Lindee Abe, APRN
First trimester vaginal bleeding can cause a difficult time for patients who are pregnant. They are adjusting to the changes in their bodies due to the pregnancy. They are also mentally adjusting to the thought of having a child. It is common to see patients with vaginal bleeding in the first trimester of pregnancy in the emergency department, but these patients can also present in family practice and urgent care settings.
Obstetric Care and First Trimester Bleeding
For most patients, the first obstetric appointment is usually not until eight weeks after the last menstrual period. A measurable embryo is generally not found until 6-7 weeks of gestation, so most obstetric offices will wait to schedule the first appointment until later in the first trimester if there are no problems. However, this means that in the first 2/3 of the first trimester, when patients have vaginal bleeding, they will most likely not be established with an obstetric provider.
Causes of First Trimester Bleeding
Vaginal bleeding is common in the first trimester, with 15-25% of patients reporting vaginal bleeding. Vaginal bleeding can be a normal finding during the first trimester due to implementation 1-2 weeks after fertilization. Bleeding can also occur following a pelvic exam, Pap test, or sexual intercourse. While there are several causes of vaginal bleeding that can be normal, pathological causes must be evaluated as well. The differential diagnoses for first-trimester vaginal bleeding should include ectopic pregnancy, heterotropic pregnancy, threatened abortion, gestational trophoblastic disease, cervicitis, vaginal lacerations, and neoplastic polyps.
Ectopic Pregnancy
Ectopic pregnancy is the can’t miss diagnosis of vaginal bleeding in the first trimester. It occurs in approximately 2% of all pregnancies. A ruptured ectopic pregnancy can result in a life-threatening abdominal hemorrhage. Any patient that presents with vaginal bleeding in the first trimester that does not have a confirmed intrauterine pregnancy requires a transvaginal ultrasound. The diagnosis can be made on transvaginal ultrasound if there is visualization of an extrauterine gestational sac with either a fetus or yolk. Additionally, if an extraovarian adnexal mass with an empty gestational sac, complex extraovarian adnexal mass, or intraperitoneal bleeding is found on transvaginal ultrasound, the provider should suspect an ectopic pregnancy.
Heterotrophic Pregnancy
Heterotrophic pregnancy occurs when there is both an intrauterine and extrauterine pregnancy that occurs simultaneously. This is a rare condition, occurring in only 1 in 30,000 pregnancies. Patients most at risk include those undergoing reproductive therapy. Diagnosis is made by transvaginal ultrasound by visualization of both the intrauterine pregnancy and a complex adnexal mass with a yolk sac or embryonic or fetal pole.
This reference slide is taken from our Emergency Medicine and Urgent Care Development Series – click to learn more.
Threatened Abortion
Threatened abortion occurs in 15-20% of pregnancies. It is a provisional diagnosis made in patients who have vaginal bleeding in the first trimester but have a closed cervix on exam and visualization of an intrauterine pregnancy with fetal cardiac activity on transvaginal ultrasound. It is important to know that pregnancy loss does not always follow vaginal bleeding, with 90% or more of threatened abortions not resulting in pregnancy loss.
Complete Abortion
Complete abortion is when the entire contents of the uterus have been expelled. Incomplete abortion occurs when the cervical os is dilated, vaginal bleeding is increasing, and cramping is present. Transvaginal ultrasound can be used to diagnose both conditions. Incomplete abortion is differentiated from threatened abortion on ultrasound by the finding of a focal hyperechoic mass in the endometrium, signifying retained products of conception.
Trophoblasic Disease
Gestational trophoblastic disorder can be further classified as a hydatidiform mole or choriocarcinoma. Hydatidiform mole, also known as a molar pregnancy, should be suspected with abnormally high hCG levels and can be confirmed with ultrasound, demonstrating a central intrauterine heterogeneous mass with numerous discrete anechoic spaces. Choriocarcinoma is rare, and a history of the hydatiform mole is a risk factor. Choriocarcinoma will appear as a mass with a heterogeneous appearance, enlarging the uterus.
Cervicitis
Cervicitis is the result of inflammation of the cervix. It can occur outside of pregnancy as well as during pregnancy. Physical exam findings include purulent discharge and bleeding on touching the cervix. Infection can cause cervicitis, and the patient should be evaluated for gonorrhea, chlamydia, herpes, and trichomoniasis.
Trauma
Vaginal laceration is another diagnosis that can occur in both pregnant and nonpregnant individuals. Vaginal lacerations can occur as a result of sexual intercourse. However, the patient should also be screened to ensure that there is no concern for sexual abuse or domestic violence.
Other Causes
There are several more conditions that affect both pregnant and nonpregnant patients that can cause vaginal bleeding. Neoplastic polyps of the cervix can cause postcoital spotting and sporadic bleeding that can be diagnosed based on visualization on the pelvic exam. Cervical cancer can cause sporadic bleeding and vaginal discharge that is diagnosed based on cervical biopsy. Fibroid can also cause heavy menstrual bleeding that can also cause reproductive dysfunction like miscarriage and obstetric complications.
Workup
There are several key components of the work-up for vaginal bleeding. These include a pelvic exam, transvaginal ultrasound, serum beta-hCG, CBC, type and screen (if > 12 weeks gestation), and urinalysis. In the urgent care and family practice setting, it can be difficult to perform adequate work-up and get the results back promptly. In many cases, it is prudent to refer the patient to the emergency room if this testing is unavailable or will take significant time to get the results.
Ultrasound
The transvaginal ultrasound is the gold-standard test for diagnosing ectopic pregnancy. Generally, a transvaginal ultrasound will show a gestational sac after the serum hCG is at least 390 mIU/mL, which occurs around 4-5 weeks gestation. The embryonic cardiac activity will not be visible until 5.5-6 weeks gestation, and the measurable embryo will not be visible until 6-7 weeks.
Serology
Serum hCG provides a specific, quantifiable amount that helps guide decisions in several ways. First, the level can be used to determine if the pregnancy should be visible on ultrasound. If the hCG level is low and there is no visible pregnancy, then it is likely that it is too early to visualize the pregnancy. If the hCG is sufficiently elevated and there is no visible pregnancy, then it is more concerning for ectopic pregnancy. The hCG level can also be used to trend the pattern over time. The hCG should double every 48 hours after implantation. If this does not occur, it could indicate threatened abortion, complete abortion, or ectopic pregnancy. CBC is needed to assess for anemia related to blood loss. The type and screen are only required in patients > 12 weeks gestation who would be candidates for anti-D immune globulin.
Summary
The patient presenting with first-trimester vaginal bleeding can be anxious due to the thought of losing the pregnancy. By thoroughly evaluating the patient to determine the underlying cause of the vaginal bleeding, providers can help to ease that anxiety. If not a surgical candidate, the treatment plan should be clear to the patient at the end of the visit and appropriate follow up already scheduled.
References:
American College of Obstetrics and Gynecologists. Bleeding during pregnancy. Retrieved from https://www.acog.org/womens-health/faqs/bleeding-during-pregnancy
Powell AM, Nyirjesy P. Acute cervicitis. UpToDate. UpToDate Inc. Accessed October 17, 2023.
https://www.uptodate.com/contents/acute-cervicitis
Norwitz ER, Park JS. Evaluation and differential diagnosis of vaginal bleeding before 20 week of gestation. UpToDate. UpToDate Inc. Accessed October 17, 2024.
https://www.uptodate.com/contents/causes-of-female-genital-tract- bleeding
Kaunitza AM. Causes of female genital tract bleeding. UpToDate. UpToDate Inc. Accessed October 17, 2023.
