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Malignant bowel obstruction ( MBO )

Criteria for Malignant bowel obstruction ( MBO ) were defined in 2007 at the International Conference on MBO as Clinical evidence of bowel obstruction Bowel obstruction beyond the ligament of Treitz and Intraabdominal primary cancer with incurable disease or Non-intraabdominal primary cancer with clear intraperitoneal disease


Recognised complication of advanced pelvic or abdominal malignancy Global prevalence is reported to range from 3 % to 15 % of cancer patients Its a challenging problem and can be seen in up to 51 % of patients with colorectal , ovarian , pancreatic and gastric cancers Most frequently reported with
○ colon ( 25 % to 40 % )
○ ovarian cancer ( 16 % to 29 % )- dominant cause in women
○ stomach ( 6 % to 19 % )
○ pancreas ( 6 % to 13 % )
○ bladder and endometrium
percentages quoted may vary slightly between studies Primary cancer of extraabdominal origin leading to MBO are due to peritoneal infiltration of breast cancer and melanoma Seen more commonly in women ( with advanced gynaecological cancers ) MBO can be the presenting feature of patients with advanced or terminal disease


Obstruction can be at any level /more than 1 level Small bowel obstruction is 4 to 5 times more common than large bowel Small and large bowel obstruction can happen simultaneously It can be complete or partial / acute or subacute Peritoneal carcinomatosis – often previously diagnosed , should raise the index of diagnostic suspicion Pathological process can be
○ mechanical ( related to extrinsic bowel compression
or endoluminal obstruction )
○ functional ( associated with tumour infiltration of autonomic nerve plexuses )
○ paraneoplastic syndromes
○ electrolyte abnormalities due to dehydration , vomiting
○ drug induced ileus ( opioids , anticholinergics , chemotherapy ) In the real world it is most likely that a mixed picture with mechanical and ileus-related elements is seen Several process contribute to further worsening for e.g when obstruction is at several levels in subacute obstruction
○ gut motility is further inhibited due to release of substance P , nitric oxide , acetylcholine , somatostatin and VIP ( also contribute to mucosal oedema )
○ ↑↑ retention of secretions leads to ↑↑ in intraluminal pressure
○ patients often are on drugs as opioids , are immobile , have poor dietary intake and have neural dysfunction –> leading to a mixed picture of mechanical obstruction and ileus.


It is important to take into account that even in cancer patients 
the obstruction may be due to a benign cause in a relatively high percentage of patients as
 stricture , hernia , adhesions radiation enteritis intra-abdominal bands fecal impaction post.


Usually associated with a poor prognosis and low median survival MBO has adverse impact on QoL In patients with inoperable MBO caused by advanced cancer mean survival 
is 4-5 weeks Another study has shown that up to 51 % of women with recurrent ovarian cancer developed MBO and their median survival following MBO diagnosis ranged from 45 to 169 days Presence of ascites in MBO patients is a well known factor of poor prognosis.


Presentation will depend upon
○ level of obstruction ○ type ○ duration ○ complete or partial

Partial obstruction allows for passage of some contents distal to the obstruction

Subacute bowel obstruction is an incomplete obstruction of the bowel lumen and patients with subacute bowel obstruction or chronic large bowel obstruction may have colicky pain , abdominal distension and vomiting which are less pronounced say in comparison to complete bowel obstruction
 Classically described presentation is
○ colicky abdominal pain
○ anorexia 
○ nausea and vomiting ( based on level of obstruction )
 nausea would be present in nearly 100 % of patients with established MBO
○ obstipation (severe constipation when the patient is unable to pass flatus ) -a duration of previous 72 hrs is important ie not passing stool or emission in last 72 hrs indicates progression to more definitive obstruction

