Changing patterns and surgical outcomes of small bowel obstruction in the era of minimally invasive surgery for colorectal cancer

Abstract

Introduction:

This study aimed to investigate whether the incidence, patterns, and surgical outcomes of small bowel obstruction (SBO) have changed in the era of minimally invasive surgery (MIS) for primary colorectal cancer (CRC).

Methods:

Consecutive patients who underwent laparotomy for SBO were divided into MIS and traditional open surgery (TOS) groups based on the previous colorectal cancer operation technique used. The MIS group was selected from 1544 consecutive patients who underwent MIS as a treatment for primary CRCs between 2014 and 2022, while the TOS group was selected from 1604 consecutive patients who underwent TOS as a treatment for primary CRCs between 2004 and 2013. The demographics, clinicopathological features, and surgical outcomes were compared between the two groups.

Results:

The SBO incidence in patients who underwent MIS for primary CRC was significantly lower than that in patients who underwent TOS (4.4%, n=68/1544 vs. 9.7%, n=156/1604, P<0.0001). Compared with the TOS group, the MIS group had significantly different (P<0.0001) SBO patterns: adhesion (48.5 vs. 91.7%), internal herniation (23.5 vs. 2.6%), external herniation (11.8 vs. 1.9%), twisted bowel limbs (4.4 vs. 0.6%), ileal volvulus with pelvic floor adhesion (5.9 vs. 1.9%), and nonspecific external compression (5.9 vs. 1.3%). A subset analysis of patients with adhesive SBO (ASBO) showed that the MIS group tended to (P<0.0001) have bands or simple adhesions (75.8%), whereas the TOS group predominantly had matted-type adhesions (59.4%). Furthermore, SBO in the MIS group had an acute (<3 months) or early (3–12 months) onset (64.7%), while that in the TOS group (P<0.0001) had an intermediate or a late onset. When the surgical outcomes of SBO were evaluated, the TOS group had significantly more (P<0.0001) blood loss and longer operation time; however, no significant difference was observed in the surgical morbidity/mortality (Clavien–Dindo classification ≧3, 11.8 vs. 14.1%, P=0.6367), hospitalization, and readmission rates between the two groups. Postoperative follow-up showed that the estimated 3-year (11.37 vs. 18.8%) and 6-year (25.54 vs. 67.4%) recurrence rates of SBO were significantly lower (P=0.016) in the MIS group than in the TOS group.

Conclusions:

The wide adoption of MIS to treat primary CRC has led to a lower incidence, altered patterns, and reduced recurrence rates of SBO. Awareness of this new trend will help develop surgical techniques to prevent incomplete restoration of anatomical defects and bowel malalignments specifically associated with MIS for CRC, as well as facilitate timely and appropriate management of SBO complications whenever they occur.

Introduction

Highlights

• The use of minimally invasive surgery (MIS) in lieu of traditional open surgery (TOS) for the treatment of primary colorectal cancer (CRC) has significantly decreased the incidence of postoperative small bowel obstruction (SBO) complications.

• The use of MIS as a substitute for TOS to treat primary CRC has changed the pattern of postoperative SBO from bowel herniation to any type of bowel obstruction.

• After the initial successful laparotomy treatment for SBO, a reduced recurrence rate of bowel obstruction was observed in patients who previously underwent MIS instead of TOS for primary CRC.

Small bowel obstruction (SBO), generally caused by postoperative bowel adhesion, represents 12–16% of emergency surgical admissions and 20% of emergency surgical procedures^1,2. Opening the peritoneal cavity, in whatever type of surgery, leads to the formation of potentially obstructive structures (adhesions or bands) in almost 95% of patients³. The adhesion is a result of the irritation of the peritoneum caused by surgical trauma or intra-abdominal infection^4,5. Furthermore, bowel adhesions can lead to clinical manifestations within a few weeks or even several years after the surgery⁶. Traditional open surgery (TOS) for primary colorectal cancer (CRC) was associated with a particularly higher risk of adhesion formation and related complications^7–9. Notably, within 2 years after colorectal surgery, 14.3% of the patients developed SBO, and 2.6% required surgical intervention to treat this obstruction. This incidence increases after rectal surgery¹⁰. In particular, adhesive SBO (ASBO) has been a clinical conundrum: nearly one-fifth of patients need readmission for a recurrent ASBO, even if they were successfully treated by surgical^11,12 or nonsurgical^13,14 methods during the index admission.

