Introductory Chapter: Diverticular Disease and Complications

1. Introduction

1.1 Concept and epidemiology

Colonic diverticula are saccular formations of the mucosa and submucosa that extend through the muscular layer of the colon. Their diameter is generally placed between 5 and 10 mm, although sometimes they can reach up to 20 mm. Most are false or “pseudo-diverticula” as they lack a muscular layer.

Diverticulosis is the most common colonic disease in the Western world. Affecting up to 10% of the population, reaching a higher prevalence in elderly people. In fact, 50% of the population over 50 years of age has diverticula, which is more common in women.

All of this represents a high amount of doctor visits and hospital admissions.

However, in recent years, an increasing incidence of episodes of acute diverticulitis has mainly been reported in young people under 44 years of age. They usually present a more aggressive course, with an increased risk of complications and increased need for surgical treatment.

In an amount of less than 5%, it can occur before the age of 40, being more prevalent in obese men. Unlike the Western world, where diverticula are preferentially located in the left colon (less than 15% have them in the right colon), in the East, where the disease is much less frequent, the predominant location (70%) is in the right colon [1].

2. Etiopathogenesis

Diverticula form at the weak points of the circular musculature of the colon, at the insertion site of the intramural vasa recta. The main mechanism responsible for this disorder is not well known and its pathogenesis probably involves intrinsic anatomical abnormalities of the colon, along with motor function disorders.

In most patients with left diverticulosis, both the tapeworms (outer longitudinal muscle layers) and the circular muscle layer are thickened due to excess elastin. At the same time, an increase in the motor activity of the colon has been detected. Both phenomena condition an increase in intraluminal pressure and an increase in intestinal segmentation [2].

As a compensatory effect, cholinergic hypersensitivity and colonic smooth muscle dysfunction would occur, facilitating the formation of diverticula.

The fact that diverticular disease of the colon more frequently affects industrialized societies in the Western world has led us to consider that low fiber intake in the diet is an important factor in its development.

Among the risk factors are included in addition to high age, a sedentary lifestyle, and obesity as the principal contributors.

3. Simple diverticulosis

3.1 Symptomatology

Approximately 75–80% of patients with colonic diverticula remain asymptomatic for life, while the remaining 20–25% may report nonspecific symptoms, such as abdominal pain predominantly located in the hypogastrium, and left hemicolon, flatulence, and/or changes in bowel habit.

In cases of diverticulosis located in the cecum and ascending colon, the symptoms refer to the right iliac fossa.

The pain usually increases with meals and improves with defecation. The clinical picture presented by these patients is largely similar to that of patients with irritable bowel syndrome [3].

The abdominal examination is normal, and the analytical determinations generally show no abnormalities. For these reasons, it is often difficult to attribute the symptoms only to the presence of colonic diverticula.

3.2 Diagnosis

For many years the opaque enema, was the most used single imaging technique for the diagnosis of colic diverticulosis, being a casual finding in routine studies performed for other reasons.

Currently, performing a colonoscopy has largely replaced this indication with great advantages, such as the possibility of detecting associated complications by performing biopsies, complemented by early screening for associated lesions.

3.3 Treatment

Some longitudinal studies suggest that a diet rich in fruits and vegetables significantly reduces the risk of complications in patients with diverticulosis. However, the levels of evidence are low, and the level of recommendation cannot be based on controlled and randomized studies. In any case, it is generally advisable to follow a diet rich in fiber, given that it increases the volume of feces, thereby reducing pressure inside the colon and increasing intestinal transit.

The incidental diagnosis of diverticulosis does not require the prescription of any pharmacological treatment or clinical follow-up.

4. Acute diverticulitis

Diverticulitis is the most frequent complication of diverticular disease (10–25%) and appears when the mucosa is abraded, generally due to the action of fecaliths, which leads to the appearance of necrotizing inflammation of a diverticulum. It has been reported that only 4–5% of people with diverticulosis end up developing acute diverticulitis [4].

Diverticulitis is considered uncomplicated when the clinical picture is limited to the appearance of “peridiverticulitis or phlegmon” and complicated, when it is accompanied by an abscess, fistula, or free perforation of the peritoneum, when signs of obstruction appear.

Various classifications have been described to study the severity of diverticulitis. The most used is the one proposed by Hinchey in 1978. Since then, other classifications have been proposed that complement or develop this classification, mainly based on the findings provided by performing an abdominal axial tomography.

4.1 Clinical symptoms and signs

The most frequent symptom in patients with sigmoid diverticulitis is the presence of abdominal pain located at the level of the left iliac fossa. In cases of right diverticulitis, the picture is similar to that of acute appendicitis.

Fever is frequent, although it only appears in the most severe cases. Other symptoms that may appear are diarrhea, constipation, and nausea.

