Diverticulitis is an acute, primary inflammation of pseudodiverticula of the colon and the surrounding soft tissue structures, which can lead to severe abdominal and septic complications.
If there is clinical suspicion of acute diverticulitis, the aim of diagnostics is to classify the disease in order to provide appropriate therapy recommendations. This is necessary because treatment options for sigmoid diverticulitis range from mere observation to immediate emergency surgery.
The indication for surgical intervention depends on the severity of the diverticulitis, the likelihood of recurrence, the subjective impairment of the patients, as well as comorbidities and medication. The response to a conservative treatment attempt must also be considered.
Acute Uncomplicated Diverticulitis
In the presence of typical signs of diverticulitis, including changes in laboratory values but without evidence of complications (phlegmon, abscess, fistulas, or perforation) in imaging diagnostics, acute uncomplicated diverticulitis is present. It should be primarily treated conservatively under close clinical monitoring, as the majority of patients treated this way become symptom-free within a short time [13, 14, 29, 45], and the risk of recurrence is generally low. Therefore, there is no indication for elective interval surgery in such cases [13, 36, 43].
If symptoms persist or the clinical picture progresses despite adequate therapy for uncomplicated diverticulitis, it is advisable to repeat the initial diagnostics, including imaging, promptly to detect undetected or newly developed complications and adjust the treatment to the recommendations for complicated diverticulitis.
Antibiotic treatment for acute uncomplicated diverticulitis is not mandatory but is recommended according to the current S2k guideline for diverticular disease/diverticulitis [34] for patients with risk indicators for recurrences and complications:
- arterial hypertension
- chronic kidney disease
- immunosuppression
- allergic predisposition
- collagenoses
- vasculitides
In this patient group, depending on the risk profile, an indication for surgery may exist even with successful conservative treatment [2, 9, 10, 19, 49], as diverticulitis after transplantation or in otherwise immunosuppressed individuals has a significantly higher mortality rate of up to 25% compared to the general population. The risk of perforation is also increased by 2.7 times [8].
The surgical therapy for phlegmonous diverticulitis (Type 1b) is controversially discussed. Although a microperforation is assumed pathophysiologically in these cases [17], only a few patients develop a recurrence after successful conservative therapy [29]. Therefore, no general surgical recommendation can be made for this patient group. This approach is fixed in the current German guideline as well as in the Anglo-American and Dutch guidelines [5, 6, 34, 38].
Acute uncomplicated diverticulitis without fever, leukocytosis, guarding, and bowel obstruction, as well as without evidence of perforation or complicated diverticulitis and only slightly elevated CRP, can indeed be treated on an outpatient basis. However, adequate compliance, sufficient oral fluid and food intake, and close medical monitoring are prerequisites [20, 40]. It remains critical to note that all patients included in the aforementioned studies were treated with antibiotics.
Acute Complicated Diverticulitis
Signs of acute complicated diverticulitis include paracolic abscess formation and free perforation. In the presence of free perforation with the clinical picture of an acute abdomen, it is an emergency situation requiring immediate surgery [28, 29, 34, 47].
Even if a perforation is excluded and clinically there is no acute abdomen, patients with complicated diverticulitis should be treated as inpatients, with the therapy initially being conservative as in the uncomplicated form [6, 11]. If the desired clinical success is not achieved within 72 hours, this indicates the persistence of the inflammatory focus, and the indication for sigmoid resection with deferred urgency must be discussed (interval surgery early-elective – within 48 hours [34]).
Paracolic Abscesses, Fistulas, Stenoses
Around 15% of patients with acute complicated diverticulitis show paracolic abscess formation in imaging [20]. For abscesses > 5 cm, percutaneous interventional drainage plus antibiotic therapy can be performed to avoid emergency surgery [12, 17, 44].
Regarding whether elective interval surgery is justified after successful conservative therapy of acute complicated diverticulitis, the data is incomplete. However, histopathological examinations show that persistent structural changes are to be expected after paracolic abscesses [26]. Furthermore, nearly 50% of those affected develop secondary complications and about 40% recurrences [3, 4]. Risk factors for these sequelae after paracolic abscesses include [24]
- positive family history of diverticulitis
- length of the affected bowel segment > 5 cm
- presence of a retroperitoneal abscess
In these constellations, elective interval surgery should be considered.
If fistulas or clinically relevant colonic stenoses develop after successful conservative therapy, elective interval surgery is also an option. In particular, fistulas to the urogenital tract pose a significant risk due to the danger of urosepsis and should be addressed electively [21, 46].
