Vascular occlusion in the management of complicated multifetal pregnancies

Clin Perinatol 30 (2003) 601 – 621

Vascular occlusion in the management of complicated multifetal pregnancies Julie S. Moldenhauer, MD, Adel Gilbert, MS, CGC, Anthony Johnson, DO* Division of Reproductive Genetics, Department of Obstetrics and Gynecology, 5th Floor Center, Hutzel Hospital, 4707 St. Antoine Boulevard, Detroit, MI 48201, USA

Over the past decade in utero therapy for complicated pregnancies has come to be accepted into the mainstream of management options in obstetric practice. Improved methodology has made for more efficient procedures that minimize maternal risk while increasing fetal benefits. Interventions are performed to improve outcome in fetuses that have congenital anomalies such as neural tube defects. Some of these procedures are done to alter the course of a multifetal gestation, as in the case with vascular occlusion. Selective termination (ST) in twins and higher-order pregnancies are performed with the goal of (1) preventing the delivery of an anomalous or severely compromised fetus, and (2) hopefully improving the perinatal outcome for the unaffected cotwin. Because placental vascular anastomoses can be expected to be present in essentially all monochorionic (MC) gestations, the use of intracardiac potassium chloride injection for ST is contraindicated because of the risk of compromise to the unaffected fetus. Rather, vascular occlusive techniques are required to achieve the stated goals. ST can be a grueling decision for the parents. Certainty in diagnosis and appropriate counseling are key in managing these patients. The indications for vascular occlusion in complicated multifetal pregnancies have been widely established, and multiple methods have been developed to carry out the task. This article reviews the indications, counseling, and methods for umbilical cord occlusion.

* Corresponding author. UNC/Chapel Hill, Department of Obstetrics and Gynecology, 101 Manning Drive, Chapel Hill, NC 27599-0001. E-mail address: [email protected] (A. Johnson). 0095-5108/03/$ – see front matter D 2003 Elsevier Inc. All rights reserved. doi:10.1016/S0095-5108(03)00054-X

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Indications Twin reversed arterial perfusion sequence Twin reversed arterial perfusion (TRAP) is a unique disorder complicating monochorionic twins. The sequence occurs in approximately 1:35,000 pregnancies and 1% of monozygotic twin pregnancies [1,2]. The TRAP sequence is characterized by the presence of a normal (pump) twin that provides the circulation for itself and the Acardiac (perfused) twin. While the etiology of the disorder is not clearly known, the most generally accepted is the vascular reverse perfusion theory, the most severe form of twin –twin transfusion syndrome. During early embryogenesis there is competition in the interfetal circulation between arterial-to-arterial vascular anastomoses. If arterial perfusion of one exceeds the other, circulation is reversed, leading to disruption of morphogenesis with the end result being the development of an Acardiac twin. The Acardiac twin has no direct vascular communication with the placenta; rather, the umbilical cord of the anomalous fetus is connected to the pump twin’s cord by way of arterial-to-arterial and venous-to-venous anastomoses, which results in the normal twin pumping blood in a reversed direction into the Acardiac twin [3]. Blood is then returned to the normal twin by way of the umbilical vein of the Acardiac. Pregnancies complicated by the TRAP sequence are at increased risk for adverse outcomes. Mortality for the Acardiac twin is uniformly 100% [3,4]. The pump twin is at risk for severe hydramnios (51%), preterm labor (79%), highoutput cardiac failure with resultant hydrops, and ultimately intrauterine fetal demise (IUFD) in upwards of 25% of cases [4,5]. In addition, fetal malformation will be found in approximately 10% of pump twins [6]. The overall perinatal mortality rate for the pump twin is estimated to be between 35% and 55% [3 –5]. A possible factor predictive of outcome is the twin:weight ratio [5]. Using the weight of the Acardiac expressed as a percentage of the weight of the pump twin, Moore et al found that a twin:weight ratio of more than 70% was associated with a preterm delivery rate of 90%, hydramnios rate of 40%, and a rate of development of congestive heart failure in the pump twin of 30%. These rates lessen with decreasing twin:weight ratios. This information might help to counsel patients more efficiently regarding potential outcomes and management options. Another consideration with Acardiac twinning is the rate of aneuploidy. Healey et al reported a 33% rate of abnormal karyotypes in Acardiac twins, including monosomy, trisomy, deletions, mosaics, and polyploidy [4]. Abnormal karyotypes, which were comprised of trisomies, were found in 8.8% of the pump twins. The average maternal age in this study was approximately 25 years, so it is recommended that a targeted anatomic survey and fetal karyotype be obtained on the pump twin before planning intervention. Some proposed management options for pregnancies complicated by the TRAP sequence have been termination of the pregnancy, expectant manage-

