AssessmentsAntepartum hemorrhage: Clinical practice
USMLE® Step 1 style questions USMLE
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A 30-year-old woman comes to the office because of vaginal bleeding. She says that she has not had a period in 12 weeks and has noted some abdominal swelling. She notes that she has been nauseated the last four weeks and has had two episodes of vomiting every morning for the past week. Physical examination shows a uterus consistent with a 20-week gestation. Urine pregnancy test is positive and serum beta-hCG is 158,000. Which of the following is the most likely diagnosis?
Content Reviewers:Rishi Desai, MD, MPH
Vaginal bleeding may affect as many as 40% of pregnant individuals. Most frequently, it occurs during the first trimester of pregnancy, meaning until week 12, but sometimes it can happen during the second or third trimesters, or between weeks 13 and 27, and weeks 28 to 40, respectively.
The first step when confronted with vaginal bleeding during pregnancy is to assess the hemodynamic stability of the individual, based on the degree of hypovolemia and vital sign status.
Stage 2 is when 1000 to 1500 milliliters have been lost. Systolic blood pressure drops to 80 to 100 mmHg, tachycardia is obvious, and there may be weakness and sweating.
Stage 3 is when 1500 to 2000 milliliters have been lost. Systolic blood pressure drops between 70 and 80 mmHg, and there may be restlessness, pallor and low urine output.
Finally, stage 4 is when more than 2000 milliliters have been lost, systolic blood pressure is less than 70 mmHg, and symptoms may include cardiovascular and respiratory collapse, loss of consciousness and anuria.
Now, before elucidating the cause, some immediate measures should be taken in order to compensate the blood loss. These follow an A-B-C pattern.
A stands for airway, so you’ll want to protect the airway, especially when there’s loss of consciousness.
B stands for breathing, so you’ll want to administer Oxygen through a non-rebreather mask.
C stands for circulation - meaning measuring vital signs and establishing the degree of hypovolemia, inserting two large caliber peripheral IV catheters - of at least 14 gauge or even larger gauge -, and starting fluid resuscitation immediately, with 500 milliliters of normal saline or lactated Ringer’s solution given over 30 minutes.
Afterwards, the rate of fluid is adjusted depending on their hemodynamic status. In individuals who have lost more than 1500 milliliters of blood, blood transfusions are indicated, typically with products containing both red blood cells and platelets.
Next, to elucidate the cause, a full work-up, including pelvic exam, a transvaginal ultrasound and laboratory tests, should be done.
During the first trimester, the most common causes of vaginal bleeding are implantation bleeding, ectopic pregnancy, miscarriage, and genital tract pathology - meaning conditions that affect the cervix, vagina or uterus.
Something to keep in mind is that miscarriage and genital tract pathology may also cause vaginal bleeding in the second trimester of pregnancy.
Now, implantation bleeding is the only physiologic cause of first trimester bleeding, and occurs because the developing embryo burrows into the uterine lining 10 to 14 days after fertilization.
It presents as light bleeding or spotting that lasts no more than a couple of days, so it’s frequently mistaken for the actual menstrual period. Implantation bleeding requires no treatment, but it is a diagnosis of exclusion - so other causes should be ruled out first.
The next common cause in the first trimester is an ectopic pregnancy.
Now, the rule of thumb, actually, is to assume that vaginal bleeding during the first trimester is caused by an ectopic pregnancy until proven otherwise.
With an ectopic pregnancy, the embryo implants somewhere other than the uterine cavity, most frequently the ampulla of the fallopian tube.
So, risk factors for ectopic pregnancy include previous ectopic pregnancies, previous tubal surgery or pathology, as well as the super rare pregnancies that occur after bilateral tubal ligation, or if the individual currently has an intrauterine device, or IUD, for contraception.
Symptoms include pain and vaginal bleeding that typically begin 6 to 8 weeks into the pregnancy.
For diagnosis, a serum HCG can be measured - and if it’s above 2000 milli international units or milliunits per milliliter, then the pregnancy - either intrauterine or ectopic - can be seen on transvaginal ultrasound.
If the serum HCG level is below that mark, then serial measurements are done every 48 to 72 hours until it reaches 2000 milli international units per milliliter.