Some of the clinical manifestations only appear in the presence of associated complications. Such occurs in patients who develop an intra-abdominal abscess. In these cases, high and permanent fever appears, despite antibiotic treatment, and is associated with a palpable mass and abdominal tenderness [5].

Patients who develop a colovesical or colovaginal fistula, may present pneumaturia or fecaluria, and patients with colic stenosis, present with symptoms suggestive of colonic closure. This happens more often in patients who have had previous episodes.

In these cases, the effects of spasm and edema, typical of acute inflammation, are added to the parietal fibrosis that follows previous episodes of inflammation. Free peritoneum perforation is uncommon.

4.2 Diagnosis

It is fundamentally based on the presence of compatible clinical data. The physical examination. It usually reveals pain on superficial and deep palpation, with signs of peritoneal irritation or filling. More than 50% of cases present obvious leukocytosis. Simple abdominal radiography can show distention of intestinal loops and the presence of air-fluid levels in cases of ileus or occlusion and pneumoperitoneum in cases with perforation.

When there are doubts in the diagnosis, computed tomography (CT) is the method of choice for diagnosis. The examination should be performed, if possible, with oral water-soluble contrast, complemented by the injection of intravenous contrast. This examination assesses the presence of intra and extra-luminal colic pathology, as well as the existence or not, of associated complications. Another added value consists of the possibility of performing an associated therapeutic intervention, through the percutaneous placement of drains, for the evacuation of possible abdominal abscesses.

Abdominal ultrasound is equally useful for the diagnosis of acute diverticulitis and can demonstrate the presence of inflamed colonic diverticula and its complications. Its main advantages are its low cost, wide availability, and its noninvasive nature. It also allows the placement of percutaneous drains. Its biggest drawback is that it is a technique that depends on the experience of the explorer [6].

Colonoscopy is formally contraindicated, when there is suspicion of severe acute diverticulitis, due to the risk of perforation, although it is actually very low. In cases of acute diverticulitis and in the absence of perforation, or presence of pericolic gas on CT, a colonoscopy with low insufflation can be performed after 5 days from the diagnosis of acute diverticulitis.

A higher frequency of advanced adenomas or colon cancer, in proximity to diverticular disease, has been described in patients with complicated diverticulitis.

4.3 Treatment

4.3.1 Uncomplicated diverticulitis

In mild diverticulitis (75% of cases), oral antibiotic treatment is recommended on an outpatient basis, if there are no complications and there is no alteration of intestinal function. Fluid intake is preserved. Taking spasmolytic drugs, such as octylonium bromide, may be recommended for the treatment of pain.

However, patients who are elderly, immunocompromised, with associated comorbidities, or who have persistent fever and leukocytosis should be hospitalized.

The antibiotics chosen must be active against Gram (−) bacilli. The recommended regimens usually include metronidazole or clindamycin to cover anaerobes and a third-generation cephalosporin or a quinolone against Gram (−) germs.

The association between fiber and rifaximin (400 mg/12 h) 1 week a month for a year not only reduces the associated symptoms of diverticulitis but also reduces the risk of recurrence of this disease [7].

5. Indications for surgical treatment

Its realization can be contemplated in the following circumstances:

1. When two or more episodes of acute diverticulitis occur, in patients controlled with conservative treatment.

2. In patients under 40 years of age, after a single episode that required hospital admission.

3. In patients who had a single acute, severe episode that resulted in perforation, obstruction, or involvement of the urinary tract.

4. In immunocompromised patients, after the first episode, since diagnosis can be difficult there is an added risk of perforation and mortality.

5. In the cases when the impossibility of ruling out underlying colorectal cancer is high.

However, the level of existing scientific evidence is still low, to establish these recommendations.

6. Elective surgical treatment

Consists of removal of the affected colon segment (generally the sigmoid) by open surgery or by laparoscopy.

The laparoscopic approach may offer a lower incidence of surgical wound infection and postoperative ileus and a lower transfusion requirement.

The proximal resection margin should include areas with abnormal thickening of the colonic wall, and it is not necessary to remove all segments with diverticula. The distal margin should reach the rectum to reduce postoperative recurrence (which occurs in 10% of patients) [8].

The most common technique used consists of resection and primary anastomosis, with relative contraindications being intra-abdominal contamination and the inability to perform presurgical lavage of the proximal colon. As a general rule, elective surgery is not recommended in cases of acute diverticulitis.

7. Severe diverticulitis

Approximately 2% of acute diverticulitis present with associated local complications (abscess, obstruction, fistula, or perforation). These cases are accompanied by greater severity in their clinical expression, including persistent pain in the left iliac fossa of greater intensity, febrile syndrome, signs of peritoneal irritation and/or a palpable abdominal mass (plastron). Some patients can evolve to a picture of septic shock. The clinical management of these patients must be individualized, in relation to the clinical state they present and/or the resulting complication.