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ment with early timed delivery, in utero medical treatment of fetal heart failure with digoxin [7], treatment of hydramnios with indomethacin [8], hysterotomy with removal of the abnormal twin (sectio parva) [9 – 11], and techniques for vascular occlusion of the Acardiac twin’s umbilical vessels as noted herein. Hysterotomy is mentioned only for historical purposes; this form of intervention is fraught with significant maternal and fetal risks to the pump twin and should be abandoned. Because of the inherent nature of the TRAP sequence, vascular occlusive techniques should not be considered to be ST; instead, these interventional strategies or therapies remove a ‘‘vascular steal’’ and offer the best chance for the pregnancy to result in the delivery of a healthy singleton. Discordant twin anomalies Another indication for ST is multifetal gestation in which the fetuses are discordant for structural anomalies or aneuploidy. Twin pregnancies are at increased risk of congenital anomalies compared with singletons [12,13]. Certain midline anomalies are known to occur more frequently in twins, particularly monozygotic twins, including congenital heart defects, gastrointestinal disorders, and central nervous system abnormalities [6]. This increase is thought to be caused by the teratogenic effect of the twinning process. In approximately 15% of cases the twins will be concordant for the abnormality. In addition, monozygotic twins might have discordant karyotypes caused by nondisjunction or anaphase lag occurring after the twinning process. Pregnancies in which one fetus has a congenital abnormality are at increased risk for overall worse pregnancy outcomes [14]. In twin gestations complicated by one anomalous twin, the risk of preterm delivery is increased with resultant perinatal morbidity and possible mortality for the normal twin. Certain congenital abnormalities might also lead to IUFD of the affected twin and can have an impact on the normal twin, including demise of the cotwin, preterm delivery, and neurologic sequelae of encephalomalacia, cerebellar necrosis, hydrocephaly, hydranencephaly, hemorrhagic infarct, and microcephaly [15,16]. Appropriate counseling of the patient is required in this situation. Carrying an affected cotwin adds real risk to the pregnancy. On the other hand, the decision to proceed with invasive therapies also adds an assumed risk to the normal twin. For some couples, however, the possibility of a malformed or handicapped child warrants ST. Patients must be made aware, however, that the decision for ST might lead to the loss or possible compromise of the normal cotwin in the event of procedural or postoperative complications. Twin – twin transfusion syndrome Approximately 10% to 15% of MC twin pairs will develop twin – twin transfusion syndrome (TTTS; see ‘‘Twin– twin transfusion syndrome’’ by Quintero elsewhere in this issue) [17,18]. Interfetal placental vascular anastomoses,

