Assessing Gestational Age in First Trimester Pregnancies: A Comparison of a New Handheld Wireless Transabdominal Ultrasound to a Portable Transabdominal Ultrasound
Conditions: Pregnancy Early
Sponsor: University of Manitoba

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Research Project Title 
 
Assessing gestational age in first trimester pregnancies:  A comparison of a new 
handheld wireless transabdominal ultrasound to a portable transabdominal 
ultrasound. 
 
Research Question 
 
This research project is designed to determine the equivalence of a handheld wireless 
(Clarius C3) transabdominal ultrasound to the current portable ultrasound with 
transabdominal and transvaginal capabilities (Zonare ZS3) when used to date first 
trimester pregnancies. 
 
Background 
 
There have been several new recommendations in the SOGC encouraging the 
provision of first trimester pregnancy ultrasound. 
In the June 2018 SOGC Clinical Practice Guideline No 360-Induced Abortion:  Surgical 
Abortion and Second Trimester Medical Methods, the authors write, “Ultrasound should 
be performed prior to induced abortion to confirm gestational age and aid in operative 
planning (Strong recommendation. Level of evidence: Low)”.  In the SOGC Clinical 
Practice Guidelines on Medical Abortion published in 2016, they recommend that 
“women with significant risk factors, signs, or symptoms of ectopic pregnancy should 
have a pretreatment ultrasound before medical abortion”, but they does not require it to 
be performed. In patients who receive medical abortion (Mifepristone 200 mg orally 
followed by misoprostol 800 mcg buccally 24 to 48 hours) under 9 weeks’ gestation, the 
product monograph states that “ultrasound shall be performed before medical abortion”.    
It is the current standard at the sites that perform medical abortion in Manitoba 
(Women’s Hospital, Winnipeg Health Clinic Portage and Brandon Hospital) that an 
ultrasound is performed prior to medical abortion to confirm an intrauterine pregnancy. 
In March 2019, the SOGC developed a Clinical Practice Guideline on the Use of First 
Trimester Ultrasound.  They recommended the following:  “First trimester ultrasound is 
recommended to date a pregnancy (ideally at 7 to 12 weeks).”   
 
The cost of wireless portable ultrasounds that connect with a tablet computer or smart 
phone has made it more accessible for the average obstetrician/gynecologist going into 
practice.  Canadian residents training in Obstetrics and Gynecology are now required to 
complete a month of training in ultrasound in their PGY1 year.  If an inexpensive 
handheld ultrasound machine can be used to appropriately date a first trimester 
pregnancy, it would allow for the average obstetrician/gynecologist to appropriately date 
a pregnancy, regardless of their location.  This would be highly valued in locations 
where ultrasound access by radiologists is not easily accessible. 
 

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In the SOGC practice guidelines Determination of Gestational Age (GA) by Ultrasound 
published February 2014, a mean sac diameter (MSD) is first used to date pregnancy 
using a transvaginal ultrasound when it is 2-3 mm or 32 to 33 days.  The growth of the 
MSD is approximately 1 mm per day.  Mean sac diameter becomes less reliable when it 
exceeds 14 mm or an embryo can be identified.  A yolk sac or embryo seen inside the 
gestational sac in an intrauterine location provides confirmation that the pregnancy is 
definitely in the uterus.  This makes an ectopic pregnancy extremely unlikely.  The yolk 
sac usually becomes visible between 5 to 6 weeks GA. The embryo is usually seen 
after 6 weeks’ GA.  Crown rump length provides the most accurate estimate of 
gestational age when the embryo is clearly seen and it is reported to be accurate within 
3-8 days.  The SOGC recommend that crown rump length be used up to 84 mm in size 
(approximately 12 weeks and 4 days with Hadlock criteria), and the biparietal diameter 
be used for measurements greater than 84 mm.  These criteria will be used to 
determine gestational age for the study. 
 
Objective: 
 
The objective of this study is to assess equivalency of the transabdominal Clarius 
handheld wifi C3 ultrasound (which uses Bluetooth to locate the ipad Mini 5 and then 
uses wifi direct to show the images) to the current standard of care in Women’s Hospital 
outpatient department the portable Zonare ZS3 in patients presenting in the first 
trimester of pregnancy. 
 
Research Design and Methodology 
 
This is a prospective clinical study in which first trimester participants who are 
presenting to discuss termination of pregnancy, will consent to have an additional 
transabdominal ultrasound with the Clarius C3 immediately prior to their standard 
ultrasound which is performed to date their pregnancy. Participants who are presenting 
for medical abortion have been prescreened to be estimated to be less than 9 weeks 
GA.  Participants who are being seen prior to surgical abortion will have been screened 
by nurses based on their last menstrual period or estimated time of conception to 
estimate their gestational age. Potential participants estimated to be less than 13 weeks 
GA, will be approached to see if they are interested in participating in the study before 
they are seen by their health care provider. The name, date of approach, and reason for 
decline of potential participants who refuse to participate will be documented.  If 
agreeable, the participant will complete consent with a study nurse or medical student 
for the additional ultrasound.  
Participants will then receive the 2 ultrasounds by the same health care provider with 
the Clarius C3 ultrasound first, then the standard care ultrasound.  Occasionally, there 
may be a different provider doing the Clarius C3 ultrasound when the patient consents. 
 