In the last decade, minimally invasive surgery (MIS), via a laparoscopic or robotic approach, has become the standard procedure for the treatment of CRC. Theoretically, MIS is associated with a lower rate of postoperative adhesions compared with TOS, because adhesion formation indicates a stepwise failure of the peritoneal tissue repair mechanisms, which can be prevented by clean dissection, minimal blood loss, and/or less environmental exposure of the bowel inherent in MIS. Some studies have supported this concept by showing that MIS colorectal surgery is associated with a lower rate of adhesion-related admissions compared with open surgery^15–18. However, most reported case series were retrospective uncontrolled studies and were liable to some uncertainty; some rare randomized controlled trials also reported contradictory conclusions^19,20. Moreover, the adhesion-caused bowel obstruction is just a variant of SBO; some studies have pointed out that MIS can paradoxically create specific types of SBO, such as internal or external herniation of the small intestine^21–30 and bowel twisting over the anastomotic site^31,32. Therefore, whether MIS colorectal resection can reduce the incidence of SBO and improve long-term bowel function compared with TOS remains unclear.

Therefore, the present study aimed to investigate whether the incidence, patterns, and treatment outcomes of postoperative SBO have changed during the era of MIS for CRC.

Methods

Study design and patients

The present study was conducted in accordance with the strengthening the reporting of cohort, cross-sectional and case–control studies in surgery (STROCSS) 2021 guidelines³³. This retrospective observational study was designed to compare the incidence, patterns, and treatment outcomes of SBO as a complication of MIS or TOS in patients undergoing initial surgical resection for primary CRC. The patients were stratified into the MIS and TOS groups.

The MIS group was selected from 1544 consecutive patients undergoing MIS for primary CRC during the 2014–2022 period, when ~70% of CRCs were operated on by MIS, while the TOS group was selected from 1604 consecutive patients undergoing TOS for primary CRC during the 2004–2013 period, when ~70% of CRCs were operated on by TOS in our institution. For the present study, only patients with CRCs who underwent curative and elective surgery were eligible for screening for SBO complications. Patients who underwent palliative or emergency surgery for the treatment of primary CRC; experienced anastomotic leakage, intra-abdominal abscess, or other surgical complications requiring additional abdominopelvic surgical or nonsurgical procedures; or simultaneously underwent other abdominal or pelvic surgical procedures before or after the primary colorectal surgery (e.g. reverse Hartmann’s procedure or closure of the temporary colostoma) were excluded from the screening. Such case-selection scenarios formed the denominators for estimating the incidence of SBO in the two study cohorts.

Before enrollment, patients with a clinical diagnosis of SBO were screened based on the inclusion and exclusion criteria. Only patients whose SBO was treated and confirmed by laparotomy were included; patients whose ileus was due to medical comorbidities, bezoar, anastomotic stricture, irradiation enteritis, or cancer recurrence, or resolved spontaneously after conservative nonsurgical treatment were excluded. However, patients who presented with chronic symptoms of partial bowel obstruction (intermittent abdominal pain, distension, and obstipation) and underwent laparotomy to treat their diseases and whose SBO was confirmed during the operation were included.

The baseline demographic characteristics including age, sex, type of initial colorectal surgery, and American Society of Anesthesiologists (ASA) class were compared between the MIS and TOS groups. The SBO patterns and surgical outcomes were evaluated and compared based on the appropriate variables.

Onset time

SBO that occurred within 3 months, 3–12 months, 1–2 years, or >2 years after the primary surgery for colorectal cancer was stratified as acute, early, intermediate, or late onset. The onset interval was calculated from the date of initial colorectal surgery to the date of index surgery for SBO.

SBO patterns

For patients with ASBO, the patterns were classified into bands (>1 cm long and <1 cm in diameter), simple adhesions (<1 cm long and >1 cm in diameter), and matted adhesions (dense, multiple, and tangled) in the operative field, incisional wounds for surgical access, specimen retrieval, trocar placement, drain-tube indwelling, and/or regional adjacent organs.

Internal herniation was defined as the protrusion of a part of the small and/or large bowel through a normal or iatrogenic mesenteric aperture within the peritoneal cavity found during surgical reoperation. External herniation was defined as the protrusion of a part of the small and/or large bowel through an abdominal wall defect that was inappropriately created during primary colorectal surgery.