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superficial and deep, exist in essentially all MC gestations. The pathophysiologic mechanism behind TTTS is believed to be caused by disproportionate shunting of blood flow through arteriovenous anastomoses. In pregnancies affected with TTTS placental studies have shown alteration in the number of interfetal vascular anastomoses, specifically a decrease in superficial arterioarterial and identifiable deep anastomoses [19,20]. This imbalance is believed to cause the clinical features. The disease process results in imbalanced blood flow from the donor to the recipient twin. In this scenario the donor develops anemia, growth restriction with oliguria manifested as a small or absent bladder, and oligohydramnios, whereas the recipient becomes plethoric with a persistently dilated bladder, hydramnios, and progression of cardiac hypertrophy, cardiac failure, hydrops, and eventual death. With advanced disease, abnormal Doppler blood flow studies might be found in the umbilical artery or vein and ductus venosus of either twin [21]. The perinatal survival rate for cases diagnosed at less than 28 weeks’ gestation is reported to be only 20% [22]. Management options for women electing to continue an affected pregnancy have included expectant observation with early delivery as disease progresses, serial amnioreduction [23 –26], septostomy [27,28], and laser ablation of communicating placental vessels [29 –31]. In some situations the disease state might have progressed rapidly at an early, previable gestational age or might have a high probability of having already resulted in irreversible damage in one of the twins. At this point, the option of ST by vascular occlusion might be a consideration to allow continuation of the cotwin to improve its intact survival. In a recent study by Taylor et al, bipolar cord coagulation (BPC) was performed in pregnancies that had advanced stages of TTTS [32]. This method resulted in a 93% cotwin survival rate. Given the inherent nature of ST, in which there is the demise of one twin, it is difficult to compare these methods equally to total pregnancy-conserving methods; however, the overall survival rate in pregnancies that have advanced disease might, in fact, not be significantly different when using certain interventions. Comparing ultrasound-guided BPC for ST and selective laser photocoagulation of placental anastomoses from pregnancies that had stage III and IV TTTS, Taylor et al reported overall survival rates of 46% and 57%, respectively [32]. Patients must be counseled regarding the possibility of poor outcome regardless of the treatment. The possibility of poor outcome is particularly dependent upon the initial status of the twin pair and the gestational age at the time of diagnosis.

Genetic counseling Too often, expecting women attend their long-awaited second trimester ultrasound appointment only to learn that their anticipated normal, healthy baby is in reality a complicated pregnancy. This is quite often the situation in MC multiple gestations. From then on, she will spend a considerable amount of time

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on an emotional rollercoaster that might eventually lead to the realm of fetal therapy. Before such a procedure, a risk assessment should be performed, which includes evaluation of the woman’s family, medical and pregnancy history, and ultrasound findings. The goal is to do everything possible before the ST to maximize the outcome for the apparently normal cofetuses. Advanced maternal age In situations in which the mother is of advanced maternal age (AMA; 35 years at estimated date of confinement [EDC]) fetal chromosome analysis should be performed. While the overwhelming majority of MC gestations will be concordant for karyotype, there are exceptions to this rule. It is advisable to offer sampling of all fetuses before intervention when mother is of AMA. Structural anomaly in one fetus When a fetus is diagnosed with an anomaly, every effort should be made to ascertain the cause. This information affects not only the potential health of the cotwins but also the risk for recurrence and testing options in future pregnancies. Because an ST precludes the option of postnatal evaluation or autopsy, a thorough targeted ultrasound of all fetuses is essential. Three-dimensional ultrasound and fetal MRI might provide further assistance when faced with a diagnostic dilemma. Cytogenetic analysis by traditional G-Banding should be obtained before in utero intervention in MC multifetal pregnancies discordant for structural anomalies. The reputed ‘‘normal’’ cotwin could be chromosomally abnormal without any identifiable anatomic defects by ultrasound. Therefore, cytogenetic analysis of both fetuses discordant for a structural anomaly should be recommended. Approximately 2% to 7% of fetuses that have an open neural tube defect (ONTD) are chromosomally abnormal; however, caution should be used when biochemical testing is done from the amniotic fluid of the ‘‘normal’’ fetus in an MC, diamniotic (DA) pregnancy. Because of the typically thin amniotic membrane, the amniotic fluid a-fetoprotein (AFAFP) and acetylcholinesterase (Ache) can readily diffuse from one fetus to another and be falsely elevated, but a normal AFAFP and negative Ache would provide greater than 98% reassurance that the fetuses are free of an ONTD [33]. Depending on the anomaly in question, molecular cytogenetics by fluorescence in situ hybridization (FISH) would also be indicated. In the case of congenital heart defects, testing for 22q deletion (DiGeorge syndrome) would be indicated. Twin – twin transfusion syndrome Typically, in a complicated MC gestation in which the TTTS has already progressed, the recipient twin will exhibit hydropic changes that are likely caused by the physiology of the vascular anastomoses. This outcome could also be caused by a chromosomal abnormality. In the authors’ center, confirmation of a

