28-year-old female presents with sudden onset sharp left lower quadrant abdominal pain radiating to her left shoulder, rated 9/10. She states she 'feels like I'm going to pass out' and has vomited once. She reports her last menstrual period was approximately 7 weeks ago but thought it might have just been 'light and late.'

G2P1 — one prior vaginal delivery, one prior spontaneous abortion. History of chlamydial infection treated 3 years ago. Has an IUD in place, placed 2 years ago. She is not sure if she is pregnant but acknowledges she may have missed her period. Denies any recent intercourse changes. No other medical history or current medications.

BP 88/58 mmHg, HR 126 bpm, RR 22 breaths/min, Temp 36.7°C, SpO2 97% on room air. Patient is diaphoretic and pale. She reports the shoulder tip pain worsens when she lies flat. Two large-bore IVs placed immediately; 1L normal saline wide open.

Abdomen is rigid with diffuse tenderness, most severe in the left lower quadrant and suprapubic region. Rebound tenderness present throughout. Referred pain to the left shoulder strongly suggests free blood under the left hemidiaphragm (Kehr's sign). Pelvic exam deferred pending OB/GYN consult given hemodynamic instability. Patient is pale, anxious, and moving minimally. OR and blood bank notified.

Urine hCG: positive. Serum beta-hCG: 3,840 mIU/mL. Hemoglobin 8.2 g/dL (acutely low — patient presenting with hemorrhagic shock). Transvaginal ultrasound: no intrauterine gestational sac identified; heterogeneous left adnexal mass measuring 3.2cm; moderate free fluid in the pelvis and peritoneal cavity (hemoperitoneum). OB/GYN taking patient emergently to OR for exploratory laparoscopy.

Diagnose It — Archive Puzzle #11