Approach to first trimester bleeding: Clinical sciences

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Introduction0:00–0:40

First trimester bleeding includes is any vaginal or uterine bleeding that occurs from the first day of a patient’s last menstrual period through 13 weeks and 6 days gestation.
Pregnant patients who present with vaginal bleeding in the first trimester require a timely evaluation to rule out any life-threatening conditions.
The most concerning cause is an ectopic pregnancy because it can progress to tubal rupture and intraperitoneal hemorrhage.
Other common etiologies include genital tract pathology, implantation bleeding, spontaneous abortion, pregnancy of unknown location, and molar pregnancy Your first step in evaluating a patient with first trimester bleeding is to perform a CABCDE assessment to determine if they are stable or unstable.

Acute Management0:40–1:14

If your patient is unstable, think about ruptured ectopic pregnancy and incomplete abortion. Regardless of the cause, your next step is to start acute management.
Stabilize airway, breathing, and circulation; consider intubation as clinically indicated; obtain IV access and a type and cross for possible packed red blood cell transfusion; and continuously monitor vital signs.

Stable Patient1:14–3:01

Alright, now that unstable patients are covered, let’s talk about stable ones. First, obtain a focused history and physical examination.
On history, determine the first day of your patient's last menstrual period, whether an intrauterine pregnancy, or IUP, has already been documented by ultrasound, and any previously assigned estimated due date.
Next, assess if the patient has any risk factors for ectopic pregnancy or pregnancy loss, such as a history of either one of these.
Also, characterize their vaginal bleeding, taking note of onset, frequency, quantity, and associated abdominal or pelvic pain.
Additionally, ask if they have passed any large blood clots or tissue prior to your evaluation. On physical exam, evaluate for any abdominal tenderness to palpation or peritoneal signs, like rebound pain and guarding.
Next, perform a speculum exam to assess the quantity and source of bleeding and evaluate if any products of conception are present in the vagina or cervix.
Also, check for any vaginal or cervical source of bleeding. On bimanual exam, evaluate uterine size and tenderness; and check for dilation of the internal cervical os.
Finally, examine any tissue that may have already passed and see if you can visualize a clear gestational sac or placental villi.Then, obtain labs, including a quantitative hCG, type and screen, and Rh status; as well as a CBC to evaluate for anemia and establish a baseline hemoglobin.
Lastly, perform a transvaginal ultrasound to evaluate the location and viability of the pregnancy, making note of whether fetal cardiac activity is present or absent.
Now, if you see an intrauterine pregnancy on ultrasound, specifically a gestational sac with a yolk sac or an embryo, you should assess for fetal cardiac activity.

Intrauterine pregnancy3:01–5:39

When cardiac activity is present and your exam reveals a closed cervix with no visualized products of conception, consider either genital tract pathology or threatened abortion.
Genital tract lesions are diagnosed by visual inspection and include vaginal lacerations, vaginitis, cervicitis, cervical polyps, fibroids, and rarely, neoplasm.
So, if on a sterile speculum exam, you observe a clear source of vaginal or cervical bleeding, that’s genital tract pathology.
On the flip side, if a vaginal or cervical lesion is absent, you will instead diagnose a threatened abortion or implantation bleeding.
A threatened abortion can present with bleeding anytime throughout the first trimester whereas implantation bleeding is generally characterized by light bleeding or spotting that occurs about 10 to 14 days after fertilization, or around the time of a missed menstrual period.Here’s a clinical pearl!
A common cause of a threatened abortion is a subchorionic hemorrhage or hematoma, which is when the chorion partially detaches from the uterine wall.
On ultrasound, subchorionic hemorrhage appears as a hypoechoic crescent-shaped area adjacent to the gestational sac in the subchorionic space.
Going back a step, if cardiac activity is present, but your exam reveals an open cervix, with ongoing bleeding and no products of conception, you can diagnose an inevitable abortion.Okay, time to see what to do if the cardiac activity is absent.
In this situation, you will again rely on the findings of your physical exam to determine the bleeding etiology.If the cervix is closed and no products of conception are visualized, refer to your ultrasound and assess the mean gestational sac diameter; or, if an embryo is present, the crown-rump length.
If the mean gestational sac diameter is at least 25 mm OR if the crown-rump length of the embryo is 7 mm or greater, you will diagnose a missed abortion.
However, if the mean gestational sac diameter is less than 25 mm OR if the crown-rump length is less than 7 mm, diagnose a pregnancy of uncertain viability.Now, if the cervix is open and products of conception are visualized on the pelvic exam, your diagnosis changes to an incomplete abortion.
Let’s shift our focus to patients with first trimester bleeding where the ultrasound shows no intrauterine or extrauterine pregnancy.