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normal karyotype is standard procedure before proceeding with vascular occlusion in a pregnancy presumed to be affected by TTTS. Family history A comprehensive three-generation pedigree should reveal whether or not the fetuses are at increased risk for genetic disease or birth defects over the general population risk (4%). Some examples of situations that might pose a risk to the fetus are (1) a maternal uncle with an X-linked disease such as Fragile X syndrome or Duchenne muscular dystrophy, (2) a dominant condition in one of the parents or grandparents such as Huntington disease or Charcot-Marie-Tooth disease, or (3) one of the parents is a carrier of an autosomal recessive condition and the status of the other parent is unknown (ie, sickle cell disease or cystic fibrosis). Population screening Almost every ethnic group is at increased risk for certain autosomal recessive genetic diseases. If this issue has not been addressed in advance, the couple should be offered the option of carrier testing for ethnic-specific disorders (Appendix 1). Couples identified as carriers for an autosomal recessive condition are at 25% risk for an affected fetus in each pregnancy. In many situations, because of the gestational age of the pregnancy or the potential risks to the other fetuses if the ST is delayed, a couple might not be able to pursue additional testing or record acquisition before the procedure. Regardless of whether or not the couple decides to pursue record acquisition, knowledge of the significance of their family history, ethnic-specific risk, and the possible implications these might have to the remaining fetuses is critical in the process of informed consent. As a source of additional information regarding the prognosis for the abnormal fetus, the option of a consultation with pediatric subspecialties should be made available before ST for nonlethal structural anomalies.

Vascular occlusion methods Embolization Embolization of the umbilical vessels was one of the first methods used to perform vascular occlusion in complicated multifetal pregnancies. This technique is performed under ultrasound guidance using needling techniques similar to amniocentesis and cordocentesis. Typically, a 20-gauge spinal needle is guided by ultrasound into the target vessel (umbilical or hepatic) or heart. The embolizing agent is then injected. Agents that have been used to achieve vascular occlusion include coils [34 –38], absolute alcohol [39 –42], and histoacryl and enbucrilate gels [43 – 45]. The maternal risks involved with this procedure are similar to those of amniocentesis/cordocentesis. Outcomes with the various

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embolization techniques are presented in Table 1. Because of the reported high procedure failure and pregnancy loss rate (23% and 32%, respectively), these methods of vascular occlusion have fallen out of favor. Fetoscopic cord ligation McCurdy and colleagues described the first attempt at fetoscopic cord ligation in 1993 [46]. Though their attempt was unsuccessful, it opened the door for the use of fetoscopic techniques. Since then a number of centers have reported the use of this technique for ST in complicated MC multifetal pregnancies [47 – 53]. The procedure involves the introduction of one or two percutaneous ports, usually 2 to 3 mm in size, into the amniotic cavity under ultrasound guidance. The endoscope is placed in one port for visualization and a suture ligature is placed through the second (or operative) port. Under fetoscopic guidance the suture is looped around the target umbilical cord and retrieved with grasping forceps through the operative port. The knot is tied extracorporeally and then secured around the umbilical cord using a knot pusher. The suture is cut intraamniotically with endoshears. The procedure is repeated to ensure complete occlusion. In some instances this technique can be performed completely under ultrasound guidance, thus avoiding the use of more than one port. Table 2 presents the outcomes for the published series of fetoscopic cord ligations. Success rates for this procedure are 88%. Pregnancy loss and premature rupture of membranes (PROM) occurred in 35% and 39% of cases, respectively. Additional reported postoperative complications are similar to those of any fetoscopic surgery, including bleeding, infection, preterm labor, and maternal problems inherent to anesthesia. Evidence of an amniotic band on the unaffected cotwin was reported in one series [52]. Whether or not the amniotic band was a result of the procedure has not been determined. Cord entanglement is a common occurrence in MC monoamniotic twins. In at least one reported case, entanglement prevented clear delineation of the targeted umbilical cord, resulting in ligation of the umbilical cord and subsequent death of the unaffected fetus in a twin pregnancy discordant for hypoplastic left heart syndrome [53]. Laser photocoagulation of the umbilical cord Laser coagulation of the umbilical vessels is also performed under fetoscopic guidance. The target is the umbilical cord root of the affected fetus. Coagulation was performed using a ‘‘no-touch’’ technique with various port sizes from an 18-gauge needle to a 5-mm trocar with a 400 um Nd:YAG laser fiber and different energy levels [54 – 57]. Initial reports suggested that the success rate of this procedure might be gestational age-dependent. Ville et al reported that laser coagulation failed in two of four cases. Having successfully used the technique at 17 and 20 weeks’ gestation, Ville et al concluded that the failure was secondary to the large edematous cords at 26 and 28 weeks’ gestation; however, the success of laser for umbilical cord occlusion in early gestation has recently been called to

