Anastomosis

Techniques

• Layers
  • Single-layer has a lower risk of stricture
  • Single layer is favoured by many surgeons when the bowel is unhealthy or access is harder
• Configuration
  • End-to-end and isoperistaltic anastomoses are easier to scope through, so may be favoured in IBD
• Tools
  • Surgeons should be comfortable choosing either stapled or sewn depending on the situation
  • Sutured and stapled have the same incidence of leak
  • Multi-layered sutured has a higher risk of stricture
  • Braided sutures cause more inflammation and can 'saw' through tissue, therefore most use monofilament (PDS, Monocryl or Prolene are acceptable)
  • Reasons to favour sutured:
    • Non-healthy bowel or difficult circumstances, according to Schein's (oedematous bowel more likely to leak if stapled)
    • Cheaper
    • Single-layer continuous isn't MUCH slower than stapled
    • Easier to subsequently scope through an end-to-end anastomosis
  • Reasons to favour stapled:
    • Faster
    • Better in difficult-to-access areas (oesophageal and rectal)
    • Laparoscopic
    • Possibly lower leak rate in IBD
• Disparity in size
  • Cheatle slit can be done in the antimesenteric border of the narrower segment
  • If >2cm disparity, end-to-side anastomosis could be considered - e.g. low colorectal join
• In summary:
  • • Deep in pelvis, use the circular stapler
    • For small bowel, I prefer single-layer interrupted with PDS
      • Colonic hand-sewn can be done in the same fashion
    • Normal bowel in an elective right hemicolectomy or small bowel resection can also reasonably have a stapled functional end-to-end anastomosis
    • For oedematous bowel, use single layer interrupted sutures with PDS. Invert the mucosa with big seromuscular bites and tiny mucosal bites, and suture inside the lumen where possible. Take bigger bites (up to 1cm) when the bowel edges are not perfect.
    • To occlude bowel, use a stapler (Hartmann's or small bowel transection in ischaemia)

Contraindications

• Multifactorial, requiring consideration of the holistic situation
• Consider whether the patient can survive a leak
• For small bowel, do not anastomose if two or more factors. For large bowel, do not anastomose if one or more factors.
  • Diffuse established peritonitis or intra-abdominal infection
  • Post-operative peritonitis
  • Leaking anastomosis
  • Mesenteric ischaemia
  • Extreme bowel oedema/distension
  • Extreme malnutrition with low serum albumin
  • Chronic steroid intake
  • Unstable patient
  • Irradiated bowel

Sutured

Single layer end to end

• • Continuous
    • Two anchor sutures - mesenteric and anti-mesenteric
    • Close the entire backwall with a single running suture (generally Lembert sutures - see below)
      • Options for sutures -  Lembert, Cushing, seromuscular
      • Seromuscular inverts the least, and may be useful when the lumen is small
    • Flip and close the other side
    • Test lumen size by invaginating the wall
  • Interrupted
    • • Use good seromuscular bites throughout and only pick up a small amount of mucosa
      • The back wall (mesenteric side) is done with vertical mattress sutures - all full-thickness with knots inside. Mesenteric stay suture first, then work alternately around in each direction.
      • Posterior wall interrupted until get to 3 and 9 o'clock - leave these untied and clipped as stays
      • Flip anterior
      • The 3 and 9 o'clock 'corner' sutures are simple interrupted full-thickness, directed back behind the previous stays. Knots on outside. Flip the previous stays up in front of them, then tie. Then you can tie the previous stays on the inside and cut them. Leave the new stays long.
      • Complete the anterior wall with seromuscular sutures with knots outside - use bisecting method.
      • Leak test with betadine on blunt needle before tying last knot

Double layer end to end

• • Most commonly the inner layer is continuous and outer layer interrupted
  • Holding sutures on either end (seromuscular at anti-mesenteric and mesenteric borders)
  • Third seromuscular suture to bisect the posterior wall
  • Complete the posterior wall with seromuscular sutures
  • Retain the two holding sutures long, but cut the others
  • Flip the bowel
  • Close the mucosal layer of the posterior wall (from anterior) with a running suture (Chassin's says use a double-ended suture)
  • Complete anterior mucosal layer using either Connell technique or a continuous Cushing suture
  • Anterior seromuscular layer
  • Inspect for leak/patency

Side to side double layer - full thickness inner layer, seromuscular outer layer; good for bypasses.

