Large Bowel Obstruction

Obstruction distal to the ileocecal valve — see Small Bowel Obstruction for the proximal analog. Content below is from a textbook reference chapter (Sabiston Ch52 - Diverticular Disease, Obstruction & Pseudo-Obstruction), not primary literature — treat as background/orientation rather than critically-appraised evidence.

Classification and etiology

Mechanical (dynamic):

Functional (adynamic/pseudo-obstruction): colonic pseudo-obstruction (Ogilvie syndrome — see Colonic Pseudo-Obstruction (Ogilvie Syndrome)), toxic megacolon, paralytic ileus.

Colorectal cancer is the most common cause of large bowel obstruction in the US (50–60% of cases, per ASCRS Ch39 - Large Bowel Obstruction). Volvulus (mostly sigmoid) is more common worldwide in Russia, Eastern Europe, Africa, the Middle East, and India, and is estimated to cause roughly a third of large bowel obstructions globally — see the new dedicated page Volvulus for full detail on sigmoid/cecal volvulus, cecal bascule, mobile cecum syndrome, and ileosigmoid knotting.

Rare causes of LBO, per ASCRS Ch39 - Large Bowel Obstruction: intussusception (1–3% of adult mechanical bowel obstructions; unlike the classic pediatric triad, adults present non-specifically; malignancy is the lead point in 65–87% of cases, so a low threshold for surgical exploration/oncologic resection is warranted even though benign lead points — adenomatous polyps, GISTs, diverticular disease, villous adenoma of the appendix — do occur). Abdominal wall hernias (femoral, inguinal, umbilical, incisional, Spigelian, lumbar, diaphragmatic) are a very rare LBO cause given the colon's larger caliber and relatively fixed position; management follows bowel rest/fluid resuscitation principles and typically requires surgical exploration. Infection (actinomycosis causing a desmoplastic reaction with extrinsic compression; Mycobacterium tuberculosis, typically treated with antibiotics; schistosomiasis or other helminthic infections). Endometriosis accounts for <1% of bowel obstruction cases; intestinal endometriosis can cause luminal stenosis via serosal infiltration, most commonly at the rectosigmoid — management is mostly described via case reports (fecal diversion, stenting, resection); see Colorectal Endometriosis for diagnosis and surgical-technique detail (shaving vs. disc excision vs. segmental resection). Other malignancies (ovarian, gastric, pancreatic, bladder) can cause LBO via intraluminal obstruction, intramural blockage, or extrinsic compression, generally managed per clinical presentation/disease extent, sometimes with a defunctioning ostomy to permit staging/cancer therapy; lymphoma accounts for <0.5% of colorectal malignancies but can perforate and cause LBO, managed with resection ± anastomosis, defunctioning ostomy, stenting, or possibly chemoradiation.

Closed-loop obstruction

Both the proximal and distal segments of a bowel loop are blocked (classically volvulus or strangulated hernia; also an obstructing cancer with a competent ileocecal valve, which prevents retrograde decompression into the small bowel). High-risk pattern — progressive distension raises intraluminal pressure toward capillary pressure, causing ischemic necrosis and perforation with little warning. Must be promptly recognized and treated. Obstructing cancers with an incompetent ileocecal valve decompress retrograde into the small bowel and present less acutely.

Diagnosis

• Plain film: localizes/screens, shows degree of distension and ileocecal valve status.
• Water-soluble or IV-contrast CT: location and etiology (including diverticulitis, IBD, extraluminal causes), plus signs of ischemia/impending perforation.
• Flexible endoscopy: diagnostic and can be therapeutic (detorsion of sigmoid volvulus — see Volvulus for technique — or stenting).
• Labs: leukocytosis, elevated lactate, base excess, and decreased pH all associate with more severe/urgent presentations.

