Editing Pregnancy test (section)

=== Ultrasound ===
[[Obstetric ultrasonography]] may also be used to detect and diagnose pregnancy. It is very common to have a positive at-home urine pregnancy test before an ultrasound. Both [[Abdominal ultrasound|abdominal]] and [[Vaginal ultrasound|vaginal]] ultrasound may be used, but vaginal ultrasound allows for earlier visualization of the pregnancy. With [[obstetric ultrasonography]] the [[gestational sac]] (intrauterine fluid collection) can be visualized at 4.5 to 5 weeks [[Gestational age (obstetrics)|gestation]], the [[yolk sac]] at 5 to 6 weeks gestation, and [[fetal pole]] at 5.5 to 6 weeks gestation. Ultrasound is used to diagnose [[multiple gestation]], which cannot be diagnosed based on the presence of hCG in urine or blood.<ref>{{Cite journal |last1=Wang |first1=Peter S. |last2=Rodgers |first2=Shuchi K. |last3=Horrow |first3=Mindy M. |date=May 2019 |title=Ultrasound of the First Trimester |url=https://linkinghub.elsevier.com/retrieve/pii/S0033838919300090 |journal=Radiologic Clinics of North America |language=en |volume=57 |issue=3 |pages=617–633 |doi=10.1016/j.rcl.2019.01.006|pmid=30928081 }}</ref> Determination of the [[gestational age]] of the [[embryo]]/[[fetus]] is an additional benefit of ultrasound compared to hCG tests.<ref>{{Cite web |last=The American College of Obstetricians and Gynecologists |date=December 2016 |title=Ultrasound in Pregnancy |url=https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2016/12/ultrasound-in-pregnancy |access-date=September 11, 2024}}</ref>