Constipation
Chelsie Sievers
Background
- Definition: presence of lumpy/hard stools, straining, use of digital maneuvers, sensation of incomplete evacuation, frequency <3 BM per week.
- Common etiologies: opioid-induced, medications (anti-depressants, iron, anticholinergics) hypothyroidism, hypokalemia, pregnancy, IBS, neurogenic (trauma, MS, Parkinson disease, diabetes, autonomic dysregulation).
- Always think about risk of obstruction (prior abdominal surgeries, oncology history or risk for GI/GU malignancies, history of IBD/Crohn’s).
Evaluation
- Evaluate etiologies plus lifestyle factors (low fiber intake, low fluid intake, reduced mobility, acute illness)
- Clinical diagnosis, no need for imaging unless concerned for obstruction → KUB/ CT
- BMP + Mg to evaluate electrolytes, consider TSH if chronic
- Rectal exam to exclude rectal mass or fecal impaction (constipation + diarrhea doesn’t exclude impaction/obstruction. Overflow around mass = encoparesis)
Management
- Stop or minimize offending medications if possible
- Optimize lifestyle factors: out of bed, walking hallways, increase fluid intake, + cup of coffee if appropriate.
- Escalating pathway: ensure meds are scheduled not PRN
- MiraLAX (PEG) 17g BID (can give TID) + Senna nightly (can increase to BID and/or 2 tabs) → Bisacodyl suppository → enema (tap water or SMOG) → stronger osmotic laxative (lactulose 20mg once, Mag-citrate, Golytely) → escalate lactulose dosing 20 – 30 mg q2hrs
Other Considerations
- Avoid Fleet enemas (sodium-phosphate) in CKD and geriatric populations
- “The hand that writes for opioids also writes a bowel regimen”
- Generally, start with scheduled MiraLAX (PEG) 17g daily + senna nightly
- If severe and unrelieved by escalating therapies, can try methylnaltrexone
- Lactulose can cause severe bloating and cramping
- In patients unable to take PO: place DHT to deliver meds or rectal lactulose (important for patients with cirrhosis with AMS/HE).
- In patients with CF (at risk for distal intestinal obstruction syndrome): ensure have pancreatic enzymes ordered, managed more like constipation than true obstruction: PO/ NGT MiraLAX QID or Golytely.
- Acute colonic pseudo-obstruction (Ogilvie's syndrome): >12cm cecal diameter = severe dilation, risk of perforation. Treated with neostigmine, 2mg IV over 3 to 5 minutes. Monitor for bradycardia, hypotension, and dysrhythmias (relative contraindications: recent MI, asthma, PUD, epilepsy). Decompression with colonoscopy used in some cases.
- Consider pelvic floor dysfunction, pelvic floor PT may be helpful
Laxatives