7.1 Abscess

The abscess is the suppurative complication of a phlegmon, and should be suspected when fever and leukocytosis persist despite antibiotic treatment, or when there is a palpable mass on examination. Diagnosis can be made by ultrasound or CT. Treatment of abscesses has traditionally been surgical, but the advent of imaging techniques that make it possible to precisely guide percutaneous drainage has modified the management of these patients. In addition, it allows the patient to be stabilized, avoiding the need for urgent surgery, which makes it possible to carry out a programmed resection without the need for a colostomy.

The drain is removed when the output is minimal (<10 ml in 24 h). In recent years, it has been confirmed that endoscopic ultrasound is also effective for endoscopic drainage of purulent collections, with similar results to percutaneous drainage.

7.2 Fistulae

The most common fistulas are colovesical. They predominate in men due to the protection exerted by the uterus in women. In fact, in half of the cases presented in them, the history of performing a previous hysterectomy is recorded. The most frequent symptoms are pneumaturia and fecaluria, with the exception of urine elimination with feces [9].

They are followed in frequency by colovaginal, coloenteric, and colouterine fistulas. CT is useful in the study of colovesical fistulas, since, in addition to showing pneumaturia, it allows evaluation of the extent and degree of pericolic inflammation. Cystoscopy can detect bladder abnormalities in most cases. The treatment of fistulas is usually surgical. In colovesical cases, resection of the diverticular area is usually sufficient, being able to preserve the bladder in most cases.

7.3 Obstruction

It can appear as a complication, both acute and/or chronic, in acute diverticulitis. When the occlusion is the result of edema and spasms associated with inflammation, the symptoms resolve as the inflammatory process disappears. If the stenosis is due to extrinsic compression of a peridiverticular abscess, percutaneous or surgical drainage is usually required. Finally, when the occlusion is the result of a retractile stenosis secondary to scar repair from previous episodes, surgical excision of the affected segment may be necessary [10].

Surgery is also indicated when there are doubts about the benign nature of the stenosis. At this point, it must be considered that colonoscopy may not resolve the differential diagnosis in approximately one-third of cases. An alternative that can avoid urgent two-phase surgery is the insertion of self-expanding metal prostheses. This procedure allows surgery to be undertaken electively and in better conditions.

7.4 Free drilling

Perforation of the free peritoneum is not frequent and occurs more likely in immunocompromised patients. It is associated with high postoperative morbidity, mainly due to sepsis, multiple organ failure, and comorbidity. The treatment of choice is urgent surgery. The most used technique is resection with sigmoid colostomy and closure of the rectal stump (Hartmann procedure). The second intervention to restore intestinal continuity and revise the colostomy is usually carried out between 3 and 6 months. In recent years, there has been a growing trend to perform primary anastomosis and laparoscopic peritoneal lavage at the same time [11].

8. Diverticular bleeding

It is generally a serious complication that appears as a consequence of the rupture of the vasa recta, the dome, or the neck of a diverticulum. Although structural alterations have been observed in the walls of these vessels, the inflammation found in these cases is little or none. It appears in 3–5% of patients with diverticulosis and is responsible for up to 40% of episodes of lower gastrointestinal bleeding. An interesting aspect is that the lesion responsible for the hemorrhage is located in the proximal colon in half of the cases, despite the fact that diverticula are located more frequently in the distal colon.

It has been postulated that this may be due to the fact that the proximal diverticula are wider, leaving the vasa recta more exposed to eventual mechanical trauma. The bleeding is usually of a significant volume, and in a third of cases, some transfusions may be required. The bleeding stops spontaneously in 75% of cases, but up to 50% may experience a hemorrhagic recurrence, with 35% requiring treatment by embolization or surgery. Due to the high bleeding rate, diverticular hemorrhage is a relevant clinical problem, as it mainly affects patients with advanced age and frequent comorbidities.

When bleeding originates from a diverticulum and a colonoscopy is performed after adequate preparation, stigmata of recent bleeding may be identified, including the presence of a visible nonbleeding vessel or firmly adherent clot in a diverticulum. These endoscopic stigmata may be present in 30–40% of patients with diverticular hemorrhage [12].

In patients with active bleeding and hemodynamic instability, urgent exploratory laparotomy should be considered in addition to applying the usual diagnostic and therapeutic measures. However, all efforts to locate the hemorrhagic lesion earlier are justified because the prognosis for blind colectomy in massive hemorrhage is dismal, with a high mortality rate, which can reach up to 30% of cases.