Sigmoid Diverticulitis

The presence of a sigmoid diverticulum is not pathological in itself since diverticula generally remain asymptomatic. Many, chiefly older people have multiple diverticula without ever experiencing complaints. As a rule of thumb it can be said that about 70% of people over age 70 have diverticula.

The cause of diverticula in the Western world can be sought in our dietary habits. A diet that routinely contains too little fiber creates low stool volume, thus increasing wall tension in the colon, mainly in the distal segments. Diverticula almost never occur in the rectum, because its wall structure and muscle layers differ from those of the rest of the colon.

Here there is no antegrade peristalsis, the rectum has rather a collection and reservoir function. This is evident macroscopically since the rectum has no tenia coli.

Stools can become lodged in diverticula, leading to diverticulitis, an inflammation of the bowel wall. This usually follows an intermittent course, the first episode being statistically the most dangerous because the risk of perforation is greatest. Such an inflammation can lead not only to perforation of the bowel but also a phlegmon of the bowel wall. A perforation that is covered by the bowel wall or mesentery is called a concealed perforation, but a free perforation in the abdominal cavity is also possible.

Typically patients describe localized pain in the left lower abdomen. On clinical examination, patients exhibit marked abdominal tenderness here. It is important on first examination to determine whether local abdominal guarding or generalized peritonism is present.

The finding of a diverticulitis is often known from a prior colonoscopy, which can provide a further anamnestic clue, as can prior episodes of diverticulitis. In the acute phase of diverticulitis, colonoscopy is contraindicated due to the clearly elevated risk of perforation. Moreover, diverticulitis is not diagnosed by colonoscopy, since the disease process occurs mainly outside the bowel and thus eludes endoluminal diagnosis. Before elective surgery for sigmoid diverticulitis, however, colonoscopy always be done to exclude a colon carcinoma. If colon carcinoma is found, oncological radical resection is indicated, not tubular resection of the sigmoid as for benign sigmoid diverticulitis.

The surgical strategy for diverticulitis is completely different from that for oncological bowel resection. A carcinoma always involves radical resection with systematic lymphadenectomy, i.e. radicular resection. For diverticulitis by contrast tubular resection, i.e. close to the bowel, is performed only on the immediate inflamed area of the large intestine. Care should always be taken, however, that distally no part of the sigmoid colon is left since otherwise there is a risk of recurrence.

In emergency situations, it should first be determined whether there is an indication for emergency surgery, such as a free perforation. This can be done by x-ray of the abdomen in a standing or left lateral position. The presence of large volumes of free abdominal air points to perforation and would require immediate surgery. Ultrasound can detect bowel wall thickening and free abdominal

fluid. If there is no radiomorphological or clinical suspicion of a free perforation, then treatment can begin with antibiotics and the patient placed on a restricted diet. This usually leads to a rapid improvement in symptoms.

For further diagnosis, computed tomography (CT) of the abdomen using a rectal contrast agent can help to reliably assess the disease’s severity. Once colon contrast enemas were used, but they are now obsolete for diagnosing the severity of acute diverticulitis since they can show only diverticula within the bowel but not the extraluminal peridiverticulitis. Because the severity of acute diverticulitis depends on the extraluminal inflammatory reaction, i.e. the peridiverticulitis, colon contrast enema here is ineffective as a diagnostic method because the extraluminal portion of the inflammation cannot be shown.