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Study

Method

Hamada et al [34] Porreco et al [35] Roberts et al [36] Bebbington et al [37] Dommergues et al [44] Holzgreve et al [39] Sepulveda et al [40] Dumler et al [43] Donner et al [45] Denbow et al [41]

Coil – UV Coil – UV Coil – UV Coil – IC Gel – UV Alcohol – UV Alcohol – UV Gel – IC Gel – UC,IC Alcohol/gel – IHV, IC

Sepulveda et al [42] Tanawattanacharoen et al [38] Totals

Alcohol – UV Coil – UV

Procedures 1 1 1 1 4 1 1 1 2 6

2 1 22

GA at procedure 23 24 23 21 23 – 26 21 23 24 26, 27 18 – 26

27, 26 24 24a (18 – 27)

Success 1 1 1 0 4 1 1 1 2 2

2 1 17 (77%)

PROM

Total loss

GA at delivery

Indication

0 0 0 0 0 0 1 0 1 0

0 0 1 1 1 0 0 0 0 3

38 39 – – 26 – 37 Term 24 31 33, 40 NA

0 0 2 (9%)

0 1 7 (32%)

35 – 37

TRAP TRAP TRAP TTTS TTTS TRAP TRAP Discordant anomaly TTTS Discordant anomaly = 1 TTTS = 4 TRAP = 1 TRAP TRAP

34a (24 – 39)

Abbreviations: GA, gestational age, wk; IC, IntrAcardiac; IHV, intrahepatic vein; NA, not available; PROM, preterm premature rupture of membranes occurring  34 wk with liveborn neonates; total loss, intrauterine fetal demise (5) and neonatal death (2); UV, umbilical vessel. a Mean gestational age and range (excludes three cases from Denbow et al [41]).

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Table 1 Published outcomes with embolization in complicated monochorionic twin pregnancies

Study

Procedures

GA at procedure

Success

PROM

Total loss

GA at delivery

Indication

McCurdy et al [46] Lemery et al [49] Willcourt et al [48] Crombleholme et al [50] Quintero et al [47,51]

1 2 1 1 14

19 27,23 24 24 16 – 25

1 2 1 1 12

– 0 0 1 4

1 0 0 0 5

– 29, 36 29 32 24 – 37

DePrest et al [52]

4

21 – 26

4

2

2

26 – 29

Young et al [53] Totals

1 24

– 7 (39%)

1 9 (35%)

– 30a (24 – 37)

TRAP TTTS TRAP Discordant anomaly TRAP = 10 Discordant anomalies = 1 TTTS = 2 TTTS = 1 TRAP = 3 Discordant anomaly

19 22a (17 – 26)

0 21 (88%)

Abbreviations: GA, gestational age, wk; PROM, preterm premature rupture of membranes occurring  34 wk with liveborn neonates; total loss, fetal demise (6) and neonatal deaths (3). a Mean gestational age and range (excludes three cases from Denbow et al [41]).

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Table 2 Published outcomes with fetoscopic cord ligation in complicated monochorionic multifetal pregnancies

