Sabiston Rectal Cancer/colon chemo Flashcards
(37 cards)
indications for neoadjuvant chemoradiation in Rectal Ca
clinically T3
node positive rectal cancers
cancers in close proximity of the sphincter in whom sphincter sparing is desired
Endoscopic submucosal dissection
- used for lesions that are superficial
- hollow cap is placed over the tip of the endoscope.
- After submucosal injection has been performed to lift the lesion away from the underlying muscularis
- suction is applied to the colonoscope when the cap is positioned over the lesion
- The lesion is drawn into the cap by suction
- the snare that fits around the cap then is tightened, cutting off the area of mucosa that has been aspirated into the cap
endoscopic submucosal resection
- for deeper through the muscle wall
- submucosal injection is performed to facilitate dissection of a lesion off the underlying colon wall after the margin has been scored
Traditional criteria for performing a local excision for a rectal cancer
- small lesions (<2 cm in diameter)
- well-differentiated cancers within reach of the index finger
- lesions that are mobile (not fixed).
- T1 lesions are ideal
- cautery is used to score a 1-cm margin around the lesion
- full-thickness incision is performed down to perirectal fat
Local excision is safe when performed for lesions that are located
lateral to or posterior to the rectum due to the presence of the mesorectum.
If these lesions are located in the anterior rectum in women, there is risk of iatrogenic rectovaginal fistula or, in the case of men, injury to the prostate
as one goes higher above 6 or 7 cm, there is concern that one may be intraperitoneal.
Low Anterior Resection
- After vascular division similar to left colectomies,
- peritoneal reflection of the rectum is divided at the level of the sacral promontory
- the rectum with its proximal mesorectum is gently pulled anteriorly entering the avascular “cotton candy” plane between the fascia of the mesorectum and the presacral fascia
- avoid any injury to the hypogastric nerves
- Anteriorly, the cul-de-sac is divided, and the rectum is dissected from the anteriorly located seminal vesicles in males and the vagina in females.
- The dissection is continued distally and the rectum and the mesorectum are divided 5 cm below the cancer
- For cancers located in the distal two thirds of the rectum, the dissection must be continued more distally, dissecting the rectum away from the prostate along the fascia of Denonvilliers.
- Posteriorly, the rectum has to be dissected distally, up to the level of the levator muscles en bloc with the entire mesorectum, keeping the mesorectal fascia intact
-colorectal anastomosis made with a circular stapler inserted transanally. - Air is then insufflated into the rectum through the anastomosis while the proximal colon is occluded, and the pelvis is filled with water in order to exclude the presence of leaks
- loop diverting ileostomy is performed to protect the distal colorectal anastomosis, especially in patients who have received preoperative chemoradiation.
what defines the quality of a TME
The integrity of the visceral fascia is a crucial point that defines the quality of a TME and is directly related to the DFS interval.
The proper excision along the anatomic plane is essential in order to obtain free circumferential radial margins, thus reducing the local recurrence rate below 5%; it also results in a significant decrease in the frequency of urinary and sexual dysfunction (retrograde ejaculation and impotence).
How long to keep The diverting stoma
The diverting stoma is usually maintained for at least 8 weeks after surgery and is closed only after the perfect healing of the anastomosis has been confirmed with a gastrografin enema or with endoscopy
Tumors located in ultradistal portion of the rectum (i.e., at the level of the dentate line or just above it)
- In young and fit patients with good preoperative sphincter function
- sphincters are not infiltrated with cancer and do not need to be sacrificed for oncologic reasons
- anastomosis between the colon and the anal canal is feasible.
- The ultradistal rectum dissection and reconstruction has to be performed transanally
- With a standard mucosectomy, the distal mucosa is peeled off from the internal sphincter. Ideally, 1 to 2 cm of mucosa above the dentate line should be saved
If the cancer is lower ans small > asymmetrical mucosectomy en bloc with the underlying internal sphincter on one side of the anal canal, sparing part of the distal mucosa and sphincter
If the cancer involves a larger part of the anal canal, an intersphincteric dissection must be done > the internal sphincter—responsible for resting pressure of the anal sphincter—is removed circumferentially: functional results are poor due to the loss of part of the sensation and the decrease of resting anal pressure.
Abdominoperineal Resection
- complete excision of both the rectum and the anus, along with the sphincter apparatus, must be performed along with creation of a permanent colostomy
- The IMA is divided, the descending colon is mobilized and divided above the rectosigmoid junction
- the rectum is dissected according to the TME principles to the level of the levator ani.
- colostomy aperture is created
- purse-string suture is placed around the anus
- an elliptical incision is made around the anus that is then excised en bloc with the sphincter.
