Nausea and Vomiting (Case 20)

Pφ

Gastroenteritis is inflammation of the lining of the stomach and small and large intestines, most often caused by invasion of the GI tract by infectious agents (viral, bacterial, or parasitic). Viruses including noroviruses, rotavirus, and enteric adenoviruses are the most common etiologies. Fecal-oral spread of these viruses is the most common route of transmission. Infants and young children are particularly at risk, as are people who work in health care settings, day care, and schools. Immunosuppressed patients are at increased risk.

TP

Patients often present with nausea and vomiting, and/or diarrhea. Signs of volume depletion are commonly noted. Diarrhea is more common with bacterial etiologies, while vomiting is especially common with viral etiologies. Fever and chills are present in 40% to 60% of cases.

Dx

Laboratory studies are generally nonspecific. Mild elevations of liver enzymes may be seen in some bacterial and viral infections. Stool leukocytes are more often demonstrated in “invasive” bacterial infections such as that caused by Salmonella, Shigella, Yersinia, Campylobacter, and with certain Escherichia coli strains. Stool testing for rotavirus and other viruses is available, but only used for epidemiologic purposes and not for routine clinical care.

Pφ

SBO is due to a physical blockage of the normal flow of intestinal contents in the small bowel. The majority of cases are caused by adhesions from prior surgeries, although cancers, incarcerated hernias, and small-bowel strictures are other causes.

TP

Patients typically present with nausea, vomiting, and abdominal distension, and often have abdominal pain that is diffuse and crampy. Absence of flatus is another common presenting symptom. Inspect for scars from previous surgery; listen for bowel sounds, which may be high-pitched, hypoactive, or absent. Tympany to percussion is usually present with distension; if guarding and/or rebound is elicited, consider peritonitis complicating the obstruction. Rectal exam typically reveals an empty rectal vault.

Dx

Upright abdominal radiographs should be ordered to first evaluate for free air. SBO will classically demonstrate multiple air-fluid levels in the small intestine with distended loops of bowel. CT scan, with water-soluble oral contrast, can be used if plain radiographs are equivocal. A transition point at the obstruction can often be identified. Lack of air or contrast in the distal small intestine or colon is suggestive of a complete obstruction.

Pφ

Ileus refers to a nonmechanical insult that disrupts the normal peristalsis of the small intestine. It is most common in the postoperative setting, usually up to 5 days. The pathogenesis is multifactorial, including inflammation of the bowel from surgical manipulation, neural inhibitory sympathetic reflexes and local neuroinhibitory peptides acting in response to the surgical insult to the bowel, and narcotic-related delay in bowel transit from systemic opioid use. Other potential etiologies for ileus include metabolic abnormalities, pancreatitis, and other inflammatory states, sepsis, medication reactions, ischemia, and neurologic processes.

TP

In addition to nausea and vomiting, patients typically present with abdominal distension, bloating, pain, absence of flatus, and/or inability to tolerate oral intake. On physical exam, patients often have abdominal distension and tympany, decreased or absent bowel sounds, and sometimes mild tenderness. The presentation is often very similar to that of an SBO.

Dx

Abdominal radiographs will show distended loops of bowel with air-fluid levels. CT scan with water-soluble contrast will show these findings as well, yet unlike with SBO, there is no transition point of obstruction. Laboratory studies may demonstrate hypokalemia or hypomagnesemia.

Pφ

Gastroparesis refers to delayed gastric emptying. Its pathophysiology probably includes disordered motility related to neurologic, hormonal, and smooth muscle factors. By definition, there are no structural abnormalities contributing to the gastric delay. The most common etiology is diabetes mellitus, with autonomic neural injury the proposed mechanism. Other less common causes include medications, infection, acidosis, metabolic disorders, pregnancy, and collagen vascular disorders. In many cases the specific cause is not clearly identified.

TP

Patients typically present with nausea, vomiting, bloating, and early satiety. Diabetics typically have poorly controlled glucose levels and evidence of end-organ damage including retinopathy and neuropathy. Abdominal exam may show tenderness to palpation, without guarding or rebound. A succussion splash may often be demonstrated.

Dx

Structural diseases, including gastric outlet obstruction related to malignancy and peptic ulcer disease, should first be excluded with either upper endoscopy or upper GI barium studies. Upper endoscopy will often show retained food debris in the stomach, even after an overnight fast. A thorough review of medications is necessary to rule out possible triggers. Once these steps have been completed, gastric emptying scintigraphy remains the gold standard for diagnosis. Retention of >10% of the ingested meal at 4 hours or >70% at 2 hours is considered diagnostic. Medications that can either delay or increase gastric emptying should be withheld 48 hours prior to scintigraphy. Blood glucose should also be optimized, as hyperglycemia can affect scintigraphy results.