Abstract
The term heterotopy of the spiral colon encompasses a dysmorphological condition in which the spiral loops of the ascending colon (SLACs) do not form an orderly spiraling mass adjacent to the left side of the mesojejunum. As a consequence, the spiral loops are spread over a larger surface, making them more or less movable. It has been hypothesized that the abnormal position of the spiral loops of the ascending colon might constitute a predisposing factor for an intestinal obstruction or an ileus condition. The objective of the present study was to evaluate the anatomy of the spiral loops of the ascending colon in a population of healthy calves and to determine the prevalence of dysmorphism. The investigation was carried out on 1113 slaughtered veal calves. In 472 out of the 1113 calves, the spiral loops showed conformational aspects different from what has so far been described as normal in reference textbooks. In 91 calves the condition was definitely considered a pathological deviation from normality: in fact, the spiral colon had lost its typical spiral shape with random spacing between the loops, and it was nearly or completely detached from the mesojejunum. The lack of a broad attachment of the spiral loops of the ascending colon to the mesentery could provoke an alteration of the intestinal centre of gravity, enhancing the already asymmetrical distribution of weight between the jejunum and the descending colon.
Highlights
In ruminants, the large colon (Colon crassum) is composed of the ascending colon (Colon ascendens), the transverse colon (Colon transversum) and the descending colon (Colon descendens)
The specific configuration of the spiral loop of the ascending colon (SLAC) was classified on the basis of the space between the loops and their abnormal superimposition as well as on the loss of the disc shape configuration: 1. equal distance between the loops to the mesojejunum: This referred to the normal anatomical situation in which the centripetal and the centrifugal coils of the SLAC were intimately attached to the left side of the mesojejunum, and the loops are ordenlty distended without any overlapping among adjacent loops (Fig 1); 2. conical shape looseness of the SLAC: The spiral loops are loosely attached to the mesojejunum and, if raised to the level of the central flexure they assume a tridimensional flaccid conical shape
While conical shape looseness, observed in 34.2% of the calves, might be accepted as a paraphysiological deviation from complete anatomical compliance, the same cannot be said for the animals with partial dystopia and complete ectopia (6.1% and 2.1%, respectively), that should be considered as pathological deviations
Summary
The large colon (Colon crassum) is composed of the ascending colon (Colon ascendens), the transverse colon (Colon transversum) and the descending colon (Colon descendens). The ascending colon is divided into the proximal loop (Ansa proximalis coli), the spiral loop (Ansa spiralis coli) and the distal loop (Ansa distalis coli) [1]. The ascending colon is functionally associated with the caecum and is often associated with any caecal abnormalities. The spiral loop of the ascending colon (SLAC) is an elliptical coil on a single plane where there are 1.5–2 centripetal gyri, and the same number of centrifugal gyri with a central flexure between them [2,3,4]. Specific anomalies affecting the spiral loop are rare. Atresia coli is a lethal congenital disease if not treated.
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