- Dissection continues cephalad until the abdominal plane of dissection is reached.
- The specimen is removed through the pelvic incision and the perineum is closed in layers
- pelvis can often be filled with an omental pedicle
- perineal defect can be closed using a rectus abdominis flap or gracilis muscle flap.
APR Cont
wider excision has been proposed that allows a more cylindrical resection avoiding the risk of “coning” toward the rectum.
After the abdominal part of the operation is completed, the patient is rotated in a prone jackknife position.
A wider elliptical incision is made up to tip of the coccyx (that can be removed with the specimen) and the sphincter apparatus is removed en bloc with the levator ani in a cylindrical manner.
The wide perineal defect, if needed, can be closed with a biologic mesh or with a muscle flap.
APR Vs LAR in Recurrence
APR carries intrinsic risk of higher recurrence rates (up to 33%) compared to low anterior resection.
This is in part explained by the fact that APR is done in more aggressive cancers, but another explanation is the fact that there is an intrinsic higher risk of specimen perforation and a higher rate of positive circumferential margins (up to 40%) in patients undergoing APR
the residual colon may be too short to reach the pelvis for a tension-free anastomosis
- complete mobilization of the splenic flexure
- colon can be transposed through a “retroileal” transmesenteric route.
- This gives the surgeon 4 to 5 cm of additional length
If the colon is still under tension
- rotate the right colon.
- the middle colic and the right colic vessels are divided.
- The colon is transected at the site of ischemic demarcation (generally the hepatic flexure) and the residual right colon, whose blood supply now relies on the ileocolic pedicle, is rotated counterclockwise and mobilized to reach the rectal stump in the pelvis
The incidence of anastomotic in ileocolic and coloanal
from 1% to 3% in ileocolic anastomoses to up to 20% in coloanal anastomoses
Risk factors associated with postoperative dehiscence (Leak)
male gender
obesity
low extraperitoneal anastomoses
ASA score III to V
emergency operations
intraoperative complications
use of oral anticoagulants
nutrition status
hospital size and volume.
The majority of leaks become apparent between
the second and seventh postoperative days
with median time of 5.5 days,
but up to 12% can appear 1 month after surgery, making the diagnosis more challenging.
Tx If the leak is subclinical with minimal discharge from the drains and no systemic signs
managed conservatively with close clinical observation, broad spectrum antibiotics, bowel rest, and parenteral nutrition
If a small perianastomotic abscess is demonstrated with no abdominal collections or free air and without systemic symptoms, an attempt of percutaneous drainage should be made with close clinical observation
In patients with signs of peritonitis or signs of sepsis, even if minimal
reoperation is required and should not be delayed.
Abdominal exploration allows peritoneal lavage and reposition of new drains if needed.
If possible, a laparoscopic approach may be preferred in order to minimize septic contamination of the abdominal wall
what extra can be done in left-sided colectomies with leak
intraoperative endoscopic exploration of the anastomosis is helpful to determine the extent of the leak, and it also allows colonic lavage.
If the leak involves less than one third of the anastomosis and the abdominal contamination is minimal
a diverting stoma may be sufficient.
If the leak is larger or the anastomosis is disrupted, it has to be dismantled with the creation of a terminal stoma.
An ileocolic anastomosis in right-sided resections can be managed ideally by redo of the anastomosis, but if the patient is unstable, the anastomosis has to be dismantled and an end ileostomy constructed.
Necrosis of the Transposed Colon
- mimic an anastomotic leak
- must be immediately differentiated from a simple dehiscence because the treatment must be more aggressive.
The diagnosis is often made with abdominal exploration or intraoperative endoscopy > shows a clear demarcation line.
Its treatment requires immediate dismantling of the anastomosis with creation of a terminal stoma.
Bleeding
Major bleeding, with hemodynamic instability
> caused by small arterioles at the staple lining.
Treatment is usually endoscopic with positioning of clips at the suture line, epinephrine injection, or electrocoagulation.
If endoscopy fails, angiographic treatment is possible, but it might lead to ischemia of the anastomotic rim and subsequent possible further leaks
Twisting
- almost exclusively in extracorporeal ileocolic anastomosis after laparoscopic hybrid right colectomies
- immediate swelling and edema of the small bowel
- can lead to ischemia and gangrene of the intestine. Immediate redo of the anastomosis is necessary
Strictures
Risk factors are the use of a small-diameter stapler (25-mm circular staplers should never be used in colorectal anastomosis in adults)
anastomotic leaks
ischemia
radiation.
Treatment is usually endoscopic with balloon dilation or placement of radial incisions or positioning of endoluminal stents.
Redo of the anastomosis may be necessary in strictures not responding to the endoscopic treatment
