Evidence - Sigmoid resection, tubular, for diverticulitis, robotically assisted

Introduction

Diverticulitis is an acute, primary inflammation of pseudodiverticula of the colon and the surrounding soft tissue structures, which can lead to the most severe abdominal and septic complications.

Sigmoid diverticulitis shows a broad spectrum of clinical courses – from acute uncomplicated inflammation to complicated courses with abscess, free perforation/peritonitis, fistula or stenosis.

If there is a clinical suspicion of acute diverticulitis, the diagnostics aim to classify the disease in order to be able to give appropriate type-specific therapy recommendations. This is necessary because the treatment options for sigmoid diverticulitis range from pure watchful waiting to immediate emergency surgery.

For surgical decision-making today, it is crucial not to operate rigidly according to the number of episodes, but stage- and symptom-oriented as well as taking into account risk constellations and quality of life.

The AWMF-S3 guideline Diverticular disease/Diverticulitis (AWMF-Reg. No. 021-020; Version 2.1, dated 21.10.2021; valid until 15.10.2026) is the central reference framework for this in Germany. It emphasizes, among other things, that after conservatively treated uncomplicated diverticulitis, many patients have a long-term course with few complications (guideline information, among other things, on recurrences and low complication rate in the long-term course) and that elective interventions are primarily to be discussed in cases of persistent complaints or complicated/chronic-complicated situations.

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 treated primarily conservatively under close clinical monitoring, as the majority of patients treated in this way become symptom-free again within a short time [13, 14, 29, 45] and the recurrence risk is generally low. Thus, there is no indication for elective interval surgery in such cases [13, 36, 43].

In case of persistent complaints or progressing clinical picture despite adequate therapy of uncomplicated diverticulitis, it is recommended to repeat the initial diagnostics including imaging promptly in order to detect unrecognized or newly developed complications and to adapt the treatment to the recommendations for complicated diverticulitis.

Antibiotic treatment for acute uncomplicated diverticulitis is not absolutely necessary, but is recommended according to the current S2k guideline Diverticular disease/Diverticulitis [34] for patients with risk indicators for recurrences and complications:

• arterial hypertension
• chronic kidney disease
• immunosuppression
• allergic disposition
• collagenoses
• vasculitides

In this patient group, depending on the risk profile, an indication for surgery may exist even after successful conservative treatment [2, 9, 10, 19, 49], as diverticulitis after transplantation or in otherwise immunosuppressed patients has a significantly higher lethality of up to 25% than in the normal population. In addition, the perforation risk is increased by 2.7 times [8].

The surgical therapy in the presence of phlegmonous diverticulitis (type 1b) is discussed controversially. Although in these cases, pathophysiologically, a microperforation can be assumed [17], only a few patients develop a recurrence after successful conservative therapy [29]. Accordingly, no general recommendation for surgery can be made for this patient group. This approach is fixed both in the current German guideline and in the Anglo-American and Dutch guidelines [5, 6, 34, 38].

Acute, uncomplicated diverticulitis without fever, without leukocytosis, without abdominal guarding and without stool retention as well as without evidence of perforation or complicated diverticulitis and with only slightly elevated CRP can certainly be treated on an outpatient basis. However, prerequisites are adequate compliance, sufficient oral fluid and food intake as well as close medical monitoring [20, 40]. It should be noted critically that in the aforementioned studies, the included patients were all treated with antibiotics.

Acute complicated diverticulitis

Signs of acute complicated diverticulitis are paracolic abscess formation as well as free perforation. In the presence of free perforation with the clinical picture of an acute abdomen, this is an emergency situation that requires immediate surgery [28, 29, 34, 47].

Even if perforation is excluded and there is no acute abdomen clinically, patients with complicated diverticulitis should be treated as inpatients, with therapy initially conservative as in the uncomplicated form [6, 11]. If the desired clinical success does not occur within 72 hours, this speaks for persistence of the inflammatory focus, whereby the indication for sigmoid resection with deferred urgency must be discussed (interval surgery early-elective – within 48 hours [34]).

