A 37-year-old woman comes to the emergency department due to vomiting and severe lower abdominal pain. The patient developed sudden-onset, sharp, right lower quadrant pain after waking up this morning. The pain has increased despite taking acetaminophen, and now she has persistent vomiting. The patient has been undergoing clomiphene ovulation induction due to anovulatory infertility, and her last menstrual period was 5 weeks ago. She has no medical conditions and has had no surgeries. Temperature is 37.8 C (100 F), blood pressure is 140/80 mm Hg, and pulse is 92/min. Abdominal examination shows tenderness over the right lower quadrant with guarding and rebound tenderness. On bimanual examination, there is tenderness in the right adnexa but no palpable masses or cervical motion tenderness. Hemoglobin level is 13 g/dL and leukocyte count is 16,000/mm³. Quantitative β-hCG is 2,840 mIU/mL. A transvaginal pelvic ultrasound shows a singleton gestation within the uterine cavity and normal bilateral adnexa with normal Doppler flow. Which of the following is the most likely diagnosis in this patient?

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11ec25c8_d19f_5667_bc81_653f6370535a_MD0003_00 In women, right adnexal tenderness can have a variety of etiologies (eg, gastrointestinal, gynecologic, obstetric) due to the proximity of anatomic structures. In women with a positive pregnancy test, initial evaluation is to determine pregnancy location (ie, intrauterine or ectopic pregnancy). This patient has an intrauterine pregnancy with normal adnexa and normal Doppler flow, which eliminates most obstetric and gynecologic emergencies. The patient's right adnexal tenderness in the presence of a normal first-trimester ultrasound is most likely due to acute appendicitis. Additional clinical features include nausea, vomiting, right lower quadrant pain, and peritoneal signs (eg, rebound, guarding) because the inflamed appendix irritates the surrounding bowel and peritoneum. Diagnosis is primarily clinical but can be confirmed with imaging. In pregnant women, a graded compression abdominal ultrasound (rather than a CT scan) is typically performed because it provides no fetal radiation exposure. Treatment is with appendectomy. (Choice B) Ectopic pregnancy can present with right lower quadrant pain and adnexal tenderness; however, patients typically have increased Doppler flow (ie, "ring of fire") around the ectopic pregnancy. This patient's pelvic ultrasound shows an intrauterine pregnancy and adnexa with normal Doppler flow. "ring of fire" (Choice C) Hyperemesis gravidarum is severe nausea and vomiting during pregnancy. Patients can develop epigastric pain due to persistent vomiting, but hyperemesis gravidarum is not associated with right lower quadrant pain. (Choice D) Ovarian hyperstimulation syndrome is an exaggerated, abnormal response to ovulation induction (eg, clomiphene) caused by overexpression of vascular endothelial growth factor (VEGF) in the ovaries. VEGF overexpression results in bilaterally enlarged, cystic ovaries with increased vascular permeability (eg, increased Doppler flow), which causes third spacing (eg, ascites, pulmonary edema). (Choice E) Ovarian torsion typically presents with sudden-onset, severe, unilateral lower abdominal pain and may have associated nausea and vomiting. Pelvic ultrasound shows an enlarged ovary with decreased or absent Doppler flow, not seen in this patient. Educational objective: Acute appendicitis can present with right adnexal tenderness and may mimic obstetric or gynecologic conditions. Patients with acute appendicitis typically have fever, nausea, vomiting, peritoneal signs, and normal adnexa on pelvic ultrasound. References: Acute appendicitis during pregnancy: different from the nonpregnant state? (http://www.ncbi.nlm.nih.gov/pubmed/27730353)

A 37-Year-Old Woman Comes to the Emergency Department Due to Vomiting