The Impact of Fecal Occult Blood Testing on Endoscopic Procedures in Hospitalized Patients with Anemia

From the 2021 HVPAA National Conference

Vinod Kumar (Division of General Internal Medicine and Geriatrics Indiana University School of Medicine), Shobha Shahani, FNU Jaydev, Jai Khatri, Areeba Kara

Background

Gastrointestinal (GI) endoscopic procedures are among the most common procedures performed during hospitalizations. Fecal occult blood tests (FOBT) are highly sensitive and have a higher likelihood of false positive results in inpatients. While the utility of FOBTs for colorectal cancer screening in ambulatory settings is established, such testing continues to be used in the inpatient setting for the evaluation of anemia.

Objective 

We undertook an evaluation of patients who developed anemia and in whom an FOBT was performed to gain insights on the utilization of these tests and their impact on management decisions.

Methods

This was a single center, retrospective study conducted at a large, Midwestern, academic, tertiary care center between January 2016 and December 2017. We identified patients who were admitted to medicine services and developed a drop in hemoglobin ≥2 grams/dL. Of these we focused on those who had an FOBT. We extracted further data and analyzed a random selection of half of these patients. Patients were categorized as having an overt GI bleed (documented symptoms of melena, hematochezia, or hematemesis) or not and compared on the basis of FOBT results.

Results

Over the study period 6,310 patients were admitted to the medicine services and developed a hemoglobin drop of ≥2 grams/dL. Of these 817 (12.9%) had an FOBT and we reviewed 407 (49.8%) randomly selected patients from this group. Those with missing FOBT results (n=13) were excluded, leaving 394 included in the final analysis.

The mean age of the sample was 62.7 years with 211 f females ( 53.7%). Concordance between objective stool descriptions documented by bedside nursing and expected stool appearance based on the admitting symptoms was poor- less than half (n=66, 48.5%) of those presenting with overt GI bleeding by history had stool described as melena or hematochezia in nursing notes while descriptions were missing in 38%.

FOBTs were performed in 34.6% of patients despite the presence of overt GI bleeding symptoms. The proportion of those who underwent endoscopic evaluation was higher in those who presented with symptoms of overt GI bleeding than those who did not (83% vs 23.6%, p < .00001).

In patients who did not present with overt GI bleeding symptoms, the proportion of patients who underwent endoscopic procedures was higher in those with a positive FOBT than those whose FOBT was negative (40.4% vs 13.2%, p < .00001) Conversely, in patients presenting with symptoms of overt GI bleeding, no differences in rates of endoscopic evaluation were noted based on FOBT results.

Conclusions

FOBTs continue to be utilized in inpatient settings for hospital acquired anemia, including in those presenting with overt GI bleeding. In those without overt GI bleeding, positive results may drive subsequent endoscopic procedures.

Clinical Implications

Understanding the drivers of FOBTs in the inpatient setting, including limitations in stool documentation and possible under-utilization of digital rectal examinations to confirm histories may help us improve processes and practices. Clinicians may appropriately disregard negative test results when the history is strongly suggestive of a GI bleed but when faced with diagnostic uncertainty, positive FOBT results may lead to confirmation bias and subsequent potentially unnecessary endoscopic evaluation.