Factors influencing obstetric ultrasound examination duration in a tertiary fetal center

Abstract

Objective

To quantify scan duration across commonly performed obstetric ultrasound examinations in a tertiary fetal imaging center and to evaluate whether exam type, maternal body mass index (BMI), and sonographer experience independently influence scan time.

Methods

We conducted a retrospective cohort study of singleton pregnancies undergoing diagnostic obstetric ultrasound between January 2023 and May 2024 at a high‐volume tertiary care center. Ultrasounds were categorized into five exam types: dating/viability (6–10 weeks), detailed first‐trimester (11–14 weeks), detailed second‐trimester anatomic survey (18–22 weeks), fetal echocardiography (22–24 weeks), and second/third‐trimester growth/Doppler (24–38 weeks) scans. Scan duration was defined using ultrasound image timestamps from the first to the last acquired image. Linear regression models with log‐transformed duration were constructed, adjusting for ultrasound type, maternal BMI (per 10‐unit increase), prior abdominal surgery, and sonographer experience (0–4, 5–9, ≥10 years). Adjusted durations were estimated using marginal standardization.

Results

A total of 870 ultrasounds were analyzed. Median scan duration varied significantly by exam type: dating (6.8 min), detailed first‐trimester (18.3 min), second‐trimester anatomy survey (29.9 min), fetal echocardiography (26.6 min), and second/third‐trimester growth/Doppler (12.5 min) scans. After adjustment, all exam types required significantly longer scan times than dating ultrasounds, with the largest increases observed for second‐trimester anatomic surveys and fetal echocardiography (p < 0.001). Greater sonographer experience was independently associated with shorter scan duration, with efficiency gains plateauing after approximately 5 years. Maternal BMI was also a significant predictor of scan duration, with each 10‐unit increase in BMI associated with an approximately 3% increase in adjusted scan time (p = 0.037).

Conclusion

Scan duration in obstetric ultrasound is strongly influenced by exam type, sonographer experience, and maternal BMI. These findings provide clinically relevant information that can be used for the creation of benchmarks, scheduling templates, staffing strategies, and workflow optimization in maternal‐fetal medicine ultrasound units.

1. INTRODUCTION

Obstetric ultrasound is the cornerstone of modern prenatal care, providing noninvasive, real‐time assessment of fetal and maternal structures throughout gestation [1, 2]. Over the past decades, advances in imaging technology have substantially expanded its diagnostic capabilities, enabling increasingly detailed anatomic assessment beginning in the first trimester [2, 3, 4]. National and international societies have established guidelines defining the indications, scope, and timing of obstetric ultrasound examinations [5, 6, 7, 8, 9, 10, 11, 12, 13]. Despite these recommendations, considerable variation persists in how ultrasound services are implemented and scheduled, particularly in tertiary referral centers, where exam complexity and patient acuity are highest.

In the United States, the number of ultrasounds performed during pregnancy has steadily increased, with women now receiving an average of 4–5 scans per pregnancy [14, 15, 16]. This trend reflects rising maternal age, increasing rates of obesity and medical comorbidities, and expanded use of assisted reproductive technologies [17]. As a result, maternal‐fetal medicine (MFM) ultrasound units face growing pressure to balance diagnostic thoroughness with operational efficiency.

Amidst this increased utilization, scheduling optimization and scan time allocation have emerged as pressing challenges for MFM units. The Society for Maternal‐Fetal Medicine recently convened the “President's Workshop on Developing an Optimal MFM Ultrasound Practice (2023)” to address national gaps in workflow design, staffing models, and quality assurance standards. One area of particular concern is the absence of clear benchmarks for the time required to perform different ultrasound types, which hinders effective scheduling and may contribute to sonographer burnout [18].

The performance of a comprehensive anatomic survey requires acquisition of numerous fetal views and careful documentation of normal and abnormal findings [19]. Published scan durations vary widely, typically ranging from 20 to 45 min depending on fetal position, gestational age, maternal body habitus, and sonographer expert [4, 19]. In a study by Catanzarite, only 8% of targeted anatomic surveys were completed in under 10 min, whereas more than 80% required up to 30 min [19].