SBO patterns resulting from other etiologies, such as twisted bowel limbs over the ileorectal anastomosis, volvulus of the small intestine in the pelvis, or external compression by nonspecific fibrosis or omental impaction over the anastomotic site, were individually listed for comparison between the two patient groups.

Operative technique

Before surgery, all patients underwent computed tomography (CT) scan to identify the bowel obstruction site and evaluate the severity of bowel strangulation, as described in previous publications^34–36.

The surgical methods adopted for ASBO were based on the presumed degree of severity: band section, lysis of simple adhesions, lysis of matted adhesions, extensive adhesiolysis, suturing of serosal defects or accidental enterotomies, and segmental bowel resection.

In patients with internal or external herniation, the surgical procedures generally consist of lysis of the associated adhesions, reduction of the incarcerated bowel loops, and closure of the mesenteric or abdominal wall defects. When the bowel appeared strangulated (ischemic) and the bowel was considered ‘nonviable’, segmental resection of the bowel was mandatory.

When the matted bowel adhesions were very extensive, a long segment of the terminal ileum dropped down to the pelvic floor with secure adhesions, or the reduction of the bowel or adhesiolysis was technically difficult or too dangerous, the bypass surgery (side-to-side intestinal anastomosis) was performed.

Surgical outcomes

The measures of surgical quality, such as blood loss, operation time, surgical complications, surgical mortality, hospitalization, and readmission, were reviewed and compared among the treatment cohorts. The length of the hospital stay was calculated from the date of surgery for SBO to the date of discharge. Postoperative morbidity and mortality were defined as those occurring within 30 days of the index procedure or in the hospital if the length of hospital stay was greater than 30 days. The Clavien–Dindo classification system was used to score the severity of the surgical complications³⁷.

Recurrence of SBO

Postoperatively, patients were regularly followed up by the operating surgeon in the Outpatient Department or through consultation with a physician in the Emergency Department. The diagnosis of SBO recurrence after the index surgery was based on the Bologna guidelines³⁸. Recurrence was strictly defined as readmission with SBO symptoms requiring nasogastric drainage, a plain abdominal radiograph showing air-fluid levels, small bowel dilatation, and absence of gas in the large bowel, followed by confirmation of the diagnosis by a water-soluble contrast study and CT scan. The recurrence time was calculated from the date of hospital discharge after the index surgery for SBO to the date of recurrence. Patients who were lost to follow-up or whose SBO-related data were missing from the medical records were censored on the date of final documentation. The median follow-up time [median (range)] in the present case series was 38.5 (3–74 months).

Data management and ethics

Our institutional database of patients with CRC undergoing surgical treatment was prospectively maintained. All demographic, medical, and follow-up data were collected by operating surgeons using a standardized data collection form.

The professional coders underwent intensive training to ensure the accuracy of the data used in the study. This study was approved by the Institutional Review Board of the tertiary referral medical center (unique protocol ID: 202306117RINA). All methods were performed in accordance with relevant guidelines and regulations.

Statistics

The primary endpoints of this study were the incidence and pattern of SBO. The secondary endpoints were surgical morbidity, mortality, and SBO recurrence rates. Kaplan–Meier curves were constructed to evaluate and compare the recurrence of SBO between the MIS and TOS groups using a two-sided log-rank test. To evaluate the variables related to the primary and secondary endpoints, the two-tailed Fisher’s exact test or χ²test with or without Yates’ correction was used to analyze categorical data. Meanwhile, continuous data were compared using the Student’s t-test. The significance level for all tests was set at a P value of <0.05.

Results

Patients who underwent MIS for primary CRC had a significantly lower incidence of postoperative SBO (4.4%, n=68/1544 vs. 9.7%, n=156/1604, P<0.0001) than those who underwent TOS (Table 1).

Table 1.

Comparison of incidence, patterns, and onset time of small bowel obstruction (SBO) between patients having undergone minimally invasive (MIS) and traditional open (TOS) surgery for primary colorectal cancer.

