Reproductive · Ectopic Pregnancy
The facts most likely to be tested
The classic clinical triad for ectopic pregnancy consists of abdominal pain, amenorrhea, and vaginal bleeding.
Hemodynamic instability (hypotension, tachycardia) in the setting of a positive pregnancy test is a surgical emergency requiring immediate laparotomy.
Transvaginal ultrasound is the diagnostic modality of choice to identify an adnexal mass or free fluid in the pouch of Douglas.
A discriminatory zone of beta-hCG > 1,500–2,000 mIU/mL is the threshold at which an intrauterine pregnancy should be visualized on ultrasound.
Methotrexate is the treatment of choice for hemodynamically stable patients who meet strict criteria, including a beta-hCG < 5,000 mIU/mL and no fetal cardiac activity.
Ruptured ectopic pregnancy is the most common cause of maternal mortality in the first trimester.
Salpingostomy or salpingectomy is indicated for patients who are hemodynamically unstable or have contraindications to methotrexate.
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A 26-year-old G1P0 woman presents to the emergency department with acute, severe right lower quadrant pain and dizziness. She reports her last menstrual period was 7 weeks ago. On physical exam, she is tachycardic at 118 bpm and hypotensive at 88/50 mmHg. Abdominal exam reveals diffuse tenderness and rebound guarding. A urine pregnancy test is positive.
What is the most appropriate next step in management?
Immediate surgical exploration (laparotomy)
The patient is hemodynamically unstable with a positive pregnancy test, indicating a ruptured ectopic pregnancy; immediate surgical intervention is required to control hemorrhage.
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Etiology / Epidemiology
Primary risk factors include prior ectopic pregnancy, tubal surgery, and PID. Most commonly occurs in the ampulla of the fallopian tube.
Clinical Manifestations
Classic triad: unilateral pelvic pain, vaginal bleeding, and amenorrhea. Rupture presents with acute abdomen and hemodynamic instability.
Diagnosis
Gold standard is transvaginal ultrasound showing an empty uterus with an adnexal mass. Serial beta-hCG failing to double every 48 hours is diagnostic.
Treatment
Ruptured cases require emergent surgical salpingectomy. Methotrexate is strictly contraindicated in ruptured cases.
Prognosis
High risk of infertility and recurrent ectopic pregnancy. Requires RhoGAM if patient is Rh-negative.
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Epidemiology & Etiology
Incidence is highest in patients with a history of tubal ligation, assisted reproductive technology, or smoking. Chlamydia trachomatis infection is a leading cause of tubal scarring. Prior ectopic pregnancy increases recurrence risk by 10-fold.
Pertinent Anatomy
The ampulla is the most common site of implantation due to its wide lumen. Implantation outside the uterine cavity leads to rapid expansion and eventual tubal rupture due to lack of distensible tissue.
Pathophysiology
Implantation occurs in the fallopian tube, causing local tissue erosion and vascular compromise. As the embryo grows, the tube reaches its limit, resulting in hemoperitoneum. This leads to hypovolemic shock and irritation of the diaphragm, causing referred shoulder pain.
Clinical Manifestations
Patients present with sudden-onset severe abdominal pain and syncope. Physical exam reveals cervical motion tenderness and a palpable adnexal mass. Peritoneal signs such as guarding and rebound tenderness indicate active intra-abdominal hemorrhage.
Diagnosis
Perform transvaginal ultrasound immediately to identify an adnexal mass or free fluid in the pouch of Douglas. A beta-hCG level above the discriminatory zone of 1,500–2,000 mIU/mL with an empty uterus confirms the diagnosis. Do not delay surgery for imaging if the patient is hemodynamically unstable.
Treatment
Hemodynamically unstable patients require emergent laparoscopy or laparotomy with salpingectomy. Methotrexate is only for stable, unruptured cases and is contraindicated in the presence of rupture, fetal cardiac activity, or high beta-hCG levels. Always administer RhoGAM to Rh-negative patients.
Prognosis
Patients face a significant risk of future infertility and a 10-15% risk of recurrent ectopic pregnancy. Post-treatment, serial beta-hCG monitoring is mandatory until levels reach undetectable to ensure complete resolution of trophoblastic tissue.
Differential Diagnosis
Appendicitis: localized RLQ pain without vaginal bleeding
Ovarian torsion: sudden onset, severe, intermittent pain, usually no bleeding
Ruptured ovarian cyst: sudden pain, often mid-cycle, no amenorrhea
Pelvic Inflammatory Disease: bilateral pain, fever, cervical discharge
Spontaneous abortion: vaginal bleeding with passage of tissue, uterus not empty