Chapter 38 - Transverse and small colon Flashcards
The transverse colon is a continuation of the right dorsal colon where is situated? What is the vessel connected?
Begins at 17th 18th thoracic vertebra, passes from right to left, cranial to cranial mesenteric artery
The small colon is situated where in the abdomen and how long is it?
- Left CdD quadrant
- 3,5 m long, 710 cm diameter
-Suspended by descending mesocolon (mesentery to mesocolon), fat
SC It is connected dorsally to __ name organ and by ______ name the structure?
Connected dorsally to pancreas and dorsal abdo cavity and by short transverse mesocolon to root of mesentery –> prohibits exteriorization
The transverse colon is connected by which fold?
Duodenocolic fold that connects transverse and small colon to duodenum
What is the blood supply of the small colon?
a - arcuate artery
b - marginal artery
c - secondary arcade
d - long artery
e - small branch supplying mesenteric tenia
f - small branch to mesocolon
Which breeds are predisposed to small colon disease? is there a predisposition of sex?
Arabian horse, ponies, american miniature
Yes, females > 15 years
What are the surgical small colon disease?
84% simple obstructions
16% vascular or strangulating lesions
What are the clinical signs in case of small colon lesions? what are the key indicators for surgery?
Slow, unspecific clinical signs (also tenesmus,abdo dist , ↓ fecal production)and deterioration systemic status –> delayed intervention
- Reflux rare (up to 30% in cases of small colon strangulation)
- Key indicators surgery : abdo dist ++, ↑ peritoneal fluid, ↑ total prot and TNCC
What is the prognosis?
good to excellent short-term and long term prongosis
What are the simple obstructions?
- fecal impaction
- enterolithiasis
- fecaliths, phytobezoars, trichobezoars
- foreign body
- meconimum impaction
Fecal impaction what are the predisposing risk factors?
-poor dentition, poorquality hay, lack of water, parasite damage, lack ofexercise, submucosal edema, motility problems
- ! Horses with diarhea –> check small colon obstruction
- Fall and winter →↓ water consumption, change feed
- > 15y, American miniature horse, pony
What are the clinical anomalies when fecal impaction occurs?
CE: Abdo pain, ↓ manure, abdo dist, diarrhea, anorexia, fever, straining todefecate, depresion, leukopenia
- Abdominocenthesis: normal
- TRP impaction palpated (7587%), distention colon/caecum, edematousrectal mucosa, blood on manure
- SNG: occasionally reflux
Could you perform medical treatment in fecal impaction? what is the medical tx?
-Aggressive oral fluids (4L/46h),
gastrocolic reflex will increment colon motility
- Mineral oil (5- 10 ml/kg)
- Dioctyl sodium sulfosuccinate (50 mg/kg in 6L water)
- Magnesium sulfate (1g/Kg in 6L water) SID for 23 d
- IV fluids (23x maint)
- Flunixine meglumine (0,25 mg/kg IV TID or 1,1 BID)
- If sepsis, leukopenia, diarrhea: antibiotics, Polymixin B (20006000 IU/kg IV),endotoxin antiserum
- Enema: soap + hot water, sedation, buscopan (0,3 mg/kg IV),gravity flow!
When should go for surgery with fecal impaction?
↑ abdo pain, dist, changes in abdo fluid
What does the surgery consist for fecal impaction?
Small colon enema and extraluminal massage
What is the considerations of postop and prognosis for fecal impaction?
Low residue pelleted diet or grass and prognosis for medical and surgical is excellent
What is the major complication in small colon fecal impaction surgical procedure?
Salmonella spp in 43% and postop antibiotics may increase the risk
what is the % of small colon diseases encoutered due to enteroliths?
The small colon is the site of obstruction in 45% to 57% ofhorses with enteroliths, accounting for up to 35% of all smallcolon diseases
How do you perform the diagnosis enteroliths? what are the clinical signs?
CE: multiple episodes of mild colic < intermittent obstruction in large colon, then whenblocked in small colon: severe colic, abdo distention, leukopenia, worsening peritonealfluid →
! Pressure necrosis -> slight elevation in TP perit fluid –> surgery
Radiographs can be taken but the sensitivity is less good in small colon than transverse colon
What is the treatment enteroliths? describe
- Antimesenteric small colon enterotomy
- Retropulsion and removal through PF enterotomy: hose inserted via rectum or PF enterotomy
- water distention and massage
- Parainguinal incision: if located aborally and not possible to exteriorise via ventral midline
- Modified teniotomy: if not exteriorizable and located orally
Where else should you check for enteroliths?
large colon! ! 50% horses with small colon enteroliths have also enteroliths in large colon
Figure 38-2. Small colon enterolithiasis. Rupture through the mesenteric tenia at the site of obstruction with accumulation of feces in the small mesocolon.
