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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Classic triad: amenorrhea, vaginal bleeding, and unilateral pelvic pain, though presentation is often incomplete
- Risk factors include prior ectopic pregnancy, PID, tubal surgery, infertility treatment, smoking, and pregnancy with IUD in place
- Diagnosis relies on transvaginal ultrasound plus serial quantitative beta-hCG
- Hemodynamic instability or suspected rupture = immediate surgical management
- Stable unruptured ectopic pregnancy may be treated with methotrexate if criteria and follow-up are appropriate
Overview
Ectopic pregnancy is implantation outside the endometrial cavity. Most are tubal, especially ampullary. It is a leading cause of first-trimester maternal morbidity and can rapidly become fatal if rupture causes hemoperitoneum. Any reproductive-age patient with abdominal pain, vaginal bleeding, syncope, or shock needs pregnancy testing.
Epidemiology
Ectopic pregnancy occurs in about 1-2% of pregnancies. Tubal damage from PID, prior ectopic pregnancy, endometriosis, tubal surgery, and assisted reproduction increases risk. A pregnancy occurring with an IUD in place is uncommon but has a higher probability of being ectopic.
Clinical Features
Symptoms
Missed period or positive pregnancy test
Unilateral pelvic or lower abdominal pain
Vaginal spotting or first-trimester bleeding
Shoulder tip pain from diaphragmatic irritation due to hemoperitoneum
Dizziness, syncope, or severe pain suggests rupture
Signs
Adnexal tenderness or cervical motion tenderness
Adnexal mass on examination or ultrasound
Peritoneal signs, guarding, or rebound tenderness
Tachycardia or hypotension from intraperitoneal hemorrhage
Uterus smaller than expected for gestational age
Investigations
First-line
Pregnancy testAll reproductive-age patients with pelvic pain or bleeding need urine or serum beta-hCG
Quantitative beta-hCGSerial 48-hour values help distinguish viable IUP, failing pregnancy, and ectopic pregnancy
Transvaginal ultrasoundLook for intrauterine gestational sac/yolk sac/embryo, adnexal mass, and free fluid
Second-line
CBC and type/screenAssess anemia and prepare transfusion if bleeding or instability
Rh statusRh-negative unsensitized patients with bleeding or ectopic pregnancy require Rh(D) immune globulin
CMP/LFTs/creatinineRequired before methotrexate to assess safety
Specialist
Diagnostic laparoscopyUsed when rupture is suspected, diagnosis remains uncertain with high concern, or surgical treatment is required
Uterine aspirationMay distinguish failed IUP from ectopic pregnancy in selected stable pregnancy-of-unknown-location cases
1
Unstable or ruptured ectopic pregnancy
- Immediate OB/GYN consultation and operative management
- Large-bore IV access, fluids, blood products as needed, and type/crossmatch
- Laparoscopy if stable enough; laparotomy if unstable or massive hemoperitoneum
- Salpingectomy if tube is ruptured, severely damaged, or bleeding is uncontrolled
2
Medical management
- Methotrexate for stable, unruptured ectopic pregnancy with reliable follow-up
- Best candidates have low beta-hCG, no fetal cardiac activity, small ectopic mass, and minimal symptoms
- Monitor beta-hCG after treatment until negative
- Avoid folic acid supplements, NSAIDs, alcohol, intercourse, and pregnancy until treatment complete
3
Surgical management
- Indicated if methotrexate contraindicated, high beta-hCG, fetal cardiac activity, large mass, rupture, or failed medical therapy
- Salpingostomy may preserve tube but requires beta-hCG follow-up
- Salpingectomy if contralateral tube is normal or tube is ruptured/severely damaged
4
Supportive care
- Give Rh(D) immune globulin to Rh-negative unsensitized patients
- Counsel on recurrence risk and early ultrasound in future pregnancies
Complications
- Tubal rupture: Hemoperitoneum, shock, and maternal death without urgent treatment
- Persistent trophoblast: Can occur after salpingostomy or incomplete methotrexate response
- Recurrent ectopic pregnancy: Risk is increased after any ectopic pregnancy
- Infertility: Related to tubal disease or surgical loss of tube
- Rh alloimmunization: Preventable in Rh-negative unsensitized patients
USMLE Step 2 CK Exam Tips
- 1Unstable pregnant patient + abdominal pain + free fluid = ruptured ectopic → surgery
- 2Stable early pregnancy bleeding = quantitative beta-hCG + transvaginal ultrasound
- 3Methotrexate is only for stable, unruptured ectopic pregnancy with follow-up
- 4Pregnancy with IUD in place is ectopic until proven otherwise
- 5Shoulder pain suggests hemoperitoneum
- 6Rh-negative patient with ectopic pregnancy = Rh(D) immune globulin
- 7Do not wait for serial beta-hCG in an unstable patient
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