Patients with appendicitis frequently run a low-grade fever, between 37.7°C and 38.3°C (100°F and 101°F), but fever may be absent in more than half the patients with peritoneal signs. Plain abdominal radiographs lack the sensitivity and specificity to be helpful in making the diagnosis, although some experts consider the finding of an appendicolith to be pathognomonic. While many patients with appendicitis complain of constipation, a few do have one or two diarrheal stools, although far from a majority. Pyuria is an infrequent finding.