Paracolic abscesses, fistulas, stenoses

About 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 the question of whether elective interval surgery is justified after successful conservative therapy of acute complicated diverticulitis, the data situation is incomplete. However, histopathological examinations prove that persistent structural changes are to be expected after paracolic abscesses [26]. In addition, almost 50% of those affected develop secondary complications and about 40% recurrences [3, 4]. The risk factors for these sequelae after paracolic abscesses include [24]

• positive family history of diverticulitis
• length of the affected intestinal segment > 5 cm
• presence of a retroperitoneal abscess

In these constellations, elective interval surgery should therefore be considered.

If fistulas or clinically relevant colonic stenoses develop after successful conservative therapy, elective interval surgery also comes into consideration. In particular, fistulas to the urogenital tract represent a relevant 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 has been made in recent decades depending on the number of disease episodes experienced: resection after the second episode [33]. This recommendation comes from T. G. Parks from 1969 [37]. He wrongly assumed an increasing complication risk and a decreasing success of conservative therapy after the second disease episode. Parks considered data over 40 years old on the spontaneous course of diverticulitis under the clinical conditions at that time.

Current data show that with increasing frequency of disease episodes, no increase in septic complications is to be expected [34]. Also, perforations that require emergency intervention occur predominantly as a primary event of diverticulitis or after the first episode. A prophylactic surgery after the second disease 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

• complaint pattern
• risk factors
• age
• severity of the disease
• life circumstances and comorbidities

[32, 34].

The main goal of surgery in chronic-recurrent diverticulitis is the elimination of disease-related complaints. Benefits and risks must therefore be carefully weighed and the surgical goals clearly defined, as neither septic complications, emergency interventions or colostomies can be avoided nor morbidity or lethality reduced by the intervention.

Diverticular bleeding

In the management of gastrointestinal bleeding, the possibilities of endoscopic diagnostics and therapy are first exhausted [1, 16, 27, 30, 35]. Emergency endoscopy is the measure of first choice here [23].

In 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 the suspected active bleeding.

The indication for surgery arises in case of persistent bleeding that cannot be controlled endoscopically or interventionally. The urgency is determined by the circulatory situation, the bleeding intensity and the pre-existing risk profile.

It is essential to strive for localization of the bleeding in order 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, 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 case of uncertain localization, subtotal colon resection is the procedure of choice [15].

Recurrent, clinically relevant diverticular bleedings (e.g. Hb drop >2 g/dl, shock) without option for conservative risk reduction for a new recurrence should be operated early-electively after individual benefit-risk assessment with known bleeding localization [34].

Patients with self-limiting or interventionally successfully treated previous diverticular bleeding should not be operated [34].

Timing of surgery

The American Society of Colon and Rectal Surgeons recommends elective resection 6 – 8 weeks after onset of symptoms [38]. The Danish and Dutch guidelines do not commit to 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 procedure than so-called "early-elective" operations [39].

Staging table (CDD scheme)

CDD classification of diverticular disease / diverticulitis (AWMF-S3)

CDD Type 0 – Asymptomatic diverticulosis

• Incidental finding of diverticula without clinical complaints or signs of inflammation

CDD Type 1 – Acute uncomplicated diverticular disease / diverticulitis

CDD 1a – Acute uncomplicated diverticulitis without surrounding reaction

• Wall thickening/diverticula without pronounced pericolic inflammatory reaction.
• No abscesses, no free air.

CDD 1b – Acute uncomplicated diverticulitis with phlegmonous reaction

• Inflammatory changes in the pericolic fatty tissue ("phlegmonous").
• No macroabscesses, no free perforation.

-> Clinically: mostly conservative therapy; indication for surgery only in persistent complaints ("smoldering diverticulitis") individualized.

