Discussion
Since the placenta covered the internal uterine ostium in the MRI image
at 30 weeks gestation, we diagnosed the patient with placenta previa
(Fig. 1a). The bladder, anterior, fundus, and posterior uterine walls
were located towards the front of the body (Figure 1b). This situation
was not predicted upon preoperative MRI. Intraoperative findings
revealed that the uterus was displaced, and the bilateral round
ligaments and oviducts were located in towards the front (Fig. 2). The
adhesions between the bladder and uterus may have resulted from
endometriosis. The patient demonstrated foci at the closed Douglas pouch
during the operation (Fig. 2 and 3). Endometriosis was observed only by
inspection and was not confirmed by pathological examination. However,
the diagnosis was assumed to be correct because there was no history of
pelvic inflammatory disease or abdominal surgery.
The obstetricians and radiologists
of the team retrospectively discussed the prenatal MRI during the
postpartum period; however, they could not detect the round ligament or
oviduct in the image because of the resolving limit. We investigated
whether there were other methods available to diagnose unusual uterine
positions.
Difficult Cesarean Sections
Visconti et al. reviewed difficult cesarean sections.1The article discussed “difficult” cesarean sections divided into four
categories: difficult access to the lower uterine segment, complicated
fetal extraction, laceration or organ damage, and abnormal placentation.
The “difficult access” category included leiomyomas, obesity, and
previous abdominal surgery, but not endometriosis. The article stated
that the degree of adhesions created after abdominal surgery varies
widely among individuals, making it impossible to predict. Therefore, if
we are unable to distinguish between endometriosis and postoperative
adhesions, adhesions caused by endometriosis are also considered
difficult to predict. Previous studies have reported several methods
that may predict intra-abdominal adhesions.
Abdominal Scar Characteristics
There are several reports on whether differences in the color and shape
of skin markers and striae gravidarum can predict intra-abdominal
adhesions in pregnant women who have had at least one prior surgery.
Prospective comparative studies have reported that factors related to
skin markers, such as scar color and length, are associated with
intra-abdominal adhesions.2-4 In contrast, Taylan et
al. denied the accuracy of predictions using these
methods,5 and Jaafer et al. demonstrated that these
markers are not clinically reliable.6
Sliding Sign
Reid et al. presented the ‘sliding sign’ technique to predict a closed
pouch of Douglas preoperatively.7,8 The technique
using transvaginal ultrasonography is well known as a non-invasive and
effective approach for detecting endometriotic adhesions in the pouch of
Douglas and deep infiltrating endometriosis. A negative ‘sliding sign’
was noted when the anterior rectosigmoid colon or the anterior rectum
was fixed to the posterior uterine fundus or retrocervix. Hudelist et
al. also concurred with these findings and deemed them
useful.9 Ichikawa et al. proposed a scoring system
that allowed for an accurate prediction of pelvic adhesion status and
may potentially be an indicator of postoperative adhesion and
infertility.10
However, all these examinations were performed in a non-pregnant state;
hence, it is doubtful whether they are useful for predicting adhesions
of the anterior wall of the uterus in pregnant women, as in this case.
Baron et al. examined the ‘sliding sign’ of the uterus under the inner
part of the fascia of the abdominal muscles during deep breathing in the
third trimester.11 They reported that it was useful
for predicting the presence or absence of intra-abdominal adhesions.
This method may be useful for this case; however, a report of 112
pregnant women in 2021 revealed low reproducibility of these
results.12
MRI
Some articles suggested that MRI cannot be used for definitive diagnosis
or endometriosis staging.13,14 Therefore, laparoscopy
remains the procedure of choice. MRI has a high sensitivity for the
diagnosis of ovarian endometriosis, but it has poor results in the
detection of other types of endometrioses, including intra-abdominal
adhesions. Randall et al. reported that the ‘sheargram,’ cine-MRI
technique depicts the amount of sliding between the abdominal contents
and the wall of the abdominal cavity during respiratory
cycles,15,16 but the results have yet to be
generalized.
In this case, MRI performed during pregnancy showed a raised bladder,
but no intra-abdominal adhesions. Therefore, we concluded that adhesions
are difficult to predict using MRI alone. Since our patient also had
adhesions in the pouch of Douglas, it may be possible that the ‘sliding
sign’ of the posterior fornix and adhesions between the abdominal wall
and uterus could be detected. However, a large clinical study of the
‘sliding sign’ technique does not exist and therefore should be a topic
for future research.
Fundal Uterine Incision
Kotsuji et al. reported a case of transverse fundal uterine incision in
2004,17 and a case series in 2014,18which showed that this procedure has the potential to avoid transection
of the placenta, preventing heavy bleeding and catastrophic fetal blood
loss. However, such a case is rare, and the actual risk of uterine
rupture and placenta accreta in subsequent pregnancies is unknown. In
our case, the anterior uterine wall adhered to the vesicouterine pouch.
We cut open the uterine corpus to create a classical incision, while
avoiding bladder damage; however, a transverse fundal uterine incision
was made, which may result in an increased risk of uterine rupture and
placenta accreta in subsequent pregnancies.
Endometriosis and Pregnancy Outcome
It has been demonstrated that women with a history of endometriosis have
an increased risk of obstetric complications, such as placenta previa,
preterm delivery, preterm premature rupture of membranes, and stillbirth
and the severity of endometriosis may have an adverse impact on
pregnancy outcomes.19-21 This case could be evaluated
as stage IV in the revised American Society for Reproductive Medicine
scoring system; the case has a high-risk for obstetrical
complications20 that may develop into placenta previa
and preterm delivery. Firm adhesion caused an atypical uterine incision.
Several methods for predicting intra-abdominal adhesions before surgery
have been reported, and it is necessary to use such procedures. However,
it is difficult to diagnose all
conditions in the abdominal cavity. Physicians should consider the
possibility of an unusual uterine incision in women with a history of
endometriosis, adenomyosis, or severe dysmenorrhea. It is also necessary
to share information with the surgical team in charge and prepare for
possible damage to the surrounding organs. Advances in and increased
utilization of assisted reproductive technology has resulted in an
increased rate of pregnancies with severe endometriosis, which means
that unexpected complications can occur during prenatal and delivery
periods.