Abstract

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Intestinal mechanical obstruction is often joined with a diffuse venous congestion.Computed Tomography (CT) is helpful in demonstrating this condition,important from a general-clinical,diagnostic and therapeutic point of view.

Introduction

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The important role of imaging techniques in the diagnosis of mechanical intestinal obstruction is universally accepted.TC is considered one of the most important mean, often permitting to detect type and site of the occlusion of small bowels and colon (1 -9).The modern methods of multidetector row CT,with intravenous contrast enhancement and the possibility of coronal and sagittal formatted reconstruction, allow to accurately study the vascular pathology of the mesentery and of the intestinal loops.Some aspects of a secondary vascular pathology  have been just described,as diagnostic of intestinal mechanical obstruction:mucosal hyperenhancement, edematous thickening of the intestinal wall, central crowding and “whirling” of the mesenteric vessels in case strangulation or volvulus of an intestinal loop (10).Here we underline the importance of diffuse mesenteric venous congestion,that confirm the clinico-radiological diagnosis of mechanical obstruction,influence the general haemodynamics,and address towards the choice of an adequate therapy.

Methods

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We have re-examined 30 cases of intestinal mechanical obstruction:20 cases interesting the small bowel and the colon,secondary to malignant colonic neoplasms,and 10 of small bowel occlusion, due to peritoneal adhesions or fibrous bands.No case of peritoneal carcinomatosis or intestinal volvulus was considered.A concomitant hepatic pathology could be excluded in all the cases and the clinico-radiological diagnosis was always confirmed at the subsequent laparotomy.This series was compared with other 10 cases of paralytic ileus,secondary to a localized peritonitis or to a retroperitoneal pathology.

Results

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Revaluating  our cases,we confirmed the value of the aforementioned classical radiological signs of intestinal mechanical occlusion,but particular attention was given to the following,not always adequately considered:
- dilatation and engorgement of the peripheral mesenteric vessels (Illustrations 1,2);
- dilatation of the major affluents to the porto-mesenteric trunk and to the inferior mesenteric vein (Illustrations 3,4).
The CT contrast-enhanced study permitted us to clearly identify the dilated venous network:
mesenteric venous dilatation was evident in 17 (80.5%) cases of concomitant ileal and  colonic obstruction, and in 7 (70.0%) of simple small bowel occlusion.No case of thrombosis of mesenteric vessels was observed. On the contrary, no evident vascular pathology was present in any case of paralytic ileus.

Discussion

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Vascular mesenteric congestion must be considered not an early but an important radiological sign,demonstrating a haemodynamic complication of the intestinal occlusion.The splanchnic  venous congestion influences the general hemodynamic balance, with the mechanism of the “third-space” fluid loss.In this condition,an eventual laparotomy, followed by a sudden abdominal decompression, can induce a further brisk sequestration of blood in the mesenteric  system,with negative influence on the systemic circulation.The sequence: intestinal bowels dilatation with contractile hyperactivity,augmented metabolic requests,increased arterial supply and venous congestion,appears logic.Congestion of the mesenteric veins appears the final morphological result of this vascular pathological sequence;it must be considered an important,but not an early sign of mechanical intestinal occlusion (Illustration 5).These considerations are based only on morphological data,but,necessarily, not on direct hemodynamic measures,too difficult to be performed in case of “acute abdomen”.

Conclusion(s)

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Vascular mesenteric congestion must be considered not an early but an important radiological sign,demonstrating a haemodynamic complication of the intestinal occlusion.The splanchnic  venous congestion influences the general hemodynamic balance, with the mechanism of the “third-space” fluid loss.In this condition,an eventual laparotomy, followed by a sudden abdominal decompression, can induce a further brisk sequestration of blood in the mesenteric  system,with negative influence on the systemic circulation.The sequence: intestinal bowels dilatation with contractile hyperactivity,augmented metabolic requests,increased arterial supply and venous congestion,appears logic.Congestion of the mesenteric veins appears the final morphological result of this vascular pathological sequence;it must be considered an important,but not an early sign of mechanical intestinal occlusion (Illustration 5).These considerations are based only on morphological data,but,necessarily, not on direct hemodynamic measures,too difficult to be performed in case of “acute abdomen”.Mesenteric venous congestion is a consequence of the mechanical intestinal occlusion;it can be  clearly demonstrated by CT and directly correlated to the severity of this condition.An equivalent situation,but limited to a segment of mesentery and interesting only a few ileal loops,can give evidence of “closed loop obstruction” or of “strangulated bowel”.Our aim has been to recall attention to the CT signs of diffuse mesenteric congestion,following the condition of intestinal mechanical obstruction, and to its general consequences.According to these considerations,in case of colonic obstruction,  surgeon can preferentially proceed, as first step,to a simple diverting colostomy or intraluminal stenting,rather than to a direct laparotomy (11).Besides, it must be underlined, once again,the diagnostic value of contrast enhanced CT,that gives precise morpho-functional information about the entire splanchnic circulation,with subsequent useful clinical correlations.

Reference(s)

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Vascular mesenteric congestion must be considered not an early but an important radiological sign,demonstrating a haemodynamic complication of the intestinal occlusion.The splanchnic  venous congestion influences the general hemodynamic balance, with the mechanism of the “third-space” fluid loss.In this condition,an eventual laparotomy, followed by a sudden abdominal decompression, can induce a further brisk sequestration of blood in the mesenteric  system,with negative influence on the systemic circulation.The sequence: intestinal bowels dilatation with contractile hyperactivity,augmented metabolic requests,increased arterial supply and venous congestion,appears logic.Congestion of the mesenteric veins appears the final morphological result of this vascular pathological sequence;it must be considered an important,but not an early sign of mechanical intestinal occlusion (Illustration 5).These considerations are based only on morphological data,but,necessarily, not on direct hemodynamic measures,too difficult to be performed in case of “acute abdomen”.Mesenteric venous congestion is a consequence of the mechanical intestinal occlusion;it can be  clearly demonstrated by CT and directly correlated to the severity of this condition.An equivalent situation,but limited to a segment of mesentery and interesting only a few ileal loops,can give evidence of “closed loop obstruction” or of “strangulated bowel”.Our aim has been to recall attention to the CT signs of diffuse mesenteric congestion,following the condition of intestinal mechanical obstruction, and to its general consequences.According to these considerations,in case of colonic obstruction,  surgeon can preferentially proceed, as first step,to a simple diverting colostomy or intraluminal stenting,rather than to a direct laparotomy (11).Besides,it must be underlined, once again,the diagnostic value of contrast enhanced CT,that gives precise morpho-functional information about the entire splanchnic circulation,with subsequent u1.Galbani A.,Paushter D.,Dachman A.H. Multidetector row CT of small bowel obstruction. Radiol.Clin:North Am. 2007;45:499-512.
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Source(s) of Funding

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None

Competing Interests

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None

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