Point-of-care ultrasound in the acute abdomen and gastrointestinal emergencies: An evidence-based guide and the case for standardisation

Table 1 Diagnostic performance, heterogeneity and risk of bias of emergency point-of-care ultrasound applications in the acute abdomen

Ref.	Population/setting	Operator	Reference standard	Diagnostic threshold	Sensitivity (95%CI)	Specificity (95%CI)	LR+/LR-	Studies/patients	Heterogeneity (%)	Risk of bias/certainty	Interpretation and limitations
SBO: Study-level meta-analysis (Gottlieb et al[9], 2018)	ED and inpatient adults with suspected SBO	Mixed (EP and others)	CT, surgery, or final diagnosis	Dilated loop > 25 mm	92.4% (89.0%-94.7%)	96.6% (88.4%-99.1%)	27.5/0.08	11/1178	NR in retrievable text	QUADAS-2 not reported in retrievable text; no GRADE	Strong rule-in; study-level pooling may overestimate sensitivity
SBO: IPD meta-analysis (Shokoohi et al[10], 2023)	Multicentre ED, adults	EP (attending and resident)	CT/surgery/final diagnosis	Dilated loop > 25 mm	83.0% (71.7%-90.4%)	93.0% (55.3%-99.3%)	11.9 (1.2-114.9)/0.2	5/433	NR in retrievable text	IPD design reduces reporting bias; no GRADE	Most conservative estimate; specificity CI so wide the parameter is effectively unestimated
SBO: Meta-analysis with QUADAS-2 (Motavaselian et al[30], 2024)	ED adults with suspected SBO	Mixed	CT/surgery/final diagnosis	Dilated loop > 25 mm	NR here (see source)	0.80 (0.77-0.83)	N/A	21/1977	62% sensitivity; 88% specificity (both P < 0.01)	QUADAS-2: High risk for patient selection and flow/timing in several studies; Egger P = 0.04	Specificity 16 points below the two estimates above; publication bias detected
SBO: Bedside-threshold analysis (Shokoohi et al[11], 2024)	ED adults	EP	CT/surgery	Loop > 2.75 cm (AUC = 0.76, 0.71-0.81); ≤ 1.7 cm 100% sensitivity; > 4 cm	N/A	Approximately 90.7% at > 4 cm	N/A	IPD secondary analysis	N/A	Unvalidated threshold-derivation study	Candidate threshold only; no measurement convention specified; age/sex shift optimum (2.95 cm at ≥ 65 years)
Acute cholecystitis: EP-POCUS meta-analysis (Wilson et al[32], 2024)	ED adults, suspected acute cholecystitis	EP	Final diagnosis	Stones + wall > 3 mm + Murphy sign + pericholecystic fluid	70.9% (62.3%-78.2%)	94.4% (88.2%-97.5%)	12.7/0.31	10 included; estimates from 7/1772	NR in retrievable text	Not reported in retrievable text	Rule-in test; negative scan does not exclude
Acute cholecystitis: All-operator meta-analysis (Huang et al[25], 2023)	Mixed settings, all specialties (EP subgroup)	All operators; EP subgroup	Final diagnosis/pathology	As above	71% (69%-72%); EP 71% (67%-74%)	85% (84%-86%); EP 92% (90%-93%)	N/A	40/8652	89.7% (87%-92%)	QUADAS-2: > 25% of studies high risk (case-control design, non-consecutive enrolment)	Operator specialty changes specificity by 7 points
Acute cholecystitis: Prospective TG18-adjudicated cohort (Nipitkul et al[33], 2026)	ED adults, high disease prevalence	EP	TG18	POCUS criteria vs TG18 (wall > 3 mm vs ≥ 4 mm scales)	86.6% (83.4%-89.4%)	17.1% (12.5-22.5)	NR/NPV 37.0%	1/783	N/A (primary study)	Prospective; single reference standard	Discordant with pooled specificity of 85%-94%; only gallstones were significantly associated with confirmed disease
Gastric: ED intubation cohort (Asokan et al[27], 2023)	ED adults undergoing urgent intubation	EP	Aspiration-relevant gastric content	Antral CSA ≥ 9.27 cm²	100%	87%	N/A	1/100	N/A	Single-centre	Risk stratification against a surrogate endpoint, not diagnosis
Gastric: Fasting IPD meta-analysis (Perlas et al[26], 2024)	Fasting adults (reference range)	Trained sonographers	Endoscopic/measured volume	95th-percentile CSA 9.9 cm² (9.4-10.4); volume 2.3 mL/kg (2.3-2.4)	Grade 0/1 → 98% probability below threshold	N/A	N/A	12/1203	NR in retrievable text	Reference-range derivation	Thresholds do not generalise across position or population
