A 28-year-old woman comes to the office with 2 days of vaginal spotting. The patient has no fever, chills, nausea, vomiting, or cramping. Her last menstrual period was 6 weeks ago, and she had a positive home pregnancy test yesterday. The patient has no chronic medical conditions or previous surgeries. She is sexually active with a new male partner and uses condoms for contraception. The patient previously used a copper intrauterine device for contraception but had it removed due to increased pain and heavy menstrual bleeding. Recent nucleic acid amplification testing for chlamydia and gonorrhea was negative. The patient does not use tobacco, alcohol, or illicit drugs. Temperature is 37.2 C (99 F), blood pressure is 108/68 mm Hg, and pulse is 81/min. The abdomen is soft and nontender with no guarding or rebound. Pelvic examination reveals dark red blood in the posterior vaginal fornix and a closed cervix. On bimanual examination, there is mild left adnexal tenderness with fullness but no cervical motion tenderness. The uterus is small and nontender. Quantitative β-hCG is 3,700 IU/L. Transvaginal ultrasound reveals a 4.6-cm left adnexal complex mass and a thickened endometrium. Which of the following is the most likely diagnosis in this patient?
Ectopic pregnancy | |
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This patient has first-trimester vaginal bleeding and a positive pregnancy test, concerning for an ectopic pregnancy. Patients with a suspected ectopic pregnancy undergo evaluation with pelvic ultrasound and a β-hCG level. An early intrauterine pregnancy can be visualized by ultrasound when the β-hCG level is above the discriminatory zone (>3,500 IU/L). This patient has a level above the discriminatory zone and an ultrasound revealing an empty uterus and a complex adnexal mass, which are diagnostic of an ectopic pregnancy.
Symptoms of an ectopic pregnancy typically occur 6-8 weeks after the last menstrual period. In addition to vaginal bleeding, lower abdominal pain and amenorrhea may occur. The most common location for ectopic pregnancy is the ampulla of the fallopian tube; other implantation sites include the ovary, abdomen, and cornual region of the uterus. Risk factors include prior ectopic pregnancy, history of pelvic surgery, tobacco use, pelvic inflammatory disease, infertility, and in vitro fertilization.
Treatment is with either medical (eg, methotrexate) or surgical management, depending on the patient's hemodynamic status and contraindications to methotrexate.
(Choice A) The corpus luteum, a physiologic ovarian cyst, develops after ovulation and produces progesterone to maintain the pregnancy until the placenta develops. The cyst appears as an adnexal mass on ultrasound; however, an associated intrauterine pregnancy is also seen on ultrasound.
(Choice B) An early pregnancy of undetermined location occurs when a pregnancy cannot be visualized on ultrasound at a β-hCG level below the discriminatory zone (≤3,500 IU/L); it can be either ectopic or intrauterine. In stable patients, the β-hCG level is repeated every 48 hours to determine whether the increase is consistent with a normal pregnancy (≥35% rise every 48 hours). Ultrasound is repeated until β-hCG is >3,500 IU/L and an intrauterine pregnancy is visualized.
(Choice D) Implantation bleeding may occur approximately 2 weeks after fertilization (or 4 weeks after the last menstrual period) as the fertilized egg attaches to the endometrium. Bleeding is scant and painless. The absence of an intrauterine gestation on ultrasound makes this diagnosis unlikely.
(Choice E) A threatened abortion presents with vaginal bleeding, a closed cervix, and an intrauterine pregnancy with normal fetal cardiac activity.
Educational objective:
An ectopic pregnancy can present with first-trimester vaginal bleeding, a positive pregnancy test, and a complex adnexal mass without evidence of an intrauterine pregnancy.