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Constipation

Rarely the disease — often the mask.

LearnQuick referenceClinical practice

Your objective: explain the approach, recognize important warning signs, then test your recall.

Abbreviations explained
ACS
Acute coronary syndrome
OMI
Occlusion myocardial infarction
ECG
Electrocardiogram
PE
Pulmonary embolism
POCUS
Point-of-care ultrasound
QTc
QT interval corrected for heart rate
LBBB
Left bundle branch block
RBBB
Right bundle branch block
hs-cTn
High-sensitivity cardiac troponin
CTA
Computed tomography angiography
ICU
Intensive care unit
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The jobRarely the disease — often the mask.

  1. Constipation is a symptom — look for obstruction, ischemia, cord, calcium, thyroid, opioids.
  2. DRE in the frail and in “diarrhea” that may be overflow.
  3. New constipation + retention or saddle numbness = MRI for cauda, not lactulose.
  4. No red flags and a benign exam: bowel regimen and follow-up, not a CT.

True simple constipation is common and benign.

The ED task is to find the masqueraders: bowel obstruction, mesenteric ischemia, fecal impaction with overflow, spinal cord/cauda equina, opioid ileus, hypercalcemia, and hypothyroidism. New severe constipation in the elderly with pain or vomiting is obstruction until imaged.

Bowel obstruction / volvulus Critical

Key: Vomiting, distension, prior surgery, hernia, tympany — CT. Sigmoid/cecal volvulus is time-critical.

Mesenteric ischemia Critical

Key: Pain out of proportion, AF, bloody stool — CTA, not a discharge laxative.

Cauda equina / cord compression Critical

Key: New constipation plus back pain, saddle anesthesia, or urinary retention — emergency MRI.

Fecal impaction with overflow / stercoral colitis Critical

Key: The frail elderly “diarrhea” that is overflow; DRE. Stercoral ulceration can perforate.

Hypercalcemia / myxedema / opioid ileus Emergent

Key: Bones, stones, groans, psychiatric overtones; delayed reflexes; the medication list.

Toxic megacolon / Ogilvie (acute colonic pseudo-obstruction) Emergent

Key: Distended silent abdomen in IBD, C. diff, or the hospitalized/post-op patient — decompression pathway.

Simple functional constipation / opioid-induced Common

Key: No red flags, benign exam — osmotic laxative, enemas as needed, bowel regimen, follow-up.

Tick what your patient has — the banner updates as you go.

Last stool, character, overflow liquid, blood, vomiting, ability to pass flatus

Prior surgeries, hernias, opioid or anticholinergic use, immobilization

Back pain, saddle numbness, urinary retention

Weight loss, iron deficiency (obstructing cancer)

Thyroid, calcium, psychiatric meds

Abdomen

distension, hernias, peritoneal signs, bowel sounds

DRE

impaction, blood, tone (cauda)

Neuro if back pain or retention

saddle sensation, post-void residual

Volume status and signs of hypothyroidism

Bedside

  • DRE; bladder scan if retention is possible
  • Glucose; POCUS for free fluid/AAA if surgical features

Labs

  • Electrolytes including K and Ca, TSH if myxedema possible, CBC, creatinine
  • β-hCG when relevant; lactate if ischemia is on the list

Imaging

  • No imaging for simple constipation with a benign exam
  • CT abdomen/pelvis when obstruction, ischemia, or stercoral colitis is possible
  • MRI spine if cauda/cord features
Medication safety reminder

Use this as a first-pass prompt; verify all medications, doses, concentrations, contraindications, weight, pregnancy status, and local protocols before administration.

Check indication, allergy, route, renal/hepatic risk, interactions, monitoring, and local formulary.

Discharge

  • Simple constipation, empty rectum after disimpaction if needed, taking oral fluids, a bowel regimen, and return precautions. Stop or reduce the offending opioid/anticholinergic when safe.

Admit

  • Fecal impaction needing serial enemas in a frail host, Ogilvie under monitoring, electrolyte or thyroid replacement, obstructing cancer staging.

Theatre / MRI / ICU

  • Obstruction with ischemia or perforation, volvulus, stercoral perforation, cauda equina.

Use objective reassessment and the local pathway.

Before the next decision · reassess and hand over

Use these learning prompts with the presentation’s pathway. They are not discharge criteria.

  1. Reassess: compare symptoms, observations and examination with the initial assessment and response to treatment.
  2. Warning signs for Constipation:
    • Vomiting, distension, or an irreducible hernia
    • Pain out of proportion or bloody stool
    • New constipation with back pain, saddle numbness, or retention
    • Fever or peritonitis (stercoral perforation, megacolon)
    • Weight loss or iron-deficiency anemia in the older adult
    • Opioid ileus with a rock-hard abdomen
  3. Reconsider: check unresolved findings and alternative explanations, including the pitfalls below.
  4. Escalate: communicate deterioration, uncertainty or needs beyond the current setting.
  5. Plan the transition: identify outstanding results, responsibility for follow-up, patient understanding and specific return advice.
Review this presentation’s disposition pathway →Practice a handover →

Clinical Pearls

  • Constipation is a symptom. Ask what you are missing: obstruction, ischemia, cord, calcium, thyroid, opioids.
  • DRE is part of the exam, not optional, in the frail and in overflow diarrhea.
  • No red flags + a benign exam = regimen and follow-up, not a CT.
  • Back pain + constipation + retention = MRI, not lactulose.

Pitfalls

  • Treating mesenteric ischemia or SBO with polyethylene glycol is a classic miss.
  • “Diarrhea” in the elderly is overflow until a DRE is done.
  • New constipation plus urinary retention is cauda equina, not a laxative trial.
  • AXR is insensitive for obstruction — CT when the story is real.
  • Discharging without a bowel regimen after opioids guarantees a bounce-back.
PRACTICE REFRESHER

Rapid recall

Test your first action and the dangerous diagnoses before revealing the answer.

01 · First move

Before you scroll, what needs to happen first?

02 · Immediate threats

Name at least two diagnoses that cannot wait.

PRIVATE TO THIS DEVICE

Your learning note

Capture a weak point, a teaching pearl, or a question to take to your next shift.

Review schedule starts when marked reviewed
Abdominal PainDiarrheaLow Back PainNausea & Vomiting

Foundational references below. No separate topic-specific guideline check is recorded here.

  • Rosen’s Emergency Medicine, 10th ed. (2023) — constipation
  • Tintinalli’s 9th ed. — bowel obstruction
  • NICE NG59 / cauda equina red flags; WSES obstruction guidance
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