No intrauterine or extrauterine pregnancy5:39–7:15

When pregnancy location cannot be determined on ultrasound, your next step is to assess whether the patient has had a previously documented intrauterine pregnancy.
In patients who have a previously documented intrauterine pregnancy, which is now no longer seen, your differential includes either an incomplete or complete abortion.
If they present with heavy ongoing vaginal bleeding and abdominal cramping; and if an exam reveals an open cervix with gestational tissue present, your diagnosis is an incomplete abortion.
This occurs when some but not all of the pregnancy tissue has been expelled.On the other hand, if the patient reports heavy vaginal bleeding which has either progressed to lighter bleeding or resolved, along with improving abdominal cramping; and if an exam reveals either an open or closed cervix with no products of conception noted on pelvic or ultrasound exam, your diagnosis is a complete abortion.Now, for those patients who have no pregnancy visualized on ultrasound and also have no previously documented IUP, the diagnosis is pregnancy of an unknown location.
Here's another clinical pearl! A pregnancy of unknown location is considered a transient diagnosis and requires close follow-up with serial ultrasounds and quantitative beta hCG measurements.
Clinically you are most concerned about an ectopic pregnancy that is not yet visible on ultrasound! Alright, let’s move on to different ultrasound findings.

Ectopic Pregnancy7:15–8:07

If the ultrasound shows no IUP and a gestational sac with a yolk sac or embryo in the adnexa OR an adnexal mass with a hypoechoic area separate from the ovary, consider an ectopic pregnancy.
Now, your patient may report a history of sexually transmitted infection, tubal damage, or a prior ectopic pregnancy. Typically they present with light vaginal bleeding and may additionally report unilateral abdominal pain or shoulder pain, which may indicate a ruptured ectopic as free fluid in the abdomen irritates the diaphragm leading to this referred pain.
Exam will show adnexal tenderness with or without a palpable adnexal mass; and labs may reveal anemia. In this case, diagnose an ectopic pregnancy.

Molar Pregnancy8:07–9:09

Finally, let’s go over our last ultrasound findings. For patients with vaginal bleeding in the first trimester, whose ultrasound shows a heterogeneous intrauterine mass with diffuse anechoic spaces, with a characteristic “bunch of grapes” or “snowstorm appearance” and peripheral vascularity, a molar pregnancy should be considered.
On history, the patient will report light or heavy vaginal bleeding along with typical pregnancy symptoms, like abdominal bloating or nausea and vomiting.
The patient may report a history of hyperemesis gravidarum in the current pregnancy or they may have had a prior molar pregnancy.
As for the exam, you may find the uterus is larger than expected for gestational age or palpable bilateral ovarian cysts, which are referred to as theca lutein cysts.
Labs will show an abnormally high hCG for the estimated gestational age and possibly abnormal thyroid function tests. With all these findings, you can diagnose molar pregnancy.Alright, as a quick recap… First trimester bleeding is any vaginal or uterine bleeding that occurs from the date of a patient’s last menstrual period through 13 weeks and 6 days gestation.

Review9:09–9:29

Common etiologies include genital tract pathology, implantation bleeding, spontaneous abortion, pregnancy of unknown location,