Time Required for Gross Examination of Routine Second and Third Trimester Singleton Placentas by Pathologists’ Assistants

Abstract

Introduction:

In both Canada and the United States, workload measurement for anatomic pathology is mainly based on complexity and clinical significance of specimens, with gross examination being a considerable contributor. While Pathologists’ Assistants (PAs) play an increasing role in gross examination, there is little known regarding the time required for PAs to complete grossing tasks. This information is essential for effective staffing and workload management in pathology laboratories. The objective of our study was to determine the time required for PAs to gross second and third trimester singleton placentas in a large tertiary hospital with a significant perinatal pathology service.

Materials and Methods:

For our study, 7 certified PAs each grossed a minimum of 10 second and third trimester singleton placentas using a standard placental grossing protocol, an electronic laboratory information system, and voice recognition dictation software. Placental specimens requiring photography, sampling for ancillary studies, or immediate pathologist’s consultation were excluded. We calculated average and standard deviation of grossing times for each PA, overall average grossing time, and 95% confidence interval using a mixed linear regression model. We analyzed the impact of PA job experience, degree obtained, and number of blocks prepared on overall average in a multivariate analysis.

Results:

The mean grossing times for each PA ranged from 11.0 (standard deviation [sd] = 2.0) to 17.8 (sd = 4.5) minutes. The overall average grossing time was 14.5 minutes, with a 95% confidence interval of 11.7 to 17.3 minutes. In multivariate analysis, an increase in the number of blocks prepared was significantly associated with longer overall average grossing time. If 4 blocks were prepared consistently, the model predicted a slightly lower overall average of 13.3 minutes, with a 95% confidence interval of 10.9 to 15.7 minutes.

Discussion:

To our knowledge, our study is the first to objectively report time required for PAs to perform gross examinations of routine second and third trimester singleton placentas. The methodology of our study is replicable and can be applied to other specimen types and laboratory settings. Previously, estimated grossing times for specimens were primarily based on retrospective surveys, which were susceptible to recall errors and subjectivity. However, our study demonstrates objective data collection is achievable. Furthermore, the data collected from this study offer valuable insights into the accuracy of previous and current pathology workload models for second and third trimester singleton placentas.

Introduction

Workload measurement plays a crucial role in determining the optimal staffing level and workload distribution for pathology laboratories. In both Canada and the United States, pathology workload is primarily based on specimen complexity and clinical significance.

In Canada, the Canadian Association of Pathologists (CAP-ACP) Workload Model assigns Level 4 Equivalent (L4E) units to surgical pathology specimens primarily based on the estimated time required for gross examination, microscopic examination, and final reporting. Each L4E unit is equivalent to approximately 10 minutes. ¹ This model has been revised a few times, and the latest version, ² updated in 2020, categorizes surgical specimens into 6 levels based on complexity, ranging from simple gross-only examinations (L1 or 0.125 L4E) to more complex resections, including benign and malignant resections and resections post-therapy with no residual tumor (L6 or 10 L4Es).

In the United States, the American Medical Association utilizes the Current Procedural Terminology (CPT) system, a standardized numerical coding system for reporting medical procedures and services. Surgical pathology specimens are assigned CPT codes ranging from 88300 to 88309, which correspond to 6 levels of interpretation. ³ These codes are based on the complexity of the examination required for each specimen, with higher-level codes indicating more complex specimens that require more physician work. The lowest level, CPT code 88300, corresponds to gross examination only, while the highest level, CPT code 88309, corresponds to gross and microscopic examination of complex specimens. ³

It should be emphasized that both the Canadian L4E and American CPT systems view the specimen as the unit of service for surgical pathology, with gross examination of the specimen included in the workload measurement. This means that in order to accurately determine the appropriate complexity and workload level for a given specimen, it is essential to have a clear understanding of the average time required for gross examination for that specific type of specimen.

Previously, pathologists were primarily responsible for handling the gross examination of surgical pathology specimens. However, there has been an increasing trend to delegate this responsibility to Pathologists’ Assistants (PAs) within anatomic pathology laboratories in both Canada and the United States. PAs are certified by the Canadian Certification Council of Pathologists’ Assistants in Canada and by the American Society for Clinical Pathology in the United States. PAs undergo rigorous training and play important roles in the grossing of pathology specimens. Despite the growing presence and importance of PAs in anatomic pathology, there has been limited research conducted on the time required for PAs to perform gross examinations. ⁴ Understanding the time required for PAs to complete gross examinations is essential in accurately evaluating workload and determining optimal staffing and workload distribution for anatomic pathology laboratories.

