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Bowel Anastomosis

Ileal conduit, neobladder, augmentation, and many continent reservoir operations require restoration of intestinal continuity after bowel harvest. An appendiceal Mitrofanoff alone does not necessarily require a bowel-to-bowel anastomosis. Separate the intestinal anastomosis from the bowel-to-urinary-tract connections when planning the operation and investigating postoperative leakage.

Most comparative evidence comes from colorectal surgery. Its findings inform technique, but ileocolic, ileoileal, and low colorectal anastomoses have different anatomy and risks.

See also: Bowel Anatomy, Bowel Handling & Injury Management, Reoperative Bowel Harvest, Bowel Segments, and ERAS.

Fundamental Principles​

  • Viability and perfusion: inspect both ends and their mesenteric supply. Color, bleeding, and pulsation provide useful information.
  • Tension and orientation: mobilize enough bowel for an unstretched join; inspect the mesentery for twist, constriction, or a damaged supplying arcade. A scoping review associated tension with up to a tenfold higher leak risk, but no objective method measures tension on human bowel, so adequate mobilization and surgeon judgment remain the working standard.[15]
  • Secure tissue approximation: capture the submucosal holding layer when sewing, avoid gaps, and preserve the lumen.
  • Hemostasis without strangulation: control cut-edge or staple-line bleeding while avoiding excessive compression or thermal injury.
  • Physiologic suitability and source control: assess shock, contamination, edema, tissue injury, and the consequences of a leak before deciding on anastomosis.[1][2]

Contamination is not an absolute prohibition on primary anastomosis. In trauma or emergency surgery, the choice among immediate repair, anastomosis, diversion, and delayed reconstruction depends on physiology, perfusion, associated injury, and source control. Ongoing resuscitation or uncertain bowel viability may favor damage-control surgery and reassessment.[2]

Hand-Sewn Versus Stapled​

EvidenceFindingApplication to urinary reconstruction
Colorectal Cochrane review (2012): 9 trials, 1,233 patientsNo statistically significant difference in overall dehiscence; stapling was 7.6 minutes faster in one 159-patient time comparison and had more strictures in the pooled older trialsThe time estimate is based on one trial.[3]
Ileocolic Cochrane review (2011): 7 trials, 1,125 patientsStapled functional end-to-end anastomoses had fewer leaks: 11/441 versus 42/684 with hand sewing; OR 0.48 (95% CI 0.24–0.95). In the cancer subgroup, 4/300 versus 35/525 (OR 0.28, 95% CI 0.10–0.75); no differences in the non-cancer subgroup (3 trials, 264 patients)[4]—
Burch randomized trial (2000)132 anastomoses: 65 single-layer continuous (3-0 polypropylene) versus 67 two-layer. Leaks were 2 (3.1%) versus 1 (1.5%); mean construction time 20.8 versus 30.7 minutes; material cost $4.61 versus $35.38Supports single-layer feasibility and shorter construction time. Few events and simultaneous changes in layers, material, and pattern limit claims about which component is best.[5]

Use a technique appropriate to the bowel, access, and operator's experience.

Hand-Sewn Technique​

What the Evidence Supports​

Single-layer anastomosis is a reasonable option and usually takes less time than a traditional two-layer construction. Slowly absorbable monofilament is commonly used; the Burch trial instead used 3-0 polypropylene for its single-layer arm.[1][5]

Continuous and interrupted techniques are both used. The Slieker review found limited direct evidence isolating stitch pattern from other technical differences. The review favored a single-layer continuous technique with inverting sutures and slowly absorbable monofilament, and found the distance from the cut edge, the intersuture distance and suture tension to be nonstandardized, so documenting them is recommended.[1]

One single-center gastric-cancer series (Yao) used a continuous non-inverting full-thickness layer with bites about 5 mm from the edge and about 6 mm apart, followed by a seromuscular second layer at the same dimensions. It reported 0/80 leaks versus 1/70 with stapling, 8 versus 9 minutes per anastomosis, and a much lower material cost. The groups were not randomized.[16]

Aim for accurate apposition without gross mucosal eversion, excessive inversion, narrowing, or strangulation. Historical colorectal “fivefold leak risk” estimates cannot quantify risk for every modern everting technique. Bite distance, spacing, depth, and tension require adjustment to wall thickness, tissue quality, and lumen size.[1]

Operative Sequence​

The following is a practical sequence for a continuous hand-sewn construction, adapted to the chosen technique:

  1. Expose and align viable bowel ends, establish orientation, and confirm that they meet freely.
  2. Place corner or stay sutures as needed to keep the posterior wall and mesenteric border visible.
  3. Approximate the posterior wall with consistent bites that capture the holding layer; avoid incorporating the opposite wall.
  4. Complete the anterior wall while controlling running-suture tension. Reassess the lumen before the final stitches are secured.
  5. Inspect the full circumference, especially the mesenteric corner. Address a gap or bleeding point selectively; reconstruct if perfusion, geometry, or tissue integrity is unacceptable.
  6. Return the bowel to its final position and repeat the orientation and tension checks.