Maternal obesity is a well‐recognized barrier to efficient ultrasound imaging. In the United States, more than half of women of reproductive age are overweight or obese, and nearly one‐third enter pregnancy with obesity [17]. Higher body mass index (BMI) is associated with longer scan times, higher rates of incomplete exams, and reduced image quality due to sound attenuation through adipose tissue, often necessitating repeat imaging [2, 3]. Sonographer expertise may further influence imaging efficiency, as experienced sonographers have been shown to obtain complete anatomic views more quickly and with higher success rates [16].

Despite these known influences, few studies have comprehensively evaluated scan duration times across multiple obstetric ultrasound types, while simultaneously accounting for maternal BMI and sonographer experience. In addition, real‐world data from high‐volume tertiary referral centers remain limited. The objective of this study is to quantify scan duration across commonly performed obstetric ultrasound examinations in a tertiary fetal center, and to evaluate whether maternal BMI and sonographer experience independently influence scan time.

2. METHODS

This was a retrospective cohort study performed at the Division of Maternal‐Fetal Medicine at Macon and Joan Brock Virginia Health Sciences at Old Dominion University (USA), between January 2023 and May 2024, following Institutional Review Board approval (23‐08‐WC‐0233‐BVHS).

We included women with singleton gestations who underwent a diagnostic obstetric ultrasound with normal findings. Ultrasounds were categorized into five clinical types based on clinical indication and gestational age: dating/viability scan: 6–10 weeks, detailed first‐trimester scan: 11–14 weeks, detailed second‐trimester anatomy scan: 18–22 weeks, fetal echocardiogram: 22–24 weeks, second or third‐trimester growth/Doppler scan: 24–38 weeks. Fetal echocardiograms often included a full anatomic survey in accordance with institutional protocols for comprehensive evaluation in referral cases. Therefore, isolated fetal echocardiography examinations were not performed, and all studies classified as fetal echocardiography in this cohort included concurrent anatomic evaluation.

Ultrasounds were excluded if they revealed any abnormal maternal, fetal, or placental findings, including early pregnancy loss, fetal demise, fetal growth abnormalities, congenital or genetic anomalies, placenta previa or accreta, or large maternal fibroids or adnexal masses. Our ultrasound unit performs a substantially larger number of examinations annually; however, the present analysis was restricted to examinations meeting predefined inclusion criteria, including singleton pregnancies with normal findings and complete timestamp data suitable for precise scan‐duration assessment.

All ultrasound examinations were performed using high‐end obstetric imaging systems from the same manufacturer (GE Healthcare), including Voluson E10 and Voluson E22 platforms. These systems have comparable imaging capabilities and were used interchangeably in our ultrasound unit, with machine assignment based on room availability rather than exam complexity.

Ultrasound data were extracted from the ViewPoint® ultrasound reporting system (version 6.10.2, GE Healthcare). A structured database query was developed to identify all eligible scans. Demographic and clinical information, including maternal age, BMI, parity, race, ethnicity, relevant medical/surgical history (e.g., prior abdominal surgeries), and gestational age at time of service, was obtained via retrospective chart review. Charts missing essential demographic or clinical data were excluded. Maternal BMI corresponded to the prepregnancy (or early pregnancy) BMI recorded in the medical record and was not measured at the time of each ultrasound examination.

The primary outcome was total scan time, defined as the duration in minutes between the timestamp of the first and the last ultrasound image captured in the study. Secondary variables included the number of images acquired per scan, anatomical areas evaluated (head, chest, abdomen, extremities, amniotic fluid, placenta), and the proportion of keepsake or nondiagnostic images. To minimize misclassification of scan time due to workflow interruptions, cases were reviewed for internal consistency in image timestamp progression. Ultrasounds showing extended time gaps between sequential image timestamps—suggesting interruption and re‐initiation of scanning—were flagged and excluded. For this study, an extended time gap was defined as an interval of ≥3 min between consecutive image acquisitions, which was considered unlikely to represent continuous scanning and more likely to reflect workflow interruption or temporary discontinuation of the examination. This ensured that scan duration reflected continuous imaging time only. Ultrasound examinations were performed according to standardized institutional protocols based on established obstetric ultrasound guidelines, with predefined imaging components for each examination type. Appointment durations were scheduled according to examination type, reflecting the expected complexity of each scan.

Sonographer experience was calculated by subtracting the year of their initial certification by the American Registry for Diagnostic Medical Sonography (ARDMS) from the year of the ultrasound being performed, provided they had maintained continuous clinical activity. Sonographers were grouped into three experience strata: 0–4 years, 5–9 years, and ≥10 years.

