Assessing Gestational Age in First Trimester Pregnancies Using Ultrasound

This is a prospective 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 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.

Inclusion criteria

• Presenting requesting medical or surgical abortion
• Estimated to be under 13 weeks gestational age based on last menstrual period or time of conception, or nurses best estimate.
• Able to provide informed consent with adult supervision of a minor or with an interpreter present

Exclusion criteria

• Unable to provide informed consent