USMLE® Step 1 style questions USMLE
A 25-year-old woman comes to the office due to vaginal bleeding and abdominal pain for the past 2 days. The patient’s last menstrual cycle was 6 weeks ago. She is sexually active with her male partner of 2 years, and they have been using the withdrawal method as contraception. Medical history is unremarkable other than an episode of pelvic pain 2 years ago that resolved spontaneously without treatment. Temperature is 37.0°C (98.6°F), pulse is 80/min, and blood pressure is 135/85 mmHg. Serum hCG is positive, measuring 1200 mIU/mL. Transvaginal ultrasound shows an empty, normal-appearing uterus and no other abnormalities. Physical examination shows mild lower right adnexal tenderness but is otherwise unremarkable. Which of the following is the underlying cause of this patient’s presentation?
Ectopic pregnancy exam links
Content Reviewers:Rishi Desai, MD, MPH
In ectopic pregnancy, ectopic means “out of place,” so an ectopic pregnancy means that a pregnancy occurs somewhere other than in the uterine cavity.
In order for an ectopic pregnancy to take place, a couple of things need to happen differently from the normal process of a pregnancy.
First, following ovulation, the egg must be fertilized and come to rest somewhere other than the endometrium of the uterine cavity.
Next, when it arrives at this destination, it must implant on a surface with a rich enough blood supply to support a developing embryo.
Ectopic pregnancies have been known to occur on various surfaces, including the ovaries, intestines, and most commonly, in the ampulla of the Fallopian tube.
After implantation, the embryo begins developing and growing just like it would in a normal pregnancy.
Over time, a few different things can happen. Sometimes the tissue can no longer provide a sufficient blood supply for the embryo, leading to its death.
On the other hand, if the tissue can supply the embryo with sufficient blood, then hormones from the corpus luteum and placenta can lead to a missed menstrual period and other body changes like nausea and fullness of breasts, which are typically seen in early pregnancy.
If the ectopic pregnancy occurs in the ampulla of the fallopian tube, it eventually runs out of space.
Slowly the ectopic pregnancy stretches the nerve fibers within the wall of the fallopian tube, causing lower abdominal pain.
Eventually, the expansion causes damage to the wall of the ampulla, potentially rupturing the fallopian tube.
A ruptured ectopic can also lead to massive hemorrhaging into the abdominal cavity, and the blood can irritate the peritoneum which can cause referred pain to the shoulder.
Occasionally, there can be light vaginal bleeding as well.
The combination of internal bleeding, severe pain, and damage to the fallopian tube make an ectopic pregnancy a medical emergency.
The cause of an ectopic pregnancy in any individual case is often unknown, but there are well known risk factors.
These include smoking, a history of pelvic inflammatory disease, conception by in-vitro fertilization, gynecologic surgery, current use of intrauterine devices, tubal ligation, or a previous ectopic pregnancy.
Symptoms of an ectopic pregnancy include amenorrhea, or a missed menstrual period, pelvic pain, and vaginal bleeding.
Typically, for an ectopic pregnancy in the fallopian tube, pressure increases as the tube stretches around six to eight weeks into the pregnancy, but if the ectopic pregnancy occurs in a place with a lot of space for the embryo to grow, pain and bleeding may not occur until several weeks later.
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- "Does This Woman Have an Ectopic Pregnancy?" JAMA (2013)
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- "Ectopic pregnancy" The Lancet (2005)