The anatomic pathology laboratory at Alberta Children’s Hospital/Alberta Precision Laboratories is responsible for examining most of the placentas submitted for pathologic examination in southern Alberta, Canada. Consequently, we regularly handle placental specimens. Over the past decade, we have consistently received 3000 to 4000 placental specimens per year. In fact, the grossing of placental specimens comprises the primary workload for our PAs.

With this in mind, the objective of our study was to determine the time required for PAs to routinely gross singleton placentas at a large tertiary medical center with a significant perinatal pathology service. By conducting this research, we hoped to gain a better understanding of workload involved in placental grossing.

Materials and Methods

This prospective study was conducted at Alberta Precision Laboratories in Alberta, Canada. In 1996, all pathology and laboratory services in Calgary were merged into a single city-wide entity, which led to the centralization of perinatal and placental pathology services. ⁵ As part of this system, placentas from deliveries at 4 adult hospitals in Calgary (Foothills Medical Centre, Rockyview General Hospital, Peter Lougheed Centre, and South Health Campus) are sent to Alberta Children’s Hospital for pathologic examination by pathologists and PAs who specialize in pediatric and perinatal pathology. Indications for placental examination were adapted from the College of American Pathologists’ (CAP) 1997 guidelines for examination of placenta ⁶ and were described in our previously published paper. ⁷

Seven certified PAs participated in this study, 4 of whom received their training from the Master of Pathologists’ Assistant program at the University of Calgary, accredited by the National Accrediting Agency for Clinical Laboratory Science, while 3 received on-the-job training with bachelor’s degrees from various universities in Canada. All participants held current and valid certifications from the Canadian Certification Council of Pathologists’ Assistants. The PAs involved in the study had a wide spectrum of work experience in grossing various types of specimens. The PAs’ experience spanned from 1 month to 23.5 years, with an average of 8 years and 4 months of practical experience in this role. Except for the least experienced PA, who had grossed fewer than 100 placental specimens, every participating PA in the study had grossed over 500 placental specimens at the start of the study.

Accessioning of Placentas

Second and third trimester singleton placentas, placed in specimen bags without fixative, were transported in biohazard buckets from the 4 adult hospitals to the anatomic pathology laboratory at Alberta Children’s Hospital. Upon arrival, a laboratory assistant (PM) or PA (CH, NE) removed the specimen bags from the biohazard buckets, reviewed the clinical history on each requisition form, and prioritized the gross examination of placentas accordingly. For example, placentas associated with newborns in the neonatal intensive care unit or suspected infections were given higher priority for examination.

After the placentas were triaged, a laboratory assistant (PM) or PA (CH, NE) entered the necessary data, including time and date of collection, patient’s information, and physician’s information on the requisition form, into the Cerner Millennium Laboratory Information System (LIS; Cerner Corporation, Kansas City, MO, USA; Version 2011.7.09.0003). This allowed for generation of accession labels, 1 of which was placed on the specimen bag and the other on the placental requisition form. The form was then scanned into Kofax for digital record-keeping purposes. The Cerner Millennium accession label was scanned, and a label printer generated 4 cassettes (4 for a singleton placenta), each imprinted with the corresponding accession number. Finally, the placental specimen package (which included the requisition form, 4 tissue cassettes, an absorbent pad, a specimen retention bag, and the placenta) was placed into a refrigerator for later gross examination by a PA.

Grossing of Placentas

For this study, each PA grossed a minimum of 10 second or third trimester singleton placentas. Placental specimens that required photography, sampling for microbiology or cytogenetic testing, or immediate pathologist’s consultation during the grossing process were excluded from the study. The remaining placentas selected for grossing were therefore characterized as “routine.”

The gross examination process commenced as the PA retrieved the placental specimen package from the refrigerator and recorded the start date and time electronically using the “F5” keystroke function in Cerner Millennium LIS.

Next, the PA removed the requisition form, tissue cassettes, absorbent pad, specimen retention bag, and placenta from the placental specimen package and placed them on the grossing bench. A standardized placenta pathology grossing protocol was followed, which included macroscopic examination for abnormalities, measurement of placental disc dimensions, removal of umbilical cord and membranes, and weighing of the trimmed placental disc on a calibrated scale. The PA then serially sectioned the placental disc at approximately 0.5–1 cm interval and inspected the cross sections for any anomalies.

