Is the use of Fleet enema (sodium phosphate rectal solution) safe during pregnancy, particularly in the first trimester?

Fleet Enema Safety in Pregnancy

Fleet enema (sodium phosphate rectal solution) should be avoided during pregnancy; tap water enemas are the recommended alternative when bowel preparation is necessary. 1

Guideline-Based Recommendations

The American Gastroenterological Association explicitly recommends tap water enemas for lower endoscopy in pregnant women because full colonoscopy rarely is indicated during pregnancy. 1 This recommendation reflects both the limited safety data for sodium phosphate preparations in pregnancy and the availability of safer alternatives.

FDA Pregnancy Classification and Safety Concerns

• Both PEG-ELS and sodium phosphate (NaP) solutions are FDA category C medications, meaning animal reproduction studies have not been conducted and it is unknown whether they can cause fetal harm. 1
• The FDA drug label for sodium phosphate states that it "should be given to a pregnant woman only if clearly needed" because no animal reproduction studies have been conducted and fetal harm potential is unknown. 2

Clinical Practice Patterns Show Divergence

• Only 7.7% of surveyed gastroenterologists would prescribe oral sodium phosphate preparations to pregnant patients, compared to 29.1% of obstetricians. 1
• This divergence suggests inconsistent awareness of the risks associated with sodium phosphate use during pregnancy. 1

Mechanism of Concern: Systemic Absorption and Electrolyte Disturbances

Sodium phosphate enemas carry significant risk of severe hyperphosphatemia, hypocalcemia, hypernatremia, and acute kidney injury through systemic absorption. 1, 3, 4

Documented Complications in High-Risk Populations

• Case reports document extreme hyperphosphatemia and hypocalcemic coma following Fleet enema administration in patients with renal impairment and older age. 3
• Severe metabolic derangements including seizures have occurred even in patients without predisposing risk factors when enemas are retained. 5
• Prolonged retention of sodium phosphate enemas markedly increases systemic absorption, heightening the risk of electrolyte disturbances and renal toxicity. 6

Pregnancy-Specific Physiologic Vulnerabilities

• Pregnant women experience altered renal function and fluid shifts that may increase susceptibility to electrolyte disturbances. 2
• The FDA label warns that sodium phosphate should be used with caution in edematous or sodium-retaining states, which can occur in pregnancy. 2

Recommended Safe Alternatives

First-Line Option: Tap Water Enemas

Tap water enemas are the preferred rectal preparation method in pregnancy because they dilate the bowel, stimulate peristalsis, and lubricate stool without causing electrolyte abnormalities. 1

• Normal saline enemas provide similar mechanical benefits with even lower risk of fluid and electrolyte shifts. 6
• These preparations should be used sparingly with awareness of possible electrolyte abnormalities, though the risk is substantially lower than with sodium phosphate. 1

When Colonoscopy Is Required During Pregnancy

• Colonoscopy should be deferred until the second trimester whenever possible and always requires a strong indication with careful risk-benefit assessment. 1
• If bowel preparation is necessary, low doses of PEG-ELS have been reported safe in 225 pregnant patients treated for constipation. 1
• PEG-ELS is considered a low-risk option compared to sodium phosphate preparations. 1

Critical Contraindications and High-Risk Scenarios

Absolute Contraindications for Sodium Phosphate

• Renal impairment or medications affecting renal function. 1, 2
• Significant comorbidities including liver disease, hypertension, diabetes, and cardiac disease. 1
• Conditions causing high risk for dehydration or electrolyte imbalance. 1
• Ileus or suspected severe colitis. 1

Monitoring Requirements If Sodium Phosphate Must Be Used

• The FDA label mandates caution in patients with renal impairment, cirrhosis, cardiac failure, and edematous or sodium-retaining states. 2
• Serum phosphorus levels should guide therapy, with limits imposed by the accompanying sodium ion load. 2

Common Clinical Pitfalls to Avoid

• Never assume sodium phosphate enemas are safe simply because they are available over-the-counter—severe complications including death have been documented even in patients without obvious risk factors. 3, 7, 5
• Do not use sodium phosphate preparations in pregnant women taking corticosteroids or corticotropin, as the FDA label specifically warns about caution with sodium-containing fluids in these patients. 2
• Recognize that older formulations and practices may not reflect current safety evidence—the oral sodium phosphate solution (Fleet Phospho-Soda) was withdrawn from the U.S. over-the-counter market in 2008 due to concerns about phosphate-induced renal disease. 1