Bowel sounds, hypoactive

Hypoactive bowel sounds, detected by auscultation, are diminished in regularity, tone, and loudness from normal bowel sounds. They may portend absent bowel sounds, which can indicate a life-threatening disorder.

Hypoactive bowel sounds result from decreased peristalsis, which, in turn, can result from a developing bowel obstruction. The obstruction may be mechanical (as from a hernia, tumor, or twisting), vascular (as from an embolism or thrombosis), or neurogenic (as from mechanical, ischemic, or toxic impairment of bowel innervation). Hypoactive bowel sounds can also result from the use of certain drugs, abdominal surgery, and radiation therapy.

History

After detecting hypoactive bowel sounds, look for related symptoms. Ask the patient about the location, onset, duration, frequency, and severity of any pain. Cramping or colicky abdominal pain usually indicates a mechanical bowel obstruction, whereas diffuse abdominal pain usually indicates intestinal distention related to paralytic ileus.

Ask the patient about any recent vomiting: When did it begin? How often does it occur? Does the vomitus look bloody? Also ask about any changes in bowel habits: Does he have a history of constipation? When was the last time he had a bowel movement or expelled gas?

Obtain a detailed medical and surgical history of any conditions that may cause mechanical bowel obstruction, such as an abdominal tumor or hernia. Does the patient have a history of severe pain; trauma; conditions that can cause paralytic ileus such as pancreatitis; bowel inflammation or gynecologic infection, which may produce peritonitis; or toxic conditions such as uremia? Has he recently had radiation therapy or abdominal surgery, or ingested a drug such as an opiate, which can decrease peristalsis and cause hypoactive bowel sounds?

Physical assessment

After the history is complete, perform a careful physical examination. Inspect the abdomen for distention, noting surgical incisions and obvious masses. Gently percuss and palpate the abdomen for masses, gas, fluid, tenderness, and rigidity. Measure abdominal girth to detect any subsequent increase in distention. Also check for poor skin turgor, hypotension, narrowed pulse pressure, and other signs of dehydration and electrolyte imbalance, which may result from paralytic ileus.

Medical causes

Mechanical intestinal obstruction

In a patient with a mechanical intestinal obstruction, bowel sounds may become hypoactive after a period of hyperactivity. The patient may also have acute colicky abdominal pain in the quadrant of obstruction, possibly radiating to the flank or lumbar region; nausea and vomiting (the higher the obstruction, the earlier and more severe the vomiting); constipation; and abdominal distention and bloating. If the obstruction becomes complete, signs of shock may occur.

Mesenteric artery occlusion

In cases of mesenteric artery occlusion, bowel sounds become hypoactive after a brief period of hyperactivity and then quickly disappear, signifying a life-threatening crisis. Associated signs and symptoms include fever; a history of colicky abdominal pain leading to sudden and severe midepigastric or periumbilical pain, followed by abdominal distention and possible bruits; vomiting; constipation; and signs of shock. Abdominal rigidity may appear late.

Paralytic ileus

With paralytic (adynamic) ileus, bowel sounds are hypoactive and may become absent. Associated signs and symptoms include abdominal distention, generalized discomfort, and constipation or passage of small, liquid stools and flatus. If the disorder follows acute abdominal infection, fever and abdominal pain may occur.

Other causes

Drugs

Certain classes of drugs reduce intestinal motility and thus produce hypoactive bowel sounds. These include opiates such as codeine, anticholinergics such as propantheline, phenothiazines such as chlorpromazine, and vinca alkaloids such as vincristine. General or spinal anesthetics produce transient hypoactive sounds.

Surgery

Hypoactive bowel sounds may occur after surgical manipulation of the bowel. Motility and bowel sounds in the small intestine usually resume within 24 hours; colonic bowel sounds, in 3 to 5 days.

Special considerations

Frequently evaluate the patient with hypoactive bowel sounds for indications of shock (thirst; anxiety; restlessness; tachycardia; cool, clammy skin; weak, thready pulse), which can develop if peristalsis continues to diminish and fluid is lost from the circulation.

Be alert for the sudden absence of bowel sounds, especially in postoperative and hypokalemic patients because they’re at increased risk for paralytic ileus. Monitor the patient’s vital signs and auscultate for bowel sounds every 2 to 4 hours.

Severe pain, abdominal rigidity, guarding, and fever, accompanied by hypoactive bowel sounds, may indicate paralytic ileus from peritonitis. If these signs and symptoms occur, prepare for emergency interventions. (See “Bowel sounds, absent,” page 94.)

The patient with hypoactive bowel sounds may require GI suction and decompression, using a nasogastric or intestinal tube. If so, restrict the patient’s oral intake. Then elevate the head of the bed at least 30 degrees, and turn the patient to facilitate passage of the tube through the GI tract.

Remember not to tape an intestinal tube to the patient’s face. Ensure tube patency by watching for drainage and properly functioning suction devices. Irrigate the tube, and closely monitor drainage.

Continue to administer I.V. fluids and electrolytes, and send a serum specimen to the laboratory for electrolyte analysis at least once per day. Recognize that the patient may need X-ray studies, endoscopic procedures, and further blood work to determine the cause of hypoactive bowel sounds.

Pediatric pointers

Hypoactive bowel sounds in a child may simply be due to bowel distention from excessive swallowing of air while the child was eating or crying. However, be sure to observe the child for further signs of illness. As with an adult, sluggish bowel sounds in a child may signal the onset of paralytic ileus or peritonitis.

Patient counseling

Encourage the patient to ambulate to stimulate peristalsis. If he can’t move, assist him in turning side to side and with range-of-motion exercises. Explain all diagnostic tests and procedures as well as the need to withhold food and fluids until bowel sounds improve.

Pictures

Book Source Details

• Book Title: Signs & Symptoms: A 2-in-1 Reference for Nurses
• Author(s): Springhouse
• Year of Publication: 2007
• Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2007 Lippincott Williams & Wilkins.

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More About This Book: Title: Signs & Symptoms: A 2-in-1 Reference for Nurses Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-318-1

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