Abstract
Objective
Early diagnostic prediction in patients with small bowel obstruction (SBO) can improve
time to definitive management and disposition in the emergency department. We sought
to develop a nomogram to leverage point-of-care ultrasound (POCUS) and maximize accuracy
of prediction of SBO diagnosis.
Methods
Using data from a prospective cohort of 125 patients with suspected SBO who were evaluated
with POCUS in the ED, we developed a nomogram integrating age, gender, comorbidities,
prior abdominal surgery, physician's pre-test probability, and POCUS findings to determine
post-test risk of SBO. The primary outcome was to develop a nomogram to allow calculating
output probabilities for predictive models using POCUS findings. The discriminative
ability of the nomogram was tested using a C-statistics, calibration plots, and receiver
operating characteristic curves.
Results
The derivation cohort included 125 patients with a median age of 54 years who underwent
POCUS for a suspected SBO. One-fourth of the patients (25.6% [32/125]) had SBO. Using
a retrospective stepwise selection of clinically important variables with the POCUS
results, the final nomogram incorporated four relevant factors for the prediction
of SBO: small bowel diameter (odds ratio [OR] per 1 mm increase, 1.10; 95% CI, 1.03–1.17;
P = 0.001), positive free intraperitoneal fluid between bowel loops (OR, 8.19; 95%
CI, 2.62–25.62; P < 0.001), clinician's moderate (OR, 5.94; 95% CI, 0.83–42.57; P = 0.08) or high pretest probability (OR, 11.26; 95% CI, 1.44–88.25; P = 0.02), and patient age (OR per 1 year increase, 1.03; 95% CI, 1.00 to1.07; P = 0.08).The discriminative ability and calibration of the nomogram revealed good
predictive ability as indicated by the C-statistic of 0.89 for the SBO diagnosis.
Conclusion
A unique nomogram incorporating patient age, physician pretest probability of SBO,
and POCUS measurements of small bowel diameter and the presence of free intraperitoneal
fluid between bowel loops was developed to accurately predict the diagnosis of SBO
in the emergency department. The nomogram should be externally validated in a novel
cohort of patients at risk for SBO to better assess predictability and generalizability.
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Article Info
Publication History
Published online: December 11, 2019
Accepted:
December 4,
2019
Received in revised form:
December 3,
2019
Received:
August 10,
2019
Footnotes
☆Study Institution: The study was conducted at the George Washington University Hospital in Washington DC.
Identification
Copyright
© 2019 Elsevier Inc. All rights reserved.