Exact suture size, knot placement, full-thickness versus extramucosal passage, and use of a second layer depend on the selected technique. They should be documented and not implied by the phrase “standard anastomosis.”[1][5]

Named Inverting Patterns​

PatternDistinguishing feature
ConnellA running inverting pattern that enters the lumen
CushingRunning inverting bites parallel to the cut edge that do not enter the lumen
LembertInverting bites oriented perpendicular to the incision; may be interrupted or continuous
HalstedAn interrupted mattress-type inverting pattern

The Parker-Kerr stitch is a related method for closing a bowel stump.

Configuration and Stapler Selection​

SituationPractical options
Ileoileal continuity after ileal harvestStapled side-to-side/functional end-to-end is common; hand-sewn construction is also an option when anatomy or access favors it. A 2026 synthesis of four retrospective comparisons (529 patients after radical cystectomy) reported no statistically significant difference in gastrointestinal complications; differences in return of bowel function were less than one day and of uncertain clinical relevance.[23]
Ileocolic continuityStapled functional end-to-end has supporting randomized evidence, with the limitations noted above
Low colorectal reconstructionConfiguration is a colorectal decision incorporating reach, reservoir function, anastomotic height, and diversion.
Caliber mismatch or limited mobilityChoose the orientation and lumen that permit safe approximation without twist or excessive tension

Martin and Corcoran describe a stapled side-to-side ileoileal anastomosis followed by transverse staple-line closure of the common opening via a side port; they describe suprapubic stapler access as an option to avoid bowel torsion toward lateral ports.[24]

For low anterior resection, a meta-analysis of six randomized trials (538 patients) found fewer leaks with end-to-side than end-to-end anastomosis (RR 0.37, 95% CI 0.15–0.93), with no difference in stenosis.[17] In a retrospective series of 1,202 laparoscopic right hemicolectomies, functional end-to-end and end-to-side anastomoses had similar leak rates (0.6% versus 0.4% after matching), and functional end-to-end had more postoperative ileus (4.9% versus 1.3%).[18]

Cartridge selection is device specific. Follow the stapler and reload instructions for compatible equipment, indicated tissue type, and compressed tissue thickness. Colors and nominal staple heights are not interchangeable between manufacturers. Confirm loading, tissue alignment, full jaw closure, and an unobstructed firing path; inspect the completed line. See Staplers.

A multicenter randomized trial of 78 patients undergoing cystectomy with ileal conduit showed more postoperative ileus with two firings of a robotic 45-mm stapler than with a handheld 60-mm stapler (24% versus 3%) and a longer stay (13 versus 8 days); the comparison changed both stapler and firing strategy, and 12-month bowel-function scores did not differ.[21] In Ghanaat's 511-patient cystectomy comparison, GIA-60 versus GIA-80 was not independently associated with ileus.[11][12] A 170-patient uncontrolled robotic series reported ileus in 7.0%, small-bowel obstruction in 4.7%, and no intraoperative bowel injury after stapled ileoileal construction.[11][12] In 565 laparoscopic nephrectomies, endovascular GIA malfunction occurred in 10 (1.7%), and 7 of the 10 were attributed to preventable causes; that series involved renal hilar vessels, and the same care with loading, jaw closure and tissue positioning applies to bowel firings.[20]

Perfusion Assessment — ICG Fluorescence Angiography​

ICG fluorescence is an adjunct to clinical assessment. The largest trials support a more nuanced conclusion than a fixed percentage reduction in every anastomotic leak. Primary endpoints differ: EssentiAL included detected grade A–C leaks, while IntAct counted clinical grade B/C leaks within 90 postoperative days.[10][9] EssentiAL did not routinely image asymptomatic patients without a diverting stoma.[10]