Figure 38-3. An intraoperative photograph of a horse with a descending colon impaction showing an area of compromised tissue.
Figure 38-4. Exteriorization of an impacted small colon through a right flank laparotomy in a standing horse.
SC
Figure 38-5. Small colon enterotomy and evacuation. The intestine is secured with Babcock tissue forceps while a nasogastric tube is inserted through the enterotomy. A hose is used to prevent fecal contamination of the serosal surface.
Figure 38-6. Using the blunt back end of a taper-point needle when placing a ligature around a partially obscured mesenteric vessel reduces the risk of inadvertent puncture of the vessel.
Figure 38-7. Penrose drains or intestinal clamps are positioned approximately 10 to 20 cm orad and aborad to the resection site to occlude the intestinal lumen and decrease contamination during the resection (not shown). Doyen intestinal clamps are placed across the descending colon, angled at approximately 30 degrees from perpendicular, leaving the antimesenteric angle of the small colon shorter than the mesenteric angle. A scalpel is used to sharply transect the colon, cutting adjacent to the Doyen intestinal clamps and using them to guide a straight transection line. The clamps are removed along with the resected segment of colon.
Hanson and Schumacher EVE 2019 published a review article Diagnosis, management and prognosis of small colon impactions. What is the prognosis?
Depends on extent and type of impaction but generally is excellent
Diagnosis, describe the picture
Fig 1: Enteroliths are smooth-surfaced spherical orpolytetrahedral with a wide variation in shape, texture and size.Solitary enteroliths a) are spherical whereas the finding of apolytetrahedral enterolith is indicative of multiple enteroliths b).Rock or mineral fragments are commonly the central nidus of the enterolith.
What are the differences of shape in enteroliths?
are smooth-surfaced spherical or polytetrahedral with wide variation in shape, texture and size
Solitary enteroliths are spherical whereas the finding of a polytetrahedral enterolith is indicative of multiplee nteroliths.
What is a fecalith?
is an inspissated ball of fecal material that form as result of poor quality diet, poor mastication or reduced water intake
What are the causes of fecaliths? risk factors?
Pathophysio: < poor quality diet, poor mastication, ↓ water intake
ponies, american miniature horses <1 y or 15<
What are phytobezoars? risk factors?
= concentration of matted plant residues formed into balls
risk factors are <3yold and poor dentition
Waht is a bezoar?
Bezoars = combinations of concentrations of magnesium ammoniumphosphate + plant (phytobezoars), hair (trichobezoars), both(phytotrichobezoars)
What is the treatment of bezoar? Prognosis
Surgical removal by enterotomy
Excellent
Foreign body the treatment is surgical removal, name the 2 methods
Enterotomy or retropulsion and PF enterotomy
Meconimum impaction is caracterized by what?
Newborn: dark black meconium (glandular secretions, bile, cellular debris, amniotic fluid) starting 1 2h after birth and finished after 24h whenyellowish milk stool appears
What are the risk factors that predispose the meconium formation?
Risk factors: delayed ingestion of colostrum,
dystocia, p
rematurity,
lowbirth weight,
birth asphyxia,
dehydration,
males (because narrow pelvic canal)
what are the clinical signs and how can you perform the diagnosis for meconium impaction?
- CE: Restless, tail flaggig, inappetence, straining to defecate –> colic, abdodistended, tachycardia, tachypnea
- TRP: palpable if in pelvic inlet BUT not if in transverse or ascending colon
- RX: gas distention oral to impation (granular material in colon), Bariumcontrast study (retrograde, 20 ml/kg 30 weight/volume barium, 100% sensi)
- US: distended large intestine, sometimes meconium identified as row of fecalballs in small colon (speckled appearance)
What is the medical tx and success rate meconium impaction?
high succes rate
Enema
Most cases: Phosphate/ soap water (300500 ml)
Difficult ones: 200 ml of 4% acetylcysteine solution retained 3045 min up to 3xAcetylcysteine cleaves disulfide bonds in the mucoprotein molecules and ↓ tenacityof meconium, its activity ↑ with ↑ pH (7 9)
–> add 20 g NaHCO3 baking soda
Recepy: 8 g of powdered Nacetylcysteine + 200 ml water + 20 g NaHCO3
IV fluids
Analgesics
when the medical treatment doesn’t work what is the following procedure? prognosis?
