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.