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

OB TRIAD

Cervical    Insufficiency

Cervical insufficiency (or cervical incompetency) has been used to describe the
inability of the uterine cervix to retain a pregnancy to viability in the absence of
contractions or labor.

Causes of cervical insufficiency include trauma from rapid forceful cervical
dilation associated with second trimester abortion procedures, cervical laceration
from rapid delivery, injury from deep cervical conization, and congenital
weakness from diethylstilbestrol (DES) exposure.

Diagnosis. Studies show the benefit of elective cervical cerclage with a history
of ≥1 unexplained second-trimester pregnancy losses. However, the benefit of
cervical cerclage placement is unclear in the following situations: sonographic
findings of a short cervix or funneling, history of cervical surgery, DES

Pregnant    18–22   weeks

Painless    cervical    dilation

Delivery    of  previable   fetus

In  the past,   a   diagnosis   was made    on  the basis   of  a   history of  painless    cervical

dilation    after   the first   trimester   with    expulsion   of  a   previable   living  fetus.

Recent  studies using   U/S to  examine cervical    length  suggest that    cervical

function    is  not an  all-or-none phenomenon, but may be  a   continuous  variable

with    a   range   of  degrees of  competency  that    may be  expressed   differently in

subsequent  pregnancies.