May i know why a retained gauze after surgery in an abdominal cavity erodes the bowel wall or migrate through it but spares the blood vessels and patient never present with tertiary hemmorhage ?
When it erodes the bowel wall is it always associated with infection? is there always peritonitis?
No interestingly it usually forms a fistulous tract and forms an enterocutaneous fistula . There are instances where the guaze actually migrates into the bowel lumen and is retrieved per rectally
= Have you ever used a seton (?) or noted that non-absorbable sutures (?) or fragments of glass, metal, staples, etc are bloodlessly extruded by the tissues thru the skin without bleeding?
=The same mechanics when healing outpaces the erosion.
As everyone knows, mesothelial cells respond to injury, inflammation, foreign body and wall this site off. So the cotton gauze left intraabdominally must also be walled off by parietal and visceral peritoneum. Visceral peritoneum the most commonly taking part in this process should be the most mobile one. Why intestine? The first reason is that intestine occupies the largest part of the abdominal cavity so the possibility of its participation is the highest. The second reason is that small bowel is the the most mobile organ. Besides intestine, greater omentum almost always takes part in walling off the injured mesothelium. This process is similar to appendiceal mass formation. Why not blood vessels? The possibility to cantact with blood vessels is very low.
Why the blood vessels aren't injured within the process of erosion, fistula formation? The first reason is that the vessels that are around the site of erosion are mostly small ones and they are thrombosed in response to inflammation. So a lot of vessels are eroded, of course, just they are small ones and thrombosed. The second reason, in my opinion, is the intraluminal pressure which is higher in blood vessels than in intestine. I think, if we put a gauze intraabdominally in the neighborhood with the both a small bowel loop and a magistral artery, the abscess formed will develop towards intestinal lumen rather than arterial lumen. However, this issue is a subject for experiment.
In addition, blood vessels can be injured by retained sponge also when it is placed in soft tissues of thigh, for example, as shown in this case: http://www.ncbi.nlm.nih.gov/pubmed/1439900.
As everyone knows, mesothelial cells respond to injury, inflammation, foreign body and wall this site off. So the cotton gauze left intraabdominally must also be walled off by parietal and visceral peritoneum. Visceral peritoneum the most commonly taking part in this process should be the most mobile one. Why intestine? The first reason is that intestine occupies the largest part of the abdominal cavity so the possibility of its participation is the highest. The second reason is that small bowel is the the most mobile organ. Besides intestine, greater omentum almost always takes part in walling off the injured mesothelium. This process is similar to appendiceal mass formation. Why not blood vessels? The possibility to cantact with blood vessels is very low.
Why the blood vessels aren't injured within the process of erosion, fistula formation? The first reason is that the vessels that are around the site of erosion are mostly small ones and they are thrombosed in response to inflammation. So a lot of vessels are eroded, of course, just they are small ones and thrombosed. The second reason, in my opinion, is the intraluminal pressure which is higher in blood vessels than in intestine. I think, if we put a gauze intraabdominally in the neighborhood with the both a small bowel loop and a magistral artery, the abscess formed will develop towards intestinal lumen rather than arterial lumen. However, this issue is a subject for experiment.
In addition, blood vessels can be injured by retained sponge also when it is placed in soft tissues of thigh, for example, as shown in this case: http://www.ncbi.nlm.nih.gov/pubmed/1439900.
=The human organism always responds to stress by feedback. If it has sufficient healing capacity ( e.g. not Addisonian) the organism will respond to any stressor --> inflammatory response.--> WBC, fibroblasts, etc. will produce scarring.during proliferative phase --> walling off of the foreign body by scarring.
If it is sterile --> no abscess. If contaminated --->abscess. If intestinal movement is active and walling off is slower--> the sponge will erode the intestine. If the intestine is quiescent --> repair will be faster and walling off occurs.
THe Blood Vessels in the area are movement passive and immobile therefore the scarring, by walling off, protects them. ( Inflammatory fluids seep out of the advanced capillaries and angiogenesis only follows the process.to continue walling off the cotton.
This is the basic principle when we pack an abscess cavity with gauze strips then pull it out to debride and allow the normal and clean granulation tissue to push out and obliterate the cavity.
While I agree with a lot of what has been written, there are a couple of basic facts that should be kept in mind:
1. The mesothelium forms a protective barrier, that regenerates rapidly, thus intraperitoneal foreign bodies are likely to remain within that cavity to begin with.
2. There are a large number of potential spaces within the abdominal cavity, and once they are breached, conditions change.
3. Thus, following an open abdominal aneurysm repair, for example, if a swab is left retroperitoneally, it lies behind the weight of the small bowel and posterior to the mesothelium; in which case it is as likely to form a foreign body mass and may erode into the major vessels as an intra-peritoneal swab.
4. Foreign bodies follow the path of least resistance, as far as pressure and resistance gradients are concerned. This is the reason why abscesses tend to point cutaneous lay, rather than towards the high pressure potential retroperitoneally space. With a retroperitoneally swab, once repetition evaluation takes place, a swab would act as a high pressure space-occupying lesion, more likely to erode into the thinner-walked, lower pressure IVC than the thick-walled, elastic, expansive wall of the aorta.
5. Intra-peritoneal acute laparotomies are more common, especially since the introduction of EVAR, than emergency laparotomies for ruptured AAAs, thus the chance of a swab being left intra-abdominally is likely to be more common than retroperitoneally.
6. The pelvic peritoneum is thicker and more resilient than the abdominal peritoneum; thus, pelvic abscesses remain loculated in situ much longer, causing signs and symptoms of sepsis, but still allowing drainage to occur before fistulation does. This is also the reason why in certain cases, but be can wait for deep pelvic abscesses to point into the infra-pelvic-peritoneal rectum allowing transanal drainage, instead of performing a further laparotomy.
Of course, the role of the omentum in localising any intra-peritoneal foreign body into a phlegmon and subsequent abscess is essential. Anatomically, both, the bowel and abdominal walls can form the walls of such an abscess, resulting in complex fistulating tracks.
Though normally the adventitia would remain intact, that is not so in cases of chronic sepsis, neoplasia, foreign body reactions, infections around grafts, etc, etc...
That could be considered part of natural 'Tropism' in gastro-intestinal autonomic system of organic defence mechanism to foreign body.
I suppose the mechanism of erosion is first pushing effect than ischemia and than penetration .As the vessel have hi O2 saturation and blood flow ,they are resistant to penetration.
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