Dr (Mrs.) V BAGRI BUCKTOWAR
Obstetrician and Gynaecologist
MBBS, MD, DGO, DPM, Dip USG.
ULTRASOUND IN RECURRENT PREGNANCY LOSS
Recurrent pregnancy loss (RPL)
Recurrent pregnancy loss (RPL) is defined as two or more
consecutive failed pregnancies documented by ultrasound or
histopathology. 1Most studies report that RPL affects about 1–2% of
women. About 50 percent of women with RPL have no clearly
defined aetiology.2
According to ESHRE guidelines, age is a key factor, and RPL is more
common in women above 40 years of age.3
The aetiology of recurrent pregnancy loss (RPL) is classified into:1
1. Genetic
2. Anatomic
3. Endocrine
4. Antiphospholipid antibody syndrome
5. Immunological
6. Environmental factors
ULTRASOUND PARAMETERS TO
DEFINE EARLY PREGNANCY FAILURE
1. Mean Gestation sac diameter (MGSD) of 20 mm & no yolk sac
2. MGSD of >25 mm & no embryo
3. Irregular gestational sac
4. Distended yolk sac > 7mm
5. Collapsed & echogenic yolk sac
6. Crown-rump length of 7 mm or more & no cardiac pulsations
7.Loss of a previously seen cardiac activity. Cardiac activity less than 85
beats per minute indicates poor prognosis
8. The MGSD-CRL ratio less than 5 mm are prone to first trimester
miscarriage
Figure 1: Transvaginal scan (TVS) image showing irregular gestation sac of
20mm& no yolk sac or embryo in a woman with eight weeks of amenorrhea.
Figure 2: TVS image showing distended yolk sac of 5mm, embryo of 1.1mm
CRL & no cardiac activity in a 39-year-old woman with 10 weeks amenorrhea
Figure 3: 2D USG image showing echogenic yolk sac& embryo
with no cardiac activity
Figure 4: 2D USG image showing embryo of 13mm CRL correlating to 7
weeks 4 days with no cardiac activity in a 42-year-old with 11 week
amenorrhea
Figure 5: TVS showing sac volume smaller than the embryo at 8
weeks amenorrhea
ANATOMIC/STRUCTURAL ANOMALIES
Anatomic/ Structural anomalies increase women’s risk and may
account for 10–50% of RPL.1
These include:
1. Congenital Mullerian Duct Anomalies
2. Acquired abnormalities like fibroids, polyps and synechiae
(Asherman syndrome)
Müllerian Duct Anomalies (MDA)
Prevalence of MDA in RPL is about 7% to 28%.5
Accurate MDA recognition & their classification according to European
Society of Human Reproduction and Embryology (ESHRE)6,
The American Society of Reproductive Medicine (ASRM)7 or Congenital
Uterine Malformation by Experts (CUME)8 is essential for effective &
efficient therapeutic planning to improve reproductive outcome.
Septate uterus is most commonly associated with first trimester
spontaneous abortion.1
This may be from abnormal endometrium & septal vascularity.
Septum is the tissue resulting in an internal indentation at the fundal
midline exceeding 50% of the uterine wall thickness.6
Figure 6: 3D Coronal rendered images of uterus showing normal fundal
contour but internal indentation dividing endometrial cavity into two.
A.Partial septate: septum above the internal os B.Complete septate:
Septum extends into cervix
Bicorporeal/bicornuate uterus
Bicorporeal/bicornuate uterus has a higher prevalence of cervical
incompetence.9
There is an abnormal external fundal contour; internal mid line
indentation divides the cavity into two endometrial cavities and
cervices.
Figure 7: Coronal images
of Bi-corporeal uterus
(ESHRE classification)
with abnormal external
fundal contour &internal
indentation.
The American Society of
Reproductive Medicine
(ASRM) classifies these as
A: Bicornuate & B: Uterine
didelphys
Hemi-uterus/ Unicornuate uterus
Hemi-uterus/ Unicornuate uterus has an abnormal configuration.
It is seen as a small, curved uterus which is located off-midline with a single
endometrial cavity & cervix.7
Figure 8 : Coronal images of right & left hemi-uterus
Figure 9: The International Federation of Gynecology and Obstetrics (FIGO) classification of
Submucous uterine fibroids.
A. Completely Intracavitary (Type 0) B. > 50% Intracavitary (Type 1) C. <50% Intracavitary (Type
2) D. Completely Intramural (type 4)
Acquired anatomical factors: These include Uterine fibroids,
endometrial polyps and uterine synechiae, which may be associated
with RPL.1
Uterine fibroids are reported in 8.2% of women with RPL.10
Ultrasound evaluation of the uterine cavity and classifying the
fibroids according to their growth into the endometrium (Fibroid
mapping) are important in the diagnosis & management of RPL.11
Submucosal fibroids deform the endometrial cavity and may affect
implantation & embryonic development.
Removal of submucosal fibroids reduces the chance of miscarriage.
Intra mural fibroids do not distort the uterine cavity & there is no
evidence that myomectomy may reduce the chances of an
abortion.10
Endometrial polyps
Endometrial polyps are benign nodular protrusions of the endometrial
surface. These have a higher prevalence in women with pregnancy loss.1
Figure 10: TVS & 3D rendered images of a homogenous echogenic polyp completely within the endometrial cavity &
showing a vascular pedicle on color flow.
Uterine synechiae
Uterine synechiae are seen as thin or thick strands of
tissue crossing the endometrium.
These are better seen when there is fluid in the
endometrial cavity.
Women with RPL are more likely to have uterine synechiae
because of curettage; the prevalence ranges from 0.5 to
28%.12
Pathophysiology in RPL is due to an abnormal functional
endometrium which may interfere with the invasion and
normal development of the placenta.
Fig 11 : Uterine Synechiae.
A: TVS: thin endometrium &linear hypoechoic scar
B. Thick bands distorting endometrium
C. Mild adhesions
D. Extensive Dense adhesions completely distorting the endometrial cavity.
E. Synechiae seen better with fluid in the endometrial cavity
Chronic endometritis
Chronic endometritis refers to inflammation or infection involving the
endometrium. This has a prevalence of 12-13% in RPL.13
Figure 12: A: Thick, heterogeneous endometrium; increased vascularity on color flow B: Loss
of normal myometrial endometrial interface C: Intra uterine air D: Intracavitary fluid E: Fluid
in the pouch of Douglas
Cervical incompetence is painless cervical dilatation in the absence of
uterine contractions due to a functional or structural defect resulting in a
second-trimester miscarriage.
This may be due to embryological maldevelopment of the Müllerian ducts
or acquired from cervical trauma.
TVS is modality of choice for assessment.1
Figure 13: Cervical incompetence A. Short cervical length < 25mm and widening of internal os
B. Complete bulging giving an hour glassappearance.
CERVICAL INCOMPETENCE
CONCLUSION
Ultrasonography has a significant role in detecting abnormal uterine morphology as a
cause for RPL.
1st trimester U/S parameters are useful diagnostic tool to prognosis pregnancy
outcome among patients
with history of recurrent 1st trimester pregnancy loss.
The introduction of pulsed Doppler ultrasonography has provided non-invasive
means for the evaluation of uterine impedance, and gives physiologic data, rather
than anatomic information alone.
The use of transvaginal Doppler ultrasonography is proposed to detect impaired
uterine perfusion as a screening test for women with RPL.
Further studies will elucidate the mechanism of pregnancy loss associated with
impaired uterine perfusion.
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14, ESHRE GUIDELINES 2022