What are the next steps for treating constipation in a pregnant patient in the 2nd trimester who has not responded to lifestyle changes, Miralax (polyethylene glycol), and Colace (docusate), and has already received one enema?

Treatment of Refractory Constipation in Second Trimester Pregnancy

After failing lifestyle modifications, Miralax, and Colace, the next step is to add lactulose or increase the Miralax dose, and if this fails, proceed to short-term use of bisacodyl (stimulant laxative) given that you are in the second trimester where the risk-benefit profile is more favorable. 1, 2

Immediate Next Steps

Optimize Current Osmotic Therapy

• Increase polyethylene glycol (Miralax) to 17g daily if not already at this dose, as this is the recommended therapeutic dose and may not have been optimized 2
• Alternatively, switch to or add lactulose, which is the only osmotic agent specifically studied in pregnancy, though it causes more bloating than PEG 1, 3, 4
• Magnesium hydroxide 400-500 mg daily is another safe osmotic option that can be added 2

Discontinue Colace

• Docusate (Colace) has minimal efficacy as monotherapy and you've already confirmed it's ineffective in this patient 5, 6
• Focus resources on more effective agents rather than continuing an ineffective stool softener 6

Second-Line Therapy: Stimulant Laxatives

If optimized osmotic therapy fails after 3-7 days, add bisacodyl 5-10 mg daily for short-term relief, as you are in the second trimester where concerns about preterm labor from tenesmus are lower than in the third trimester 2, 4

Key Points About Stimulant Laxatives in Pregnancy

• The American Gastroenterological Association states that stimulant laxatives should be avoided as routine therapy but can be used cautiously for short-term relief when other methods fail 1, 2
• Safety data are conflicting, but bisacodyl and senna have been used extensively without clear evidence of harm 1, 5, 6
• The main concern is tenesmus potentially triggering preterm contractions, which is more relevant in the third trimester 4
• Limit use to short-term or occasional dosing to avoid electrolyte imbalances and dehydration 5, 6

Enema Use

The single enema you administered was appropriate for immediate relief, but repeated enemas should be avoided 2

• Glycerin suppositories are safer for repeated use if local stimulation is needed 2
• Reserve additional enemas only for suspected fecal impaction 1

What NOT to Do

Avoid These Medications

• Do not use newer secretagogues (linaclotide, plecanatide, lubiprostone) as they lack safety data in pregnancy 3
• Do not use mineral oil chronically as it can interfere with fat-soluble vitamin absorption 4

Common Pitfalls

• Do not continue ineffective therapy indefinitely—if dietary changes plus PEG and docusate have failed after 1-2 weeks, escalate treatment 2, 6
• Do not withhold treatment due to excessive caution, as constipation affects 20-40% of pregnant women and significantly impacts quality of life 7, 3
• Evaluate for secondary causes including hypothyroidism, hypercalcemia, and iron supplementation effects 1, 3

Treatment Algorithm Summary

1. Optimize osmotic laxatives: Increase PEG dose to 17g daily or switch to/add lactulose 2, 4
2. Wait 3-7 days for response while ensuring adequate hydration (at least 8 glasses of water daily) 1, 7
3. If still refractory, add bisacodyl 5-10 mg daily for short-term use (1-2 weeks maximum) 2, 4
4. Use glycerin suppositories for immediate relief if needed, rather than repeated enemas 2
5. Reassess after each intervention with goal of soft, formed stools every 1-2 days 2

Special Considerations for Second Trimester

The second trimester offers the safest window for more aggressive constipation management because:

• Organogenesis is complete, reducing teratogenic concerns 1
• The uterus is not yet large enough to cause significant mechanical obstruction 1, 7
• Risk of stimulant-induced preterm contractions is lower than in third trimester 4

Monitor for hemorrhoids, which occur in approximately 80% of pregnant women and may complicate management; hydrocortisone foam is safe if needed 1, 7, 3