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question [54]. Lewi et al recently reported a consecutive case series of 50 complicated MC multifetal pregnancies [58]. The primary procedure for pregnancies less than 21 weeks’ gestation was laser. Seventeen of the 37 laser cases failed (46%) and required bipolar thermal coagulation. The authors have used a 600 um Nd:YAG laser fiber as intervention in two Acardiac cases, one a dichorionic (DC) triamniotic (TA) triplet gestation at 21 weeks’ gestation and the other a DC, quadamniotic quadruplet gestation at 22 weeks’ gestation. The procedures were preformed under ultrasound guidance through a 16-gauge needle. When the needle was placed within the abdomen of the Acardiac, the fiber was advanced to an area adjacent to the intra-abdominal umbilical cord vessels, and thermal occlusion was obtained with only two to three 10-second bursts of laser energy. Additional complications that might be seen with this procedure include bleeding, infection, rupture of membranes, preterm labor, and fetal death. The authors have seen the latter as an acute event. Laser coagulation of the umbilical cord was attempted in an MC, TA triplet gestation affected with stage IV TTTS at 17 weeks’ gestation [21]. The procedure was initially to have been laser photocoagulation of placental anastomoses, but the position of the recipient fetus prevented access to the vessels. During the laser occlusion the recipient’s umbilical cord ruptured, resulting in the exsanguination and death of all three fetuses. Monopolar cord coagulation Rodeck and colleagues have described a method in which monopolar thermocoagulation was used to arrest fetal blood flow in Acardiac twins [59]. The authors developed in-house a 1-mm wire electrode that is insulated along its length except for the distal 3 mm. The technique they described called for the electrode to be inserted transabdominally through an 18-gauge needle under ultrasound guidance targeting the aorta of the Acardiac. If the vessel was of sufficient size the electrode was placed within the lumen. If it was small, the tip of the wire was placed adjacent to the vessel. Power was delivered in 5- to 15-second bursts starting at 10 Watts (W) and increased 5 to 10 W until a hyperechoic area developed at the tip of the wire and around the vessel. Pulsed and color flow Doppler studies were used to confirm cessation of vascular flow. The procedure was reported to be relatively quick, requiring only 5 to 10 minutes, with patients discharged home in 1 hour. As with laser coagulation Rodeck et al noted that cessation of flow was slow to occur later in gestation, when vessels were large and edematous. In three of four cases the procedure was performed before 20 weeks’ gestation and required only 20 to 35 W of energy for successful vascular occlusion. The remaining case proved to be a bit more difficult. At 24 weeks’ gestation the initial attempt was to occlude the umbilical cord at the fetal insertion. After 60 W of power the larger, edematous cord had reduced, but flow continued. The Acardiac stopped growing after 2 weeks and hydrops in the pump twin improved; however, the patient was

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delivered at 32 weeks’ gestation because of the development of severe preeclampsia. The child survived, but it had hyaline membrane disease and intraventricular hemorrhage with resultant developmental delay. The remaining three cases delivered at term with good outcomes. The authors’ in vivo experience with the Elmed (Elmed Incorporated, Addison, Illinois) monopolar needle electrode, an insulated microneedle with a diameter of 1 mm and length of 35 cm, has been less rewarding. Direct placement of the needle into and adjacent to small surface vessels created some thermal damage with blanching of the tissues, but it failed to provide complete vascular occlusion in early second trimester placentas. Bipolar cord coagulation In general, centers follow the technique originally described by DePrest et al for BPC [60]. The procedures are done under standard sterile technique. While general and conduction anesthesia is used in selective cases, the majority are done with intravenous (IV) sedation and 1% lidocaine administered locally into the skin and deep into the myometrium [32,60 –62]. The procedures are done under

Fig. 1. Bipolar umbilical cord coagulations. (A) Ultrasound guidance: arrows indicate umbilical cord and endoscopic forceps. (B) Thermal occlusion: cord within forceps; ‘‘streaming bubbles’’ within amniotic fluid indicates thermal damage to cord. (C) Postprocedure occlusion site: arrow indicates indentation of cord following thermal occlusion.

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Fig. 2. Fetoscopy of umbilical cord in affected fetus. (A) Before bipolar cord coagulation. (B) Postocclusion: arrow indicates occlusion site; note blanching and indentation.

continuous ultrasound guidance. A placental free window is found and the targeted umbilical cord is located. A small skin incision is made to allow access of the enodoscopic trocar. When secured in the amniotic sac, the obturator is removed and the forceps are advanced to the cord. The cord is grasped and positioned away from the amnion and thermal energy is applied. Signs of successful coagulation are the ultrasound appearance of turbulence with bubbles raising from the forcep and an audible ‘‘pop.’’ Pulse and color flow Doppler blood flow studies are done to confirm cord occlusion. Figs. 1– 3 show sonographic and fetoscopic images from various aspects of BPC.

Fig. 3. Commercially available endoscopic bipolar coagulation forceps. The three devices have been used for ST in complicated MC multifetal pregnancies at Wayne State University. The majority of clinical experience reported to date has been with the 3-mm Everest Medical device.

