES: A 23-month-old child with a repaired anorectal malformation and associated unilateral renal hypodysplasia presented with hypocalcaemic tetany (minimum serum calcium level, 1.11 mmol/L), hyperphosphataemia (maximum serum phosphate level, 6.06 mmol/L), hypokalaemia (minimum serum potassium level, 1.9 mmol/L) and dehydration 10 hours after the administration of two phosphate enemas for acute on chronic faecal retention. MANAGEMENT AND OUTCOME: Management consisted of parenteral rehydration, potassium supplementation, calcium gluconate, an enterally administered phosphate binder and saline bowel washouts to evacuate the remaining enema. She was discharged on day eight, with normal biochemical parameters and no neurological sequelae. CONCLUSION: The use of phosphate enemas in children under five years of age is associated with significant morbidity due to hyperphosphataemia, hypocalcaemia, hypokalaemia and dehydration. They should not be used in children under two years of age, and should be used only with extreme caution in children aged two to five years, especially in those with underlying bowel or renal dysfunction.” [2]

 

The second case report, one by Marraffa states:

 

“…We report a case of electrolyte disturbance and seizure secondary to the rectal administration of 2 Fleet pediatric enemas. CASE REPORT: A 4-year-old white female with spinal muscular atrophy and chronic constipation was brought to the emergency department with complaints of lethargy and difficulty breathing following the administration of 2 Fleet pediatric enemas. In the emergency department, physical examination was significant for a depressed level of consciousness and shallow respirations. A basic metabolic profile was significant for a calcium of 3.3 mg/dL, phosphate of 23 mg/dL, and sodium of 153 mEq/L. Arterial blood gases revealed a pH of 7.24, Pco2 of 38 mm Hg, Po2 of 220 mm Hg. Electrocardiogram revealed a prolonged QT interval of 340 milliseconds with a corrected QT interval of 498 milliseconds. Sixteen hours postexposure, she experienced a generalized seizure unresponsive to multiple doses of lorazepam and responsive only to 100 mg of intravenous calcium chloride. Two days after presentation, the patient experienced complete resolution of symptoms. CONCLUSION: Osmotically acting hypertonic phosphate enemas can result in severe toxicity if retained. This is true even in patients without predisposing risk factors.” [3]

 

References
1. CKS. Quick reference guide to constipation in adults. (http://cks.library.nhs.uk/qrg/constipation_adults.pdf
2. Craig JC, Hodson EM and Martin HC. Phosphate enema poisoning in children. Med J Aust. 1994 Mar 21;160(6):347-51. (http://www.hubmed.org/display.cgi?uids=8133819)
3. Marraffa JM, Hui A and Stork CM. Severe hyperphosphatemia and hypocalcemia following the rectal administration of a phosphate-containing Fleet pediatric enema. Pediatr Emerg Care. 2004 Jul;20(7):453-6. (http://www.hubmed.org/display.cgi?uids=15232246).

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