Colic happens as the bowel tries to push the contents against the obstruction and comes in waves lasting few minutes
 Presentation can also be with paradoxical diarrhoea and faecal incontinence ( overflow diarrhoea ) in cases of incomplete obstruction
 Insidious presentation with weeks of increasingly frequent and prolonged self limiting sub occlusive episodes marked by nausea , emesis , brief obstipation , colicky abdominal pain and distension
 Small bowel obstruction -symptoms that may indicate SB obstruction include large-volume bilious emesis , anorexia , periumbilical pain and mild to moderate abdominal distension
 Large bowel obstruction – markedly distended abdomen , squalid small volumes emesis and localised pain
 Ileus- will have similar effect as BO and will present as absent bowel sounds , distension


Examination -Haemodynamic state Dehydration / nutritional state Any colic visible by bedside Distension – previous incisions / hernias Abdominal distension may not be present if the obstruction is high and it may be difficult to palpate in obese patients Palpation ? any mass palpable for e.g woody abdomen secondary to diffuse malignant infiltration Mild diffuse abdominal tenderness is common but peritoneal findings may suggest strangulation Percussion -tympanic note of bowel obstruction or a dull percussion note in ascites Bowel sounds- hyperactive in true obstruction / borborygmi but if a paralytic ileus is the cause bowel sounds may be absent Vomitus ? bilious ? feculent DRE – is essential as severe constipation can mimic worsen or co-exist with symptoms of intestinal obstruction Neither normal bowel sounds nor stool in rectum excludes the diagnosis of BO


Imaging -Plain abdominal XR is inexpensive and can show constipation but is less accurate and has limited utility in MBO Multidetector contrasted CT ( MDCT ) is the diagnostic tool of choice for MBO ( inexpensive and widely available ) Gadolinium- enhanced MRI offers comparable accuracy as CT and may be superior in evaluating the extent of peritoneal dissemination


Management -Management would be individualized based on the level of obstruction , clinical stage of cancer ,overall prognosis , nutritional status , presence of ascites , response to previous therapy , advanced directives as well as patients performance status Multidisciplinary approach is recommended which includes primary care physicians , surgeons , oncologists and palliative care specialists Above factors should guide in determining individual goals of care and stratification Medical management is the mainstay of treatment although at the current moment their is limited data to support a standardized clinical management strategy It has been shown that medical management is associated with less hospital utilization , fewer in-hospital deaths and more frequent discharges home – but readmission rates for obstruction are high The aim of treatment is often to achieve adequate symptom palliation and to optimize the patients QoL over the remaining lifespan while to minimize the proposed intervention morbidity Management of MBO remains challenging as decision making needs delicate balance between pros and cons of intervention Three broad categories of interventions include.


Nausea and vomiting -intractable N/V affects majority of MBO patients optimal management involves targeting various central and peripheral receptors causes are usually multifactorial but activation of CTZ and gastrointestinal afferent fibers are implicated please check local policy of preferred agents as superiority of any particular agent is largely based on expert consensus use antiemetics via parenteral route and give regularly few examples are as follows
○ haloperidol -useful in post-operative nausea is often described as drug of choice in MBO patients ( has less sedative effects )
○ other 2nd line agents include metocolpramide , olanzapine , ondansetron and chlorpromazine
○ Aaron J et al in the Journal of Oncology Practice mention that olanzapine has been validated in both acute and chronic nausea in palliative care setting of advanced malignancy with negligible treatment related toxicity
○ prokinetic agent metoclopramide may help resolve incomplete obstruction and in cases of functional BO but is not recommended in cases of complete BO or gastric outlet obstruction
○ distinguishing between partial and complete bowel obstruction may not always be easy Cyclizine is also recommended via s/c route Hyoscine butylbromide could be used if the patient is experiencing colic with nausea specialists may consider using a phenothiazine derivative -levomepromazine if everything else fails


Antisecretory agents -helps reduce bowel edema and intraluminal hypersecretion agents available include somatostatin inhibitors , PPIs, anticholinergics and H2 antagonists Octreotide ( somatostatin analogue ) can inhibit the release of multiple hormones , ↓↓ secretions , peristalsis and splanchnic blood flow while enhancing water and electrolyte absorption
○ some studies have shown superiority of octreotide over anticholinergic drugs but definitive conclusion about its efficacy in such settings is lacking
○ check local guidance as some Trusts may use it as 1st line anti-secretory agent PPIs and H2 blockers are utilised as part of multidrug regimen


