A 36-year-old woman comes to the office due to vaginal spotting for the past 4 days. The patient has a history of heavy menstrual bleeding for which she had a progestin-containing intrauterine device placed 3 years ago. She has been amenorrhoeic for the past 2 years but started having vaginal spotting a few days ago and some mild pelvic cramping. The patient has no significant medical history and has never been pregnant. She has no prior sexually transmitted infections. BMI is 30 kg/m2. Temperature is 36.7 C (98.1 F), blood pressure is 110/70 mm Hg, pulse is 80/min, and respirations are 18/min. Physical examination shows right adnexal tenderness and a closed cervix. Urine pregnancy test is positive. Transabdominal ultrasound shows a small uterus with a thin endometrium and an intrauterine device in place. Which of the following is the best next step in management of this patient?
Ectopic pregnancy | |
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This patient with new-onset vaginal spotting, right adnexal tenderness, and a positive pregnancy test likely has an ectopic pregnancy (ie, extrauterine pregnancy implantation, most commonly in the fallopian tube). Although patients with an intrauterine device (IUD) have a lower absolute risk for ectopic pregnancy (due to overall lower rates of pregnancy), they are at higher risk for extrauterine implantation if pregnancy occurs.
This patient's transabdominal ultrasound shows a thin endometrium and does not reveal a pregnancy (ie, pregnancy of unknown location). Pregnancy normally induces endometrial thickening (ie, decidualization) to encourage intrauterine implantation; however, patients with a progestin-containing IUD develop endometrial atrophy (ie, thinning), which can induce amenorrhea but also promote extrauterine implantation. Because an ectopic pregnancy can present with vaginal bleeding, patients with an IUD who develop an abrupt change in bleeding pattern and concomitant adnexal tenderness require evaluation.
If transabdominal ultrasonography cannot locate the pregnancy, transvaginal ultrasonography is performed because it is more sensitive and can better visualize the adnexa, particularly in obese patients or those with an early gestation.
(Choice A) Surgical exploration (eg, diagnostic laparoscopy) is indicated in hemodynamically unstable patients with a suspected ruptured ectopic pregnancy (or in those with contraindications to medical therapy with methotrexate). This patient is hemodynamically stable and should undergo transvaginal ultrasonography to determine pregnancy location.
(Choice B) Endometrial biopsies are used to evaluate for endometrial hyperplasia/cancer in nonpregnant women with abnormal uterine bleeding. Although this patient has vaginal bleeding and obesity (a risk factor for endometrial hyperplasia), hyperplasia is unlikely in this patient with a progestin-containing IUD (protective against hyperplasia) and thin endometrium.
(Choice C) FSH, TSH, and prolactin levels can be used to evaluate abnormal uterine bleeding. However, this patient's bleeding is likely pregnancy-related, and these hormone levels would not affect management.
(Choice D) IUD removal is recommended for patients with an ultrasound-confirmed intrauterine pregnancy who wish to continue pregnancy; removal decreases the risks of IUD-associated spontaneous abortion, intraamniotic infection, and preterm delivery. This patient's pregnancy should be located prior to offering IUD removal because an IUD can be left in place with no additional adverse effects if the pregnancy is extrauterine.
Educational objective:
Although patients with an intrauterine device have a lower absolute risk for ectopic pregnancy, they are at higher risk for ectopic implantation should pregnancy occur. Diagnosis is with transvaginal ultrasonography, which has better visualization of pelvic structures compared to transabdominal ultrasonography.