ISSN 2398-2977      

Colon: displacement - pelvic flexure

pequis

Synonym(s): colon displacement


Introduction

  • Displacement of the pelvic flexure is a cause of colic that may need surgical treatment.
  • Cause: unknown, changes in motility implicated as well as colon impaction.
  • Signs: mild to moderate abdominal pain.
  • Diagnosis: rectal examination Urogenital: rectal palpation, laparotomy may be required for definitive diagnosis.
  • Treatment: medical management, surgery if unresponsive.
  • Prognosis: good if treated early.

Pathogenesis

Etiology

  • Unknown, but changes in motility are implicated, ie hypomotility and hypermotility.
  • Pelvic flexure of colon may move secondary to impaction. Alternatively, contents of colon may dehydrate and impact secondary to displacement and decreased movement of water into the colon.
  • Accumulation of gas → colon 'floats' to abnormal position.
  • Pelvic flexure retroflexed to lie by the sternum and diaphragm but does not continue to displace to the right of the cecum or to the left into the nephrosplenic space.

Predisposing factors

General

Pathophysiology

  • Colon is relatively mobile - the left ventral and dorsal colon including the pelvic flexure can move to:
    • Left dorsal area → nephrosplenic or renosplenic entrapment.
    • Cranially → pelvic flexure displacement.
    • Rotate on its long axis around the cecum → right displacement of the large colon.
  • Displacement of the large colon (either left dorsal, right dorsal, or pelvic flexure displacement) partial colonic luminal obstruction and a partial vascular obstruction → pain due to mesenteric traction, secondary distension of more proximal gut, and ischemia.
  • Further changes in gut motility may → worsening of the displacement, and possible complete luminal and vascular obstruction.
  • Secondary volvulus can also occur.
  • Partial luminal obstruction → distension of more proximal intestines, which results in mild pain.
  • Progression of luminal obstructions → mechanical obstruction → secondary gastric distension, which may be relieved with the passage of a nasogastric tube Gastrointestinal: nasogastric intubation.
  • Mild dehydration while fluid can be reabsorbed in cecum → more severe when complete obstruction forms.
  • Progressive vascular occlusion if condition is not treated (if a volvulus develops) →  
  • Lost circulating blood volume, due to impaired venous drainage → swelling, edema, and congestion → hypovolemia.
  • Progressive arterial obstruction → cyanosis and ischemia → gut spasm → proximal distension of bowel with gas and fluid.
  • Intraluminal distension → progressive ischemia and disruption of the mucosal layers → necrosis and cell sloughing.
  • Protein rich fluid leaks into the gut lumen and the peritoneal cavity.
  • Endotoxins and bacteria leak into the bloodstream and peritoneal cavity → damage to epithelial cells and platelets (uncommon with displacement of pelvic flexure).
  • Secondary increases in packed cell volume (PCV Blood: packed cell volume (PCV)) and plasma proteins (TPP Blood: biochemistry - total protein) may be seen, and metabolic acidosis can occur causing tachypnea.

Timecourse

  • Depends on degree of displacement, and where the pelvic flexure is located at a given time (as it likely moves and changes position throughout progression of the case).
  • Mild cases that consist of little more than partial displacement causing incomplete luminal obstruction may be asymptomatic, or cause low grade pain for days, and may even resolve spontaneously.
  • Where vascular obstruction develops, when the condition is left untreated or volvulus occurs → rapid progression → severe pain, and even death, can result in hours.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Schoster A, Altermatt N, Torgerson P R & Bischofberger A (2020) Outcome and complications following transrectal and transabdominal large intestinal trocarization in equids with colic: 228 cases (2004-2015). JAVMA 257 (2), 189-195 PubMed.
  • Whyard J M & Brounts S H (2019) Complications and survival in horses with surgically confirmed right dorsal displacement of the large colon. Can Vet J 60 (4), 381-385 PubMed.
  • Dunkel B, Buonpane A & Chang Y M (2017) Differences in gastrointestinal lesions in different horse types. Vet Rec 181 (11), 291 PubMed.
  • McGladdery A J (1992) Ultrasonography as an aid to the diagnosis of equine colic. Equine Vet Educ (1), 19-23 WileyOnline.

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