Bowel Obstruction
Bowel obstruction may occur due to the disease itself or complex metastatic disease within the peritoneum. It can be caused by mechanical obstruction (narrowing of the intestinal lumen from either internal or external masses) or a reduction in motility or a combination of the two. This makes it a complex condition with multiple symptoms which can be difficult to control. Early referral to specialist palliative care is therefore recommended, especially in advanced disease.
Symptoms
Section titled “Symptoms”- Vomiting - often without much nausea
- Constipation although small volumes of stool or flatus may continue to be passed
- Abdominal pain either colicky or generalised
- Abdominal swelling
- Reduction in bowel sounds or high-pitched “tinkling” bowel sounds
Causes
Section titled “Causes”- Primary tumours - colonic or ovarian most commonly
- Peritoneal metastases
- Post operative adhesions or radiation fibrosis
- Bowel wall malignant infiltration disrupting peristalsis
- Autonomic nerve plexus damage due to tumour infiltration
- Medications e.g. opioids and antimuscarinics
- Reduced functional ability leading to faecal impaction
Non-drug treatment
Section titled “Non-drug treatment”- Surgical interventions - resection or stenting
- Nasogastric tube insertion to decompress stomach and drain volume
- Venting PEG insertion
- Hydration with IV fluids needs careful consideration in the context of cause, prognosis, and proposed treatments
- Consider nutritional factors
Drug treatments
Section titled “Drug treatments”Presence of colic (more likely in mechanical obstruction)
Section titled “Presence of colic (more likely in mechanical obstruction)”- Constant abdominal pain may respond to opioids (a syringe driver may be required as vomiting and obstruction will reduce or prevent oral absorption)
- Stop bowel stimulant medications such as senna and prokinetics
- Anticholinergic drugs (hyoscine butylbromide) may reduce colic and improve nausea by reducing gastric secretions
- Levomepromazine is a second-line antiemetic, with or without colic
- If vomiting persists despite two or more antiemetics plus hyoscine butylbromide, other anti-secretories may be considered (octreotide, granisetron)
Without colic (more likely in functional obstruction, e.g. ileus)
Section titled “Without colic (more likely in functional obstruction, e.g. ileus)”- Constant abdominal pain may respond to opioids (a syringe driver may be required as vomiting and obstruction will reduce or prevent oral absorption)
- Nausea without colic may improve with a prokinetic antiemetic
- In partial or intermittent obstruction, softening laxatives may be beneficial, but avoid stimulant or osmotic preparations
- Levomepromazine is a second-line antiemetic, with or without colic
- If vomiting persists despite two or more antiemetics plus hyoscine butylbromide, other anti-secretories may be considered (octreotide, granisetron)
Other options when a malignant mass is causative
Section titled “Other options when a malignant mass is causative”- Chemotherapy and radiotherapy may be considered to shrink tumour bulk and relieve obstruction
- If the patient is too unwell or chemoradiotherapy is not planned, dexamethasone 8-16 mg daily may reduce oedema at tumour sites and alleviate obstruction