Major randomized trialPopulation and primary findingInterpretation
EssentiAL (2023)Minimally invasive rectal-cancer surgery: 850 randomized, 839 in the modified intention-to-treat analysis. Anastomotic leakage of grades A–C assessed during admission and at 1-month follow-up was 7.6% versus 11.8%; RR 0.645 (95% CI 0.422–0.987)A positive primary comparison, with a 4.2-percentage-point reduction rather than the anticipated 6 points.[10]
AVOID (2024)Mixed minimally invasive colorectal surgery: 982 randomized, 931 analyzed after postrandomization exclusions. Clinically relevant 90-day leakage was 32/463 versus 42/468; RR 0.77 (95% CI 0.50–1.20), P=0.24The overall primary endpoint was not statistically significant.[7]
ICG-COLORAL (2025)Laparoscopic colorectal surgery planned excluding low anterior resection: 1,136 in the intention-to-treat analysis (59 later excluded from the modified analysis). Overall CT-diagnosed anastomotic leakage was 33/567 versus 45/569; OR 0.73 (95% CI 0.48–1.13), P=0.16The primary comparison was not statistically significant.[8]
IntAct (2025)Rectal-cancer surgery: 766 randomized; 698 in the complete-case primary analysis. Clinical grade B/C leakage within 90 days was 36/343 versus 54/355; adjusted OR 0.667 (95% CI 0.419–1.060), P=0.087The clinical primary endpoint was not statistically significant. Lower any-grade leakage was a secondary finding.[9]

A systematic review of 16 mostly retrospective studies (3,231 patients) reported that ICG angiography changed the surgical plan in 16.3% of cases, most often the level of bowel transection.[19]

2026 synthesis: Ryan and colleagues pooled nine RCTs involving 4,754 patients. The published abstract reports lower overall leakage (RR 0.66, 95% CI 0.56–0.78) and leakage requiring intervention (RR 0.73, 95% CI 0.60–0.89), with the clearest benefit in left-sided or rectal surgery and no demonstrated benefit in right-sided resections.[6] The 2025 SAGES guideline recommends ICG fluorescence assessment for left-sided colorectal anastomosis .[22] This recommendation does not address ileoileal reconstruction after urinary-diversion harvest.[22] These pooled results support selective use, while the individual trial designs and endpoints remain relevant. The nine pooled RCTs did not assess bowel-to-bowel anastomosis after urinary-diversion harvest.[6]

Practical Use​

  1. Assess the proposed bowel ends clinically and preserve the supplying vessels.
  2. Give ICG using the applicable product instructions and institutional protocol; trials used different doses and imaging systems (5 mg boluses in AVOID and ICG-COLORAL; 12.5 mg in EssentiAL).[7][8][10]
  3. Evaluate fluorescence at the intended division site and, where appropriate, after construction. Interpret it alongside blood pressure, tissue appearance, and mesenteric anatomy.
  4. If a segment appears poorly perfused, reassess the cause and revise the plan as appropriate.
  5. Document what was assessed and whether imaging changed the operation.

There is no universally validated fluorescence intensity or time cutoff across all cameras and settings. EssentiAL used a device-specific 60-second criterion for perfusion assessment.[10]

For preparation, contraindications, cumulative dosing, and hypersensitivity precautions, use the ICG pharmacology page. ICG-related anaphylaxis can occur.

Anastomotic Leak​

Risk and Prevention​

Risk depends on the anastomotic site, operation, underlying disease, and definition of leakage. Low rectal trial rates do not estimate ileoileal leak risk, and the “0.5–2.5% expected leak rate” is not a rate for every urinary reconstruction. Consider tissue perfusion, tension, malnutrition, smoking, diabetes, immunosuppression, prior irradiation, blood loss, emergency presentation, and perioperative physiology together.[2][13]

A systematic review of colorectal leaks (prevalence 1–19%) associated leak with male sex, ASA grade above II, renal disease, prior radiotherapy, distal tumor site, tumor larger than 3 cm, advanced stage, emergency surgery, metastatic disease, smoking, obesity, poor nutrition, alcohol excess, immunosuppressants, blood loss or transfusion, and operative time over 4 hours. Stomas lessened the consequences of a leak but not its prevalence.[13]

Bowel preparation, antibiotic prophylaxis, and postoperative analgesia need procedure-specific decisions:

  • Bowel preparation: Routine mechanical preparation is generally unnecessary for uncomplicated ileal diversion; oral-antibiotic decisions depend on the planned segment and local pathway. See Bowel Preparation.
  • NSAIDs. observational leak signals differ by agent and procedure. A blanket prohibition on every NSAID after bowel surgery overstates the evidence; balance anastomotic, renal, bleeding, and analgesic considerations with the perioperative team. See Analgesia.
  • Protective diversion: may reduce clinically apparent leakage and its consequences in selected low rectal operations.[13] This is not a routine requirement for an uncomplicated ileoileal join.[13]