Because this was a retrospective cohort including all eligible ultrasounds performed during the study period, a formal a priori sample size calculation was not performed. Instead, we used a precision‐based rationale, which is recommended for retrospective efficiency studies. By including the full dataset of 870 scans, the study was designed to provide narrow confidence intervals around the mean and adjusted differences in scan duration across ultrasound types. Prior literature demonstrates that differences in exam duration between scan types typically exceed 10–15 min; with our sample size, the detectable effect size for between‐group comparisons is well below this threshold. Therefore, the available sample was expected to provide adequate precision to detect clinically meaningful differences in scan duration without the need for prospective power estimation.

Descriptive statistics were used to characterize the cohort. Categorical variables were analyzed using Chi‐square, and continuous variables using One‐way ANOVA or the Kruskal–Wallis test, as appropriate based on distribution. The duration of the ultrasound was log‐transformed to improve normality. To compare scan duration across ultrasound types, we fitted linear regression models with log‐transformed duration as the dependent variable, adjusting for maternal BMI (kg/m² modeled per 10‐unit increase), history of prior abdominal surgery, and sonographer experience (0–4, 5–9, and ≥ 10 years). We estimated marginal predictions of procedure duration for each ultrasound type using marginal standardization, holding all covariates at their average levels. To further enhance interpretability, we examined differences in adjusted ultrasound time by sonographer experience within each ultrasound type using marginal means, and we assessed the incremental effect of maternal BMI on scan duration. For BMI, the effect was scaled to represent a 10‐unit increase. All analyses were performed using Stata/SE 18.5 (StataCorp). A p value < 0.05 was considered statistically significant.

3. RESULTS

A total of 870 diagnostic obstetric ultrasound examinations met inclusion criteria. These were categorized into five clinically relevant types: 44 dating scans, 49 first‐trimester scans, 494 second‐trimester anatomy scans, 87 fetal echocardiograms, and 196 second/third‐trimester growth and Doppler scans (Table 1).

TABLE 1.

Demographics, sonographer characteristics, and scan efficiency by ultrasound type.

	Dating	First trimester	Anatomy	Echo	Second/third trimester	p value
N	44	49	494	87	196
Patient information
Body mass index (kg/m2)	29.6 (± 6.0)	35.6 (± 11.7)	36.0 (± 8.4)	35.1 (± 7.5)	38.4 (± 8.7)	0.024
Race						<0.001
American Indian/Alaska Native	0 (0.0)	0 (0.0)	2 (0.4)	0 (0.0)	0 (0.0)
Asian	0 (0.0)	3 (6.1)	11 (2.2)	6 (6.9)	9 (4.6)
Native Hawaiian/Pacific Islander	0 (0.0)	0 (0.0)	0 (0.0)	1 (1.1)	0 (0.0)
Black/African American	17 (38.6)	17 (34.7)	191 (38.7)	26 (29.9)	93 (47.7)
White	16 (36.4)	15 (30.6)	199 (40.4)	43 (49.4)	74 (37.9)
Did not disclose/missing	3 (6.8)	12 (24.5)	67 (13.6)	4 (4.6)	11 (5.6)
Ethnicity						0.015
Hispanic/Latino	8 (18.2)	9 (18.4)	66 (13.4)	4 (4.6)	15 (7.7)
Non‐Hispanic/Latino	36 (81.8)	36 (73.5)	399 (80.8)	74 (85.1)	171 (87.7)
Did not disclose/missing	0 (0.0)	4 (8.2)	29 (5.9)	9 (10.3)	9 (4.6)
Surgical history	20 (45.5)	22 (44.9)	165 (33.6)	25 (28.7)	73 (37.6)	0.153
Ultrasound information
Duration of exam	6.8 (5.3, 9.0)	18.3 (12.2, 22.6)	29.9 (25.8, 35.3)	26.6 (21.9, 35.9)	12.5 (10.0, 16.9)
Number of images	19.0 (17.0, 27.5)	53.0 (43.0, 62.0)	87.0 (76.0, 97.0)	96.0 (84.0, 106.0)	41.0 (35.0, 48.0)	<0.001
Number of images/minute	3.3 (± 0.9)	3.2 (± 1.1)	3.0 (± 0.8)	3.6 (± 1.2)	3.3 (± 1.1)	<0.001
Sonographer experience (years)						<0.001
0–4	32 (72.7)	34 (69.4)	370 (74.9)	4 (4.6)	133 (67.9)
5–9	4 (9.1)	4 (8.2)	23 (4.7)	14 (16.1)	21 (10.7)
10 or greater	8 (18.2)	11 (22.4)	101 (20.4)	69 (79.3)	42 (21.4)

Note: Numbers are shown as n (%), mean (± SD), or median (25th, 75th percentile).