Treatment (etiology-specific)

• Sigmoid and cecal volvulus: see the dedicated Volvulus page for full detoursion/surgical technique detail — briefly, sigmoid volvulus is managed with endoscopic decompression (rigid or flexible sigmoidoscope, rectal tube proximal to the torsion) first-line, with interval sigmoid resection recommended given the high recurrence rate without resection; cecal volvulus, in contrast, is generally taken straight to surgery (ileocolectomy with anastomosis) given low nonoperative detorsion success.
• IBD-related obstruction: active-disease strictures often respond initially to steroids; fibrostenotic strictures may need surgery.
• Paracolic abscess: percutaneous drainage.
• Foreign body: usually endoscopic removal.
• Fecal impaction: stool softeners/laxatives plus manual disimpaction (bedside or OR).
• Hernia causing obstruction: usually requires surgery.
• Malignant obstruction:
• Low/mid rectal cancer: usually needs an initial diverting stoma to allow neoadjuvant chemoradiation before definitive surgery. Corroborating detail, per ASCRS Ch39 - Large Bowel Obstruction: it's rare for an extraperitoneal rectal cancer to cause LBO at all; emergent resection should be avoided if possible given the higher risk of suboptimal oncologic resection, with management instead focused on relieving obstruction (diverting loop colostomy, or a loop ileostomy if the ileocecal valve is competent, since proximal colonic distension can otherwise persist) to permit clinical staging and neoadjuvant therapy ahead of definitive TME. SEMS placement in the extraperitoneal rectum is problematic given stent migration/tenesmus risk.
• Sigmoid/left colon: endoscopic stenting as a bridge to surgery, or straight to surgery — see Endoscopic Polypectomy, EMR & ESD's Colonic Stenting section for technique, outcomes (fivefold lower permanent-stoma rate, more primary anastomosis, fewer wound infections vs. straight-to-surgery), and complication rates (perforation 5%, migration 4–10%, reobstruction 30%) — filling this page's previously flagged gap. Current guidance is risk-stratified: ESGE recommends against stenting as the preferred method in an otherwise-healthy patient, but supports considering it in higher-anesthetic-risk patients (ASA ≥3 or age >70); newer meta-analyses suggest oncologic safety broadly. That section now also carries detail on the named SEMS trials (Dutch Stent-In 2, Pirlet, Alcantara, CREST) and meta-analyses (Arezzo, Mashar) underlying this guidance, per ASCRS Ch39 - Large Bowel Obstruction — not repeated here to avoid duplication. Surgical options: Hartmann's procedure, or primary anastomosis with or without a diverting stoma. Staging history and current evidence, per ASCRS Ch39 - Large Bowel Obstruction: management of left-sided malignant LBO has evolved over the past 30 years away from the traditional two-/three-stage approach (loop colostomy → resection → colostomy closure) — a randomized trial found no significant difference in morbidity/survival between defunctioning colostomy alone and primary tumor resection, a finding endorsed by a Cochrane review, so the two-/three-stage approach is now generally reserved for very frail patients needing an expedited palliative procedure or those with unresectable disease. Surgical dogma has favored a Hartmann's procedure (resection + end colostomy) over primary anastomosis in this setting, given bowel wall edema and an unprepared colon; one RCT (Lim et al., n=49) found on-table lavage (OTL) took significantly longer than decompression alone (31 vs. 13 minutes) with no significant difference in overall morbidity or (underpowered) anastomotic leak rate (8% decompression-alone vs. 0% OTL). Segmental colectomy vs. subtotal colectomy is a related question — addressed by the SCOTIA trial (91 patients randomized to segmental colectomy ± OTL vs. subtotal colectomy): no significant difference in anastomotic leak or overall mortality, but the subtotal-colectomy group reported significantly higher bowel frequency (≥3 motions/day: 41% vs. 9%, p=.01) persisting to 4-month follow-up — a concrete functional cost to the more extensive resection. Multiple prospective case series report primary resection-with-anastomosis leak rates of 2–12% for malignant LBO, similar to reported leak rates for elective left-sided resections (2–8%), though non-randomized comparisons here carry confounding-by-indication risk (surgeons more likely to anastomose favorable cases and divert unfavorable ones). No RCT has examined whether a diverting loop ostomy is efficacious after resection and anastomosis for malignant LBO; one large series (743 patients) found no significant difference in anastomotic leak rate between primary anastomosis with vs. without a diverting loop ileostomy (7% vs. 8%) or reoperation (5.6% vs. 5.7%). The UK's Association of Coloproctology of Great Britain and Ireland (ACPGBI) malignant-LBO audit identified patient age, ASA grade, operative urgency, and cancer stage as significantly associated with in-hospital postoperative mortality.
• Ischemic/nonviable cecum: subtotal colectomy.
• Right-sided obstruction: right hemicolectomy with primary anastomosis (generally well tolerated even in the obstructed setting). Corroborating data, per ASCRS Ch39 - Large Bowel Obstruction: right-sided cancers still account for 30–40% of malignant LBO cases despite the right colon's wider diameter/typically liquid contents, which intuitively should make it less obstruction-prone. A prospective audit of 776 patients with malignant right-sided LBO (Mege et al.) found 92% underwent primary tumor resection and 82% had an anastomosis formed, with a 10% postoperative mortality rate and 14% anastomotic leak rate (replicated in other studies) — notably higher than the leak rates reported for left-sided malignant LBO above, though there's no robust data yet to guide which patients are better served by primary anastomosis vs. an ostomy (end or covering loop); intraoperative surgeon judgment (blood supply, tissue quality assessment) remains central to this decision.
• Unresectable disease: per ASCRS Ch39 - Large Bowel Obstruction, roughly 10–15% of patients with malignant LBO have unresectable disease at presentation (local tumor infiltration, metastatic disease, or a debilitated state precluding oncologic resection). Absent bowel ischemia or perforation, a diverting ostomy or SEMS can be considered for effective palliation.
• Unstable patients at high risk of anastomotic failure: temporary diverting stoma, or exteriorization of the anastomosis as a loop ileostomy.

