Diagnostic accuracy of RBC scintigraphy and CTA for detection of patients with suspected lower gastrointestinal bleeding: a systematic review and meta-analysis

OBJECTIVE

Detection of lower gastrointestinal bleeding (LGIB) through noninvasive modalities is very important in the successful management of LGIB. RBC scintigraphy and CT have a role in the detection of LGIB and guiding the management of patient by localization of the bleeding site. However, only a small number of studies have evaluated the role of RBC scintigraphy and CT in the diagnosis of LGIB. This systematic review was conducted to evaluate the diagnostic performance of RBC scintigraphy and CT in the detection of LGIB in patients with clinical or biochemical findings suspicious of LGIB.

METHODS

This systematic review followed PRISMA guidelines. Searches in PubMed, Scopus, and Embase were conducted using relevant keywords, and articles published through 30 April 2022, were included. Using endoscopy or surgical outcomes as the reference standard, the numbers of true and false positives and true and false negatives were extracted. Pooled estimates of diagnostic test accuracy - including sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and summary ROC (SROC) curve - were generated using bivariate random-effects meta-analysis.

RESULTS

Three studies comprising 171 patients were included in the systematic review and meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for the detection of LGIB using RBC scintigraphy were 0.787 (95% CI, 0.643-0.893), 0.289 (95% CI, 0.164-0.443), 1.214 (95% CI, 0.923-1.597) and 0.576 (95% CI, 0.296-1.121) respectively. The area under the SROC curve was 0.73. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for the detection of LGIB using CT were 0.931 (95% CI, 0.772-0.992), 0.870 (95% CI, 0.737-0.951), 6.085 (95% CI, 0.840-44.097), 0.126 (95% CI, 0.006-2.509) respectively. The area under the SROC curve was 0.095.

CONCLUSION

RBC scintigraphy has overall good sensitivity and CTA has excellent sensitivity specificity, positive and negative likelihood ratio in the detection of LGIB in patients with clinical or biochemical findings suspicious for LGIB.CTA along with RBC scintigraphy can be used algorithmically to rule out patients who do not have a localization for the site of LGIB thereby helping these patients to avoid invasive procedures like endoscopy or surgical explorations.

Association of inferior vena cava diameter ratio with outcomes in patients with gastrointestinal bleeding

Objective

To examine the association of inferior vena cava (IVC) diameter ratio measured using computed tomography with outcomes in patients with gastrointestinal bleeding (GIB).

Methods

A single-center retrospective observational study was conducted on consecutive patients with GIB who presented to the emergency department. The IVC diameter ratio was calculated by dividing the maximum transverse and anteroposterior diameters perpendicular to it. The association of the IVC diameter ratio with outcomes was examined using multivariable logistic regression analysis. The primary outcome was in-hospital mortality. The area under the receiver operator characteristic curve (AUC) of the IVC diameter ratio was calculated, and the sensitivity and specificity, including the cutoff values, were computed.

Results

In total, 585 patients were included in the final analysis. The in-hospital mortality rate was 4.6% (n=27). The IVC diameter ratio was significantly associated with higher in-hospital mortality in multivariable logistic regression analysis (odds ratio, 1.793; 95% confidence interval [CI], 1.239–2.597; P=0.002). The AUC of the IVC diameter ratio for in-hospital mortality was 0.616 (95% CI, 0.498–0.735). With a cutoff of the IVC diameter ratio (≥2.1), the sensitivity and specificity for predicting in-hospital mortality were 44% (95% CI, 26%–65%) and 71% (95% CI, 67%–75%), respectively.

Conclusion

The IVC diameter ratio was independently associated with in-hospital mortality in patients with GIB. However, the AUC of the IVC diameter ratio for in-hospital mortality was low.