Alimentary Tract Obstruction and Intestinal Injuries

Clinical Picture

The most common symptoms resulting from disorders involving the alimentary tract include pain and alterations in bowel habit. Of these symptoms, abdominal pain is the most frequent and variable and may reflect a broad spectrum of problems, from the least threatening to the most urgent.

Abdominal pain of abrupt onset is often encountered in serious illness requiring urgent intervention, whereas a history of chronic discomfort is frequently related to an indolent disorder. Equally important are the changes in pattern, character, progression, location, and its association to meals.

Alterations in bowel habit can result from either disruption of normal intestinal motility or significant structural abnormality. The onset of worsening constipation in an adult with previously regular habits, especially when accompanied by systemic symptoms such as weight loss, suggests an underlying obstructing process, particularly malignancy.

Pathophysiology

In the newborn, various congenital anomalies —esophageal or intestinal abnormalities, anal atresias, colonic malrotation, volvulus of the midgut, meconium ileus, and aganglionic megacolon—result in obstruction. Early symptoms that suggest obstruction include increased salivation, feeding intolerance with regurgitation or vomiting, abdominal distention, and failure to pass meconium.

Duodenal obstruction may manifest early in the newborn period or within the first year of life, but sometimes it does not manifest until years into childhood. The common area of blockage is just beyond the ampulla of Vater. On occasion, incarceration occurs in an internal hernia, or a bowel segment may become caught in the ring of a congenital, traumatic, or surgical defect in the diaphragm.

Esophageal diseases such as achalasia can interfere with the normal passage of fluids and solids through the gullet (uppermost row in Fig. 47.1 ). Fibrotic narrowing has also been observed after anastomotic or plastic procedures at the lower end of the esophagus. A similar picture results from extraluminal pressure on the esophagus by a mass.

Gastric obstruction may be caused by accumulation in the stomach of ingested material, such as trichobezoar and phytobezoar, or development of hypertrophic pyloric stenosis, spastic or cicatricial occlusion related to prepyloric or postpyloric peptic ulcer, or malignant neoplasm.