Management of Large Fecal Impaction in Rectal Vault
The first-line treatment is manual disimpaction (digital fragmentation and extraction) after administering analgesia and/or anxiolytic, followed immediately by enema administration and implementation of a maintenance bowel regimen to prevent recurrence. 1
Immediate Pre-Procedure Steps
Before attempting disimpaction, you must:
- Administer appropriate analgesia and/or anxiolytic - this is critical as patients have significant stool burden and face potential risk of bradycardic arrest and death during rectal manipulation 1
- Position patient in left lateral decubitus or lithotomy position 1
- Consider mild sedation or anesthesia for difficult cases 1
- Rule out complications such as perforation or bleeding before proceeding 1
Manual Disimpaction Technique
Perform digital fragmentation and extraction of the stool - this is successful in 80% of fecal impaction cases 2. The procedure involves:
- Breaking up the hard fecal mass with your gloved finger 1
- Extracting fragments piece by piece 1
- Continue until the rectal vault is cleared 3
Immediate Post-Disimpaction Treatment
After manual removal, administer a water or oil retention enema to facilitate passage of remaining stool 1. Your options include:
- Warm oil retention enema (arachis/mineral oil) - recommended to facilitate passage 1
- Hypertonic sodium phosphate enema 1
- Docusate sodium enema 1
- Bisacodyl enema 1
- Glycerol suppositories as a rectal stimulant 1
Critical Contraindications for Enemas
Do NOT use enemas if the patient has: 1
- Neutropenia or thrombocytopenia
- Paralytic ileus or intestinal obstruction
- Recent colorectal or gynecological surgery
- Recent anal or rectal trauma
- Severe colitis, inflammation, or infection of the abdomen
- Toxic megacolon
- Undiagnosed abdominal pain
- Recent radiotherapy to the pelvic area
If Manual Disimpaction Fails or Impaction is Proximal
If the impaction is in the proximal rectum or sigmoid colon (where digital rectal exam may be non-diagnostic), or if manual disimpaction is unsuccessful 1:
Administer lavage with PEG (polyethylene glycol) solutions containing electrolytes to soften or wash out stool, assuming no complete bowel obstruction is present 1, 3
Additional laxatives to consider adding 1:
- Bisacodyl suppository (one rectally daily-BID) 4
- Lactulose 30-60 mL BID-QID 4
- Sorbitol 30 mL every 2 hours x 3, then PRN 4
- Magnesium hydroxide 30-60 mL daily-BID 4
- Magnesium citrate 8 oz daily 4
In severe treatment-resistant cases without peritonitis, endoscopic disimpaction should be considered before surgery, as it is far less invasive 5.
Essential Prevention Strategy
Implement a maintenance bowel regimen immediately after disimpaction - this is non-negotiable as recurrence is common 1, 6. The regimen should include:
Preferred laxatives: 1
- Osmotic laxatives: PEG (17 g/day for elderly), lactulose, or magnesium salts
- Stimulant laxatives: Senna ± docusate (2-3 tablets BID-TID), bisacodyl (10-15 mg daily-TID), cascara, or sodium picosulfate
Critical pitfall to avoid: Do NOT use bulk laxatives such as psyllium, especially in patients with opioid-induced constipation or limited mobility 1
Additional Preventive Measures
- Increase daily water and fiber intake (only if adequate fluid intake and physical activity are present) 4, 6
- Discontinue any non-essential constipating medications 4
- Educate patient to attempt defecation at least twice daily, usually 30 minutes after meals 1
- Ensure access to toilets, especially for patients with decreased mobility 1
- Consider methylnaltrexone 0.15 mg/kg subcutaneously every other day for opioid-induced constipation (except for post-op ileus and mechanical bowel obstruction) 4
When Surgery is Required
Immediate surgical intervention is indicated if the patient has: 4
- Signs of shock
- Gangrene or perforation of bowel
- Peritonitis
Surgical resection is reserved for peritonitis resulting from bowel perforation 6. An abdominal open approach is recommended for hemodynamically unstable patients 4.