Algorithm for the initial evaluation of an infant or child with rectal bleeding

LGI: lower gastrointestinal tract; UGI: upper gastrointestinal tract; CBC: complete blood count; ESR: erythrocyte sedimentation rate; PT: prothrombin time; PTT: partial thromboplastin time. 
* Refer to UpToDate topics on shock in children.
¶ Rarely, hematochezia (bright red blood per rectum) can be caused by upper gastrointestinal bleeding, especially in an infant (due to short intestinal transit time), or because of a massive UGI bleed in an older individual.
Δ The evaluation varies with the age and clinical presentation of the patient. For those with more than minimal bleeding or who are ill-appearing, initial laboratory tests include a CBC with differential, ESR, basic metabolic panel, hepatic function panel, coagulation studies (PT/PTT), and a urine analysis. If diarrhea is present, test stool for fecal calprotectin and enteric pathogens.