Key words
bladder injury - placental implantation abnormality - placenta percreta - urinary
system injury
Schlüsselwörter
Blasenverletzung - plazentare Implantationsstörung - Placenta percreta - Verletzung
des Urogenitalsystems
Introduction
Placenta percreta is a placental adhesive disorder defined by abnormal trophoblastic
invasion through the uterine serosa layer and potentially beyond [1]. The reported incidence is approximately 5 – 7% of pregnancies with placental adhesive
disorders [2]. Increased cesarean section (CS) rates may be one reason for this high incidence.
Previous cesarean delivery is the most important risk factor, followed by placenta
previa and advanced maternal age [3]. Antenatal diagnosis is helpful to reduce intraoperative urologic complications
and the need for blood transfusions [4]. Sonographic and color Doppler examination is generally accepted as the first choice
of imaging method for the diagnosis of placental adhesive disorders [5]. In addition to the risk of severe hemorrhage, there is also a risk of unintentional
urinary tract (UT) injury, which may result in urinary fistula, ureteral transection,
and bladder laceration necessitating partial or total cystectomy [6]. To date, there is no prospective randomized study in the English literature on
the effect of filling the bladder during the surgical management of placenta percreta
for the prevention of genitourinary system complications.
The aim of our study was to evaluate the effect of filling the bladder on peripartum
genitourinary injuries (especially bladder complications) in women with placenta percreta
who underwent planned cesarean hysterectomy and to compare patient characteristics.
Patients and Methods
Study design
This prospective cohort study included pregnant women with placenta percreta who underwent
CS at the Department of Obstetrics and Gynecology of Gaziantep University Hospital
between January 2015 and August 2017. All women included in the study gave their written
informed consent.
Diagnostic features of Doppler ultrasonography
Patients were diagnosed by Doppler ultrasonography ([Fig. 1]) in the antenatal period, and the diagnosis was confirmed during surgery performed
by the same clinicians. Turbulent flow, the presence of lacunae, increased vascularity
at the bladder–placenta border, and damage to myometrial integrity are the standard
diagnostic criteria in ultrasonography ([Fig. 1]).
Fig. 1 a Ultrasonographic image of placenta percreta in a 35-week-old pregnancy. Lacunar structures
are indicated by arrows. Note the thin border between uterus and bladder (pl = placenta,
cx = cervix, bl = bladder); b Doppler ultrasonography image of the same patient with increased vascularity at the
vesicouterine junction and lacunar structures.
Surgical characteristics
All specimens obtained were sent for pathological examination. Placenta percreta is
defined as the penetration of trophoblastic tissue into all layers of the uterus.
All operations were performed under general anesthesia in the dorsal lithotomy position.
We included only cases with placenta percreta in whom we performed planned cesarean
hysterectomy between the 34th and 36th week of gestation. The decision of the surgeons
regarding the appropriate surgical approach for cesarean hysterectomy depended on
the severity of disease. Their assessment was based on the presence of increased vascularity
in the lower uterine segment/bladder zone and the extent of invasion of the uterine
artery.
Bladder filling as a method to determine the vesicouterine border
Patients were randomized either into the filled-bladder or the not filled-bladder
group. The first step in all surgeries was a midline periumbilical incision. The infant
was delivered through a fundal vertical uterine incision. The bladder was filled with
300 ml saline (this surgical technique was first defined by the head gynecologic oncologist
Prof. Dr. Ozcan Balat) to help determine the borders better and enable dissection
of the lower uterine segment without excessive bleeding or unintended injury ([Fig. 2]). At the end of the surgical procedure we filled the bladder of all patients with
diluted methylene blue to check for the presence of any missed bladder injuries.
Fig. 2 Intraoperative image of placenta percreta in which the bladder was filled with 300 ml
saline (asterisk, arrows, and plus sign indicate the uterus, vesicouterine border
and bladder, respectively).
Multidisciplinary approach to surgical management
Bladder complications without ureter involvement were treated by the obstetrician
alone or a consulting urologist. A urologist was consulted when patients experienced
complications that included ureter involvement. All patients with bladder injuries
received antibiotic prophylaxis (cefazolin sodium 1 g 2 × 1 i. v.). All patients were
managed by a multidisciplinary approach which included an obstetrician, a gynecological
oncologist, an anesthetist, an intensive care physician, and a urologist. The same
surgical team carried out all operations. The surgical team that participated in this
study has the skills to treat the retroperitoneal space, bladder, and ureter, and
are experienced in the surgical management of placenta percreta. We planned to prospectively
include women into the study for 20 months. The Institutional Ethics Committee approved
our study.
Statistical analysis
Normality of distribution of continuous variables was tested with the Shapiro-Wilk
test. Studentʼs t-test was used to compare two independent groups of normally distributed
variables. χ2 test was used to assess the relationships between categorical variables. Statistical
analysis was performed using SPSS for Windows, version 11.5®. A p-value < 0.05 was considered statistically significant.
