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Original Research |
1 Department of Diagnostic Radiology, Singapore General Hospital, Outram Road,
Singapore 169608.
2 Department of Maternal and Fetal Medicine, KK Women's and Children's Hospital,
Singapore.
3 Department of Obstetrics and Gynaecology, KK Women's and Children's Hospital,
Singapore.
4 Department of Obstetrics and Gynaecology, Singapore General Hospital,
Singapore.
Received April 5, 2007;
accepted after revision May 18, 2007.
Address correspondence to K. H. Tay
(tay.kiang.hiong{at}sgh.com.sg).
Abstract
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MATERIALS AND METHODS. Over a 30-month period, 11 patients with placenta accreta or its variants underwent cesarean delivery after bilateral internal iliac artery occlusion balloon placement (study group). The intraoperative blood loss and transfusion volumes, immediate postoperative change in hemoglobin levels, duration of surgery, and length of ICU stay and hospitalization of this study group were compared with 14 similar patients who underwent cesarean delivery without occlusion balloon placement over a 36-month period (control group).
RESULTS. The mean intraoperative blood loss in the study group (2,011 mL; range, 400–5,000 mL) was 39.4% less than in the control group (3,316 mL; range, 1,000–4,000 mL) (p = 0.042). The mean volume of blood transfused was 52.1% less in the study group (1,058 mL; range, 0–3,600 mL) than in the control group (2,211 mL; range, 1,190–3,980 mL) (p = 0.005). There was no significant difference in the immediate postoperative change in hemoglobin levels (p = 0.44), length of hospitalization (p = 0.203), or ICU admission (p = 0.614). The duration of the surgery was significantly less in the study group (p = 0.046).
CONCLUSION. Perioperative internal iliac artery occlusion balloon placement is a safe and minimally invasive technique that reduces intraoperative blood loss and transfusion requirements in patients with placenta accreta and its variants undergoing cesarean delivery.
Keywords: balloon occlusion • cesarean delivery • internal iliac artery • placenta accreta
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Placenta accreta occurs in approximately one in 2,500 deliveries, with advanced maternal age cited as an independent risk factor [1]. Other risk factors include previous cesarean sections. Up to 88% of patients have concomitant placenta previa [2]. Placenta accreta is associated with massive blood loss at delivery [3], which is over and above the risk associated with placenta previa alone [4]. The majority of these patients will require cesarean delivery. Even so, large amounts (3,000 mL or more) of intraoperative blood loss are common [2, 5].
Many of the techniques that have been developed to contain intraoperative blood loss have focused on reducing pelvic circulation, primarily of the internal iliac arteries or their branches. This has been accomplished with varying success, either extraluminally (commonly ligation) or endovascularly by the use of occlusion balloons, embolization, or a combination of both.
We sought to evaluate the efficacy of perioperative endovascular occlusion balloon placement in reducing intraoperative blood loss during cesarean delivery for women with placenta accreta and its variants.
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All but one of the occlusion balloon placement procedures were performed by the same interventional radiologist. Two cases were performed in the operating theater. The rest were performed in the angiography suite. Patients underwent cesarean delivery in the operating theater immediately after balloon placement. The proximity between our main operating theaters and angiography suites allowed a smooth transition between occlusion balloon placement and subsequent cesarean surgery.
The technique involved bilateral femoral arterial punctures and insertion of 6-French vascular sheaths under local anesthesia. Over a 0.035-inch angled guidewire (Flow Directed Balloon Catheter, Cook), a 5-French cobra-shaped catheter (Cobra, Terumo) was used to cannulate the contralateral internal iliac artery. This was exchanged for a 5.5-French occlusion balloon catheter (Starterwire, Boston Scientific), which was positioned with its tip in the proximal portion of the contralateral internal iliac artery, just after the common iliac artery bifurcation. Once both balloon catheters were correctly positioned, a test volume of dilute water-soluble contrast material was injected to inflate the occlusion balloons to the optimal size. We found that 0.8 mL of contrast material was generally sufficient to occlude the arteries. The exact same volume was subsequently used to inflate the balloons, hence eliminating the need for additional fluoroscopic exposure during cesarean delivery. Once positioning was satisfactory, the catheters were securely taped to the skin.
The occlusion balloons were inflated at the time immediately after the baby was delivered, and the umbilical cord was clamped so as to minimize the risk of fetal ischemia. In those who underwent hysterectomy or had the placentas delivered, the balloons were deflated just before skin closure after ensuring that hemostasis within the pelvic cavity was secured. In those in whom the placentas were retained, the balloons were left inflated until embolization was performed. Arterial imaging for distal patency of the distal internal iliac arteries was not routinely performed.