• • Lay the two segments side to side for 8cm with a continuous posterior seromuscular suture
  • Incise the anti-mesenteric borders for 5cm
  • Inner wall left - continuous over-and-over technique plus Connell suture for the corners.
    • Start in middle of back wall with over-and-over technique towards left side
    • In to out on near side corner, then out to in on far side
    • Now do the true Connell stitch, out-to-in then in-to-out on the same side before crossing over to the other side
    • Go about halfway then stop and leave long
  • Inner wall right - start again on the posterior wall, coming around the corner with another Connell, then meeting for the front wall and tying
  • Outer front layer seromuscular continuous - Lembert

Types of sutures

Seromuscular suture technique

• This allows inversion of the mucosal layer
• The suture should only penetrate as far as the submucosa
• Interrupted sutures only

Lembert stitch

• This can be applied in a continuous fashion
• Catch about 5mm of tissue and emerge 1-2mm proximal to the cut edge of the serosa
• Can be used for single-layer anastomosis
• Idea is to invert the bowel edge
• Should be seromuscular bites

Cushing stitch

• Similar to Lembert, but inserted parallel to and 2-4mm from the cut edge of bowel
• Catches about 5mm of bowel
• Can be either interrupted or continuous

Connell stitch

• Originally for performing a single-layer end-to-end anastomosis
• Also often used for the outer layer of a double-layered anastomosis, because it is intended to invert/bury and to be water-tight
• 'Go into the bar, then out of the bar, then cross the street and go into the bar, then out of the bar, then cross the street…' etc
• Not extremely effective as a haemostatic suture

Halsted stitch

• A variation of the Cushing stitch with seromuscular depth
• Provides seromuscular apposition in a bowel anastomosis
• Excessive tension can cause strangulation of a larger bite of tissue

Stapled

Functional end-to-end extracorporeal

• • Ask for - 2x soft bowel clamps, GIA 80 blue stapler with one reload available; other stuff should be on set-up already.
  • Divide mesentery between the two points where you will be inserting the stapler
    • Ligasure/Harmonic - score mesentery then directly across, double burning
    • Ties - score mesentery with diathermy; thin out a window 2 inches away between two fingers; clamp above and below with Roberts forceps; cut across with scissors
  • Downstream soft bowel clamps - one click
  • Protect the wound with packs
  • Position the bowel so that anti-mesenteric borders are in apposition
    • Optional - suture near the planned enterotomies to hold the bowel in apposition, if having trouble keeping it still
  • Create small enterotomies at the anti-mesenteric edge with cutting diathermy and insert a linear cutting stapler (usually blue GIA 80). Check mesentery is free at each end. Be sure to support the bowel well, so it doesn't get any tension from the weight of the staplers.
  • Fire the stapler
  • Remove the stapler and apply Babcock clamps to two lips of the enterotomy, offsetting the opposing staple lines. Check for intra-luminal bleeding, and oversew if with 3/0 PDS if needed.
  • Close the defect by firing a new stapler cartridge transversely across the top
    • Haemostasis by very conservative diathermy or interrupted PDS figure-of-eight
    • Underrun the staple line with 3/0 PDS continuous, and consider inverting/imbricating the ends of the staple line
  • Crotch suture x2
  • Close the mesenteric defect with interrupted 3/0 PDS
  • Cover the anastomosis with omentum if feasible

Anastomotic leak

Incidence

• • Ileocolic anastomosis: 1-3%
  • Colo-anal anastomosis: 20%
  • Majority become apparent between day 2 and 7 (median 5.5), but up to 12% can appear 1 month after surgery

Risk factors:

• • Patient factors:
    • Patient nutritional status
      • Often use albumin as a proxy for nutritional status
      • However, the difference is probably small unless profound malnutrition is present
    • Microbiome
      • E.g. some species may favour production of certain proteins
      • Unanswered questions around the role of pre-op Abx and the role of topical Abx at anastomotic site
    • Medications
    • Radiotherapy to area
    • Male gender
    • Obesity
    • ASA score III or IV
    • Emergency operation
    • Use of oral anticoagulants
  • Operative factors:
    • Tension
      • Unsubstantiated at individual patient level
    • Hypoperfusion
      • Especially any vasopressor requirement
      • ?diminished oxygen tension - hypoxia may impair collagen synthesis
      • Coronary artery disease
      • Radiotherapy to pelvis prior
    • Multiple stapler firings
    • Needs to be water- and air-tight, and technically sound, regardless of specific technique used
    • Mesentery
      • Kono-S anastomosis may help by excluding diseased mesentery
    • Geometrical anastomosis construction
    • Low extraperitoneal anastomosis
    • Surgeon experience
    • Diverting stoma
      • Does not decrease incidence of leak, but does reduce severity and lower risk of re-operation

Presentation/evaluation:

• • Clinically - fever sepsis, abdominal pain, prolonged ileus, leucocytosis, CRP, raised pro-calcitonin
  • Using CRP
    • Probably worth doing daily CRP up to day 5
    • If there are two >50 increases in a row, pretty specific for leak
    • If do all five days and never increases by >50 between any two, sensitivity 0.85 for leak
    • Increase >50 between two days on day 3 or later is >0.90 specific for leak
    • Mean values from a 2023 meta-analysis comparing leak/no leak. Note multiply mg/dl by 10 to reach mg/L.
      • CRP >159 on D3 is 77% sp/74% se/LR+ 3.21/LR- 0.29
      • CRP >114 on D4 is 76% sp/78% se/LR+ 3.29/LR- 0.24
      • CRP >109 on D5 is 80% sp/76% se/LR+ 3.81/LR- 0.26

• CT - intra-abdominal or peri-anastomotic fluid collections and gas, or based on Gastrografin enema

Treatment

• • Subclinical (minimal discharge from drains, no systemic signs) - conservative management with close observation, antibiotics, bowel rest, TPN
    • If there are no drains, likely get enteric contents leaking, leave it as a controlled fistula, apply SNAPS principles
    • Large proportion will close spontaneously
    • If it hasn't closed by six weeks, elective re-operation to make a new anastomosis
  • Abscess
    • Small peri-anastomotic abscess - percutaneous drainage with medical management
    • Complex intra-abdominal abscesses not suitable for or responding to percutaneous drainage - surgery
  • Peritonitis or sepsis (even if minimal) - re-operation as soon as possible
    • Only resect and re-anastomose in VERY select patients - stable patient, minimally compromised, minimal peritonitis, good-quality bowel
    • Leak involves less than a third of anastomosis and minimal contamination: diverting stoma or directly exteriorise the leak
    • Leak is larger or the anastomosis is disrupted: dismantle the anastomosis and create a terminal stoma (can consider just redoing the anastomosis for an ileocolic anastomosis, but safer to bring out as end ileostomy)

Anastomotic stricture (4-10% of circular anastomosis)

• Risk factors
  • E-E configuration with circular stapler
  • Small circular staplers (25mm or smaller)
  • Multi-layer
  • Leak
  • Radiation
  • Ischaemia
• Treatment
  • Balloon dilatation, radial incisions, or endoluminal stents
  • Redo may be necessary if endoscopic treatment doesn't work

Bleeding

• Minor - very common - observation
• Major bleeding requiring transfusion (4%)
  • Generally caused by small arterioles at the staple line
  • Treat endoscopically in most cases - place clips, adrenaline, or diathermy
  • Angiographic treatment is possible but dangerous for the anastomosis

Twisting

• Rare but serious
• Occurs in extracorporeal ileocolic anastomosis - caused by suboptimal visualisation of the mesentery and mesocolon through the mini-laparotomy
• Causes immediate oedema of the small bowel that leads to ischaemia and gangrene unless treated with prompt redo