Rarely, the ectopic pregnancy can implant in the cervix, in which case it’s referred to as a cervical pregnancy.
In this case, vaginal bleeding is often painless and profuse, and often results in hemodynamic instability.
Cervical pregnancy is diagnosed with a transvaginal ultrasound, and treatment is to terminate the pregnancy.
In hemodynamically stable individuals, termination is done medically, with methotrexate.
In hemodynamically unstable individuals, immediate evacuation is done, through dilation and endocervical curettage.
The next possible cause is a miscarriage, and there’s two types: threatened, which means that the embryo may or may not be eliminated at some point, and inevitable, in which case the embryo is definitely going to be eliminated.
With a threatened miscarriage, the physical examination shows a closed cervix and the ultrasound shows an intrauterine pregnancy with detectable fetal cardiac activity.
In this case, expectant management is an option until symptoms resolve, or there is progression to inevitable miscarriage.
With an inevitable miscarriage, the cervix is dilated, vaginal bleeding is increasing gradually, and there may also be painful uterine cramps, or contractions.
Sometimes, gestational tissue can be felt or seen through the cervical opening, and it’s usually eliminated in two to four weeks after diagnosis.
So in hemodynamically stable individuals, with no signs of infection, expectant management and reevaluation at 4 weeks is an option.
After 4 weeks, the inevitable miscarriage can be complete, meaning everything inside the uterine cavity has been evacuated, or incomplete, if there’s something like placental tissue left behind.
For incomplete miscarriages, medical or surgical evacuation are required.
In the first trimester, medical treatment is recommended, with mifepristone, a progesterone antagonist, and misoprostol, a prostaglandin E1 analogue. So 200 milligrams of mifepristone are given orally, and 24 hours later, 800 micrograms of misoprostol, are administered intravaginally.
If mifepristone is not available, 800 micrograms of misoprostol can be given, and a repeat dose may be given 7 days later, if there was no response to the first one.
For second trimester miscarriages, surgical treatment is preferred, and it’s usually done with dilation and curettage, which is when the cervix is dilated, and then the contents of the uterine cavity are either scraped off with a curette, or suctioned out with aspiration.
Finally, vaginal bleeding during pregnancy in the first and second trimesters may occur because of vaginal pathology, like vaginitis, vaginal tumors or warts, cervical pathology like cervical ectropion or polyps, or uterine polyps or fibroids.
Vaginitis can be suspected based on abnormal vaginal discharge, which may be bloody and purulent, and can be diagnosed with a wet mount of a vaginal discharge sample, and treatment is usually done with antibiotics.
If a vaginal tumor or wart is identified, it’s usually removed, and then analyzed histopathologically to determine whether it’s benign or malignant.
Next, are cervical pathologies. First, cervical ectropion is when the glandular epithelium of the endocervix is present inside the vagina because of endocervical eversion - which makes the exocervix look bright red on a speculum exam.
This is a common, benign finding that occurs in response to hormonal fluctuations during pregnancy - but the columnar epithelium is prone to light bleeding when touched, so bleeding may occur following intercourse, or during the speculum examination.
No treatment is necessary in this case, but a pap smear should be done to screen for cervical neoplasia, which may present the same.
Cervical polyps can also be seen on a speculum exam, and can be surgically removed.
Polyps don’t usually cause complications, but large fibroids may cause complications like fetal growth restriction, miscarriage, and preterm birth - something to keep in mind for later in the course of the pregnancy.
Tricky part is that during pregnancy, removing polyps or fibroids carries more risks than benefits, so it’s usually done after delivery.
One final cause of vaginal bleeding in the second trimester for pregnancies less than 20 weeks is cervical insufficiency - which is when there’s cervical dilation and effacement, which means thinning, too early in the pregnancy. Other symptoms may include vaginal fullness, pelvic pressure or discomfort, and lower back pain.
Now, the diagnosis can be made based on clinical examination, obstetrical history or ultrasound findings.
So first let’s look at the clinical signs. These include cervical dilation and effacement, and fetal membranes may be visible through the cervical opening, or protrude into the vagina, in the absence of uterine contractions.