Recognition and Management​

New tachycardia, increasing abdominal pain, ileus that is worsening rather than resolving, fever or hypothermia, organ dysfunction, or enteric drainage requires prompt assessment. Do not dismiss deterioration as routine postoperative ileus or wait for a particular postoperative day. Investigate urinary and enteric sources when both anastomotic systems are present. Imaging, antibiotics, drainage, and operative source control depend on stability, anatomy, and the extent of contamination; diffuse peritonitis or instability warrants urgent surgical assessment.[2]

ISREC Grading​

The International Study Group of Rectal Cancer (ISREC) classification describes severity by the treatment required, originally after anterior rectal resection:[14]

GradeManagement consequence
ANo change in management
BActive treatment without reoperation, such as antibiotics or drainage
CReoperation required

State whether a reported outcome includes grade A or only grades B/C, and specify the follow-up interval.

Urinary-Reconstruction Checklist​

  • Confirm which bowel segment is being isolated and which remaining ends must be joined.
  • Preserve a secure vascular pedicle to the urinary segment and viable perfusion to both intestinal ends.
  • Check the bowel and mesenteric orientation after the reservoir or conduit is placed in its final position.
  • Address potential internal-hernia spaces while avoiding pedicle constriction, bowel kinking, or a hazardous closure.
  • Preserve functional bowel length and terminal ileum when feasible. A single distance from the ileocecal valve does not guarantee normal B12 or bile-salt absorption; account for previous resections and diseased or excluded bowel.
  • Document the intestinal anastomosis separately from ureteroenteric, reservoir, or urethral connections, including technique, perfusion concerns, and any change in plan.

For segment selection and longer-term consequences, use Reoperative Bowel Harvest and Urinary Diversion Principles.

Videos​

Technique demonstrations of hand-sewn bowel anastomosis.

Hand-sewn bowel anastomosis
Hand-sewn bowel anastomosis
Hand-sewn bowel anastomosis
Hand-sewn bowel anastomosis
Hand-sewn bowel anastomosis

References​

1. Slieker JC, Daams F, Mulder IM, Jeekel J, Lange JF. "Systematic Review of the Technique of Colorectal Anastomosis." JAMA Surg. 2013;148(2):190–201. doi:10.1001/2013.jamasurg.33

2. Smyth L, Bendinelli C, Lee N, et al. WSES guidelines on blunt and penetrating bowel injury: diagnosis, investigations, and treatment. World J Emerg Surg. 2022;17:13. doi:10.1186/s13017-022-00418-y.

3. Neutzling CB, Lustosa SA, Proenca IM, da Silva EM, Matos D. "Stapled Versus Handsewn Methods for Colorectal Anastomosis Surgery." Cochrane Database Syst Rev. 2012;(2):CD003144. doi:10.1002/14651858.CD003144.pub2

4. Choy PY, Bissett IP, Docherty JG, et al. "Stapled Versus Handsewn Methods for Ileocolic Anastomoses." Cochrane Database Syst Rev. 2011;(9):CD004320. doi:10.1002/14651858.CD004320.pub3

5. Burch JM, Franciose RJ, Moore EE, Biffl WL, Offner PJ. "Single-Layer Continuous Versus Two-Layer Interrupted Intestinal Anastomosis: A Prospective Randomized Trial." Ann Surg. 2000;231(6):832–7. doi:10.1097/00000658-200006000-00007

6. Ryan ÉJ, Ryan OK, Corrigan N, et al. "Indocyanine Green Fluorescence Angiography for Anastomotic Perfusion Assessment in Colorectal Surgery: A Systematic Review With Meta-Analysis, Meta-Regression, and Trial Sequential Analyses." Lancet Gastroenterol Hepatol. 2026;11(5):367–379. doi:10.1016/S2468-1253(25)00373-5

7. Faber RA, Meijer RPJ, Droogh DHM, et al. Indocyanine green near-infrared fluorescence bowel perfusion assessment to prevent anastomotic leakage in minimally invasive colorectal surgery (AVOID): a multicentre, randomised, controlled, phase 3 trial. Lancet Gastroenterol Hepatol. 2024;9(10):924–934. doi:10.1016/S2468-1253(24)00198-5.

8. Rinne JKA, Huhta H, Pinta T, et al. Indocyanine Green Fluorescence Imaging in Prevention of Colorectal Anastomotic Leakage: A Randomized Clinical Trial. JAMA Surg. 2025. doi:10.1001/jamasurg.2025.0006.