Chronic Recurrent Diverticulitis
The recommendation for elective sigmoid resection in chronic recurrent diverticulitis was made in past decades depending on the number of disease episodes experienced: resection after the second episode [33]. This recommendation comes from T. G. Parks in 1969 [37]. He mistakenly assumed an increasing risk of complications and a decreasing success of conservative therapy after the second episode. Parks considered over 40-year-old data on the spontaneous course of diverticulitis under the clinical conditions of that time.
Current data show that with increasing frequency of disease episodes, an increase in septic complications is not to be expected [34]. Perforations requiring emergency intervention also occur predominantly as a primary event of diverticulitis or after the first episode. A prophylactic operation after the second episode, as was common until a few years ago, is therefore no longer justified.
The indication for surgery in chronic recurrent diverticulitis should be made individually, taking into account
- symptomatology
- risk factors
- age
- severity of the disease
- life circumstances and comorbidities
[32, 34].
The main goal of surgery in chronic recurrent diverticulitis is to eliminate disease-related symptoms. Therefore, benefits and risks must be carefully weighed, and the surgical goals clearly defined, as neither septic complications, emergency interventions, or colostomies can be avoided, nor can morbidity or mortality be reduced by the intervention.
Diverticular Bleeding
In the management of gastrointestinal bleeding, the possibilities of endoscopic diagnostics and therapy are initially exhausted [1, 16, 27, 30, 35]. Emergency endoscopy is the first-choice measure [23].
In the case of repeated or persistent bleeding without an endoscopically clearly identifiable source, angiography (possibly also CT angiography) should be performed for localization diagnostics at the time of suspected active bleeding.
The indication for surgery arises in the case of persistent bleeding that cannot be controlled endoscopically or interventionally. The urgency is determined by the circulatory situation, the intensity of the bleeding, and the pre-existing risk profile.
It is essential to strive for localization of the bleeding to proceed surgically in a targeted manner. If localization of the bleeding source is not successful, it cannot be assumed that the bleeding originates from the sigmoid. In these very rare cases of non-localizable bleeding, a subtotal colectomy with ileorectostomy must be discussed. "Blind" colon segment resections have a high risk of persistent or recurrent bleeding and should not be performed [42]. In cases of uncertain localization, subtotal colon resection is the procedure of choice [15].
Recurrent, clinically relevant diverticular bleeding (e.g., Hb drop >2 g/dl, shock) without the option of conservative risk reduction for another recurrence should be operated on early electively after individual benefit-risk assessment [34].
Patients with self-limiting or interventionally successfully treated previous diverticular bleeding should not be operated on [34].
Timing of Surgery
The American Society of Colon and Rectal Surgeons recommends elective resection 6 – 8 weeks after the onset of symptoms [38]. The Danish and Dutch guidelines do not specify the optimal timing of surgery [5, 6]. Resections in the inflammation-free interval after 6 – 8 weeks show lower rates of anastomotic insufficiencies, wound healing disorders, and conversions to open procedures than so-called "early-elective" operations [39].
Technical Aspects of Sigmoid Resection
The goal of elective surgery for sigmoid diverticulitis is the complete removal of the entire sigmoid colon and the creation of a tension-free anastomosis in the upper rectum.
There is no correlation between the number of residual diverticula in the remaining colon and the risk of a diverticulitis recurrence, so an extension of the resection is not indicated [48]. The location of the distal resection plane has a decisive influence on the recurrence rate: If the resection plane is in the distal rectum, the risk of recurrence can be significantly reduced [7].
The mobilization of the left colonic flexure is not mandatory if the descending colon is of sufficient length. To minimize the risk of anastomotic insufficiencies and sexual dysfunctions, some authors favor preserving the inferior mesenteric artery [25].
Laparoscopic or laparoscopic-assisted surgery is preferred over open resection unless there are compelling reasons against it (e.g., patient preference, lack of surgeon expertise) [2]. This also applies to complicated and recurrent sigmoid diverticulitis [25].
In direct comparison with open sigmoid resection in the postoperative short-term course, laparoscopic sigmoid resection is associated with less blood loss, faster recovery, shorter hospital stay, quicker return of bowel motility, overall lower morbidity, and lower total costs [18, 22]. However, in terms of quality of life and complications 6 months after surgery, the laparoscopic procedure is not superior [31].