Corticosteroids -modulate the inflammatory response associated with bowel obstruction indirect analgesia secondary to minimising distension and central antiemetic effect several UK guidelines advocate a short ( e.g 5 days ) trial of dexamethasone s/c 6 to 16 mg in all patients it does not affect length of survival


Analgesia -parenteral analgesia with use of opioid and non opioid medications to target pain strong opiates like morphine / diamorphine are therapy of choice if colics pain anticholinergics like hyoscine butylbromide can be helpful


Laxatives -to treat/prevent co-existent constipation laxido can be effective if volume of fluid can be tolerated docusate sodium can be an alternative no laxative should be used in complete obstruction


Endoluminal and decompressive interventions -Nasogastric tube
○ wide bore NG tube is an accepted first line intervention to provide relief from nausea , emesis and painful abdominal distension
○ usually well tolerated other than mild discomfort related to placement but long term use is associated with ↑↑ ed risk of aspiration , sinusitis and ulceration
 Palliative Venting gastrostomy -
○ usually 48-76 hrs after NGT is decompression is still needed 
○ to relieve refractory N&V particularly if the obstruction is at multiple levels with gut dysfunction and surgery is not possible
○ can be very effective and are better tolerated than NG tubes and allows the patient to eat and drink & be cared at home
○ allows for removal of NGT
○ complications of venting gastrostomy include peristomal leakage , haemorrhage , cellulitis , clogging or dislodgement of the tube
 Endoscopic stenting – to alleviate symptoms in those not fit for surgery related to a single point of obstruction.


Surgery for MBO is associated with very high rates of post-operative complications and mortality Patients often have advanced cancer , show cancer related catabolism and malnutrition, have other co-morbidities Despite reservations and risk of complications there may a role for surgical management in appropriately selected patients.


  1. Thaker, Darshit A et al. “Palliative management of malignant bowel obstruction in the terminally ill patient.” Indian journal of palliative care vol. 16,2 (2010): 97-100. doi:10.4103/0973-1075.68403
  2. Guidelines for the Medical Management of Malignant Bowel Obstruction Cheshire and Merseyside Palliative and End of Life Care Strategic Clinical Network Group Guidelines *Malignant_Bowel_Obstruction_2015_FINAL_S__G.pdf (
  3. Constipation and malignant bowel obstruction in palliative care Physical Problems Volume 48 Issue 1 P18-22 January 01, 2020
  4. Winslet MBarraclough KCampbell Hewson GSubacute small bowel obstruction or chronic large bowel obstruction doi:10.1136/bmj.n1765
    ( Abstract ) 
  5. O’Connor B, Creedon B. Pharmacological treatment of bowel obstruction in cancer patients. Expert Opin Pharmacother. 2011 Oct;12(14):2205-14. doi: 10.1517/14656566.2011.597382. Epub 2011 Jun 30. PMID: 21714777
  6. .Malignant Bowel Obstruction Nadege T Fackche MD and Fabian M Johnston MD , MHS Advances in Surgery , 2021-09-01 , Volume 55 , Pages 35-48
  7. Considerations in the Management of Malignant Bowel Obstruction Caitilin T Yeo BSc , MD and Shaila J Merchant MSc , MHSc , MD , FRCS Surgical Oncology Clinics of North America , 2021-07-01 , Volume 30 , Issue 3 , Pages 461-474
  8. Aaron J. FrankeAtif IqbalJason S. StarrRajesh M. Nair, and Thomas J. GeorgeJr

    Journal of Oncology Practice 2017 13:7426-434

  9. Tuca, Albert et al. “Malignant bowel obstruction in advanced cancer patients: epidemiology, management, and factors influencing spontaneous resolution.” Cancer management and research vol. 4 (2012): 159-69. doi:10.2147/CMAR.S29297
  10. Huang X, Xue J, Gao M, et al. Medical Management of Inoperable Malignant Bowel Obstruction. Annals of Pharmacotherapy. 2021;55(9):1134-1145. doi:10.1177/1060028020979773


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