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The initial report used a standard-size laparoscopic trocar and 5-mm forceps [60]. Since then, the sizes employed have varied between 2.2- to 3.0-mm forceps [32,60 –62]. Fig. 3 demonstrates the three forceps that have been used at Wayne State University for BPC. The 5-mm Everest Medical (Everest Medical, Gyrus Group, Maple Grove, Minnesota) device has a knife built into the forceps that could be used to incise the cord after occlusion before releasing it from the forceps; however, the size of the device is prohibitive and outweighs this theoretical benefit. The authors found that any potential benefit from the smaller Imagyn Medical (Imagyn Medical, Irvine, California) device was lost because of the inability to visualize the thin forcep blades when extended within the amniotic sac. The majority of BPCs have been performed with the 3.0-mm bipolar diathermy forceps from Everest Medical [32,60 –62]. There have been subtle differences among the reporting centers in factors such as the amount and duration of thermal energy, the number of occlusion sites, the use of amnioreduction or infusion, and the length of stay following the procedure. DePrest and colleagues start coagulating at a power level of 20 W and increase in increments of 5 W at 30-second intervals up to 45 W or until occlusion is confirmed [60]. The procedure is repeated in two adjacent sites. Nicolini et al perform their coagulations using 50 W at 10- to 30-second intervals. If cessation of blood flow is not confirmed with first diathermy, the procedure is repeated in one to two additional sites [61]. Like the Leven group, Taylor et al start at 20 W and increase by 10 W increments to a total of 50 W applied in up to 60-second periods [32]. The authors have found that 40 W at 30-second duration in two to three sites is successful in 100% of cases. There have been no cases of cord disruption or adherence. It has been suggested that the audible ‘‘pop’’ that is quite often heard is indicative of successful cord occlusion [61]; however, with in vivo experiments the authors have found that the ‘‘pop’’ simply represents the disruption of Wharton’s jelly and not necessarily occlusion of the umbilical vessels. Occlusion of vessels does correlate with the cessation of streaming of bubbles in the amniotic fluid during the thermal application (Figs. 4, 5). In addition, the authors have found because of spiral of the umbilical cord that it is

Fig. 4. Umbilical cord: gross examination at different durations of thermal occlusion. Gross section demonstrates compression and external thermal damage at 18 seconds and 50 seconds. The occlusion was stopped at 18 seconds when an audible ‘‘pop’’ was heard. Thermal occlusion was discontinued at 50 seconds with streaming bubbles were no longer seen rising from the forceps sonographically.

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Fig. 5. Umbilical cord: histologic examination at different durations of thermal occlusion. At 18 seconds there is minimal damage to the vessels and surrounding Wharton’s jelly. At 50 seconds there is significant damage to the exterior aspect of the cord and proximal vessels (small arrow). The distal artery (large arrow) shows minimal damage, indicating the need for two to three sites occlusion sites.

essential to occlude multiple sites to assure complete vascular occlusion regardless of the duration or wattage (Fig. 5). To date, the reported success rate for this procedure has been 100%. Table 3 displays the outcomes from previous published reports and the Wayne State University experience with BPC. PROM and total loss rates were 21% and 18%, respectively. Maternal morbidities have been reported to be minimal. At the authors’ institution the authors have developed a protocol for patients undergoing BPC. During the initial visit the patient undergoes thorough genetic counseling with all potential options presented. The authors follow a checklist to ensure that every possible management plan has been discussed (Appendix 1, Fig. 6). Next, intensive two-dimensional and, when necessary for aiding in diagnosis, three-dimensional ultrasound examinations are conducted and the findings are reviewed with the patient. Patients are offered consultation with a perinatal loss/grief counselor, social worker, or staff psychologist. For the actual procedure, patients are admitted to the labor and delivery unit. They receive IV prophylactic antibiotics before the procedure. The procedures are performed in an operative suite. General anesthesia or conduction anesthesia have been used in selective cases, but in most cases the authors have found that IV sedation with local infiltration was sufficient with less maternal morbidity. Postoperative patients remain on bed rest for prolonged observation with a Foley catheter in place on labor and delivery. They also receive subsequent doses of antibiotics and empiric indomethacin treatment. If, after 24 hours, there is no evidence of preterm labor, leaking amniotic fluid, or bleeding, the patient is allowed minimal ambulation. Upon discharge patients are instructed to continue with modified bed rest for a couple of weeks. Should complications arise, patients are usually kept in-house. Bipolar cord coagulation has many obvious advantages over other vascular occlusion techniques. Based on reports to date using standard commercially

