A 28-year-old woman presents to the emergency department with acute lower abdominal pain and vaginal bleeding for 2 days. She reports a missed period 6 weeks ago. Vital signs: BP 100/62 mmHg, HR 110/min, RR 20/min. On examination, she is pale, with severe left lower quadrant tenderness and cervical motion tenderness. Urine pregnancy test is positive. Transvaginal ultrasound shows an empty uterus with free fluid in the pouch of Douglas. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Ruptured Ectopic Pregnancy ### Key Clinical Features **Key Point:** The constellation of positive pregnancy test, empty uterus on ultrasound, free intra-abdominal fluid, and haemodynamic instability (tachycardia, hypotension) with acute pain is pathognomonic for ruptured ectopic pregnancy. ### Diagnostic Criteria Met | Feature | Finding | Significance | |---------|---------|---------------| | Pregnancy status | Positive urine hCG | Confirms pregnancy | | Uterine cavity | Empty on TVS | Rules out intrauterine pregnancy | | Free fluid | Present in POD | Indicates rupture and haemoperitoneum | | Haemodynamics | BP 100/62, HR 110 | Signs of hypovolaemic shock | | Peritoneal signs | Severe tenderness, CMT | Acute peritonitis from bleeding | ### Pathophysiology of Rupture 1. Embryo implants in fallopian tube (most common site: ampulla) 2. Trophoblast erodes tubal wall 3. Rupture occurs (typically 8–12 weeks gestation) 4. Massive intra-abdominal haemorrhage ensues 5. Shock develops if >2 L blood loss **High-Yield:** The **empty uterus + positive pregnancy test + free fluid** triad is diagnostic. No need to wait for serial hCG or repeat ultrasound in a haemodynamically unstable patient — proceed to emergency laparotomy. ### Clinical Pearl Ruptured ectopic pregnancy is a **surgical emergency**. Mortality is 1–2% if treated promptly; rises to 5–10% if diagnosis is delayed. The patient requires immediate IV access, cross-matched blood, and surgical intervention (salpingostomy or salpingectomy depending on contralateral tube status). ### Risk Factors for Ectopic Pregnancy **Mnemonic: PID-STIR** - **P**revious ectopic pregnancy - **I**ntrauterine device (IUD) - **D**iethylstilbestrol (DES) exposure - **S**urgery (tubal, pelvic) - **T**ubal pathology (endometriosis, adhesions) - **I**nfection (PID, STIs) - **R**everse peristalsis / abnormal tubal motility [cite:Williams Obstetrics 26e Ch 19]