Results
Patient characteristics
A total of 66 women were included in the study: 32 women whose bladders were filled
with saline before surgery (filled-bladder group) and 34 women whose bladders were
not filled before surgery (not filled-bladder group). The mean age of all women was
32.62 ± 4.49 years (range: 23 – 41 years). Mean body mass index (kg/m2) was 28.38 ± 1.52 (range: 25 – 31). Parity, gravidity and gestational age (weeks)
at surgery were 3.41 ± 1.12 (range: 1 – 7), 4.86 ± 1.65 (range: 2 – 10) and 35.35 ± 3.27
(range: 22 – 40), respectively. Six women (9.1%) had had 2 previous cesarean sections
and 60 women (90.9%) had had > 3 previous CS.
Operative outcomes
Mean preoperative and postoperative hemoglobin levels of women were 10.91 ± 1.63 g/dl
(range: 5.2 – 13.7) and 10.47 ± 1.69 g/dl (range: 2.4 – 13.8), respectively. Erythrocyte
suspensions and fresh frozen plasma replacements of 2.97 ± 1.93 units (range: 0 – 8)
and 2.58 ± 1.82 units (range: 0 – 7) were transfused, respectively. The mean operation
time was 91.36 ± 33.78 minutes (range: 60 – 210). The mean length of hospital stay
for all women was 5.09 ± 4.22 days (range: 1 – 19).
Influence of bladder filling on outcomes
Comparisons of demographic, obstetrical and surgical data, the need for transfusion
and bladder injury rates for the two groups (filled-bladder group vs. not filled-bladder
group) revealed no significant differences. Data are shown in [Table 1]. We did not observe any effect of filling the bladder on intraoperative or postoperative
complications when compared with cases whose bladders were not filled (p = 0.339).
The complications reported for the women in our study, listed from the most common
to the least common, were bladder injury (69.2%), pelvic hematoma leading to re-laparotomy
(15.3%), ureteral injury (3.8%), external iliac vein injury (3.8%), pelvic hematoma
follow-up (3.8%), and ileus (3.8%) ([Table 2]).
Table 1 Comparison of patient groups with filled and unfilled bladders.
|
|
Filled bladder (n = 32)
|
Not filled bladder (n = 34)
|
p
|
|
* mean ± SD
|
|
Maternal characteristics
|
|
|
|
|
|
32.31 ± 4.25
|
32.91 ± 4.74
|
0.591
|
|
|
28.28 ± 1.53
|
28.47 ± 1.52
|
0.616
|
|
|
4.66 ± 1.15
|
5.06 ± 1.69
|
0.265
|
|
|
3.34 ± 0.97
|
3.47 ± 1.26
|
0.650
|
|
|
3.25 ± 0.8
|
3.15 ± 0.66
|
0.570
|
|
|
35.5 ± 2.72
|
35.47 ± 4.06
|
0.973
|
|
|
85.31 ± 35.01
|
97.06 ± 32.05
|
0.160
|
|
Postoperative stay in hospital (days)*
|
4.97 ± 3.86
|
5.21 ± 4.59
|
0.822
|
|
ICU admission, n (%)
|
8 (25)
|
8 (23.5)
|
0.889
|
|
Blood transfusion (units)*
|
|
|
|
|
|
2.97 ± 2.09
|
2.97 ± 1.82
|
0.997
|
|
|
2.47 ± 1.83
|
2.68 ± 1.84
|
0.647
|
|
Bladder injury, n (%)
|
7 (21.9)
|
11 (32.4)
|
0.339
|
Table 2 Number and percentage of intraoperative complications.
|
|
Filled bladder (%)
|
Not filled bladder (%)
|
|
Intraoperative complication
|
|
|
|
|
7 (21.9)
|
11 (32.4)
|
|
|
1 (3.1)
|
0
|
|
|
0
|
1 (2.9)
|
|
Postoperative complication
|
|
|
|
|
1 (3.1)
|
0
|
|
|
2 (6.3)
|
2 (5.9)
|
|
|
0
|
1 (2.9)
|
Discussion
The incidence of placental invasion abnormalities is increasing and presents surgical
and diagnostic challenges for obstetricians. Our hospital is the biggest regional
tertiary referral center for complicated obstetrical surgery in southeastern Turkey.
The high rate of cases with placenta percreta can therefore be explained by the high
rates of referral. A history of multiple CS or placenta previa increases the risk
of placental invasion abnormalities [7]. A high number (> 3) of previous cesarean sections is an obvious risk factor for
complications; in addition, the complication rate for patients with placenta percreta
is much higher due to deep placental and vascular infiltration.