Surgery with transluminal massage with wam wate and enema
or enterotomy
excellent short term but adhesions in 33% of cases soreduced long term prog
What are the vascular lesions in small colon of horses?
1) Intramural hematoma
2)Mesocolic rupture
3)Nonstrangulating infarction
intramural hematoma represents how many surgical colics?
Less 1% and is described only in mature horses of at least 8 years of age
Explain the pathophysiology of intramural hematoma
Initially, the intramural hematoma causes luminal obstruction, but it ultimately leadsto ischemic necrosis of the bowel wall. Unless surgical correctionis pursued, septic peritonitis, endotoxemia, circulatory shock,and death will occur
Surgical exploration allows to ID a lesion that is a solid mass usually of what size? What is required to do as treatment?
20-55 cm lenght that occupies the bowel lumen and is attached to the bowel wall.
Complete surgical resection and anastomosis is required and carries a favorable prognosis if it is performed before transmural necrosis or bowelrupture leads to bacterial peritonitis.
What should you do if the lesion is too far caudal?
Parainguinal approach or colostomy
Mesocolic rupture is a complication seen in which horses?
< complication of parturition (middle aged, pluriparous mares)
< type III or IV rectal prolapse with more than 30 cm protruding from anus
- Ischemic necrosis
What is the treatment mesocolic rupture? prognosis?
TTM: resection and anastomosis, evtl colostomy
Poor and depends to the extent of the tear and delay in surgical intervention
How do you perform the diagnosis of mesocolic rupture?
- CE: variable severity of colic 0-24 hours from foaling
- DD! mild abdo discomfort might be incorrectly attributed to uterine involution
- Abdominocent: ↑ TP/ TNNC, intraabdo hemorrhage in some cases
Nonstrangulating infarction is a rare condition why?
Because majority of blood supply comes from caudal mesenteric artery and is not a common site of occlusive verminous arteritis
Tx is the same as mesocolic rupture and clinical signs as well, the only difference is that there is no blood in abdominocenthesis
What are the strangulating obstructions that can be found in small colon?
1)Strangulating lipomas
2)Volvulus
3)Herniation
4)Intussusception
What is the most common reason for small colon resection and anastomosis
Strangulating lipomas
What are the clinical findings for strangulating lipoma?
- CE: interestinglty only mild colic
- TRP: unspecific, sometimes constriction palpated
- Abdominocenthesis: ↑ TNCC/TP
- US transrectal: ↑ thickness small colon
What is the treatment for strangulating lipoma?
Ventral midline or parainguinal incision approach
resection and anastomosis and removal of lipoma.
New article Durket et al 2019 removes by standing pararectal approach using a hoocked bistoury designed for treating entrapped epiglottis
What are the potential causes of volvulus of the small colon?
associated with adhesions and abcess
What types of hernias can result in herniation of the small colon, leading to a strangulating obstruction?
Umbilical, inguinal, and body wall hernias, as well as omental, mesenteric, uterine, vaginal, broad ligament, and gastrosplenic ligament tears can cause herniation.
How can intussusception of the small colon manifest in foals?
Intussusception of the small colon may occur without a rectal prolapse. In rare cases, the intussusceptum may protrude from the anus.
How can the preliminary diagnosis of a protruded intussusceptum be confirmed?
by inserting a finger between protruding bowel and the anal sphincter and advanced cranially
What are the clinical signs and findings on rectal examination in cases of herniation or intussusception of the small colon?
Clinical signs and findings are similar to those seen with strangulating lipomas of the small colon, including tension in herniation cases and blood-stained feces in intussusception cases
What is the typical color of peritoneal fluid in cases of herniation or intussusception?
Peritoneal fluid is often serosanguinous in color, with increased nucleated cell count and protein concentration.
What is the recommended treatment for volvulus, herniation, or intussusception of the small colon?
Treatment involves surgical resection and anastomosis through a ventral midline laparotomy.
How is rectocolostomy performed as a treatment for aborally intussuscepted small colon protruding through the anus?
In rectocolostomy, an encircling incision is made in the outer layer of the intussusception, and ligatures are placed around the mesenteric vessels. Continuity is restored by a colorectostomy using simple-interrupted sutures.
What is atresia coli, and what is its proposed etiology in foals?
Atresia coli is a rare finding in foals, and it is proposed that vascular injury during fetal development results in necrosis and resorption of the affected intestine.
What is the characteristic finding in atresia coli, and why can historical information from the owner be misleading?