Maternal BMI increased progressively across ultrasound categories, with the lowest mean BMI observed in the dating group (29.6 ± 6.0 kg/m²) and the highest in second/third‐trimester scans (38.4 ± 8.7 kg/m²; p = 0.024). Race and ethnicity were unevenly distributed across scan types (p < 0.001 and p = 0.015, respectively), with the proportion of Hispanic and Black patients increasing in higher complexity exams such as anatomy and fetal echocardiography. The overall cohort was racially diverse, with underrepresentation of Asian and Native American individuals across all groups (Table 1).

Median ultrasound duration varied significantly across exam categories (Table 1 and Figure 1): dating: 6.8 min (IQR 5.3–9.0), first trimester: 18.3 min (IQR 12.2–22.6), second‐trimester anatomy: 29.9 min (IQR 25.8–35.3), fetal echocardiography: 26.6 min (IQR 21.9–35.9), and second/third trimester: 12.5 min (IQR 10.0–16.9). As expected, scan duration varied substantially across examination types due to differences in clinical scope and the number of required imaging components.

FIGURE 1.

Difference in adjusted duration according to the ultrasound type.

The number of images acquired also differed significantly (p < 0.001), with medians of 19.0 (17.0–27.5) for dating, 53.0 (43.0–62.0) for first‐trimester, 87.0 (76.0–97.0) for anatomy, 96.0 (84.0–106.0) for fetal echocardiography, and 41.0 (35.0–48.0) for second/third‐trimester exams. Image acquisition rates ranged from 3.0 to 3.6 images/min (p < 0.001). Because each examination type requires a different number of predefined imaging views, the total number of images obtained varies substantially across examination categories.

To adjust for potential confounders, including maternal BMI, gestational age, prior abdominal surgery, and sonographer experience, a linear regression model was constructed (Table 2). Using dating scans as the reference group, the adjusted regression coefficients demonstrated significant longer times for all other ultrasound types. Compared with dating exams, first‐trimester scans had a coefficient of 0.807 (95% CI, 0.620–0.994; p < 0.001), anatomy scans had a coefficient of 1.392 (95% CI, 1.251–1.533; p < 0.001), fetal echocardiograms had the largest coefficient of 1.496 (95% CI, 1.328–1.664; p < 0.001), and second/third‐trimester scans had a coefficient of 0.551 (95% CI, 0.404–0.698; p < 0.001).

TABLE 2.

Results of linear regression models.

Regression model	Coefficient	p value
Ultrasound type
Dating	[Reference]	[Reference]
First trimester	0.807 (0.620, 0.994)	<0.001
Anatomy	1.392 (1.251, 1.533)	<0.001
Fetal echo	1.496 (1.328, 1.664)	<0.001
Growth	0.551 (0.404, 0.698)	<0.001
BMI (kg/m2) (each 10 units)	0.032 (0.002, 0.061)	0.037
Surgical history	−0.008 (−0.060, 0.044)	0.764
Sonographer experience (years)
0–4	[Reference]	[Reference]
5–9	−0.224 (−0.332, −0.116)	<0.001
10 or greater	−0.216 (−0.280, −0.152)	<0.001

Note: Coefficients and p values were adjusted for ultrasound type, BMI, surgical history, and experience.

Abbreviation: BMI, body mass index.