For histologic processing, representative sections of the placenta were placed into tissue cassettes, which included 2 cross-sections of the umbilical cord, 1 of the placental membrane, 3 full-thickness sections of the placental disc, and additional sections of any focal lesions. To document the gross findings, the PA utilized the Dragon Medical Desktop speech-recognition program (Nuance Communications, Burlington, MA, USA; version 5.1.2) to dictate into a placental grossing template [Supplemental Material] in the Cerner Millennium LIS.

After the sections were sampled into tissue cassettes, the placenta was placed into the specimen retention bag and filled with formalin. Finally, the PA used the F5 keystroke to electronically record the end date and time of the gross examination. At the conclusion of each day, a PA (CH) recorded the start and end dates and times for each case in a Microsoft Excel spreadsheet.

Data Analysis

The average and standard deviation (sd) of grossing times were calculated for each PA, and an overall average with 95% confidence intervals was computed using a mixed linear regression model. The analysis treated PAs as the subject of analysis, with grossing times clustered within PAs. To explore the impact of PA job experience (time in practice), degree obtained (master’s vs bachelor’s with on-the-job training), and the number of blocks prepared on grossing time, we performed a multivariate analysis with these variables included as covariates in the regression model. If any were statistically significant, we re-calculated the overall average holding those variables at constant values.

All statistical analysis was conducted using SAS Studio (SAS Institute, Cary, NC, USA; release 3.81). A P-value <.05 was considered statistically significant.

Results

The mean grossing time for each PA varied from 11.0 (sd = 2.0) to 17.8 (sd = 4.5) minutes. The overall average was 14.5 minutes, with a 95% confidence interval of 11.7 to 17.3 minutes (Figure 1).

Figure 1.

Boxplot of grossing times for second and third trimester singleton placentas by Pathologists’ Assistants. The upper and lower limits of the whiskers indicate the location of the maximum and minimum values for each PA. The upper and lower limits of each box indicate the location of the 75th and 25th percentiles for each PA (interquartile range [IQR])). The diamond within each box indicates the location of the mean for each PA. The horizontal line within each box indicates the location of the median for each PA. The overall mean across all PAs was 14.5 minutes, with a 95% confidence interval of 11.7 to 17.3 minutes.

In the multivariate analysis, job experience (range: 1 month–23.5 years) and degree obtained (3 bachelor’s, 4 master’s) were not significantly associated with grossing time (Table 1). However, an increase in the number of blocks (range: 4–8) prepared was significantly associated with longer grossing time (+1.75 minutes per additional block). Using a regression model containing the number of blocks prepared as the sole predictor, we recalculated overall grossing time at the median number (which was also the minimum number) of 4 blocks. This yielded an adjusted overall average of 13.3 minutes with a 95% confidence interval of 10.9 to 15.7 minutes.

Table 1.

Multivariate Analysis.

Covariate	Change in overall average grossing time (minutes) per 1 unit increase in covariate	Standard error	P value
Job experience (months in practice)	−0.02	0.01	.25
Number of blocks prepared	+1.75	0.33	<.01
Master’s degree compared to Bachelor’s degree with on-the-job training	+0.98	1.98	.65

Discussion

This study is the first to objectively determine the time required for PAs to perform gross examinations of second and third trimester singleton placentas. PAs are highly trained, certified allied healthcare professionals who play a crucial role in anatomic pathology, fulfilling various responsibilities in surgical pathology, autopsy pathology, and laboratory operations. ⁸ One of their key responsibilities is grossing surgical pathology specimens, which involves macroscopic inspection, description, dissection, and submission of tissue for processing.

In spite of the growing presence and expanding roles of PAs in anatomic pathology, there remains a dearth of research examining the time required for PAs to conduct gross examinations of specific specimen types. Currently, only 1 study by Volel et al ⁴ has investigated this topic, but their study provided gross dissection time for each CPT level, rather than for individual specimen types. Therefore, there is a need for additional research to investigate the amount of time necessary for PAs to perform gross examinations of specific specimen types, especially when those specific specimen types constitute a substantial portion of the overall grossing workload.

Among the 7 PAs with varying levels of grossing experience, our study revealed that the overall average grossing time for a second or third trimester singleton placenta was 14.5 minutes, with a 95% confidence interval of 11.7 to 17.3 minutes. If 4 blocks were prepared consistently, our model predicted a slightly lower overall average of 13.3 minutes with a 95% confidence interval of 10.9 to 15.7 minutes.

