In terms of causes, a distinction is generally made between paralytic and mechanical ileus.
In mechanical ileus, an external or internal obstruction partially or completely blocks the natural passage of intestinal contents. The small intestine is affected significantly more often than the large intestine. Possible causes of mechanical ileus include:
A blocked intestine is referred to as a mechanical intestinal obstruction © psdesign1 / Fotolia
In contrast, paralytic ileus involves a functional rather than a structural disorder. Intestinal transit comes to a standstill due to a lack of intestinal movements. This absence of intestinal peristalsis can result, for example, from vascular occlusions. The acute occlusion of a vessel supplying the intestine is also referred to by medical professionals as a mesenteric infarction. Such a mesenteric vascular occlusion typically affects older adults with cardiovascular diseases.
Chronic inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis can also cause paralytic ileus. The same applies to medications such as antidepressants or opioids, as well as to various toxins. Toxins can, for example, be excreted by pathogens that cause diarrheal diseases.
Reflex-induced paralytic ileus can be caused by
.
Electrolyte imbalances or severe kidney disease can also lead to paralysis of the intestinal muscles.
In paralytic ileus, parts of the intestine are completely paralyzed, so there are no signs of bowel movements. No bowel sounds can be heard, and the intestine is also severely distended.
If peritonitis develops as a result of the intestinal obstruction, the abdominal wall is hard and distinctly tender to pressure. This is also referred to as a “drum-like abdomen.” In addition to diffuse abdominal pain, patients also suffer from hiccups. However, there is no bowel movement or flatulence. As the condition progresses, projectile vomiting may occur.
In the case of a mechanical intestinal obstruction, however, the intestine tends to exhibit hyperactivity. Hyperperistalsis is the body’s attempt to push the chyme past the narrowing in the intestine. For the patient, this results in colicky pain.
When auscultating with a stethoscope, the doctor may hear
- ringing,
- splashing, or
- whistling
bowel sounds in the area of the obstruction.
The blockage in the intestine leads to increased gas buildup, causing the abdomen to appear distended. However, the intestinal gas cannot be expelled, resulting in both constipation and tenesmus. Severe nausea and profuse vomiting are also characteristic symptoms of mechanical ileus.
If an intestinal obstruction is suspected, the doctor will ask during the medical history interview (anamnesis)
- the exact location of the pain,
- the time of the last bowel movement, and
- any possible triggers, such as surgery or underlying medical conditions.
Further clues to an ileus are provided by auscultation, in which the doctor listens to the abdomen with a stethoscope.
In the case of mechanical ileus, gurgling or ringing sounds can be heard, whereas in paralytic ileus, no bowel sounds are audible at all. Doctors refer to this condition as “dead silence in the abdomen.”
Intestinal obstruction can also be diagnosed using X-rays. As early as a few hours after the onset of symptoms, distended bowel loops become visible on these images. If the obstruction is located in the large intestine, an X-ray examination using a contrast agent may also be performed. The contrast agent is administered into the intestine via an enema.
The exact location of the intestinal obstruction can be determined using ultrasound. This technique reveals large amounts of gas as well as fluid accumulations. If a definitive diagnosis cannot be made after these tests, spiral computed tomography (CT) can provide further insight.
An intestinal obstruction is always life-threatening and therefore requires urgent emergency medical treatment. The type of treatment depends on both the cause and the exact location of the intestinal obstruction.
To reduce pressure in the intestine, a nasogastric tube is inserted through the patient’s mouth into the intestine. This special tube, which is connected to a suction pump, allows the accumulated chyme to be suctioned out. In cases of paralytic ileus, bowel movements can often be stimulated by an enema.
In cases of mechanical ileus, the constricting obstruction must be surgically removed so that the chyme can pass through the intestine again. Necrotic intestinal tissue is also removed during the operation. The healthy sections of the intestine are then reconnected. If the ileus lasts longer than a few hours, the doctor will also administer antibiotics to prevent inflammation of the abdominal cavity or bacterial sepsis.
Mechanical ileus caused by a benign condition has the best prognosis. However, if the mechanical intestinal obstruction persists, it can progress to paralytic ileus.
Therefore, a rapid diagnosis followed by early treatment is very important. The rule of thumb is: the sooner the diagnosis is made, the better the prognosis.
An untreated intestinal obstruction, on the other hand, can lead to serious complications. For example, intestinal contents can rupture through the intestinal wall and spread into the abdominal cavity. This usually leads to severe inflammation of the peritoneum, which can spread throughout the entire body (sepsis).
In addition, an obstruction not only restricts the transport of food; it also impairs the organ’s ability to absorb nutrients. This can lead to circulatory shock due to the loss of fluids and electrolytes. The lack of electrolytes can also impair electrical conduction in the heart, leading to cardiac arrhythmias.
What is paralytic ileus?
Paralytic ileus is a condition in which bowel movements cease. This form of ileus is also called functional ileus, as there is no mechanically caused obstruction. In paralytic ileus, intestinal transit comes to a halt due to paralysis of the intestinal muscles. The condition can develop after surgery, due to inflammation, or from other possible causes.
What are the symptoms of paralytic ileus?
Typical symptoms of ileus include nausea, vomiting, abdominal pain, constipation, and a distended abdomen. In addition, bowel sounds are often absent because peristalsis is disrupted. The severity of symptoms can vary depending on the location and extent of the intestinal paralysis. In severe cases, life-threatening complications may occur.
What is the difference between paralytic and mechanical ileus?
In mechanical ileus, intestinal transit is blocked by mechanical obstructions such as a tumor, intussusception, or adhesions. In mechanical ileus, there is therefore an actual blockage. Paralytic ileus, on the other hand, results from intestinal paralysis without a mechanical cause. Both forms can cause similar symptoms but differ in terms of diagnosis and treatment.
How is paralytic ileus diagnosed and treated?
Diagnosis of ileus involves a medical history, physical examination, and imaging studies with contrast media. The diagnostic process also includes assessment of bowel sounds, bowel loops, and the intestinal wall. Treatment of ileus is usually conservative and involves a nasogastric tube, intravenous fluids, medication, and fluid and electrolyte replacement. Surgery may be necessary if complications arise or if a mechanical bowel obstruction is suspected.
What are the possible causes of paralytic ileus?
A common cause of paralytic ileus is intestinal paralysis following surgery, which is why it is also referred to as postoperative ileus. Other possible causes include peritonitis, sepsis, hypokalemia, inflammation in the abdominal cavity, or impaired blood flow to the intestines. Certain medications can also impair peristalsis. The exact cause determines the course of further conservative treatment and the progression of the condition.