Sonographer experience was strongly associated with scan complexity (Table 1 and Figure 2). Among lower‐complexity exams, such as dating and second/third trimester scans, the majority (72.7% and 67.9%, respectively) were performed by sonographers with 0–4 years of experience. In contrast, 79.3% of fetal echocardiograms and 20.4% of anatomy scans were completed by sonographers with ≥10 years of experience. In the adjusted linear regression model, sonographer experience ≥5 years was significantly associated with shorter scan time. Compared to sonographers with 0–4 years of experience, those with 5–9 years had a regression coefficient of −0.224 (95% CI, −0.332 to −0.0116; p < 0.001) and those with ≥10 years had a coefficient of −0.216 (95% CI, −0.280 to −0.152; p < 0.001), reflecting shorter adjusted durations on the log‐transformed scale. Image acquisition efficiency also varied by exam type, with fetal echocardiography demonstrating the highest images‐per‐minute rate (3.6 ± 1.2) compared with anatomy scans (3.0 ± 0.8, p < 0.001). Additionally, each 10‐unit increase in BMI was associated with 3% increase in adjusted scan duration (0.0032; 95% CI, 0.002–0.661; p = 0.037), emphasizing the incremental burden of maternal body habitus on imaging efficiency (Table 2 and Figure 3). A review of timestamp metadata indicated significant variability in the time allocated to specific anatomical regions, with fetal head and heart requiring the longest continuous probe time (Table 3). Nondiagnostic “keepsake” images accounted for < 5% of image volume in all groups.

FIGURE 2.

Difference in adjusted duration according to the ultrasound type and sonographer experience.

FIGURE 3.

Adjusted increase in ultrasound duration per 10‐unit increase in maternal BMI, stratified by exam type. BMI, body mass index.

TABLE 3.

Number of images allocated to specific anatomic regions.

	Detailed second trimester	Second/third trimester
Total number of images	87 (76–97)	41 (35–48)
Cervix	7 (6–9)	3 (1–5)
CNS‐face	14 (11–17)	8 (6–10)
Chest–heart	19 (14–24)	9 (7–12)
Abdomen–pelvis	17 (13–20)	10 (7–13)
Extremity	18 (14–22)	5 (3–8)
Fluid–placenta	5 (4–6)	4 (3–5)
Doppler (only FGR cases)	1 (1–1)	2 (1–5)
Adnexa	2 (2–2)	2 (2–2)
Keepsake image	2 (1–2)	1 (1–2)

Note: Median (25th–75th percentile).

4. DISCUSSION

4.1. Principal findings

In this retrospective cohort study, we evaluated scan durations across five types of obstetric ultrasounds and examined the influence of maternal and procedural factors on imaging efficiency. We found that second‐trimester anatomic surveys and fetal echocardiograms required substantially longer scan times than dating ultrasounds, with the largest adjusted increases observed for these two exam types. Sonographer experience was a strong independent predictor of scan duration, with efficiency gains plateauing after approximately 5 years of practice. Maternal BMI was also an independent contributor to prolonged scan time, with each 10‐unit increase associated with an approximate 3% increase in adjusted duration.

4.2. Results in the context of what is known

Our findings corroborate prior studies highlighting the time‐intensive nature of detailed anatomic assessments. Catanzarite et al. reported that second‐trimester anatomic surveys often require up to 30 min for adequate evaluation, especially in earlier gestations and challenging maternal body habitus [19]. Our median scan time of 29.9 min for anatomy scans aligns closely with this, as does the 26.6‐minute median for fetal echocardiograms. These durations are significantly longer than the 6.8‐minute median for dating scans, reinforcing the known complexity and breadth of second‐trimester and cardiac evaluations.

The scan duration observed for detailed first‐trimester examinations warrants specific contextualization. Although these studies involve comprehensive early fetal assessment, their relatively shorter duration likely reflects the long‐standing incorporation of detailed first‐trimester ultrasound into routine practice at our institution. Both sonographers and interpreting physicians have extensive experience with early anatomic protocols, nuchal translucency measurement, and systematic first‐trimester evaluation. Standardized acquisition workflows and high operator familiarity with early gestational imaging likely contribute to efficient image acquisition without diminishing exam scope or diagnostic intent. Sripilaipong et al. evaluated the feasibility and learning curve associated with performing detailed first‐trimester fetal anatomy screening using the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) protocol. In their prospective study, the mean scan duration ranged from approximately 11.3 ± 4.8 min for a more experienced operator to 15.0 ± 6.2 min for a less experienced operator, with scan times decreasing as operator experience increased [20]. In this context, the observed first‐trimester scan duration should be interpreted as a marker of workflow maturity rather than reduced exam complexity [9].

Poehlmann et al. highlighted institutional variability in the time allocated per ultrasound, noting that national guidelines often lack specific duration benchmarks, leading to inconsistent expectations [4]. While their study emphasized perceptions of efficiency and workflow disruption, our findings offer quantitative confirmation that different exam types inherently require different durations. Ruma et al. showed that use of a protocol‐based scanning approach improved diagnostic accuracy and reduced unnecessary variation, though they did not directly analyze scan duration. Our study expands on that work by correlating scan time with real‐world parameters such as BMI, sonographer experience, and gestational age [16].