The results of this study have important implications for clinical practice. In Canada and the United States, workload measurement in pathology is predominantly based on the estimated time required to complete the gross examination, microscopic examination, and final reporting of a specimen. For example, the CAP-ACP workload model in Canada has been revised over time, resulting in changes in the number of L4E units assigned for gross and microscopic examination of a singleton placenta with 4 standard blocks (Table 2). In 2014, 1.33 L4E units were assigned, equivalent to approximately 13 minutes. In 2018, 1 L4E unit was assigned, equivalent to approximately 10 minutes. In the latest iteration in 2020 (only applicable to subspecialist pediatric/perinatal pathologists or gynecologic/perinatal pathologists), ⁹ 2 L4E units were assigned, equivalent to approximately 20 minutes.

Table 2.

Singleton Placenta Valuation According to the Canadian Association of Pathologists Workload Model.

Year	L4E assigned	Approximate time equivalent
2014 (under Rule 4-0.333 L4E/block a	1.33 L4E (if 4 standard blocks; additional blocks add 0.333 L4E/block; discounted by 10% if grossed by PA)	13 min
2018 (under gynecologic 18) a	1 L4E (discounted by 10% if grossed by PA)	10 min
2020 b	2 L4E (additional blocks add 0.25 L4E/block; discounted by 5% if grossed by PA)	20 min

Table adapted from Wright et al. ⁹

^aApplies to all pathologists.

^bApplies only to subspecialist pediatric-perinatal pathologists or gynecologic-perinatal pathologists.

Based on our study, we found that the average duration for the gross examination of a second or third trimester singleton placenta with at least 4 blocks prepared was 14.5 minutes. This indicates that the time allocation provided in the 2014 (~13 minutes) and 2018 (~10 minutes) CAP-ACP workload models was significantly insufficient for pathologists to complete both microscopic examination and final reporting in addition to the gross examination.

In contrast, the latest 2020 model is more realistic and more accurately reflects time needed for complete pathologic examination of a singleton placenta. It is important to note that some placentas are more complex than others and may require more time to gross. Our study excluded these more complex cases, which may involve procedures such as photography, microbiology testing, cytogenetics analysis, electron microscopy, or immediate consultation with a pathologist during the grossing process. Therefore, the average gross examination time of 14.5 minutes is at the lower end of the time required for performing this examination.

With regards to the assessment of placental pathology in tertiary/quaternary care centers by subspecialist placental pathologists, it is important to note that the current CAP-ACP workload model includes a 5% discount rule when a PA performs the gross examination of a specimen. ⁹ Essentially, when a placenta is grossed by a PA instead of by a pathologist, the L4E values are discounted by 5%. While this discount may seem minor, it is worth considering the fact that the gross examination is a delegated responsibility from the pathologist, who bears ultimate medical and legal responsibility for the work performed by the PA. As Wright et al ⁹ noted in a recent paper, the pathologist may also need additional time deciphering the gross description to understand the specimen and map the blocks taken. Thus, the discount for grossing performed by a PA is not meant to directly replace the 1:1 time spent by the PA grossing the specimen.

This study also highlights a common practice in many anatomic pathology laboratories, including our own, where many specimens such as placentas are grossed in the fresh and unfixed state, posing an infectious risk. Additionally, the process of placenta grossing often involves the use of a sizable blade, increasing the risk of injuries. By having access to accurate gross examination time data, it becomes possible to ensure adequate PA staffing, reduce health risks, and maintain a safe working environment.

We acknowledge that there can be significant variation in accessioning and grossing procedures for placentas across different hospitals and laboratories, including differences in fixation procedures, information technology systems, grossing templates, dictation systems, section sampling, photography techniques, and PA expertise, among other factors that may affect the time required to gross a placental specimen.

Finally, the time data does not reflect the true daily workload of a PA, as a PA does more than grossing. As mentioned earlier, a PA has a wide scope of responsibilities, such as teaching, management, quality assurance, maintaining workplace health and safety, and handling requests from various departments.

In summary, our study provides important objective data on the time required for PAs to perform routine gross examinations of second and third trimester singleton placentas, which is essential for determining adequate PA staffing levels in anatomic pathology laboratories, particularly ones with a large perinatal and placental pathology service. The methodology of our study is replicable and can be applied to other specimen types and laboratory settings. In addition, previously, estimated grossing times for specimens were mainly based on experience, retrospective surveys, and interviews, ⁹ which are prone to recall errors and subjectivity. Our study demonstrates that collecting such data can be done objectively and with ease. Finally, our findings shed light on the long-standing inadequacy of the time (or L4E units) allocated to singleton placentas according to the 2014 and 2018 CAP-ACP Workload Models. In contrast, our data indicates that the most recent 2020 CAP-ACP Workload Model for subspecialty placental pathology aligns more closely with the actual time required to examine a second and third trimester singleton placenta.