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Diverticulitis of the Colon
Definition
Colonic diverticuli are mucosal outpouchings that usually appear with aging(50% of people beyond 60 will develop it),mainly in the left colon,leading to what we call diverticular disease. Formerly, this condition was largely misanderstood, since only the inflamation of these structures were taught to cause clinical manifestations( diverticulitis), something like a "left-sided acute appendicitis". Nowadays, we do already know that diverticula, even in the abscence of inflamation may cause pain with a cramping pattern in the lower abdomen that may sometimes be continual. However, most of people who has colonic diverticula will never develop any clinical manifestation. In these cases the diverticuli are found in necropsy or radiologic studies for other reasons.
Recently, there has been an increase in the incidence of divertilitis, but this was atributted to the aging of the population.
Pathology
In general, there is an hipertrophy in the musculature of diseased segments. The longitudinal taenias are also proeminent, and little dilations of 0.5-1.0cm can be seen in their margins. The perforation of the diveticula initiate the inflamatory process. Iniatially, inflamation spreads locally to pericolic fat, resulting in peridiverticulitis. Lately, dissemination to peritoneum is the rule, leading to peritonitis and maybe acute abdomen or abscess or fistulas, as we will see in greater details later. With time fibrotic stricture of the colon may develop.
Pathophysiology
The development of mucosal diverticuli has largely associated with two factors:
The presence of fragile points in the muscular layer of the colonic wall that predisposes to the herniation of the mucosa and submucosa. Many different studies showed that this fragility occurs in the regions where the arterial vessels penetrate trough the muscular stratum.
Another predisposing factor that is frequently evoked, althogh there are many controversies, is the role of a high intraluminal pressure. It has been proposed that a low fiber diet would reduce the amount of feces formed, requiring incresead peristaltic contractions. However, these findings were not observed in many patients known to have diverticular disease. Nevertheless, it is well documented that even though a low fiber diet and vigorous peristaltic contractions may not cause diverticula, they are associated with a higher incidence of clinical manifestations.
Clinical Presentation
As we have discussed before, diverticuli develops with aging and remains assintomatic in the majority of persons. Only 20% of the people having diverticular disease will have clinical manisfestations during their lifetimes. There are a variety of presentations of the disease including intermitent lower abdominal pain, constipation, diarrea, mild chronic bleeding or even gross hemorrage, none of them being the most common. One must exclude other diseases before atributting these symptons to diverticulosis.
In fact the most common presentation is that of diverticulitis: an elderly person with a subacute left-sided lower abdominal(sigmoid diverticulitis) and constant discomfort, that tends to increase in severity with time. The location of pain depends on the affected segment of the colon. Fever is almost always present, but a high fever must remember the possibility of sepsis resulting from generalized peritonitis due to perforation and spreading of inflamation in the peritoneum.
The main differential diagnosis include bacterial colitis with fever, pain and inflamatory diarrhea, ischemic colitis or inflamatory bowel disease. When peritonitis is present the diferential diagnosis to be made is with all the causes of acute abdomen. In women, ginecologic pathologies must also be considered.
Diagnostic Studies
Leukocytosis is common althouig inespecific as is the presence of proteins and white blood cells in urinalysis. Plain abdomen radiographs may show extraluminal gas, distended colon or colonic mucosal abnormalities but its greater importance lies in excluding the differntial diagnosis discussed above, mainly the surgical causes of acute abdomen.
The abdominal CT is the nest way to make the diagnosis, as it can show the diverticuli and abscess. Barium enema is also a good exam when carefully performed. In fact, these techniques have a comolemantary role since neither of then is 100% sensitive or specific.
Endoscopic examination should not be performed because of the risk of exacerbating the perforation, except when a neoplasm or inflamatory bowel disease are the main diagnostic hypothesis.
Treatment
Initial measures include bowel rest and broad spectrum antibiotics against the most common pathogens, gram negative bacteria and anaerobes including Bacteroides fragilis. Some possible schemes are aminoglicosides with cloranfenicol, metronidazol or clindamicina; or the utilization of a second generation penicilin( cefoxitin) alone; or imipenem or a third cefalosporin associated with metronidazol or clindamicina in a more seriouslly disabled patient.
In fact, the initial antibiotic choice will depend on the clinical status of the patient, i.e., the presence of mild localized process versus a generalized peritonitis with abdominal sepsis. Also, the need of surgery, blood cultures and even hemodinamic monitoring may be necessary in a little number of cases.
Finally, it should be emphasized that early surgical evaluation is a very important measure since abcess formation, requiring drainage, or acute abdomen with generalized peritonitis indicating the need of surgical intervention may develop.
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