The vascular sheaths were left in situ for 24 hours after surgery, with a view for emergency embolization in the event of severe postpartum hemorrhage. Slow continuous normal saline infusion (10 mL/h) through the sheaths was used to maintain patency of the sheaths without the use of heparin or anticoagulants. After removal of the sheaths, firm manual compression over the insertion site was performed for at least 20 minutes in all cases. No closure devices were used.
Among the study group, four patients underwent hysterectomy, two had the placentas delivered, and five had the placentas retained. In the last subgroup, the patients underwent uterine artery embolization with absorbable gelatin sponge in the angiography suite immediately after cesarean section in the operating theater.
The cases were compared with a similar group of patients with similar diagnoses from the same institutions over a preceding 3-year period from January 2001 to December 2003. The control group was composed of 14 patients. All patients (both study and control groups) had concomitant placenta previa and underwent elective cesarean sections.
The patients were compared in terms of intraoperative blood loss, which was the estimated amount of blood lost as recorded by the anesthetist, and the volume of packed cells transfused during surgery. The immediate preoperative and postoperative hemoglobin levels were also compared to provide a better reflection of the actual transfusion requirements in the patients. The statistical significance of these values was calculated using the Mann-Whitney U test.
Other variables that were studied include the duration of the cesarean surgery (not taking into account the duration of occlusion balloon placement), length of hospitalization after surgery, and the duration of ICU admission immediately after surgery. The fluoroscopy and angiography procedure times for the study group, which were available in eight patients, were also examined. The duration of arterial occlusion (time of delivery to time of skin closure) was retrospectively studied by reviewing the anesthesia records.
Further, comparisons of the same variables were performed for the patients within the study group. The differences between the intraoperative blood losses, volume of packed cells transfused, and change in hemoglobin levels were compared between the patients who had the placentas retained against those who did not. This comparison also applied to the patients who underwent immediate postoperative embolization of the uterine arteries because they were essentially the same.
All patients were examined by the interventional radiologist during hospitalization for complications of vascular access. The patients were also examined in the clinic by the referring obstetrician (maternal and fetal medicine specialist) at least once in the high-risk pregnancy clinic on discharge.
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Table 2 compares the blood loss parameters between the study and control groups. These include the mean estimated intraoperative blood and the mean volume of packed cells transfused during surgery. Both parameters were significantly lower in the study group when compared with the control group (p < 0.05). At the same time, there was no significant difference in the mean change in hemoglobin levels between the two groups.
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The mean duration of the cesarean surgery was significantly less in the study group (p < 0.05). There is no statistical difference in terms of the length of hospitalization after surgery and the duration of ICU admission immediately after surgery between the two groups (p > 0.05). These are shown in Table 3.
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The technique of leaving the placenta in situ was performed in five of our patients, with two of them developing severe postpartum hemorrhage. One of them required relaparotomy and total hysterectomy on postoperative day 3 after cesarean delivery. The other was managed conservatively and required 4 units of packed cells over two recurrent admissions. Her recovery was also complicated by endometritis. A third patient developed postoperative disseminated intravascular coagulopathy, which may have been related to the large amount of blood transfusion given.
Comparing the patients who had the placentas retained against those who either had the placentas delivered or underwent hysterectomy also reveals no statistically significant difference in terms of the amount of intraoperative blood loss, volume of packed cells transfused during surgery, and the change in postoperative hemoglobin levels (p > 0.05) (Figs. 1A, 1B, 1C, 1D and 2A, 2B, 2C, 2D; Table 4).
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The mean procedure time for our balloon placement technique was 44.5 minutes (range, 30–55 minutes), with a mean fluoroscopy time of 2.9 minutes (range, 2.3–3.1 minutes). When combined with postoperative embolization in patients in whom the placenta was retained, there was an added procedure time of 89 minutes (range, 45–130 minutes) and an additional mean fluoroscopy time of 15.8 minutes (range, 12.7–39 minutes). On the basis of the anesthesia records, the average duration of arterial occlusion (from the time of cord clamping to skin closure) was 84.1 minutes (range, 36–156 minutes). When the time of occlusion for those who had embolization performed is included, the mean duration of arterial occlusion was approximately 124.5 minutes (range, 87–213 minutes). Prolonged retention of the balloon catheter within the internal iliac artery that could have led to thrombotic or ischemic complications was avoided.