CDD Type 2 – Acute complicated diverticulitis

CDD 2a – Microabscess / covered perforation

• Small pericolic air or fluid collections.
• Local inflammatory complication without large abscess.

CDD 2b – Macroabscess

• Larger abscesses (e.g. pericolic, pelvic), often requiring intervention.
• After successful conservative/interventional therapy, elective sigmoid resection in the interval can be considered.

CDD 2c – Free perforation with generalized peritonitis

Subdivision according to type of peritonitis:

• CDD 2c1 – purulent peritonitis
• CDD 2c2 – fecal peritonitis

-> Clinically: mostly emergency surgery required.

CDD Type 3 – Chronic diverticular disease

CDD 3a – Symptomatic uncomplicated diverticular disease (SUDD)

• Chronic or recurrent complaints without structural complication.

CDD 3b – Recurrent diverticulitis without complications

• Multiple inflammatory episodes, but without fistula, stenosis or abscess.

CDD 3c – Chronic complicated diverticulitis

• Structural consequences of inflammation, e.g.:
  • Fistula (colovesical, colovaginal etc.)
  • inflammatory stenosis
  • conglomerate-like changes

-> Here, according to S3 guideline, there is mostly a clear indication for surgery (esp. fistula/stenosis).

CDD Type 4 – Diverticular bleeding

• Acute diverticular bleeding without inflammation.
• Belongs to diverticular disease, but not to diverticulitis in the narrower sense.

 Short commentary

• Type 1 = acute uncomplicated
• Type 2 = acute complicated (abscess/perforation)
• Type 3 = chronic courses
• Type 4 = bleeding

The indication for surgery is essentially derived from CDD 2b, CDD 2c as well as CDD 3c; for CDD 1 and CDD 3a/bthe decision is primarily symptom- and quality of life-oriented according to AWMF-S3.

Algorithm “When to operate?” (CDD-related, AWMF-oriented)

1) CDD Type 1 (uncomplicated)

Symptom-free after healed episode → no elective sigmoid resection. 
Persistent complaints / smoldering → elective sigmoid resection can be considered for symptom and QoL improvement (individualized decision). 
Recurrent + relevant symptomatic → Indication is patient-centered (suffering/QoL, risk profile, surgical risk); RCTs (DIRECT, LASER) show QoL benefits for selected patients, with simultaneous weighing of surgery-related risks. 

2) CDD Type 2 (complicated)

Macroabscess after successful conservative/interventional therapy → elective resection in the inflammation-free interval offer/consider (recurrence/complicated recurrence risk higher than in uncomplicated courses). 
Free perforation with generalized peritonitis → emergency surgery (see “How to operate?”). 

3) CDD Type 3 (chronic/chronic complicated)

Fistula → surgical therapy should be performed. 
Symptomatic stenosis → surgical therapy should be performed. 

Algorithm “How to operate?” (elective vs. emergency)

A) Elective (interval surgery)

1. Access route: If technically possible, minimally invasive (laparoscopic/robot-assisted) preferred. 
2. Resection principle: Resection of the inflamed sigmoid segment with oral resection margin directly proximal to the inflammatory changes; no “prophylactic” extension into only diverticula-bearing, unremarkable sections. 
3. Anastomosis: Primary anastomosis is the rule electively (stoma only in individual risk constellation). 
4. Expected benefit situation (in symptomatic/refractory courses): QoL improvement is shown in RCTs for selected patients (DIRECT, LASER; long-term data available). 

B) Emergency (perforated diverticulitis / generalized peritonitis)

1. Primary goal: Sepsis control and safe sanitation.
2. Surgical strategy: In suitable situation, sigmoid resection with primary anastomosis plus protective ileostomy is named as preferred strategy; in unstable/septic patients, the Hartmann procedureis the option. 
3. Laparoscopic lavage (selected cases): In purulent peritonitis, lavage/drainage without resection is discussed as a possible alternative, but with indications of re-intervention/abscess problems in studies and strict patient selection. 

