What is Constipation - Meaning and definition

Published by Roberto Wenk. Last updated date: March 25, 2021.

Infrequent or difficult evacuation of feces; stool is hard, dry, often small and round, and painful to pass.
These symptoms are associated with a variety of causes, including low dietary fiber intake, emotional or nervous disturbances, systemic and structural disorders, drug-induced aggravation, and infections.

DeCS. Health Sciences Descriptors. Internet. Accessed July 15, 2009.

Published by Roberto Wenk. Reviewed by Alison Ramsey. Last updated date: March 25, 2021.

Is a symptom (a subjective phenomenon) characterized by diminished frequency of defecation associated with difficulty or discomfort.
It is usually distressing when present, and occasionally poses various risks.
Associated symptoms include abdominal pain, bloating and distention, and sometimes anorexia and nausea. Untreated constipation may progress to obstipation, which may potentially lead to life-threatening complications associated with bowel obstruction.

Derby S and Portenoy KR. Topics in palliative care. Vol. 1. New York. Oxford University Press. 1997. pp. 95-130.

Published by Roberto Wenk. Reviewed by Alison Ramsey. Last updated date: October 31, 2018.

As with other symptoms, rational therapy should be based on a sound understanding of underlying physiology.
Four major components affect the production of a normal bowel movement: solid waste, water, motility, and lubrication.

Solid waste Too much or too little is a problem. The intestine is most efficient pushing intermediate volumes. Patients on fiber-poor diets may improve if fiber is added.
Note: In patients with minimal fluid intake or poor gut motility (e.g., the dying patient) additional fiber can worsen the situation, causing a 'soft impaction.'

Water content Stool water content depends on how much water we drink, our general hydration status, how much water is absorbed from and secreted into the intestine, and how fast stool moves through the bowel.
Any of these variables can be manipulated.
It is easiest to limit absorption (and increase secretion into the gut) by adding osmotically active particles that retain water (e.g., Mg salts, non-absorbable sugars such as sorbitol and lactulose, or polyethylene glycol [PEG]).
Note: Magnesium and phosphorus salts are contraindicated in renal failure. Hyperosmolar solutions may worsen dehydration by drawing body water into the gut lumen. Sickly-sweet sorbitol and lactulose may be difficult to for patients to tolerate. PEGs are flavorless and may be better tolerated.

Motility Patients with low-activity levels (bedridden, dying patients and patients with advanced neurodegenerative disorders) and use of certain drugs lead to motility problems. Senna preparations, which stimulate the myenteric plexus, are generally favored.
Note: Before increasing motility, evacuate existing constipated stool with an enema or cramping can result.

Lubrication simply eases passage and minimizes pain that can interfere with excretion. Most commonly used is dioctyl sodium sulfosuccinate (DSS), which decreases stool surface tension, much like soap.
Note: DSS is commonly used in combination with senna in opioid-induced constipation, but is generally inadequate as a sole agent.
Mineral oil can be used as an enema but should not be given PO, as pneumonitis can result if aspirated.
Glycerin suppositories can provide lubrication and draw in water due to osmotically active particles.

Medications that can cause or exacerbate constipation: opioids, anticholinergics, tricyclic antidepressants, scopolamine, oxybutinin, promethazine, diphenhydramine, lithium, verapamil, bismuth, iron, aluminum, calcium salts.

Adapted from Hallenbeck J. Palliative Care Network of Wisconsin. Fast facts and concepts #15. Constipation. Internet. Accessed on January 25, 2016.

Published by Roberto Wenk. Reviewed by Alison Ramsey. Last updated date: October 31, 2018.

Recommended medicines: DOCUSATE SODIUM and SENNA
Recommended formulations:
Docusate sodium
Capsule: 100 mg; Oral liquid: 50 mg/5 mL
Senna
Oral liquid: 7.5 mg/5 mL
Sodium picosulfate
Oral liquid 7.5 mg/mL

Definition
Constipation is defined as a condition in which there is difficulty in emptying the bowels, usually associated with hardened feces. There is a wide range in normal bowel habit and constipation cannot simply be defined in terms of stool frequency. Severe constipation includes obstipation and fecal impaction, which can progress to bowel obstruction.

