Constipation

Introduction

• Affects 80% of critically unwell patients and has direct effect on mortality in this group
• Rome Criteria = 2 or more of:

• Straining >25% of the time
• Hard stools >25% of the time
• Incomplete evacuation >25% of the time
• <3 bowel motions per week
• Chronic constipation = Symptoms for at least 12 weeks in the preceding 12 months

Pathophysiology

• Acute

• GI: Rapidly growing tumours, adhesions, strictures, volvulus, hernias, inflammatory conditions
• Medicinal: Narcotics, anticholinergics, antipyschotics, antacids, antihistamines
• Reduced activity, fibre intake or fluid intake
• Painful anal pathology: Fissures, haemorrhoids, abscess, proctitis
• Chronic

• GI: Slow growing tumor, colonic dysmotility, chronic anal pathology
• Medicinal: Chronic laxative abuse, narcotics, antipsychotics, anticholinergic, antacid, antihistamines
• Neurologic: Neuropathies, parkinsons, DM, cerebral palsy, paraplegia
• Endocrine: Hypothyroid, hyperparathyroid, DM
• Electrolytes:  Hypomagnesaemia, hypercalcaemia, hypokalaemia
• Rheumatological: Amyloidosis, scleroderma
• Toxic: Lead, iron

Clinical

• Red flags

• Rapid onset
• Nausea and vomiting
• Inability to pass flatus
• Severe abdominal pain
• Distension
• Unexplained weight loss
• Unexplained iron deficiency anaemia
• Rectal bleeding
• FHx of colon cancer
• Fever
• Change in stool calibre

Clinical

• Examination

• Abdo/pelvis – hernias, masses, BS
• Ascites suggests ovarian or uterine neoplasm in women
• Rectal
  • Mass
  • Tone
  • Impaction
• Positive FOBT/gross blood with constipation suggests

• Cancer
• IBD
• Bowel ischaemia
• Stercoral ulcer

Imaging

• If obstruction suspected, AXR may show air-fluid and dilated loops
• If rectal impaction suspected, AXR may show:

• Colonic or rectal dilation with/without air-fluid levels
• Normal colon <6cm, normal rectum <4cm
• Obtain CT if ongoing suspicion of obstruction if normal AXR

Functional constipation

• Need at least 1.5L/day fluid, 10g fibre per day, exercise and laxatives
• No evidence for one laxative type over another
• Fecal impaction
• Must be manually disimpacted (may require sedation)

Intestinal pseudo-obstruction
 – Ogilvie’s sndrome

• Presents as acute large bowel obstruction with no evidence of distal colonic obstruction
• Colon may distend >10cm
• If bowel not decompressed, risk of perforation, peritonitis and death
• Predisposing factors include recent surgery, underlying neurological disorders and critical illness

Last Updated on October 28, 2020 by Andrew Crofton