Key Take-Home Messages

• Do not operate “according to the number of episodes”, but stage- and symptom-oriented (AWMF-S3 as guide). 
• After uncomplicated diverticulitis: symptom-free → no elective surgery. 
• Smoldering/persistent complaints: Elective resection can improve QoL (DIRECT/LASER support benefit in selected patients). 
• After macroabscess: Interval resection offer/consider. 
• Fistula and symptomatic stenosis: Surgery should be performed. 
• Emergency peritonitis: Resection is standard; primary anastomosis + protective ileostomy often preferred, Hartmann in instability; lavage only selectively. 

Robot-assisted vs. laparoscopic sigmoid resection in sigmoid diverticulitis

Classification within the AWMF-S3 guideline

The AWMF-S3 guideline recommends for elective sigmoid resection, if technically possible and appropriate expertise is available, basically a minimally invasive access. Laparoscopic, robot-assisted and hand-assisted procedures are considered established and safe options, without a clear evidence-based advantage of a single minimally invasive subtype being formulated currently. Decisive remains the experience of the center as well as patient selection.

Technical differences of both procedures

Laparoscopic sigmoid resection

The conventional laparoscopic resection continues to represent the standard access. It enables good visualization and is associated with low morbidity as well as rapid convalescence. However, limitations exist especially in:

pronounced inflammatory fibrosis

obese patients

narrow male pelvis

complex chronic-inflammatory changes (CDD Type 3c)

Robot-assisted sigmoid resection

The robotic platform expands minimally invasive surgery through:

articulating instruments with higher degree of freedom control

stabilized 3D optics

improved ergonomics in deep pelvic preparation

more precise dissection in fibrotic tissue

Especially in chronic-complicated diverticulitis with inflammatory conglomerates or fistulas, the robotic technique can facilitate technically controlled preparation.

Operative results in comparison (current reviews and meta-analyses)

Conversion rate

Several current reviews report tendentially lower conversion rates for robotic procedures, especially in difficult anatomy or advanced inflammation. This advantage seems particularly relevant in complex cases.

Morbidity and complications

The postoperative overall morbidity as well as the anastomotic insufficiency rate do not differ significantly between laparoscopic and robotic sigmoid resection in most analyses. Both procedures are considered safe.

Operation duration

Robotic interventions are associated with longer operation times in many series. With increasing experience and standardized setups, this difference can be reduced.

Hospital stay and convalescence

The length of stay and functional recovery show no clear difference between both procedures in most studies.

Costs

A consistent disadvantage of robotic procedures remains the higher cost structure, which arises mainly from system costs and longer OR times.

Specific advantages of robotics in diverticulitis

In colorectal surgery, robotics is particularly discussed when inflammatory changes complicate laparoscopic preparation:

chronic-inflammatory sigmoid diverticulitis (CDD 3c)

fistulizing courses

pronounced adhesions after multiple episodes

obese patients

A potential advantage arises from finer preparation in the small pelvis as well as better sparing of autonomic nerve structures.

Current evidence and limitations

The existing literature consists predominantly of retrospective cohort studies and systematic reviews; randomized studies specifically on diverticulitis are limited so far. Many data come from mixed colorectal collectives (diverticulitis and tumor surgery), which limits transferability.

Current reviews show overall:

comparable oncological and functional results

possible advantages of robotics in technically demanding cases

no clear general outcome advantage over laparoscopy

Thus, the choice of access remains primarily a question of expertise, case selection and structural resources of a center.

Practical classification 

From a surgical-didactic point of view, robotic sigmoid resection can be understood as further development of minimally invasive technique, which particularly plays to its strengths in complex inflammatory situations. However, laparoscopic resection remains an excellent standard access with high evidence base.

Take Home

Laparoscopic: proven standard, efficient, cost-effective.

Robotic: technically more precise in complex inflammatory anatomy, but with higher resource requirements.