isthmic pregnancy

medicine

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Last updated

June 17, 2026

Quick Summary

An isthmic pregnancy is a specific type of ectopic pregnancy, a serious medical condition where a fertilized egg implants outside the main cavity of the uterus. In an isthmic pregnancy, the implantation occurs in the narrow section of the fallopian tube closest to the uterus.12

This location is problematic because the narrow tube cannot expand. As a result, rupture of the fallopian tube and severe internal bleeding often occur early in the pregnancy, typically within eight weeks of conception. Ectopic pregnancies, including isthmic ones, are a significant cause of maternal illness and death during the first trimester of pregnancy. Prompt surgical intervention is usually required for treatment.21

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pregnancy
Ectopic pregnancy
An isthmic pregnancy differs from one in the ampulla or infundibulum because the narrow tube cannot expand. Rupture of the affected tube with profuse intra-abdominal hemorrhage occurs early, usually within eight weeks after conception.
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An isthmic pregnancy differs from one in the ampulla or infundibulum because the narrow tube cannot expand. Rupture of the affected tube with profuse intra-abdominal hemorrhage occurs early, usually within eight weeks after conception.
Read More