From the Guidelines
The pathophysiology of ectopic pregnancy involves implantation of a fertilized egg outside the uterine cavity, most commonly in the fallopian tube, due to factors such as damage to the fallopian tube epithelium from previous pelvic inflammatory disease, prior surgery, endometriosis, or smoking, as reported in the most recent study 1. The primary mechanism involves damage to the fallopian tube epithelium, which creates an environment where the blastocyst can implant in the tube's damaged mucosa.
- Once implanted, the developing embryo causes progressive distension of the fallopian tube, which lacks the expansile capacity of the uterus.
- As the pregnancy grows, it erodes into adjacent blood vessels, causing internal bleeding.
- The tube may eventually rupture, leading to significant hemorrhage and a surgical emergency. Other less common implantation sites include the ovary, cervix, abdominal cavity, and cesarean section scars, each with unique pathophysiological considerations.
- Hormonal factors and altered embryo-tubal transport may also contribute to ectopic implantation. Early diagnosis is critical as ruptured ectopic pregnancy remains a leading cause of first-trimester maternal mortality, as emphasized in the study 1. The location of a pregnancy is divided into normal, abnormal, and unknown, with lexicon terms and definitions provided in the study 1 and 1, which helps differentiate pregnancies that are temporarily located in the lower uterine segment. However, the most recent and highest quality study 1 provides the most accurate and up-to-date information on the pathophysiology of ectopic pregnancy.
From the Research
Pathophysiology of Ectopic Pregnancy
- Ectopic pregnancy occurs when a fertilized ovum implants outside of the uterine cavity, with the majority of cases implanting in a fallopian tube 2.
- Risk factors for ectopic pregnancy include a history of pelvic inflammatory disease, cigarette smoking, fallopian tube surgery, previous ectopic pregnancy, and infertility 3.
- The implantation of the fertilized ovum outside the uterine cavity can lead to acute complications such as rupture of the fallopian tube or rupture of ectopic pregnancy, hemorrhage, and hypovolaemic shock 2.
Diagnosis of Ectopic Pregnancy
- The definitive diagnosis of ectopic pregnancy can be made with ultrasound visualization of a yolk sac and/or embryo in the adnexa 3.
- However, most ectopic pregnancies do not reach this stage, and diagnosis is often made through a combination of patient symptoms, serial ultrasonography, and trends in beta human chorionic gonadotropin levels 3.
- Pregnancy of unknown location refers to a transient state in which a pregnancy test is positive but ultrasonography shows neither intrauterine nor ectopic pregnancy, and serial beta human chorionic gonadotropin levels, serial ultrasonography, and uterine aspiration can be used to arrive at a definitive diagnosis 3.
Treatment of Ectopic Pregnancy
- Treatment options for ectopic pregnancy include medical management with intramuscular methotrexate, surgical management via salpingostomy or salpingectomy, and expectant management 3, 4, 5, 6.
- The choice of treatment depends on various factors, including the patient's symptoms, the size and location of the ectopic pregnancy, and the patient's desire to preserve fertility 4, 5, 6.
- Systemic methotrexate and laparoscopic salpingostomy have been shown to be effective in treating ectopic pregnancy, with no significant difference in homolateral patency rate between the two treatments 5.
- A meta-analysis found that laparoscopic surgery is the most cost-effective treatment for tubal ectopic pregnancy, while systemic methotrexate is a good alternative in selected patients with low serum hCG concentrations 6.