Surgical Emergencies
A 76 year old man presents to the Emergency Department with a 6 day history of constipation. He recently injured his right knee and his GP had prescribed co-codamol. On examination you note hard impacted stool in the rectum. Which of the following is the most appropriate management step?
Answer:
- Treat faecal loading and/or impaction:
- For hard stools, consider using a high dose of an oral macrogol
- For soft stool (or ongoing hard stools after treatment with macrogol) consider starting or adding an oral stimulant laxative e.g. bisacodyl, senna or glycerol
- If response to oral laxatives is insufficient or too slow consider using a suppository e.g. bisacodyl +/- glycerol, a mini-enema e.g. docusate, sodium citrate
- If the response to treatment is still inadequate, consider prescribing a sodium phosphate retention enema
Constipation
Gastroenterology & Hepatology / Surgical Emergencies
Last Updated: 4th August 2022
Constipation is unsatisfactory defecation because of infrequent stools, difficult stool passage, or the sensation of incomplete emptying. Stools are often dry and hard or lumpy, and may be abnormally large or small.
Chronic constipation usually describes symptoms which are present for at least 12 weeks in the preceding six months. Faecal loading/impaction is retention of faeces to the extent that spontaneous evacuation is unlikely. Overflow incontinence is leakage of liquid stool from the proximal colon around impacted faeces.
Causes
Risk factors for developing constipation include:
- Social
- Low fibre diet or low calorie intake
- Lack of exercise or reduced mobility
- Difficult access or privacy to the toilet
- Psychological
- Eating disorders
- History of sexual abuse
- Anxiety or depression
- Physical
- Female sex
- Older age
- Pyrexia, dehydration, immobility
Secondary causes of constipation:
- Drugs
- Endocrine/metabolic causes
- Diabetes mellitus (with autonomic myopathy)
- Hypercalcaemia/hypermagnesaemia
- Hypokalaemia
- Hypothyroidism
- Uraemia
- Myopathic causes
- Amyloidosis
- Myotonic dystrophy
- Scleroderma
- Neurological causes
- Autonomic neuropathy
- Cerebrovascular disease
- Multiple sclerosis
- Parkinson’s disease
- Spinal cord injuries
- Structural abnormalities
- Anal fissures
- Haemorrhoids
- Colonic strictures
- Inflammatory bowel disease
- Diverticular disease
- Obstructive colonic mass lesions
- Rectal prolapse or rectocele
Complications
- Complications of chronic constipation include:
- Haemorrhoids or anal fissure.
- Progressive faecal retention, distension of the rectum, and loss of sensory and motor function.
- Faecal loading and impaction.
- Complications of chronic faecal loading and impaction include:
- Faecal incontinence, which can be embarrassing and distressing.
- Chronic dilatation of the colon may cause megacolon.
- Bowel obstruction, perforation, or ulceration.
- Recurrent urinary tract infections, obstructive uropathy.
- Rectal bleeding.
- Rectal prolapse.
Diagnosis
Suspect a diagnosis of constipation if an adult presents with defecation which is unsatisfactory because of infrequent stools, difficulty passing stools, or a sensation of incomplete emptying. Additional symptoms may include lower abdominal pain or discomfort, distension, or bloating.
Consider a diagnosis of constipation in the elderly if there are non-specific symptoms, such as:
- Confusion or delirium, functional decline.
- Nausea or loss of appetite.
- Overflow diarrhoea.
- Urinary retention.
Suspect a diagnosis of faecal loading or impaction if there is history of:
- Hard, lumpy stools, which may be large and infrequent (for example passed every 7–10 days), or small and relatively frequent (for example passed every 2–3 days).
- Having to use manual methods to extract faeces.
- Overflow faecal incontinence, or loose stool.
Examine the patient:
- Assess for signs of weight loss and general nutritional status.
- Perform an abdominal examination to check for abdominal pain, distension, masses, or a palpable colon (suggesting retained faecal masses).
- Perform an internal rectal examination, checking for:
- Anal fissures, haemorrhoids, skin tags, rectal prolapse, rectocele, skin erythema or excoriation (may be a sign of faecal leakage).
- Resting anal sphincter tone; rectal mass lesions and retained faecal masses, which may also be felt on external peri-anal palpation. Note: a faecal mass can be distinguished from a tumour or cyst, as firm pressure exerted by a finger will typically leave a palpable indentation in hard faeces.
- Pelvic floor dysfunction (if appropriate) — while asking the person to 'bear down', there may be paradoxical contraction of the anal sphincter on straining.
- Leakage of stool; rectal or anal pain.
Management
- Treat faecal loading and/or impaction
- For hard stools, consider using a high dose of an oral macrogol
- For soft stool (or ongoing hard stools after treatment with macrogol) consider starting or adding an oral stimulant laxative e.g. bisacodyl, senna or glycerol
- If response to oral laxatives is insufficient or too slow consider using a suppository e.g. bisacodyl +/- glycerol, a mini-enema e.g. docusate, sodium citrate
- If the response to treatment is still inadequate, consider prescribing a sodium phosphate retention enema
- Advice about increasing dietary fibre, drinking an adequate fluid intake and exercising
- If laxatives are required:
- Start with bulk-forming laxatives e.g. ispaghula husk (except in opioid-induced constipation)
- If stools remain hard, add or switch to an osmotic laxative e.g. macrogol or lactulose
- If stools are soft, but still difficult or pass or empty inadequately, add a stimulant laxative
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