Groups parameters	MIS group (n=68)	TOS group (n=156)	P
Incidence	4.4% (68/1544)	9.7% (156/1604)	< 0.0001
Types of primary surgery, n (%)			0.4538
Colon cancer surgery	39 (57.4%)	88 (56.4%)
Right/Left hemicolectomy	14/7	31/11
Transverse colectomy	2	4
Anterior resection	16	42
Rectal cancer surgery	24 (35.5%)	63 (40.4%)
LAR/APR	20/4	54/9
Total colectomy with ileorectal anastomosis	3 (4.4%)	2 (1.3%)
Total proctocolectomy with ileal J-pouch-anal anastomosis	2 (2.9%)	3 (1.9%)
Patterns of SBO, n (%)			< 0.0001
Adhesions	33 (48.5%)	143 (91.7%)
Bands	15 (45.5%)	14 (9.8%)
Simple adhesions	10 (30.3%)	44 (30.8%)	< 0.0001
Matted adhesions	8 (24.2%)	85 (59.4%)
Herniation	24 (35.3%)	7 (4.5%)
Internal herniation	16 (23.5%)	4 (2.6%)
Mesenteric aperture	11	2
Peritoneal defect	5	2
External herniation	8 (11.8%)	3 (1.9%)
Trocar site	4	0
Drain hole	2	1
Parastoma area	1	1
Incision site	1	1
Twisted bowel limb	3 (4.4%)	1 (0.6%)
Ileal volvulus with pelvic-floor adhesions	4 (5.9%)	3 (1.9%)
Nonspecific external compression	4 (5.9%)	2 (1.3%)
Omentum impaction	2	1
Extraluminal fibrosis	2	1
Onset time, n (%)			< 0.0001
Acute (<3 months)	23 (33.8%)	14 (9.0%)
Early (3–12 months)	21 (30.9%)	28 (18.0%)
Intermediate (1–2 years)	14 (20.6%)	52 (33.3%)
Late (≧2 years)	10 (14.7%)	62 (39.7%)

APR, abdominoperineal resection; LAR, low anterior resection.

When patients who developed SBO after radical excision of primary CRC were examined, no significant difference (P=0.4538) was found between the MIS (n=68) and TOS (n=156) groups according to the type of surgery (Table 1). However, most patients (91.7%) with complicated SBO in the TOS group exhibited adhesions. In the MIS group, SBO tended to result from various types of internal or external bowel herniations (Fig. 1), twisted bowel limbs proximal to the anastomotic site, ileal volvulus with pelvic floor adhesions (Fig. 2, Case 2), and nonspecific external compression over the bowel anastomotic site (P<0.0001). A subset analysis of patients with ASBO showed that the MIS group tended to have milder forms of adhesions (bands or simple adhesions, Fig. 2, Case 1), whereas most patients in the TOS group tended to have more severely matted adhesions (P<0.0001). Additionally, SBO in the MIS group tended to have an acute (<3 months) or early (3–12 months) onset (P<0.0001), while that in the TOS group had an intermediate or a late onset (Table 1).

Figure 1.

Three cases of small bowel obstruction related to internal and external herniation after undergoing different types of surgeries for primary colorectal cancer. In Patient 1, a trans-mesenteric internal herniation was observed after the right hemicolectomy. Computed tomography (CT) showed clustered small-bowel loops in the omental bursa with a transitional zone (arrow) (A). During laparotomy, a mesenteric aperture was discovered (B). After reducing the herniated bowel, a transitional zone of obstruction was identified (C). In Patient 2, transmesenteric internal herniation occurred after the left hemicolectomy. CT revealed clustered dilated small bowel loops in the left upper abdominal quadrant along with a collapsed neodescending colon (D, E). Laparotomy confirms these findings (F). In Patient 3, an external herniation occurred after robotic low anterior resection of rectal cancer. CT showed bulging of the small bowel loops and incarceration over the trocar site of the abdominal wall (G). The incarcerated ischemic bowel segment was exteriorized (H), transected, reanastomosed, and then returned to the aperture (arrow) of the abdominal fascial defect (I).

Figure 2.

Two patients with small bowel obstruction (SBO). In Patient 1, a band was responsible for the intestinal obstruction with a clear transitional zone (arrow) observed on computed tomography scan during the workup of SBO complicated by minimally invasive surgery of sigmoid colon cancer (A, B). During laparotomy for SBO, the transitional zone was confirmed (C). In Patient 2, an incarcerated SBO occurred after abdominoperineal resection of rectal cancer. A plain abdominal film demonstrated air-fluid levels suggestive of SBO (D). During laparotomy, the terminal ileum was incarcerated over the peritoneal reflection (arrow) with a volvulus and secured adhesions to the pelvic floor (E).