Scope
• Management of constipation comprises identification and, if appropriate, treatment of possible underlying cause(s)
• Non-pharmacological management of constipation with attention to fluid intake, nutrition, and mobility is important but may be limited by anorexia and general debilitation in palliative care.

Overview of management options: laxatives
• Stimulant laxatives
• Osmotic laxatives (stool softeners)

Recommendations:
 Constipation is one of the most troublesome and persistent symptoms in palliative care patients and should be treated with laxatives.
 An extensive literature search confirmed there is limited good quality evidence to confirm the effectiveness of laxatives in constipation associated with palliative care in adults and children.
 There is a lack of evidence to support the use of one laxative, or combination of laxatives, over another and choice can be related to cost effectiveness and availability as much as to efficacy.
 Constipation is an almost inevitable consequence of opioid use. Laxatives must be prescribed for any patient receiving strong opioids, which is very common in palliative care.

Evidence for management of this symptom:
 The evidence supports the efficacy of laxatives in the management of functional constipation. However there is insufficient evidence to recommend one laxative over another.
 Considering the low level of evidence from clinical trials, the recommendation for docusate sodium, senna, and sodium picosulfate is based on expert opinion.

Additional supporting information for these medications:
DOCUSATE SODIUM
 A fecal softener that passively acts as an adjunct drug, docusate sodium is commonly listed as a laxative, but it does not directly stimulate bowel emptying.
 It is widely available with an established safety profile.
 It is available as both capsules and a liquid formulation
 It appears to be better tolerated, particularly at high doses, than lactulose, which is associated with bloating and colic.
 Approximate costs indicate a unit dose of docusate sodium (oral solution) is cheaper than lactulose.

SENNA
 Senna is the name given to the sennosides, which are hydroxyanthracene glycosides derived from senna leaves.
 Causes local irritation in colon, which promotes peristalsis and bowel evacuation. Softens feces by increasing water and electrolytes in large intestine.
 Senna is available in both oral liquid and oral tablet formulations. It is inexpensive and widely used as a stimulant laxative.

SODIUM PICOSULFATE
 Sodium picosulfate is hydrolyzed by colonic bacteria to the active form, which causes local irritation in the colon, which promotes peristalsis and bowel evacuation. The pharmacology is similar to senna.
 It is available in oral tablet formulations. It is inexpensive and widely used as a stimulant laxative.
 There is insufficient evidence for using sodium picosulfate alone for the management of this symptom:

Constipation, due to increase in gastrointestinal transit time is an inevitable consequence of opioid use. Therefore use of a stimulant laxative is the most appropriate choice in opioid-induced constipation.
 Laxatives and stool softeners may be needed at high doses, particularly in opioid-induced constipation in palliative care.
 Where high-dose stimulant laxative is insufficient to manage constipation, expert opinion supports the use of a combination of stimulant laxative and osmotic agent.
 Bulk-forming laxatives are unlikely to be appropriate in palliative care.
 There is little good quality trial evidence to confirm the effectiveness of laxatives in constipation associated with palliative care.
 In addition, there is a lack of evidence to recommend the use of one laxative, or combination of laxatives, over another.
 In the absence of any data showing greater efficacy of one agent over another, the choice of laxative is likely to be determined by factors such as availability of suitable
formulations, route of administration, pharmacokinetics, and cost-effectiveness.

Adapted from Radbruch L et al. Essential medicines in palliative care - An application for the 19th WHO Expert committee on the selection and use of essential medicines. Kindle Edition. Published in June 2013 by IAHPC Press. Available at https://www.amazon.com/Essential-Medicines-Palliative-Care-Application-ebook/dp/B00D7S2D0C

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