Participants will receive standard care for medical or surgical abortion.  The following 
information will be documented from their chart: 
Height and weight, age, Obstetrical history (Gravida, para, number cesareans, ectopic 
pregnancies, spontaneous abortions, therapeutic abortions). If they do not have a 

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documented intrauterine pregnancy, the standard questions to rule out possibility of 
ectopic pregnancy will be determined, and any positive answers will be documented in 
the chart.  Anyone without a documented intrauterine pregnancy (no gestational sac or 
a gestational sac with no definite crown rump length or yolk sac) will be followed until a 
final outcome is determined or they are lost to follow up.  When the patient has a 
pregnancy of unknown location (no evidence of a pregnancy inside or outside of the 
uterus, their data will not be used to compare the two ultrasounds but future outcome 
will be recorded. 
The final outcome of their pregnancy and any complications will be determined within 
the next 6 weeks with the following potential outcomes: 
completed medical abortion, completed surgical abortion (possibily following failed 
medical abortion), lost to follow up, continuing pregnancy, or ectopic pregnancy. 
 
If a participant is determined to be over 13 weeks GA, they will receive a dating 
ultrasound with the Clarius C3 ultrasound using biparietal diameter as appropriate but it 
will not be included in the final study measurements.  
 
For each participant, ultrasound reports and data from the “Research Participant Data 
Collection Form” will have a unique code and all information stored on a password-
protected SPSS document on a locked desktop computer in the Research Office 
WS021 which is locked.   
 
Sample Size 
 
Sample size was estimated based on a one sided McNemar’s test, 15% clinically 
significant difference (estimating 60% of subjects would allow a transabdominal 
ultrasound to see a gestational sac and a yolk sac with the Zonare ZS3 and 45% with 
the Clarius C3) at a power of .8 and alpha value of 0.05.  This would require 131 
participants to be recruited for the study. 
 
Statistical Analysis 
 
McNemar’s test would be used to determine the ability of the transabdominal 
ultrasounds to measure the presence or absence of an intrauterine pregnancy. 
A paired t-test would be used to compare gestational sac measurements or crown rump 
lengths between the two ultrasound machines. 
 
Inclusion Criteria 
1. Presenting requesting medical or surgical abortion 
2. Estimated to be under 13 weeks gestational age based on last menstrual period 
or time of conception, or nurses best estimate. 
3. Able to provide informed consent with adult supervision of a minor or with an 
interpreter present 
 
Exclusion Criteria 
1. Unable to provide informed consent 

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Timeline 
We anticipate data collection to occur over a 9-month period. 
 
Budget 
Data collection by the participating physicians will be on a volunteer basis. A medical 
student volunteer will not be paid for the procedure.  Physicians who perform ultrasound 
for medical and surgical abortion will be reimbursed by Manitoba Health for their 
procedure with no additional funding for participation in the study. The study nurses 
involved in recruiting, consenting and collecting data will be paid by the Department of 
Obstetrics and Gynecology.   
 
Conflict of interest 
There is no conflict of interest identified in this study. 
 
Discussion of Ethics 
Informed consent 
Potential participants will be identified by nursing or physician.  A volunteer medical 
student or research nurse will approach the patient to request consent. 
 
Potential Benefits and Harms 
The additional ultrasound may be associated with minimal physical discomfort due to 
pressure on their bladder.  There is minimal risk to a developing pregnancy due to 
ultrasound.  Participants will be chosen among patients requesting termination of 
pregnancy. 
 
Alternative Procedures 
The patient may choose to receive usual care and not receive a second ultrasound. 
 
Protection of privacy and harm reduction 
- Participation is strictly voluntary  
- All personal information contained on the consent forms will be kept in a  
locked cabinet in the Research Office WS021 which itself is locked. These  
paper records will be destroyed via shredding at the end of the study.  
- Ultrasound images obtained from patients will be initially stored on Clarius cloud using 
anonymized data and printed out to be placed in the study chart 
- Information gathered from patient charts, and ultrasound image reports will be 
identified by a unique code and stored on a password-protected SPSS Document 
stored on a locked Desktop computer in the locked Research Office WS021. These 
files will be destroyed using the permanent deletion function on the computer if no 
further secondary research is planned within seven years.  
 
Dissemination of information 

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Final results will be presented locally and also at a national or international forum. The 
data may be used to design future studies with regard to performing ultrasound in 
remote locations in Manitoba or Nunavut. 
 
References 
 
Butt K, Lim K et al. Determination of Gestational Age by Ultrasound. J Obstet Gynaecol Can 
2014;36(2):171-181 
 
Van den Hof M, Smithies M, Nevo O, et al. No. 375- Clinical Practice Guideline on the Use of 
First Trimester Ultrasound. J Obstet Gynaecol Can 2019;41(3):388-395 
 
Costescu D, Guilbert E, Bernardin J, et al.  Medical Abortion J Obstet Gynaecol Can 
2016;38(4):366-389 
 
Costescu D, Guilbert E et al. No 360-Induced Abortion:  Surgical Abortion and Second 
Trimester Medical Methods. J Obstet Gynaecol Can 2018;40(6):750-783 
 
Van den Hof M, No 359-Obstetric Ultrasound Biological Effects and Safety. J Obstet Gynaecol 
Can. 2018;40(5):627-632