Sonographer experience was a key driver of scan efficiency. Compared to those with 0–4 years of experience, sonographers with 5–9 years and ≥10 years completed studies substantially faster, consistent with the reduced adjusted scan duration observed in our regression model. Interestingly, efficiency gains plateaued after the first 5 years, suggesting that the steepest learning curve occurs early in a sonographer's career. This supports the qualitative conclusions from Catanzarite et al., who emphasized the technical proficiency required for high‐quality anatomic imaging [19]. Our findings also demonstrate the practical impact of internal credentialing and task allocation: 79.3% of fetal echocardiograms were performed by sonographers with ≥10 years of experience, likely reflecting institutional policies prioritizing expertise for complex exams.

Maternal BMI also contributed to scan duration. Increased adiposity leads to poorer acoustic windows, requiring more time and effort to achieve diagnostic‐quality images, a finding consistently supported by prior studies and now confirmed in our adjusted model [4, 17]. Gupta et al. evaluated 6522 detailed second‐trimester anatomic ultrasounds and demonstrated a clear association between maternal BMI and scan duration, with examinations in patients with class III obesity lasting approximately 8.9 min longer than those in patients with normal BMI. Similar to their findings, our study also identified maternal BMI as an independent contributor to prolonged scan time [21]. However, while Gupta et al. focused exclusively on detailed second‐trimester anatomic examinations, our analysis expands these observations by evaluating multiple types of obstetric ultrasound examinations within a single dataset, allowing comparison of how BMI influences scan duration across different imaging contexts.

Our data support this physiologic link and suggest that real‐world scan workflows are measurably impacted by increasing BMI.

Scan efficiency, measured as images per minute, was highest for fetal echocardiography (3.6 ± 1.2) and lowest for anatomic surveys (3.0 ± 0.8). While this may appear counterintuitive, it likely reflects the structured, focused nature of fetal cardiac protocols and the advanced training of sonographers performing them. In contrast, anatomy scans require a broader survey of multiple fetal systems, are often interrupted by fetal movement or suboptimal positioning, and are more frequently assigned to less experienced sonographers.

4.3. Clinical implications

These findings carry several clinical and operational implications. First, they emphasize the importance of aligning ultrasound scheduling with realistic expectations for scan duration. Uniform time slots across all exam types may fail to account for the complexity and imaging demands of second‐trimester anatomic surveys and fetal echocardiograms, leading to time pressure, diagnostic fatigue, and potentially decreased quality of care. Importantly, the mean or median scan duration reported in this study should not be interpreted as the recommended time for scheduling individual patient appointments, as real‐world scheduling must account for variability in examination duration as well as additional workflow components beyond image acquisition.

Second, the strong association between sonographer experience and efficiency supports tiered staffing models and targeted credentialing, particularly for fetal echocardiography. Allocating high‐complexity studies to more experienced personnel may optimize both time management and diagnostic accuracy.

Third, the impact of maternal BMI suggests a need for tailored counseling and anticipatory planning in this population. Even a 10‐unit increase in BMI was associated with longer adjusted scan duration, reinforcing the importance of considering body habitus in scheduling templates.

Lastly, our findings reinforce the value of detailed image documentation and acquisition logs for continuous quality assurance. By quantifying how much time is spent per exam type and how experience and BMI influence efficiency, institutions can better benchmark performance, identify bottlenecks, and guide training priorities.

4.4. Research implications

Future research should explore whether scan duration correlates with diagnostic yield or image quality, particularly in populations with higher BMI or among less experienced sonographers, given the significant associations observed in our analysis. A prospective, multi‐institutional analysis would enhance generalizability and could help develop standardized benchmarks for exam time based on patient and provider characteristics. Another promising area is the integration of artificial intelligence and automation in ultrasound workflows. Several platforms now offer tools for plane detection and real‐time guidance, which could reduce scan time variability, particularly among novice sonographers. The literature to date has focused more on accuracy than on workflow optimization, and our findings highlight an important opportunity to evaluate time‐based outcomes in future trials. Current national guidelines, including those from American College of Obstetricians and Gynecologists (ACOG) and American Institute of Ultrasound in Medicine (AIUM) [2, 5, 6, 7, 8], provide limited recommendations regarding scan duration expectations. More specific guidance grounded in real‐world data could help improve efficiency and standardize care delivery across institutions.