9. Jayne D, Croft J, Corrigan N, et al. Intraoperative fluorescence angiography with indocyanine green to prevent anastomotic leak in rectal cancer surgery (IntAct): an unblinded randomised controlled trial. Lancet Gastroenterol Hepatol. 2025;10:806–817. doi:10.1016/S2468-1253(25)00101-3.

10. Watanabe J, Takemasa I, Kotake M, et al. Blood Perfusion Assessment by Indocyanine Green Fluorescence Imaging for Minimally Invasive Rectal Cancer Surgery (EssentiAL trial): A Randomized Clinical Trial. Ann Surg. 2023;278(4):e688–e694. doi:10.1097/SLA.0000000000005907.

11. Ghanaat M, Winer AG, Sjoberg DD, et al. "Comparison of postradical cystectomy ileus rates using GIA-80 versus GIA-60 intestinal stapler device." Urology. 2018;122:121–126. doi:10.1016/j.urology.2018.09.010

12. Saxena S, Kim K, Billah MS, et al. "Outcomes of stapled ileo-ileal anastomosis during robot-assisted radical cystectomy with urinary diversion: points of technique." J Endourol. 2026;40(1):48–53. doi:10.1177/08927790251390881

13. McDermott FD, Heeney A, Kelly ME, et al. "Systematic Review of Preoperative, Intraoperative and Postoperative Risk Factors for Colorectal Anastomotic Leaks." Br J Surg. 2015;102(5):462–79. doi:10.1002/bjs.9697

14. Rahbari NN, Weitz J, Hohenberger W, et al. Definition and grading of anastomotic leakage following anterior resection of the rectum: a proposal by the International Study Group of Rectal Cancer. Surgery. 2010;147(3):339–351. doi:10.1016/j.surg.2009.10.012.

15. Khalid MU, Ali D, Wu JY, Lee H, Khan A. "Impact and Measurement of Mechanical Tension in Bowel Anastomosis: A Scoping Review of the Current Literature." J Surg Res. 2025;308:161–173. doi:10.1016/j.jss.2025.02.011

16. Yao L, Li C, Zhu X, et al. "An Effective New Intestinal Anastomosis Method." Med Sci Monit. 2016;22:4570–4576. doi:10.12659/msm.902000

17. McKechnie T, Sharma S, Daniel R, Eskicioglu C. "End-to-End Versus End-to-Side Anastomosis for Low Anterior Resection: A Systematic Review and Meta-Analysis of Randomized Controlled Trials." Surgery. 2021;170(2):397–404. doi:10.1016/j.surg.2020.12.030

18. Kim S, Huh JW, Lee WY, et al. "Comparative Analysis of Functional End-to-End and End-to-Side Anastomosis in Laparoscopic Right Hemicolectomy for Colon Cancer." Surgery. 2025;180:109051. doi:10.1016/j.surg.2024.109051

19. Hussain K, Balamurugan G, Ravindra C, et al. "The Impact of Indocyanine Green Fluorescence Angiography (ICG-FA) on Anastomotic Leak Rates and Postoperative Outcomes in Colorectal Anastomoses: A Systematic Review." Surg Endosc. 2025;39(2):749–765. doi:10.1007/s00464-025-11547-1

20. Chan D, Bishoff JT, Ratner L, Kavoussi LR, Jarrett TW. "Endovascular Gastrointestinal Stapler Device Malfunction During Laparoscopic Nephrectomy: Early Recognition and Management." J Urol. 2000;164(2):319–321. doi:10.1016/s0022-5347(05)67349-1. PMID 10893574

21. Bak R, Fabrin K, Jensen TK, et al. "Comparison of the EndoGIA versus the Endowrist stapler in intracorporeal urinary diversion in robotic assisted radical cystectomy (EGIAES) - a randomized multicentre trial." J Robot Surg. 2026;20(1):51. doi:10.1007/s11701-025-03009-6

22. Calabrese EC, Kumar S, Shehata D, et al. "SAGES 2025 guidelines for fluorescence image-guided gastrointestinal surgery using indocyanine green." Surg Endosc. 2025;39(12):7935–7957. doi:10.1007/s00464-025-12356-2

23. Abdelshafi A, Mohamed T, Mohamed H, et al. "Hand-sewn versus stapled ileo-ileal anastomosis following radical cystectomy: A systematic review and meta-analysis." Urol Oncol. 2026;44(7):215–224. doi:10.1016/j.urolonc.2026.04.009

24. Martin AS, Corcoran AT. "Contemporary techniques and outcomes of robotic assisted radical cystectomy with intracorporeal urinary diversion." Transl Androl Urol. 2021;10(5):2216–2232. doi:10.21037/tau.2019.09.45