Absence of meconium passage or staining, even after repeated enemas, is considered a characteristic finding. Historical information from the owner can be misleading.
What types of intestinal atresia are described in animals, and which type is typically associated with atresia coli in foals?
Three basic types of intestinal atresia are described:
membrane atresia (Type 1),
cord atresia (Type 2),
and blind end atresia (Type 3).
Atresia coli in foals is typically described as Type 3.
How is atresia coli diagnosed, and what diagnostic tools can be used?
Radiographic examination may show gas distention of the intestine orad to the atretic segment, and retrograde contrast radiography may indicate a blind end.
Colonoscopy can provide a definite diagnosis.
What surgical approach can be attempted in cases of atresia coli, and what are the considerations for this procedure?
Colocolonic end-to-end anastomosis can be attempted if the atretic segment is not too long, both blind ends are accessible, and of sufficient diameter. Considerations include the possible friability of the tissue and the potential for anastomosis failure.
What are some rare causes of small colon obstruction in foals, other than atresia coli?
Abdominal testicular teratomas, strangulating ovarian pedicles, and ulcerative colitis with secondary stricture have been reported as causes of small colon obstruction in foals.
What surgical procedure is used for resolving fecal impactions in the small colon, and how is it performed?
A small colon enema in combination with gentle extraluminal massage is typically used to resolve fecal impactions. The small colon is exteriorized through a ventral midline celiotomy, and warm water is introduced through a stomach tube to distend the colon around the impaction. Extraluminal massage is used to break up the impaction. If unsuccessful, an enterotomy may be performed.
When is small colon enterotomy indicated?
Small colon enterotomy is indicated to:
- remove intraluminal obstructions from the small colon,
- including fecal impactions,
- enteroliths,
- fecaliths,
- foreign bodies.
What incision is commonly used to access the small colon during enterotomy?
The small colon is usually accessed through a ventral midline celiotomy.
In what cases might a parainguinal incision be preferred for small colon enterotomy?
A parainguinal incision may provide better access to the lesion in cases of non exteriorazable portion of small cólon affected.
What are the advantages of performing the enterotomy at the antimesenteric tenia?
Enterotomies at the antimesenteric tenia have been found to be stronger, allow easier apposition, develop less intraoperative hemorrhage, and maintain a larger postoperative lumen compared to enterotomies at alternate sites.
Describe the closure technique used for small colon enterotomy.
A two-layer closure is performed using a full-thickness or mucosal simple-continuous pattern followed by a seromuscular inverting pattern with 2-0 polyglactin 910.
What is the recommended closure pattern for enterotomy incisions made through compromised tissue?
A Lembert pattern, with its bites oriented perpendicular to the longitudinal fibers of the antimesenteric band, is recommended for closures through compromised tissue.
What is a modified teniotomy, and when is it performed?
A modified teniotomy is performed to facilitate normograde movement of an obstruction to a more accessible location. It is done when the obstruction is too far orally to be exteriorized, and retropulsion into the right dorsal colon is not feasible.
How is a modified teniotomy performed?
Stay sutures are placed within the antimesenteric tenia, orad and aborad 10-15 cm away from the obstruction. Using a scalpel blade, a 1-cm longitudinal seromuscular incision is made in the antimesenteric band 10 to 15 cm aborad to the obstruction. This seromuscular incision is continued orally with Metzenbaum scissors until the widest part of the obstruction is reached. Gentle pressure to the colon is then used to advance the obstruction to a more accessible location.
What is the recommended small colon anastomosis technique?
A hand-sutured, double-layer, end-to-end anastomosis provides the best combination of good anastomotic diameter and holding strength. most surgeons prefer the combination of a simple continuous pattern in the mucosa/submucosa with a Lembert or Cushing pattern.
What closure pattern is typically used for small colon anastomosis?
Surgeons often prefer the combination of a simple continuous pattern in the mucosa/submucosa with a Lembert or Cushing pattern.
How is the vascular arcade supplying the compromised small colon identified during resection and anastomosis?
The marginal artery orad and aborad to the lesion is identified, isolated within the mesenteric fat, and triple-ligated.
How are vessels supplying the intestine to be removed managed during small colon resection?
Vessels supplying the intestine to be removed are triple-ligated and sectioned, leaving two ligatures on the remaining vascular stump.
What is the purpose of using Doyen intestinal clamps during small colon resection?
Doyen intestinal clamps are placed to prevent the influx of new ingesta and improve blood supply to the antimesenteric border during small colon resection.