Free fluid: Ectopic pregnancy (Moore et al[31], 2007)	ED women, suspected ectopic pregnancy	EP	Operative intervention	Any free fluid in Morison's pouch	N/A	N/A	LR+ 112 (15-831)	1/242	N/A	Single-centre; estimate rests on 10 fluid-positive patients	Decisive rule-in in a high-pretest obstetric population only
Free fluid: Prehospital FAST meta-analysis (Lin et al[19], 2024)	Prehospital trauma	Prehospital providers	CT/laparotomy	Any free fluid	0.596 (0.345-0.822)	0.970 (0.953-0.983)	N/A	6/1356	94%a	GRADE: Sensitivity very low (inconsistency, imprecision, publication bias); specificity high	Trauma population, indirect evidence for non-traumatic disease; indicates the sensitivity ceiling
Free fluid: Cochrane review, blunt trauma (Stengel et al[18], 2018)	Blunt thoracoabdominal trauma, adults and children	Mixed	CT/laparotomy/clinical follow-up	Any free fluid	0.74 (0.65-0.81); children 0.63 (0.46-0.77)	0.96 (0.94-0.98)	N/A	34 studies	Reported in source	Cochrane methodology	At 28% prevalence, 73 injured adults and 118 injured children missed per 1000 scanned
Appendicitis: POCUS meta-analysis (Matthew Fields et al[35], 2017)	ED adults and children	Non-radiologist physicians; EP subgroup	Pathology/final diagnosis	Non-compressible, dilated appendix	91% (83%-96%); EP subgroup 80%	97% (91%-99%); EP subgroup 92%	N/A	21/NR	99% (99%-100%)	Not reported in retrievable text	Extreme heterogeneity; EP-only performance lower than the headline figure
Appendicitis: Paediatric meta-analysis (Miller et al[36], 2026)	Children	Mixed	Pathology/final diagnosis	Non-compressible, dilated appendix	85.6% (68.9%-94.1%)	90.2%	N/A	8/993	Sensitivity range 53%-100% across studies	Recent; see source	Between-study range wider than the pooled CI implies
Hydronephrosis/renal colic (Wong et al[37], 2018)	ED adults, suspected renal colic	EP	CT	Any hydronephrosis	70.2% (67.1%-73.2%)	N/A	N/A	NR in retrievable text	NR in retrievable text	Not reported in retrievable text	Risk stratification only; cannot exclude
AAA (Shaban et al[34], 2025)	ED adults, symptomatic	EP	CT/operative/final diagnosis	Aortic diameter ≥ 3 cm (aneurysm definition)	98.33%	99.84%	N/A	9/NR	NR in retrievable text	Not reported in retrievable text	Identifies an aneurysmal aorta; does NOT identify rupture, for which CT angiography is the reference standard

^aFor Lin et al[19], 2024 the source reports this 94% number for sensitivity from a χ² test of heterogeneity, not as an I² statistic, and reports 45% for specificity by the same test; the value is reproduced here as published and the column is therefore headed heterogeneity rather than I².

Values are reproduced from the cited sources; no estimates were recalculated. Every value in this table was checked against the cited source; NR denotes a value that the source itself does not report, and is therefore a finding about the source rather than an unverified entry. Full source-by-source extraction details, including the location of each value within its source, are given in Supplementary Table 2. AAA: Abdominal aortic aneurysm; AUC: Area under the receiver-operating-characteristic curve; CI: Confidence interval; CSA: Cross-sectional area; CT: Computed tomography; ED: Emergency department; EP: Emergency physician; GRADE: Grading of Recommendations Assessment, Development and Evaluation; IPD: Individual-patient-data; LR+: Positive likelihood ratio; LR-: Negative likelihood ratio; NPV: Negative predictive value; NR: Not report; QUADAS-2: Quality Assessment of Diagnostic Accuracy Studies 2; SBO: Small-bowel obstruction; TG18: Tokyo Guidelines 2018; POCUS: Point-of-care ultrasound; N/A: Not applicable.