No contrast material–related adverse events were recorded. In addition, no catheter placement–related complications were recorded by either the interventional radiologist or obstetrician during postoperative hospitalization (average duration, 6.7 days). On subsequent clinic follow-up by the obstetrician (average duration, 18 months), no long-term complications were recorded. Two patients were lost to follow-up after the first visit at 1 month after discharge from the hospital.
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Placenta accreta occurs in approximately one of 2,500 deliveries. A median maternal age of 34 years with a median parity of 2.5 has been reported [2]. The risk of developing placenta accreta increases with the number of previous cesarean deliveries. These range from 2–9% in those with no prior cesarean delivery to 39–60% in those with two or more prior cesarean deliveries [1, 4, 6]. Up to 88% of these patients have concomitant placenta previa [2]. In addition, this condition can be associated with massive blood loss at delivery [3], which is over and above the risk associated with placenta previa alone [4].
As a result of the high morbidity associated with this condition, accurate preoperative imaging diagnosis of placenta accreta plays an important role. Antenatal sonographic and MRI techniques are used to establish the diagnosis and guide clinical management, leading to favorable outcomes [7].
During the cesarean delivery, the surgeon may elect to perform a total hysterectomy or opt for what has been termed a "conservative" approach, by leaving the placenta in situ, particularly when the uterus is strongly adhered to the pelvic organs, commonly the urinary bladder in cases of placenta percreta. Numerous anecdotal reports regarding the latter technique have been published, many reporting complete involution of the placenta after an uneventful postoperative recovery [7–11]. In a study by Kayem et al. [12], which directly compared patients with the placentas retained and those without, there appears to be a reduced amount of blood transfused and postoperative disseminated intravascular coagulation when the placenta is retained. Two patients even went on to have subsequent successful pregnancies. Methotrexate has been used successfully in some cases to expedite the involution process. However, the routine use of this technique has been limited by the paucity of scientific data, and there are isolated reports of serious morbidity with this technique [13, 14].
The technique of leaving the placenta in situ was performed in five of our patients, with three of them developing severe postoperative complications. Two of these developed severe postpartum hemorrhage and the third developed postoperative disseminated intravascular coagulopathy. Although this technique may potentially reduce intraoperative blood loss and duration of surgery, there is a high risk of postoperative complications. It is important to note that the aim of placenta retention was not to conserve the uterus but rather to prevent further damage to the surrounding affected organs in the course of the hysterectomy.
Many of the techniques that have been developed to contain intraoperative blood loss have focused on reducing pelvic circulation, primarily of the internal iliac arteries or their branches. The common objective among these techniques is to achieve selective disruption of the arterial supply to the uterus while trying to minimize the risk of ischemic complications to the rest of the pelvic organs and, more important, of the lower limbs. This has been accomplished with varying success, either extraluminally (most commonly ligation) or endovascularly by the use of occlusion balloons with or without embolization.
Surgical ligation of the pelvic arteries appears to be less effective for postpartum hemorrhage secondary to placenta accreta than in cases with uterine atony [15], with success rates of less than 50% in the former. Isolated cases reporting the efficacy of tourniquet compression [16] and devascularization [17] of the uterine arteries have been published but the techniques have not been popular thus far.
Arterial embolization is a safe and effective treatment for persistent postpartum hemorrhage that is unresponsive to conservative management [18]. Uterine artery embolization has been relatively successful in controlling postpartum hemorrhage from various causes in approximately 95% of cases [19], whereas preoperative prophylactic internal iliac artery embolization apparently reduces intraoperative blood loss and transfusion requirements in patients with placenta accreta when compared with historical controls [20]. Absorbable gelatin sponge particles, which provide a transient vascular blockade of from 2 to 4 weeks, are often the agents of choice, although endovascular coiling of the pelvic arteries has been reported [14].
Placement of occlusion balloons has been performed at various sites from as proximal as the aorta [21] to more distally within the anterior division of the internal iliac arteries [22]. More often than not, this technique has been combined with concomitant arterial embolization. The majority of the published reports have been anecdotal, involving one or two patients [16, 21–23], with only a handful consisting of five to seven patients [24–26]. Thus far, the results have been equivocal and are largely limited by the small sample sizes.
Studies involving the sole use of occlusion balloons in controlling hemorrhage in patients with placenta accreta are even less common. More recent reports of occlusion balloon placement in the common iliac arteries [23], the internal iliac arteries [27], and the anterior divisions of the internal iliac arteries [15] seem to suggest that this technique may be effective in controlling intraoperative hemorrhage. Our study, which involved the use of occlusion balloons that remained inflated in the internal iliac arteries from the point of cord clamping to skin closure in 11 patients may represent the largest series to date.