We did not detect any significant difference in the number of previous CS on the presence
or absence of complications. Given the high morbidity and mortality rates associated
with placental adhesive disorders, antenatal diagnosis improves the outcome [8]. The sensitivity and specificity for a diagnosis of placental invasion abnormalities
diagnosed using ultrasound is 80 – 90% in specialized centers [9], but these rates are likely to be much lower for standard providers of obstetrical
care. In our study, we did not include the records of patients with a false-positive
diagnosis of placenta percreta based on antenatal ultrasonography examination. Analysis
of the sensitivity and specificity of ultrasonography is therefore beyond the scope
of our study. Poor access to ultrasound and limited experience on the part of the
obstetrician are factors reducing the likelihood of making an antenatal diagnosis.
Turbulent flow and the presence of lacunae, increased vascularity at the bladder-placenta
border, and damage to myometrial integrity are the standard diagnostic criteria in
ultrasonography [10]. A planned hysterectomy carried out by an experienced team is the recommended procedure
for the management of placental adhesive disorders [11]. Segment resection of the lower uterine segment, hysterectomy, or leaving the placenta
in situ to be resorbed are alternative approaches for the management of placental
invasion anomalies [12]. In most patients with placenta percreta aggressive treatment is a must. Massive
blood transfusions, urological injuries, and infections are major issues in this complicated
treatment [13].
Massive and/or persistent hemorrhage, bladder injury, ureteral damage, and bowel injury
are the most common complications resulting in admission to the intensive care unit
[14]. Eller et al., reporting on 76 cases, found that blood transfusion was required
in more than 80% of cases [15]. This rate is comparable with the figures in our study (91%). Maternal and prenatal
fetal deaths from massive hemorrhage are the worst scenarios in women with placenta
percreta. There was one maternal death in our study (1.5%). Bladder injury, ureteral
dilation, ureteral transection, and fistula between the bladder and cervix are known
urological complications of placenta percreta [16].
The incidence of unintentional genitourinary injuries with placental adhesive disorders
is reported to be as high as 29% [17]. Bladder injury is the most common surgical complication in cases with adhesive
placental disorders and this finding is related to the uncertain borders between the
bladder and the adhesive tissue that occur as a result of placental invasion [18]. Ureteral injury rates can vary from 10 to 15% [17]. There are many reports in the literature aiming to decrease these serious urological
complications. Preserving the bladder border is an important step in the surgical
approach to treat invasive placental disorders. Additional procedures such as filling
the bladder with saline, administering intravenous dye, or instilling sterilized milk
are used to preserve the bladder or determine bladder injury [19]. In our study, bladder and ureteral injury rates were 27.2 and 1.5%, respectively.
The enormously increased risk of bladder injury in placenta percreta cases became
much more obvious when we retrospectively analyzed the rate of bladder injuries after
normal CS in our clinic, which was around 0.26% (12/4801) over a period of five years.
In the majority of placental adhesive disorders, the placenta invades the lower uterine
segment and/or the cervix. There are a number of approaches to treat placental invasive
disorders. The treatment of choice is primarily surgical and consists of hysterectomy
[18]. Results of a questionnaire study issued to members of the Society of Perinatal
Obstetricians stated that 93% of cases with placenta percreta were managed by total
hysterectomy [20]. In line with this finding we preferred total hysterectomy as the surgery of choice
for all hysterectomies in our study.
Maternal morbidity is a significant problem for women with placenta percreta. Urinary
tract injury is more common during hysterectomies for placental invasive disorders
than for hysterectomies performed for gynecological reasons (29 vs. 4.8%) [21]. Performing different types of procedures can prevent inadvertent genitourinary
injuries. Subtotal hysterectomy, delayed hysterectomy, and placing ureteric catheters
before CS are the most significant surgical approaches [22]. We used a specific surgical approach in our study that involved both filling the
bladder with saline and mobilization of the bladder following delivery of the fetus.
Statistical analysis revealed that, on average, 14.3 women would have to undergo filling
of their bladder (rather than no filling) to prevent one additional patient suffering
an additional bladder injury. It is imperative on any obstetric surgeon treating placenta
percreta to develop an individualized protocol that includes management of maternal
hemorrhage. The most important step is detecting pregnant women at risk for placenta
percreta and directing them to appropriate centers in case of emergency. There is
also an evident need to define the most appropriate surgical techniques and approaches.
Our study is just another such step.
As far as we know, our study is the largest prospective study in the English literature
on filling the bladder as a surgical approach in the management of placenta percreta.
The limitations of our study include the relatively small number of women treated,
given the fact that the number needed to treat to prevent further bladder injury is
14.3. Because of the absence of conclusive data, the big question remains on to how
to choose the appropriate surgical approach for a specific placental invasive disorder.
Conclusion
Filling the bladder with saline and mobilization of the bladder from the lower uterine
segment did not have a statistically significant beneficial effect on preventing complications
of the urinary system (especially of the bladder). But although the results were not
significant, shorter operation times, shorter postoperative stays in hospital, and
fewer bladder injuries were observed in patients whose bladders were filled prior
to surgery. Depending on his or her surgical experience, the surgeon may prefer to
fill the bladder prior to surgery, and this approach may be considered, especially
in cases with placenta percreta where anatomical landmarks are unclear.
Funding
Our study did not receive any funding.
