Equis ISSN 2398-2977

Colon: displacement - pelvic flexure

Synonym(s): Nephrosplenic entrapment, renosplenic entrapment

Contributor(s): Peter Rakestraw

Introduction

  • Left dorsal displacement and pelvic flexure displacement of the colon are rare causes of colic that generally need surgical treatment.
  • Cause: unknown, changes in motility implicated.
  • Signs: mild abdominal pain. Unresponsive to conservative or medical treatment.
  • Diagnosis: rectal examination   Urogenital: rectal palpation  , laparotomy may be required for definitive diagnosis.
  • Treatment: surgery is usually necessary.
  • Prognosis: good if treated early.

Pathogenesis

Etiology

  • Unknown, but changes in motility are implicated, ie hypomotility and hypermotility.
  • Accumulation of gas   →   colon 'floats' to abnormal position.
  • Tympany of the left colon, distension of the stomach, and concurrent rapid splenic contraction   →   left colon moves up, the distended stomach forces the spleen to move away from the body wall   →   as the spleen refills, it entraps the colon.
  • All or part of the colon trapped over the nephro-splenic ligament; complete entrapment   →   spleen comes to lie latero-dorsal to the colon; partial   →   spleen lies ventral to the displaced bowel.
  • The spleen often becomes enlarged, and the colon is almost always twisted through 180° along its long axis so that the ventral colon lies above the dorsal colon over the ligament. The colon is often trapped as far as the middle of the right dorsal and right ventral areas. The diaphragmatic and sternal flexures come to lie between the stomach and the left lobe of the liver.

Predisposing factors

General
  • Larger breeds, eg warmbloods   Dutch warmblood  and heavy horses (colonic displacement).

Pathophysiology

  • Colon is relatively mobile - it 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 torsions 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 (particularly if a torsion 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.
  • Platelets release thromboxane and serotonin   →   vasoconstriction. Endothelial cell damage   →   stimulation of neutrophils.
  • Hypovolemia, endotoxic shock, electrolyte and acid/base abnormalities.
  • The severity of pathology depends on the extent of vascular compromise.
  • Cardiovascular compromise occurs late in the course of the disease: tachycardia, a decrease in pulse quality, mucous membrane congestion or cyanosis, and an increase in capillary refill time.
  • 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 whether or not torsion is present.
  • 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 torsion occurs   →   rapid progression   →   severe pain, and even death, can result in hours.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Leendertse I P (1993)Treatment of left dorsal displacement of the left colon (LDDLC) - a clinical review.Equine Vet Educ5(6), 326-328 VetMedResource.
  • McGladdery A J (1992)Ultrasonography as an aid to the diagnosis of equine colic.Equine Vet Educ3(1), 19-23 Wiley Online Library.


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