Chapter 2

Symptoms of HUS

What are the signs and symptoms of Post-Diarrheal Hemolytic Syndrome (D+HUS) and how is the diagnosis made?

The bowel inflammation that occurs prior to the onset of HUS is generally referred to as the “prodrome.” Usually within a week (although the range can be one to 10 days) after ingesting STEC, the colon becomes severely inflamed, causing diarrhea that frequently becomes bloody.

A stool specimen obtained within the first 10 days of illness is usually positive for E. coli O157:H7 or Shiga toxin. However, in many patients, the window for capturing E. coli O157:H7 is narrow.

During the prodromal phase of HUS, the initial diagnosis is often acute surgical abdomen, acute appendicitis, or ulcerative colitis. Large bowel inflammation (colitis) can be mistaken for acute appendicitis because the site of intense inflammation is in the right lower part of the abdomen. If an appendectomy results, the appendix is almost always found to be normal, but the surrounding bowel is swollen and hemorrhagic. If a colonoscopy is conducted, severe inflammation, ulceration, and pseudomembranes (comprised of sloughed mucosal cells, white blood cells, and fibrin) are found. If computerized tomography (CT) of the abdomen is performed, a thickened (inflamed) colon is usually identified.

After several days of diarrhea, thrombocytopenia, hemolytic anemia (secondary to the destruction of red blood cells), and acute kidney injury converge to form the trilogy that defines HUS.

What are the physical signs and laboratory values on admission to the hospital with HUS?

Physical findings on admission to the hospital may include lethargy, abdominal tenderness, blood spots or skin hemorrhages (purpura), swelling, or dehydration. Features on admission that portend a severe or fatal outcome include coma, rectal prolapse, decreased or absent urine output, or an elevated white blood cell count (WBC)—one greater than 20 x 10^9/L (i.e. greater than 20,000 per liter).