Large Bowel Obstruction Flashcards
MC Cause of Large Bowel Obstruction
- Colorectal carcinoma is the most common etiology
- Diverticular disease is the second most common > Chronic inflammation in the sigmoid can cause a stricture
complicated diverticulitis with significant inflammation > inflammatory stricture, phlegmon, or abscess.
- The third most common cause of large bowel obstruction is volvulus,
involves the mesentery > High risk of strangulation and ischemia - Functional causes of large bowel obstruction are less common > colonic pseudo-obstruction (Ogilvie’s syndrome), narcotic-induced adynamic ileus, and adynamic ileus due to systemic illness such as toxic megacolon from Clostridium difficile infection.
How many cm of Cecum is concerning
Cecal distension of 9 to 12 cm on plain abdominal film is concerning for impending perforation.
MC Procedures associated with Colonic Pseudo obstruction
Recent orthopedic or gynecologic procedures
What causes air-fluid levels of the small bowel with distension.
- Incompetent ileocecal valve > reflux of contents back into the small intestine may reflect as air-fluid levels of the small bowel with distension.
the classic findings of Volvolus on plain films
- Sigmoid volvulus > “bent inner tube” sign or
“omega loop.” - Cecal volvulus > “coffee bean”
Other classic findings of volvulus and obstructing cancer with Contrast Enema
“bird’s beak” deformity at the site of a volvulus
“apple core lesion” at the site of an obstructing cancer.
Contrast Enema Result in Pseudo obstruction and fecal impaction
- Colonic pseudo-obstruction > contrast will freely flow without evidence of transition point.
- fecal impaction > contrast may be therapeutic.
Who requires emergent intervention.
- Patients who present with impending perforation on imaging
- pneumoperitoneum (evidence of existing perforation),
- peritonitis
- clinical signs of sepsis
The Goal of Surgery
Decompress the Bowel
Stoma or No stoma ?
- under emergent setting where the patient is unstable or with gross intraabdominal contamination
> primary anastomosis is contraindicated
Segmental resection with an end stoma is the safest choice.
Rt Side vs Lt Side Lesions
Rt Side, proximal to the splenic flexure
> right hemicolectomy with end ileostomy
Lt Side lesions >
Hartmann procedure should be performed.
When is subtotal colectomy is indicated
- perforation
- large serosal injuries
- or synchronous lesions are found at the time of exploration.
- When performing a subtotal colectomy in the emergent setting, creation of an end ileostomy is often necessary.
when to Consider Diverting loop colostomy ?
- unresectable malignancy
- diffuse carcinomatosis
- severe inflammation
- patients who are extremely unstable
> a diverting loop colostomy proximal to the obstruction is indicated
Loop Vs End Colostomy
- A loop colostomy is preferred over an end colostomy as the blind end that is left in the abdomen may perforate.
- A colostomy relieves patients of their symptoms and limits subsequent concerns for an anastomotic leak.
colostomies associated Morbidity
- high rates of parastomal hernia (50%)
- decreased quality of life
- and low rates of stoma closure.
Non emergent Setting for Rt side Lesion
In the absence of generalized peritonitis, perforation, or sepsis
- Rt side obstruction and the point of obstruction is proximal to the splenic flexure >
right hemicolectomy with primary anastomosis
low anastomotic leak rates (< 5%)
Alternative ?
- Right hemicolectomy with primary anastomosis and proximal diverting loop ileostomy.
- Considered in patients with high Concern for leak and may delay chemo later
> Small bowel dilation
> immunosuppressed
> on steroids
> or malnourished from chronic obstruction
Additionally, reversal of a loop ileostomy is a less morbid surgery than reversal of an end ileostomy.
Obstructing lesion arising in the descending sigmoid colon, rectum, or anus
- Traditionally, primary anastomosis at the initial procedure was avoided because of the higher rates of anastomotic leak (20%).
- Currently, segmental resection with primary anastomosis is a good option for carefully selected patients if the proximal colon is not dilated significantly.
High Risk patient with Left side Obstruction
- Segmental colectomy, anastomosis, and a diverting loop ileostomy.
