The Diameter of the Uterine Isthmus During the Menstrual Cycle, Pregnancy and the Puerperium

Abstract

Summary The diameter of the uterine isthmus was measured in 188 patients under different physiological conditions. It was found that measurements were reproducible with a low mean coefficient of variation (3 per cent). In the non‐pregnant patient the highest measurements were recorded during the menstrual period and the lowest in the preceding week. The isthmic diameter increased during the first trimester of pregnancy when it was slightly greater in parous than in nulliparous patients. Even 9 to 12 weeks after delivery, the diameter of the isthmus had not fallen to the size recorded in parous patients more than four months postpartum.

Risk of Damage to the Cervix by Dilatation for First-Trimester-Induced Abortion by Suction Aspiration

“…It has been demonstrated that dilatation for induced abortion may cause remaining alterations of the internal os of the cervix. Johnstone et al [21 ] found a more dilated cervix at a six-week follow-up in patients dilated to more than 10 mm, than in patients less dilated; and Bergman and Svennerud [22], using a trac tion test, showed that patients with a history of consecu tive abortions had a wider internal cervical os than patients with full-time pregnancies. A wide cervical canal has also been associated with the clinical diagnosis of cer vical incompetence [23,24].…”