USMLE Step 2 CK Lecture Notes 2019: Obstetrics/Gynecology (Kaplan Test Prep)

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FAILURE TO DISSOLVE SEPTUM


Septate Uterus


A septate uterus results from a problem in stage 2 or 3 of uterine development.
The two Müllerian ducts fuse normally; however, there is a failure in
degeneration of the median septum.


Because this uterine anomaly occurs later in uterine development after complete
duct fusion, the external shape of the uterus is a normal-appearing single unit.
This is distinct from the bicornuate uterus, which can be seen branching into 2
distinct horns when viewed from the outside.


Preterm delivery and malpresentation are common with pregnancy.


Arcuate Uterus


This type of uterus is essentially normal in shape with a small midline
indentation in the uterine fundus, which results from failure to dissolve the
median septum completely. It is given a distinct classification because it seems


If  the failure is  “complete,” a   median  septum  persists    in  the entire  uterus,
separating the uterine cavity into 2 single-horned uteri that share one cervix.
If the failure is “partial,” resorption of the lower part of the median septum
occurs in stage 2 but the top of the septum fails to dissolve in stage 3. Thus,
there is a single cervix and uterine cavity at the bottom, but at the top that
cavity divides into 2 distinct horns.
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