With regard to the surgical outcomes of SBO (Table 2), no significant differences were found between the MIS and TOS groups in terms of age (P=0.3377), sex (P=0.6957), or ASA class (P=0.8395). However, patients in the TOS group tended to undergo more complex surgical procedures, including lysis of extensive adhesions, segmental bowel resection with reanastomosis, and intestinal bypass, with a higher possibility of accidental enterotomy and protective stoma creation. By contrast, the MIS group was predisposed to undergoing simpler surgical procedures (P<0.0001), such as band sections or lysis of simple adhesions. Conducting more complex surgical procedures for the treatment of SBO resulted in significantly greater blood loss and longer operative times (P<0.0001) in the TOS group than in the MIS group. However, no significant difference was observed in the surgical complications related to the treatment of SBO between the TOS and MIS groups, according to the Clavien–Dindo classification (≧Ⅱ, 26.5 vs. 26.3%, P=0.9765; ≧Ⅲ, 11.8 vs. 14.1%, P=0.6367). Moreover, no significant difference was found between the two study groups in terms of hospitalization (18.2±4.4 vs. 19.5±5.2, P=0.0733) and readmission rates (7.4 vs. 8.3%, P=0.8040).

Table 2.

Comparison of demographics, clinicopathologic features, and surgical outcomes between TOS and MIS group of patients with small bowel obstruction requiring laparotomy.

Groups parameters	MIS group (n=68)	TOS group (n=156)	P
Age (years, mean±SD)	66.4±12.4	64.2±13.1	0.3377
Sex (male/female)	36/32	87/69	0.6957
ASA physical status (I/II;/III/IV)	6/41/17/4	17/99/31/9	0.8359
Operation procedures			<0.0001
Band section	20	18
Lysis of simple adhesions	40	52
Lysis of extensive adhesions	8	85
Reduction of bowel incarceration	24	7
Accidental enterotomy	8	28
Segmental bowel resection with reanastomosis	9	19
Intestinal bypass	8	22
Protective-stoma creation	2	5
Blood loss (mean±SD, ml)	124±48	244±54	<0.0001
Operation time (mean±SD, min)	189±32	234±44	<0.0001
Surgical complications (Clavien–Dindo classification), n%
≧II	18 (26.5%)	41(26.3%)	0.9765
≧III	8 (11.8%)	22 (14.1%)	0.6367
II	10 (14.7%)	19 (12.2%)	0.9849
IIIa/IIIb	4 (5.9%)	11 (7.1%)
IVa	2 (2.9%)	4 (2.6%)
IVb	1 (1.5%)	3 (1.9%)
V(operative mortality)	1 (1.5%)	4 (2.6%)
Hospitalization (mean±SD, days)	18.2±4.4	19.5±5.2	0.0733
Re-admission (n, %)	5 (7.4%)	13(8.3%)	0.8040

☆One patient may subject to multiple surgical procedures.

ASA, American Society of Anesthesiologists.

During the follow-up of 220 patients who underwent surgical treatment for SBO (67 in the MIS group and 153 in the TOS group), the estimated 3-year (11.37 vs. 18.8%) and 6-year (25.54 vs. 67.4%) recurrence rates of SBO were significantly lower (P=0.016) in the MIS group than in the TOS group (Fig. 3).

Figure 3.

Kaplan–Meier curves demonstrated that the estimated 3-year and 6-year recurrence rates of small bowel obstruction were significantly lower in the minimally invasive surgery group than in the traditional open surgery.

Discussion

Postoperative adhesions have significant implications for health services. Economically, adhesions lead to major healthcare expenses mainly related to readmission and the need for repeat surgery^8–12. This study demonstrated that the adoption of MIS for the treatment of primary CRC can reduce the incidence of postoperative SBO complications, the severity of intra-abdominal adhesions, and the recurrence rate of SBO in patients who have undergone laparotomy to treat this complication. Remarkably, Dupree et al. ²⁴ had reported that although the postoperative SBO requiring hospitalization with conservative management less frequently occurred in laparoscopy-assisted bowel resection patients, compared with traditional open surgery patients (1.9 vs. 6.1%, P=0.016), the need for surgical release of SBO was similar between the two groups (1.4 vs. 1.6%, P=0.87). Their data implied that although the risk of adhesion formation is not completely eradicated using a laparoscopic approach, MIS access for bowel resection significantly reduced the need for hospitalization to treat the postoperative SBO complications, thus providing a reduced morbidity and cost savings for patients. Taken together, the MIS surgical approach has opened a new pathway in the quest for adhesion prevention and has become the most cost-effective surgical method for treating colorectal cancer in the modern era.