- This still allows for diversion of the fecal stream
> in the event of an anastomotic leak
intraabdominal sepsis is contained and can usually be managed nonoperatively with percutaneous drainage and antibiotics
Loop ileostomy vs Hartmann’s
- Loop ileostomy reversal is a less invasive operation and patients will more likely undergo this procedure to have their intestinal continuity restored as compared to reversing a Hartmann’s procedure.
Colonic Lavage
- Colonic lavage may permit a single-stage surgery in the setting of a left-sided large bowel obstruction.
- Following the resection
- colon fully mobilized at both hepatic and splenic flexures
- Allow descending colon to extend beyond the abdominal cavity
- Appendectomy is performed, and a catheter is passed into the cecum and secured with a purse-string suture.
- Catheter is attached to a large bag of warmed saline
- If the cecum is thinned, insert the catheter into the terminal ileum
-The staple line at the distal segment of colon is opened and a generous length of sterile corrugated tubing is placed into the lumen of the descending colon. - 3-6 Liters of warmed saline is then flushed through the colon.
- This is continued until the effluent clears
With Colon Lavage, Before Anastomosis Do What ?
Before the anastomosis,
- the colon is inspected for injuries that may have occurred during the lavage.
> anastomosis is then performed
either end-to-end or side-to-side if there is a large bowel size discrepancy.
Alternative Method ?
A modified version of this method uses a Y-shaped connector
> One limb allows for retrograde infusion of saline through the descending colon and the other is attached to drainage tubing.
> obviates the need for the appendectomy or cecostomy.
Indications for Stent and Why ?
- Palliation of an inoperable obstructing lesion (e.g., stage IV colorectal cancer)
- Temporizing “bridge” to definitive therapy in a patient with a curable or potentially curable lesion.
To Allow colonic decompression
medical optimization
endoscopic evaluation for synchronous lesions
and increases the likelihood of a single-stage operation.
Contraindications to stent placement
- Any indications for emergent surgery
- an abscess/ infection closely associated with the lesion
- Short and tethered colon
- Lesion less than 5 cm from the anal verge.
MC Feared Complication of Stent and how to decrease it ?
- Perforation
> To mitigate the procedural risk of perforation, insufflation with carbon dioxide is preferred over room air because of the dramatically faster clearance time.
The most common stents used
- uncovered, self-expanding metal stents (SEM).
- Through-the-scope (TTS) and over-the-wire, also referred to as non-TTS,
Pre Stent Should do What ?
- No need Abx
-Gentle tap water enemas should be used to evacuate stool - Oral bowel preparation > only if the obstruction is partial
How to put stent ( overlap ) ?
Most TTS systems encourage a proximal and distal stent overlap of 2 cm
To reduce development of rapid restenosis
the intraluminal diameter at the midportion of the stent should be at least 24 mm.
If imaging does not demonstrate flaring at one or both ends of the stent
- Additional stenting is likely necessary and typically done in an end-to-end fashion.
Patients should expect gradual improvement of symptoms over
- 3 to 5 days as the stents reach maximal expansion and the colon decompresses.
For descending colon and beyond, patients are advised to consume
- low-residue, low-fiber diet along with daily laxatives (e.g., polyethylene glycol) to promote soft stools that are unlikely to become impacted at the stent.
When should definitive therapy happen after Stent
- Should be done within 7 to 14 days following placement of the stent.
- Patients who receive stenting for palliation and the anticipated duration greater than 2 weeks have a significantly increased risk of stent complications, primarily perforation.
Success Rate , Complications, Factors for failure
- Successful stent placement for acute large bowel obstruction between 70% and 90%.
- 25% Risk of Complications
> Most common complications stent migration, reobstruction, and perforation.
perforation > 4% to 5% of patients.
Intrinsic factors that may increase the risk of stent-related perforation include
> longer segment of obstruction (median length of 64 mm), benign etiology, and extraluminal origin.
The two primary goals for management of sigmoid volvulus
- Relieve the obstruction
- prevent recurrence.
