This page is for adult patients; for pediatric patients see constipation (peds).


Normal inner diameters of colon sections.
  • Acute constipation is intestinal obstruction until proven otherwise

Red flags

Clinical Features

Bristol Stool Chart.
  • Decreased frequency of bowel movements
  • Hard, dry, and/or difficult to pass stool

Differential Diagnosis


Anorectal Disorders

Abdominal distention


Work up

  • Digital rectal exam
  • Abdominal panel
    • CBC
    • Chemistry (hypokalemia or hypercalcemia)
    • LFTs + lipase
    • Consider coagulation studies (PT, PTT, INR), as a marker of liver function
  • Consider TSH if concern for hypothyroid related constipation
  • Consider lactate if concern for stercoral colitis
  • CT if abdominal tenderness, elderly, or severe presentation
    • Constipation should not cause abdominal tenderness on exam
    • CT may show stool burden in colon/rectum


  • Diagnosis is frequently clinical
  • In patients with concerning symptoms/risk factors, CT can confirm diagnosis and rule out more emergent conditions


  • Adequate fluid (1.5L per day)
  • Fiber (10gm per day)
    • Bran: 1 cup daily
    • Psyllium (Metamucil): 1-2 teaspoon TID
  • Exercise

Medication options

  • Emollient
    • Docusate (Colace): 100mg QD-BID (facilitates mixture of stool fat and water)
    • Mineral oil (long term use causes malabsorption)
  • Stimulants
  • Saline laxative
    • Milk of mangesia: 15-30 mL QD-BID
    • Magnesium citrate: 100-240 mL QD-BID
  • Hyperosmolar agents
    • Lactulose 15-30 mL QD-BID
    • PEG: 1 gallon/4h
    • PEG(Miralax): 17gm
    • Glycerin: 1 adult suppository PR, onset of action 15-30 min, then 1-2 doses per day
  • Enemas
    • Soap suds, saline, tap water enema (rectal distention, causing evacuation)[1]
    • May add 50-100 mg of docusate liquid to saline or water enema
    • Fleet Phospho-soda: 118 ml single enema dose, with maximum of x2 doses at least 1 hr apart

Gastrografin PO

  • Gastrografin through NG or OG decreases bowel wall edema and increases bowel motility[5]
    • Diagnostic and therapeutic[6]
    • 100 cc of gastrografin through NG tube
    • Transit may be observed through serial radiographs
      • Contrast within the large bowel within 24 hrs suggest partial small bowel obstruction
      • Contrast failing to reach large bowel within 24-48 hrs suggests complete obstruction, requiring laparotomy
    • Therapeutic, may reduce necessary operative rate by ~75%[7]
  • Avoid barium as it becomes inspissated in bowel, causing complete obstruction[8]
    • If perforation occurs with barium, leakage can be lethal
    • Gastrografin is water-soluble and relatively safer if perforation occurs
    • Be aware that anaphylactoid reactions and serious aspirations have occurred rarely with Gastrografin, however[9]


  • Normally outpatient

See Also


  1. Portalatin M and Winstead N. Medical Management of Constipation. Clin Colon Rectal Surg. 2012 Mar; 25(1): 12–19.
  2. Farah R. Fatal acute sodium phosphate enemas intoxication. Acta Gastroenterol Belg. 2005 Jul-Sep;68(3):392-3.
  3. Reedy JC, Zwiren GT. Enema-induced hypocalcemia and hyperphosphatemia leading to cardiac arrest during induction of anesthesia in an outpatient surgery center. Anesthesiology. 1983 Dec;59(6):578-9.
  4. Korzets A, Dicker D, Chaimoff C, Zevin D. Life-threatening hyperphosphatemia and hypocalcemic tetany following the use of fleet enemas. J Am Geriatr Soc. 1992 Jun;40(6):620-1.
  5. Assalia A, Schein M, Kopelman D, et al. Therapeutic effect of oral Gastrografin in adhesive, partial small-bowel obstruction: A prospective randomized trial. Surgery 1994; 115: 433-437.
  6. Chen SC, Lin FY, Lee PH, et al. Water-soluble contrast study predicts the need for early surgery in adhesive small bowel obstruction. Br J Surg 1998; 85: 1692-1694.
  7. Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).
  8. Choi HK et al. Therapeutic Value of Gastrografin in Adhesive Small Bowel Obstruction After Unsuccessful Conservative Treatment: A Prospective Randomized Trial. Annals of Surgery. 2002;236(1).
  9. Skucas J. Anaphylactoid reactions with gastrointestinal contrast media. AJR Am J Roentgenol 1997; 168: 962-964.