4.5. Strengths and limitations

This study offers a comprehensive, real‐world evaluation of scan durations across a broad spectrum of obstetric ultrasound examinations, conducted within a high‐volume tertiary care fetal imaging center. Among its key strengths is the inclusion of five clinically relevant ultrasound categories—from early dating to fetal echocardiography—allowing for nuanced comparisons of scan duration and imaging efficiency. The sample size of 870 normal diagnostic scans is one of the largest to date for this type of analysis, with a wide distribution of maternal characteristics and procedural complexity. Our use of granular timestamp data, rather than scheduled time slots or sonographer recall, adds a high degree of objectivity and reliability to scan duration measurements.

The study also incorporated real‐time procedural variables such as maternal BMI and sonographer years of experience—both rarely captured in prior research—and employed multivariable modeling to isolate their independent effects. By adjusting for key covariates using log‐transformed regression models and marginal standardization, we were able to generate adjusted duration estimates that were both statistically robust and clinically interpretable. The stratification of sonographer experience into meaningful bands (0–4, 5–9, ≥10 years) and the strong signal observed in regression analyses (p < 0.001) support the internal validity of these findings.

Despite these strengths, several limitations must be acknowledged. First, the retrospective design limits control over unmeasured confounders. While we adjusted for key maternal and procedural factors, we could not account for fetal position, uterine anomalies, or amniotic fluid abnormalities, which may affect scan difficulty and were not reliably extractable from the data set. Second, this analysis was restricted to “normal” ultrasounds, excluding any scan with abnormal maternal, fetal, or placental findings. This was done to avoid bias introduced by increased documentation needs in abnormal cases, but it may limit generalizability to more complex clinical scenarios—particularly in high‐risk centers where abnormal findings are common. Third, while timestamp analysis provides a robust method of assessing scan duration, we recognize that imaging sessions may be interrupted due to patient needs, staffing flow, or clinical priorities. To mitigate this, we implemented a quality assurance step by reviewing all timestamp sequences and excluding studies that showed prolonged gaps between image acquisition timepoints—a surrogate for scan interruption or restart. While this method substantially reduces the risk of inflating scan duration due to non‐continuous scanning, brief or subtle workflow disruptions may have gone undetected. Fourth, although scan duration was rigorously measured using image timestamps, our analysis was limited to the active scanning period—defined from the time of the first image to the last. Deliberately, this approach excluded time spent reviewing images, generating reports, and conducting patient counseling, which may also contribute significantly to overall workflow demands. While this method offers a clean assessment of scanning efficiency, future studies should evaluate the full encounter duration to better capture the total workload and inform staffing models. Fifth, this study focused on factors associated with ultrasound examination duration and did not evaluate completeness of the anatomic survey during the initial examination. Scan duration alone does not fully capture examination quality or completeness, and future studies evaluating workflow efficiency alongside completion rates would provide additional insight. Sixth, this was a single‐center study conducted at a highly specialized academic institution. As a result, workflow patterns and scan durations observed in this unit may not be generalizable to other institutions, including other tertiary or quaternary care centers with different staffing models, levels of operator experience, or patient populations. Nonetheless, our large sample size and use of standardized imaging protocols provide a valuable benchmark for institutions with similar resources. Finally, although a formal a priori sample size calculation was not performed, the study included all eligible scans during the study period and was designed to provide sufficient precision around adjusted estimates of scan duration, supporting the reliability of the findings.

5. CONCLUSION

This study offers a comprehensive analysis of scan time variability across routine obstetric ultrasound examinations and identifies three major drivers of efficiency: exam type, sonographer experience, and maternal BMI. These findings highlight the need for nuanced scheduling protocols, targeted staff deployment, and further research into scalable workflow solutions. By acknowledging the practical realities of obstetric imaging—including substantial impact of exam complexity, the efficiency gains associated with sonographer experience, and the modest but meaningful influence of maternal BMI—clinicians and administrators can improve resource allocation, reduce provider fatigue, and enhance diagnostic performance across the care continuum.

AUTHOR CONTRIBUTIONS

All authors contributed to the study.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflicts of interest.

FUNDING INFORMATION

The authors received no specific funding for this work.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.