Perioperative endovascular techniques, being minimally invasive, appear to have been relatively safe so far. Sole use of occlusion balloons has the added theoretic advantage of being completely reversible nearly immediately, eliminating the risk of prolonged organ ischemia. No ischemic complication was reported in our study group. More important, the occlusion balloons were inflated from the point of cord clamping (after delivery of the baby) to the point of skin closure or beyond, hence eliminating the theoretic risk of placental ischemia before delivery of the fetus.
Intraoperative blood loss was assessed using the estimated blood loss and the total volume of packed cells transfused intraoperatively. The differences between the preoperative and immediate postoperative hemoglobin levels were used to better estimate the true significance of the transfusion requirements between the studied groups.
Our study has shown that apart from this being a safe procedure, there is a statistically significant difference in the amount of blood loss during surgery. This is based on both the estimated intraoperative blood loss and the transfusion requirements to maintain the hemoglobin levels at a comparable level. The duration of the cesarean surgery was also significantly less in the study group, and this may be a partial contributory factor as well. In addition, there was no significant difference in the duration of ICU stay and length of hospitalization after delivery. The value of postoperative embolization was not addressed in this study because the estimated blood loss and blood transfusion requirement were based on intraoperative events and thus were not related.
A major advantage of this technique over intraoperative embolization is a significant reduction in the exposure of both the patient and the fetus to ionizing radiation. In uterine artery embolization, the mean fluoroscopic time may amount to almost 22 minutes, with an estimated mean absorbed ovarian dose of about 22 cGy, although this is not likely to pose a negative impact on fertility or genetic risk [28].
In our study, the mean fluoroscopy time for internal iliac artery occlusion balloon placement was 2.9 minutes. This is significantly less when compared with 22 minutes of fluoroscopy time used in the standard embolization technique. When combined with postdelivery embolization of the placenta, the overall mean fluoroscopy time was 18.7 minutes. One way in which radiation exposure was minimized was by accurately determining the amount of contrast solution required to inflate the balloons at the time of catheter placement. The same amount of contrast solution was then used to inflate the balloons intraoperatively without having to expose the patient to radiation a second time. Embolization, which accounts for a large proportion of the radiation dose, was performed postoperatively, greatly reducing the exposure to the fetus.
In terms of surveillance of vascular access complications, the interventional radiologist was able to check for these in the patients during hospitalization. After discharge from the hospital, the patients were followed up in high-risk pregnancy clinics by their referring obstetricians (maternal and fetal medicine specialists) who were aware of the medium- and long-term complications of the occlusion balloon placement procedure. Close liaison with the interventional radiologist was also maintained in all cases. Although ours may be a fairly safe procedure with few potential complications, continued vigilance during follow-up, both in the short and long term, is important.
There are several limitations to this study. First, sample selection bias could not be avoided. The referring obstetrician selected cases for this procedure when massive intraoperative blood loss was expected. This may explain the slightly higher proportion of placenta percreta cases in our study group (seven of 11) than in the control group (seven of 14).
Second, the histologic diagnoses of placenta accreta for the patients who did not undergo hysterectomy could not be determined. The diagnoses in these patients therefore relied on a combination of sonography, MRI, and intraoperative findings. For the control group, histologic confirmation of the diagnoses was achieved in all cases.
Although the study and control groups were fairly similar in terms of the maternal age, gestational age, history of cesarean section, and severity of placenta accreta, we were not able to directly compare the patients who underwent hysterectomy alone because of the small sample size. The difference in surgical technique, by leaving the placenta in situ, may be a confounding factor, even though there was no statistical significance in the degree of blood loss, transfusion requirement, and duration of surgery between the patients who had the placentas retained and the rest of the study group.
In conclusion, perioperative placement of internal iliac artery occlusion balloons is a safe and minimally invasive technique that reduces the intraoperative blood loss and transfusion requirements of patients with placenta accreta and its variants undergoing cesarean delivery. This procedure is associated with a shorter duration of cesarean surgery, with no significant increase in the duration of ICU stay or hospitalization. It also leads to shorter fluoroscopy times and reduces radiation dose to the fetus when compared with intraoperative endovascular embolization techniques.
Acknowledgments
We thank Richard Lo Hoau Gong and Kei Pin Lin of the Department of
Diagnostic Radiology, Singapore General Hospital; Yong Tze Tein and Lee Sook
Ling of the Department of Obstetrics and Gynaecology, Singapore General
Hospital; and Mr. Chen Yuming of the Clinical Trials & Epidemiology
Research Unit in Singapore for their assistance.
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