What is a potential complication associated with small colon resection and anastomosis in horses?
Diarrhea is a common complication, seen in up to 70% of horses that have undergone small colon resection and anastomosis.
When might impaction at the anastomotic site be a concern after small colon surgery?
Lack of manure production for an extended period, with concurrent signs of intestinal obstruction (gas distention, colic, etc.), may indicate impaction at the anastomotic site.
What are some complications associated with small colon surgery?
Complications may include stricture formation, dehiscence of the anastomosis, peritonitis, thrombophlebitis, and laminitis, generally associated with endotoxemia and sepsis.
What factors are proposed to adversely affect small colon surgery?
Proposed factors include the high concentration of collagenase, high bacterial concentration, mechanical stress from firm fecal balls, and poor vascular supply in the small colon.
Despite potential complications, what is the suggested prognosis for horses after small colon surgery?
With good surgical technique and careful postoperative management, horses have a good prognosis after small colon surgery, even after resection and anastomosis.
Meja et al 2021 describes a retrograde intussusception of the descending colon secondary to multiple hamartomas in a foal. What is a hamartoma?
Hamartomas are lesions with similar characteristics to tumors but are not typically neoplastic and rarely undergo malignant transformation. They enlarge with time and cease to grow when the gost reaches maturity
How to diagnose atresia of the transverse and small colon in foals less than 30days of age?
By retrograde positive contrast colonography using aqueous iodinated contrast media or 30% w/v barium at a dose rate of 5-20 mg/kg bwt instilled into the small colon through cuffed Foley kt through rectum
What is the retrograde colonography sensitivity and specificity for diagnosis of transverse and small colon atresia?
100% and 100%
What other exam could you perform if the atresia is <30 cm from anus?
Colonoscopy and give butylscopalammonium bromide (0,3mg/kg btw iv) may be used to suppress the normal peristalsis
What other exam could you perform if the atresia is <30 cm from anus?
Colonoscopy and give butylscopalammonium bromide (0,3mg/kg btw iv) may be used to suppress the normal peristalsis
What was the surgery performed by Skov Hansen et al 2021 in the presence of atresic pelvic flexure?
They did side to side anastomosis between the left ventral and left dorsal colon with blind ends in the left ventral aborally and left dorsal colons orally to avoid blind loop syndrome
Gas distended ventral large colon and atresic segment (black arrow heads) are shown, noye the small hypoplastic dorsal left large colon
Durket et al EVE 2019 mentions pararectal approach to tx small colon obstruction by pedunculated artery. Surgery landmarks and artery to be careful?
10 cm incision vertical between anus and semimembranus muscle and digital dissection between semimembranous and external anal sphincter
**
Internal pudendal artery and caudal artery!! Pudendal and caudal rectal nerves!!**
Amaral Rosa EVE 2023 Small colon obstruction by a smooth spherical enterolith withthe irregular surface measuring approximately 9 cm in diameter wasdetected during laparotomy. The site of obstruction was exterior-ised and elevated approximately 5 cm above the midline incision. A2-cm-long enterotomy incision was created in the small colon, nextto the site of obstruction and distant 15 cm from the enterolith. Thisincision was used for device (60-cm-long shaft) introduction.Holding the obstructed bowel in one hand, the surgeon used hisfree hand to advance the device rod all the way to the calculus. Voicecommands (start/stop, increase/decrease pressure) were then givento the operator. Using the trigger to start or stop the procedure, theoperator controlled the amount of pressure applied. Fragmentationwas achieved within 6 min. Fragments were further broken intosmaller pieces and removed via the enterotomy incision created fordevice introduction.
name the instrument
Amaral Rosa EVE 2023
Pneumatic lithotripsy device (a) Device parts. (b) Blunt, chisel-like device tip, impact rod diameter (1.5 cm) and externalcannula.pistol external cannulaimpact rod(a) (b)pneuma③c supply hosechisel blunt
Pararectal approach complications? what are the vessels in the way?
Toth makes a good review and mentions:
internal pudendal artery and vein
the ventral erineal and cauda rectal arteries and veins
Pudendal nerve and its branches is critical to maintain innervation of the perineum and the anal sphincter
Risk of evisceration
Where is the incision made in the standing pararectal approach of Durket et al 2019?
10 cm vertical skin incision was made with nº10 between the anus and the left semimembranous muscle
Pneumatic lithotripsy device, how much does it generate with compress air in rod imact? how many per minute?
to generate rod impacts at a rate of 4500 per minute with 60–92 mm stroke