The present study showed that the application of MIS changed the pattern of SBO (from adhesions to various types of MIS-associated herniations or malalignments of bowel continuity). External or internal herniation-caused SBO has been sporadically reported in the literature^21–30; it is an MIS-genic surgical complication rarely reported in patients who underwent TOS. The occurrence of internal herniation after MIS for colorectal cancer may be due to the decreased postoperative adhesion that limits bowel mobility after MIS, incomplete or nonclosure of the mesenteric defects created during MIS, and anatomical considerations, such as the axis of the root of the small bowel mesentery, which creates a tendency for the small bowel to lie downward toward the left iliac fossa²⁸. Furthermore, tension of the left colon mesentery may result if the splenic flexure is incompletely mobilized or not mobilized during MIS; consequently, any small bowel that lies behind the mesentery of the left colon is at an increased risk of incarceration. By contrast, external herniation over the trocar sites or drain holes generally occurs in elderly multiparous female patients with weakened floppy abdominal walls, as shown in the present case series.

Nearly all internal and external herniations develop early in the postoperative period, with symptoms such as abdominal distention, intermittent colicky pain, nausea, vomiting, and profuse nasogastric drainage^28–30. However, they can remain asymptomatic or cause equivocal symptoms, including mild abdominal discomfort, intermittent flatus passage, or moderate nasogastric drainage. Hence, these herniations are often misdiagnosed and treated as a normal paralytic-ileus condition during the postoperative course. Most patients with herniation-induced SBO in the present case series were diagnosed using a delay-prescribed CT scan when the ileus symptoms occurred for 3–4 weeks after colorectal surgery. CT has a high diagnostic sensitivity for herniation-induced SBO. Therefore, prolonged postoperative ileus should prompt colorectal surgeons to prescribe a CT examination to rule out this serious condition^34–36.

Theoretically, all internal and external herniation procedures could be avoided. Following right hemicolectomy, most surgeons still routinely close the mesenteric defects, although to do this via MIS is time-consuming and technically challenging. Remarkably, ileocolic mesenteric defects are generally closed extracorporeally via a limited space created by the wound protector. In our experience, this practice is unlikely to allow for a safe and complete closure of the defect in most patients, given the small incision primarily used for specimen retrieval during MIS right hemicolectomy. A narrow residual defect (2–5 cm) due to incomplete closure may paradoxically increase the risk of incarcerated internal herniation^22,30; therefore, closure of the mesenteric defect can be better performed intracorporeally. Alternatively, leaving the mesenteric defect open is a viable option as this defect is not linked to a notable incidence of clinically relevant internal herniation after right hemicolectomy²⁵.

Mesenteric defects created by left hemicolectomy or colonic anterior resection are even more difficult to repair intracorporeally via MIS. After a left hemicolectomy, the resultant mesenteric defect may be narrow and tight. Moreover, neosplenic flexure may lie below or to the right of the duodenojejunal flexure. In this position, the proximal jejunum lies to the left and the terminal ileum lies to the right side of the colonic anastomosis; hence, there is inevitable internal herniation of the proximal small intestinal loops behind the colonic anastomosis. In such conditions, the duodenojejunal angle should be completely liberated by cutting the Treitz ligament to decrease the tendency of the proximal small bowel to pass beneath the mesocolon. However, there is not enough evidence to generally recommend this technique^25,26,28. On the other hand, following the anterior resection for descending or sigmoid colon cancer, closure of the space under the neo-left colon can be technically challenging and carries the risk of inadvertent injury to the left ureter, the retroperitoneal structures, and/or the marginal vessels that maintain the blood supply to the anastomosis²⁷. With the abovementioned reasons in mind, the closure of mesenteric defects may not be essential; however, before finishing any MIS colorectal procedures, the small intestine should be carefully and meticulously traced from the Treitz ligament to the colonic anastomotic site. This meticulous approach is essential for restoring the bowel to its natural position, thus preventing internal herniation.

External herniation is caused by poor planning of the port sites on the abdomen, excessive fascial injury of the abdominal wall during trocar insertion, and/or improper closure of facial defects³⁹. Because novice surgeons generally perform such preparatory work, the appearance of such rare complications emphasizes the importance of proctoring for surgical residents prior to their entry into the MIS subspecialty. For patients who develop ileus symptoms after MIS, inspection of the abdominal wound should be the initial step toward diagnosing external herniation.

