ectopic

Ectopic is a term used in biology and medicine to describe tissue or growth occurring in an abnormal location, outside its normal site. It derives from the Greek ektopos, meaning out of place.

The most familiar use is ectopic pregnancy, in which a fertilized egg implants outside the uterine cavity, most often in a fallopian tube. Less commonly, implantation may occur in the abdomen, ovary, or cervix. Ectopic pregnancy can be life-threatening if rupture occurs, causing internal bleeding.

Risk factors for ectopic pregnancy include prior tubal disease, previous ectopic pregnancy, pelvic inflammatory disease, infertility treatments, and smoking. Symptoms typically include abdominal pain with or without vaginal bleeding; dizziness or fainting may occur with rupture. Diagnosis relies on clinical assessment, serial measurements of human chorionic gonadotropin (hCG), and imaging such as transvaginal ultrasound. Treatment depends on location, stability, and size: methotrexate can terminate small, unruptured ectopic pregnancies; surgical intervention may be required for rupture or nonresponse, with options such as salpingostomy or salpingectomy. Serial hCG monitoring is used to confirm resolution.

Beyond pregnancy, ectopic can describe tissue or cells located in an abnormal place, a phenomenon known as heterotopia. Examples include ectopic thyroid tissue, such as a lingual thyroid at the base of the tongue; ectopic gastric mucosa in Meckel’s diverticulum; and ectopic pancreatic tissue. In cardiology, ectopic beats arise from an abnormal focus in the atria or ventricles rather than the normal sinoatrial node. In genetics and cell biology, ectopic expression refers to gene expression in an unusual tissue or developmental stage.