Study

GA at procedure

Success

GA at delivery

Indication

Deprest et al [60]

10

18 – 24

10/10

2

2

26 – 39

Nicolini et al [61]

17

18 – 27

17/17

3

4

27 – 41

Taylor et al [32] Johnson et al [62]

15 21

18 – 28 21a

15/15 21/21

3 2

2 2

24 – 38 32a

Wayne State University (unpublished)

45

13 – 24

45/45

11

9

25 – 40

TRAP = 5 TTTS = 5 TTTS = 9 TRAP = 2 Discordant anomaly = 6 TTTS = 15 TRAP = 9 TTTS = 6 Discordant anomaly = 6 TRAP = 9 TTTS = 7 Discordant anomaly = 29

21 (13 – 28)

100%

21 (21%)

Total

Procedures

108

PROM

Total loss

19 (18%)

33 (24 – 41)

Abbreviations: GA, gestational age, wk; PROM, preterm premature rupture of membranes occuring 34 wk; total loss = termination of co-term (3) fetal demise (9) and neonatal deaths (7); excluded three undelivered from Johnson et al [62]. a Mean gestational age; raw data not available.

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Table 3 Published outcomes with bipolar cord coagulation in complicated monochorionic multifetal pregnancies

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available endoscopic forceps, successful cord occlusion should be reproducible from operator to operator. Compared with cord ligation BPC is a much more efficient and safer procedure that provides assurance of vascular occlusion in complicated MC multifetal pregnancies; however, as with other endoscopic fetal interventions, the Achilles heel of BPC is PROM. More than 20% of the perinatal morbidity and mortality associated with these procedures is attributable to PROM. It is the authors’ hope that as further experience is gained in performing these procedures the various risk factors operative and inherent to the disease state itself that predispose the pregnancy to PROM and perinatal loss will be understood. With meticulous recording of events it might be possible to develop prophylactic measures to further improve the outcome of these complicated gestations.

Psychosocial aspects of selective termination For many couples, the emotional turmoil experienced during and after this decision-making period can disrupt their relationship, mental health, and family life. How each couple deals with the grief that accompanies this loss, and the level of support they receive, will directly affect the healing process. In some cases couples might choose, for fear of criticism and ridicule, not to share with others that one of the fetuses was selectively terminated. Other couples who have supportive families and friends might still have difficulty dealing with their decision and suffer periods of grief, regret, and guilt. Providing couples with referrals for grief counseling and psychological support can be helpful, as can acknowledging that the decision they made can be kept private. A complete assessment with the most appropriate diagnosis can be helpful in alleviating some anxiety for the parents. Offering and exhausting all possible therapeutic techniques for couples in this situation is of the utmost importance. Many couples have numerous questions regarding what happens to the reduced fetus over the course of the pregnancy and how the remains will appear at the time of the delivery. These concerns can be abated by the explanation that over the course of the pregnancy the selectively terminated fetus will reduce in size significantly and at the time of delivery the fetus papyraceous will not be clearly recognizable to them.

Summary The decision to undergo ST is a personal one for the involved couple, and it can have many psychosocial implications. Appropriate counseling including offering all possible management options with related risks is imperative. Choosing the technique that best serves the clinical situation with minimization of maternal risks should be done taking under consideration the operator’s experience. Ultimately, vascular occlusion techniques can help improve multifetal pregnancy outcomes in otherwise challenged gestations.

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Acknowledgments The authors would like to acknowledge Jean Charbonneau and Connie Rapacki for their assistance in the review and preparation of this manuscript.

Appendix 1 The checklist below (Fig. 6) exemplifies the protocol checklist used at the authors’ institution for patients undergoing BPC.

Fig. 6. In Utero Vascular Occlusion patient checklist.

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Fig. 6 (continued ).

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