Related pages

• Volvulus — full sigmoid/cecal volvulus, cecal bascule, mobile cecum syndrome, and ileosigmoid knotting detail, only briefly summarized above.
• Colonic Pseudo-Obstruction (Ogilvie Syndrome) — the functional/adynamic counterpart to this page's mechanical-obstruction focus.
• Endoscopic Polypectomy, EMR & ESD — full colonic stenting technique, trial, and outcomes detail underlying this page's malignant-LBO stenting summary.
• Diverticulitis — diverticular stricture as a mural-obstruction cause; see that page's Obstruction section for diverticulitis-specific detail.

Open items / gaps

• ~~Stenting-as-bridge-to-surgery outcomes/complication rates are now covered (see above, via Endoscopic Polypectomy, EMR & ESD), but still no primary trial data directly in this wiki — the two RCTs that were closed early for stent-related complications aren't independently ingested/appraised here yet.~~ Partially resolved by ASCRS Ch39 - Large Bowel Obstruction: those RCTs are now named (Dutch Stent-In 2, Pirlet, Alcantara) alongside the CREST trial and two meta-analyses, with headline results captured on Endoscopic Polypectomy, EMR & ESD — still not independently ingested from primary literature.
• ~~Cross-link to Diverticulitis for diverticular stricture as a mural cause once that overlap is worth spelling out explicitly.~~ Resolved by ASCRS Ch38 - Colonic Diverticular Disease: that page's new Obstruction section confirms diverticulitis-related LBO should be treated surgically (stenting generally unsuccessful in this benign condition, mirroring this page's general stenting-limitations content), with the key diagnostic task being differentiation of a diverticular stricture from colorectal cancer — see Diverticulitis for full detail.
• The SCOTIA trial, the Lim on-table-lavage RCT, the Mege right-sided-LBO audit, and the ACPGBI malignant-LBO audit (all per ASCRS Ch39 - Large Bowel Obstruction) are cited at the textbook/secondary level only — none independently ingested from primary literature.
• No data yet on right- vs. left-sided malignant LBO leak-rate differences beyond the single-study comparison noted above (14% right-sided vs. 2–12% left-sided) — worth checking whether this reflects a genuine anatomic/technical difference or differing case mix across the underlying studies.