The present study identified another MIS-predisposed SBO pattern: twisting or even volvulus of the proximal bowel segment during ileocolic, colon-to-colon, colorectal, or ileorectal stapling anastomoses. To prevent this complication, natural bowel alignment should be maintained by tracing the bowel back to a fixed anatomical origin before firing the stapling instrument for anastomosis. On the other hand, in this study, a few patients (n=7) who underwent proctocolectomy or abdominoperineal resection developed postoperative SBO due to the terminal ileum dropping down and securely adhering to the pelvic floor. And, the percentage of this rare form of SBO seemed to be significantly higher in the MIS group than in the TOS group (5.9 versus 1.9%, P<0.0001). In the era of TOS for CRCs, this complication was initially reported by Fazio et al. ⁴⁰; moreover, van Goor et al. ⁴¹ demonstrated a high incidence (24%) of ASBO after total or subtotal colectomy, with the most common site of obstructing adhesions being the pelvis (35.7%), based on a 10-year retrospective review. However, Young-Fadok et al. ³¹ reported that laparoscopic ileal pouch-anal anastomosis could significantly reduce the risk of postoperative abdominal and pelvic adhesions. The occurrence of this rare SBO type might result from the poor or absence of reconstruction of the giant pelvic dead space that was left after proctocolectomy. To prevent such conditions, peritonization of the pelvic cavity is recommended to elevate the small intestine outside the pelvis above the sacral promontory. Remarkably, some surgeons also introduced the omental transposition flap or mesh plug to ensure a tension-free repair of the pelvic peritoneum⁴². However, if the closure of the pelvic peritoneal reflection is technically unfeasible via MIS, various commercialized mechanical barriers can be applied over the raw surface of the pelvic floor⁴³. Using mechanical barriers around the surgical area to keep the injured peritoneal and serosal surfaces apart until mesothelialization and complete healing are achieved is a safe and cost-effective method for preventing adhesions⁴⁴.

No significant differences were observed between the MIS and TOS groups in terms of surgical morbidity/mortality, hospitalization, or readmission related to SBO surgery. Although the magnitude of surgery for the treatment of SBO was smaller in the MIS group, a significant proportion (33.8%) of patients with acute-onset SBO underwent an urgent laparotomy during the same hospitalization period for the treatment of primary CRC. Presumably, the favorable and unfavorable variables related to SBO surgery in the MIS group were counterbalanced, resulting in surgical outcomes similar to those in the TOS group.

The present study has several limitations. First, this was a retrospective study, which may have been associated with inherent uncontrolled uncertainties. Second, only patients whose SBO was confirmed by laparotomy were included in the numerators when calculating the incidence; therefore, the incidence of SBO was underestimated. Third, because SBO recurrence was strictly defined as readmission with evident clinical and CT presentations, the recurrence rate may have been underestimated. Fourth, the MIS and TOS groups were identified and managed in two different decades; during this period, the treatment strategy evolved; therefore, the evaluation of surgical outcomes was subject to bias.

In conclusion, MIS has been in its prime for treating colorectal cancer because it contributes to a lower incidence and postsurgical recurrence rate of SBO complications. In parallel with these new trends, the MIS-genic patterns of the SBO appeared paradoxically. Awareness of MIS-specific SBO is helpful for the intraoperative prevention and appropriate management of serious surgical complications as soon as they occur.

Ethical approval

The study was approved by the Institutional Review Board of NTUH, which waived the requirement for informed consent (Unique Protocol ID: 202306117RINA).

Consent

The study was approved by the institutional review board at each participating hospital, and the need for informed consent was waived due to the retrospective nature of the study.

Sources of funding

This study was granted by National Taiwan University Hospital (110-S5110).

Author contribution

J.-T.L.: supervise study design, conduction, data analysis data and manuscript writing of the present study; J.H.: assist the conduction the study; Y.-T.L., T.-C.C., J.-S.H.: assist the conduction and analysis data of the present study.

Conflicts of interest disclosure

The authors declare no conflicts of interests.

Research registration unique identifying number (UIN)

The present study was registered in the name of ‘Changing Patterns and Surgical Outcomes for Small Bowel Obstruction in the Era of Minimally Invasive Colorectal Surgery’ and designated as ClinicalTrials.gov ID: NCT05924282.

Guarantor

Jin-Tung Liang.

Data availability statement

All data are provided on request from the authors.

Provenance and peer review

None.