The gold standard in the management of uncomplicated sigmoid volvulus is endoscopic detorsion,
gross inspection
and placement of a drainage catheter
(successful in up to 70%– 90% of patients).
Converts an emergency situation into an elective one
Failure of endoscopic reduction and/ or presence of bowel ischemia is an indication for emergent resection
Rate of recurrence
50% to 80% range.
Types of cecal Volvulus
- Axial cecal volvulus: A twist of the intestines in which the affected cecum remains in the right lower quadrant
- Loop cecal volvulus: The cecum and terminal ileum are twisted in the axial plane and the affected cecum typically lies in the left upper quadrant.
- Cecal bascule: A redundant cecum folds in the sagittal plane onto itself and the proximal ascending colon leaving the affected cecum within the right upper quadrant.
Which one is common
- Types 1 and 2 are the most common, accounting for roughly 80% of cecal volvuli.
Unlike types 1 and 2, type 3 does not exhibit torsion.
Endoscopy role ?
Endoscopic management is not recommended for cecal volvulus or bascule because of a low rate of successful detorsion, and colonic ischemia can be missed in up to 25% of patients.
Management
- Nonviable cecum > resection and creation of end ileostomy, with consideration for mucous fistula.
- If the cecum is viable or with patchy ischemia, there is less consensus on the appropriate management.
- Nonresectional options include detorsion with cecopexy and cecostomy.
Distillation of the current data favors
ileocecectomy with primary anastomosis for patients with acute cecal volvulus, even when bowel appears viable.
Patient with Ogilvie can pass stool ?
A significant portion of these patients will continue to pass loose stool.
The gold standard imaging modality
CT
> Diffuse colonic distension, possible transition point near splenic flexure, and, importantly, no evidence of a mechanical obstruction.
Non Op Tx
- Aggressive fluid resuscitation
- repletion of serum electrolytes
- cessation of possible offending medications
(e.g., opioids, anticholinergics) - bowel rest.
- Nasogastric and rectal tubes for decompression
- Continued for up to 72 hours.
Monitor the patient > serial imaging and physical examination.
Failure to improve over this period
- Neostigmine. ( antiacetylcholinesterase mechanism )
> increases the availability of acetylcholine
> improved contractility and generalized motility.
Before Given Neostigmine
- Before administration
> Transferred to a unit with continuous cardiopulmonary monitoring
> Keep atropine, glycopyrrolate, or both Ready
Neostigmine is contraindicated in
- Suspicion for ischemia or perforation
- severe acute bronchospasm
- poorly controlled cardiac dysrhythmia
- or pregnancy.
How its given
- Continuous monitoring
- the first dose > 2 to 5 mg is given intravenously over 1 to 5 minutes.
- Success is achieved with passage of flatus, stool, or decreased abdominal distension.
- Patient observed > next 80 minutes.
- Atropine and glycopyrrolate should be readily available if there is development of bradycardia or bronchospasm, respectively.
successful in more than 90% of cases.
or patients who are partial responders or nonresponders after one dose
Second Dose can be administered with high rates of success.
who fail to respond to neostigmine, the next step in management is
- Endoscopic decompression
- clinical success in 95% > single intervention
- 18% needed at least one additional colonoscopy
for patients who did not receive a decompression tube at the time of the procedure, clinical success was only achieved in 25%.
technical considerations
- insufflation minimized with carbon dioxide
- The scope advanced into the right colon.
- A decompression tube is strongly recommended should originate from the right colon
- Evidence support the use of polyethylene glycol solution after endoscopy and neostigmine to lower recurrence rate.
- Remove as much gas as possible during withdrawal
If endoscopic decompression is not possible or unsuccessful
- Percutaneous cecostomy
Then Last :
- Operative management > minilaparotomy assess the viability of the colon
If no evidence of perforation or ischemia, a tube cecostomy or surgical cecostomy may be sufficient.
If ischemia > affected region should be resected, including subtotal colectomy if indicated.
Primary anastomosis is not recommended but rather the creation of end colostomy with or without mucous fistula.
