Lactology Foundation

Intestinal Pain

Ileus
Ileus can be classified into two main types:
➤ mechanical ileus
➤ paralytic ileus

Mechanical Ileus
Clinical Features
Mechanical or obstruction ileus causes colicky abdominal pain, frequently with periumbilical localization. Intestinal colic, which results from painful contraction of the intestine to overcome an obstruction, lasts from seconds to a few minutes. It can easily be distinguished from urethral or gallstone colic, which lasts much longer. Acute gas and stool retention always indicates ileus and represents one of the most important early symptoms together with pain and possibly vomiting. Palpation of the abdomen frequently triggers a colic.
Initially, provided the intestinal wall is no longer seriously damaged, there are almost no signs of peritonitis, i. e., the abdominal pain is mild and rebound tenderness is only minor. Signs of inflammation are absent or mild (no or only mild leukocytosis, normal ESR). The clinical picture changes in later stages. The colicky pain becomes continuous pain, and symptoms of abdominal wall necrosis appear (peritonism, leukocytosis, shock).
An asymmetric abdomen indicates a localized intestinal distension resulting from an organic obstruction (DD: acute urinary retention).
Diagnosis
The bowel sounds are initially increased on auscultation, and disappear when, with time, the mechanical ileus progresses to the paralytic stage.
Abnormal intestinal movements (stiffness), which are caused by intestinal stenoses, can be palpated in some cases or can be directly observed during inspection of the abdomen. The inconstant character is particularly typical.
Radiologically, the plain abdominal radiograph shows distended intestinal loops with fluid levels at an early stage. With colonic stenosis, the proximal intestine is distended and the haustra can be detected.
Distal to the stenosis there is no air in the intestine. Sonography can be helpful diagnostically by demonstrating pathologic intestinal motility and distended intestinal loops. The character of the following four main symptoms enables localization of the mechanical ileus.
➤ vomiting
➤ pain
➤ meteorism
➤ gas and stool retention
Complications
If perfusion of the intestinal wall is impaired due to mechanical ileus, paralytic ileus with continuous pain, localized peritonitis, shock, and leukocytosis will occur. The blood pressure is reduced, the pulse becomes rapid and weak. Facies hippocratica with sunken cheeks develops. Vomiting occurs in all stages. With complete ileus fecal vomiting (copremesis) occurs. Gas and stool retention are observed in most cases. However, some patients also have diarrhea.
Causes of Mechanical Ileus
The most common causes of mechanical ileus are previous abdominal surgery (i.e., adhesions), neoplasms, sliding hernia, volvulus, invagination, and various other factors (e.g., foreign bodies, Crohn disease, diverticulitis, mesenteric artery infarction.

Mechanical ileus with seriously distended colon in a 73-year-old woman with carcinoma in the descending colon. Distal to the stenosis there is no air in the intestine.

Sliding hernias, postoperative adhesions (e.g., after appendectomy) or other surgical interventions, are frequent causes of a mechanical ileus. Therefore, sliding hernia and surgical scars must be considered in patients with an ileus. In children, and less frequently in young adults, an invagination and torsion of the intestine (volvulus) must also be considered. In both cases bloody stools are generally encountered. Obstruction of the intestine in adults is generally caused by a colorectal carcinoma. Carcinomas of the small intestine, which also cause ileus, are rare. In older patients with an acute abdomen a mesenteric infarction must be considered, which initially often presents with a clinical picture similar to that of mechanical ileus. Typical radiologic signs are gas-free intestines and later gas in the intestinal wall and portal vein.

Rarely, the horizontal part of the duodenum is obstructed by the Treitz ligament and the mesenteric arteries (superior mesenteric artery; superior mesenteric artery syndrome or mesenteric artery duodenal compression). Postprandial vomiting of bile, increased when standing or lying down, is the most important indicator. Radiologic demonstration of duodenal compression without typical clinical symptoms is not sufficient to diagnose duodenal obstruction. In adults the diagnosis must be made only with great caution and after exclusion of all other possible causes (including irritable stomach).
Very rare causes of a mechanical ileus are a large Meckel diverticulum or endometriosis, which is generally localized in the sigmoid colon. In endometriosis the temporal association between menstruation and occurrence of the symptoms will result in the correct diagnosis. Passage of gallstones into the intestine (biliary-digestive fistula or more rarely via the common bile duct) can cause an ileus (gallstone ileus). Lodging of these gallstones most often occurs in the distal or middle ileum, rarely in the jejunum, and primarily affects older patients. Sonographic or radiologic confirmation of air in the bile ducts (pneumobilia) indicates a biliary-digestive fistula and probably gallstone ileus. The clinical−radiologic picture of the mechanical small intestine (and colonic) ileus can also be rarely caused by idiopathic intestinal pseudoobstruction, which often occurs in waves. Slow-onset abdominal colic with vomiting and increasing meteorism and tendency to diarrhea are typical symptoms. Radiologic diagnosis shows distended intestinal loops and fluid in the small and possibly the large intestine. However, there are no signs of an intestinal stenosis with no air distally. The episode frequently subsides spontaneously within a few days.

Paralytic Ileus
Clinical Features
In paralytic ileus the intestinal musculature is paralyzed while the intestinal lumen is not obstructed. The inhibition of the motor intestinal activity prevents transport of the contents of the intestine. Distension of the abdomen occurs and it is painful upon pressure. Gases are not emitted and intestinal sounds cannot be detected by auscultation (deathly silence). In later stages feculent, bilious and liquid stomach contents may be vomited.

Mechanical small intestine ileus due to adhesions in a 70-year-old man (image taken in supine position).

Diagnosis
Distended bowel loops with smooth wall contours and fluid levels throughout the entire gastrointestinal tract can be demonstrated by radiography.
Complications
Respiration is accelerated as a result of intestinal intoxication and excessive distension (diaphragm under high pressure). Tachycardia, hypotension, and exsiccosis occur. The face is sunken with halos around the eyes and pale corners of the mouth being particularly evident.
Causes of Paralytic Ileus
Common causes of paralytic ileus are:
➤ postoperative (reflex intestinal atonia)
➤ peritonitis (e.g., after intestinal perforation)
➤ strangulation ileus
➤ serious infections (Gram-negative sepsis)
➤ metabolic disorders (uremia, diabetic coma)
➤ electrolyte disorders
➤ pelvic or spinal fracture
➤ retroperitoneal diseases (e. g., pancreatitis, hema-
Tom)
➤ mesenteric ischemia
➤ neurological disorders