Open hysterotomy, characterized by a surgical incision through the multiple layers of the uterus , including the maternal abdominal wall, uterus , and the membrane surrounding the fetus , was developed by pediatric surgeons Alfred de Lorimier and Michael R.
The surgeons developed the technique to repair fetal myelomeningocele. Myelomeningocele is a common form of spina bifida , a neural tube defect whereby the lower spine does not close during development. The fetus was born healthy, and as news spread in the medical community about this technique, more interest in fetal surgery fostered new methods to treat other life-threatening conditions facing the fetus in utero.
Around the same time, doctors began to conduct fetal surgery to mitigate twin-to-twin transfusion syndrome , an often fatal circulatory disorder that impacts identical twins, whereby one twin monopolizes the blood supply from the pregnant woman. The most common consequences of twin-to-twin transfusion syndrome are preterm delivery or the death of one or both twins. By using percutaneous fetal therapy to reduce excess volumes of amniotic fluid hydramnios doctors improve fetal hemodynamics, which decreases pressure on the placental surface and results in a more even distribution of blood between twins.
In doctors in France, Switzerland, and Belgium began to treat twin-to-twin transfusion syndrome with fetoscopic laser coagulation. For that technique, doctors use endoscopic laser coagulation to sever the fetal circulatory tissues responsible for the abnormal distribution of blood between twins, while the pregnant woman is under local or regional anesthetic.
The institutes conducting the study concluded that the treatment was more effective than frequent amniotic fluid withdrawals when the condition is diagnosed before 26 weeks of gestation. In , UCSF surgeons also attempted to repair congenital diaphragmatic hernia, a condition where a fetus 's abdominal organs migrate through a hole in its diaphragm up into its chest cavity.
The area occupied by the abdominal organs severely limits lung development, leaving newborns with underdeveloped hypoplastic lungs. Michael Harrison led an early clinical trial to test how effective hysterotomy was in treating congential diaphragmatic hernia in fetuses. Harrison developed a second technique for repairing congenital diaphragmatic hernia in by working with lambs to test a considerably less invasive endoscopic technique called tracheal occlusion.
Harrison and collegues demonstrated that by blocking the trachea, pressure increased within the fetal lung cavity, counteracting lung hypoplasia. Tracheal occlusion increased lung growth in normal and hypoplastic lungs and allowed the lungs to mature in utero , limiting the effect of the diaphragmatic hernia.
Fetal endoscopic tracheal occlusion surgery has been offered since to pregnant women whose fetuses have diaphragmatic hernia. Three European centers, one in Spain, one in the UK, and another in Belgium, reported in of an ongoing clinical study in which doctors closed holes in fetal diaphragms by using a balloon to block the trachea and to increase pressure in the fetuses' chest cavities. The balloon was removed pre-birth by fetoscopy or ultrasound -guided puncture, or after birth by tracheoscopy using an endoscope or a percutaneous puncture.
Gretaer than women participated in the European study, which showed that fetal endoscopic tracheal occlusion, compared to open surgery, to be a minimally invasive procedure for improving diaphragmatic hernias.
Aiding in diagnoses of fetal anomolies are improved imaging technologies, such as magnetic resonance imaging MRI and high resolution ultrasound—with its ability to measure the flow of blood through vessels to detect leaks. Many people assist in fetal surgeries, such as pediatric radiologists, ultrasonographers, perinatologists, neonatologists, neonatal surgeons, anesthesiologists, obstetrical and neonatal intensive care nurse practioners, social workers, and chaplains, who all often work together to provide information, coordination, education, technical skills and support.
Fetal surgery remains an option in less than one percent of all births. Keywords: Medical procedures , Fetus. Fetal Surgery Fetal surgeries are a range of medical interventions performed in utero on the developing fetus of a pregnant woman to treat a number of congential abnormalities. Sources Adzick, N. Scott, Elizabeth A. Thom, Catherine Y. Burrows, Mark P. Johnson, Lori J. Howell, Jody A. Farrell, Mary E. Dabrowiak, Leslie N. Sutton, Nalin Gupta, Noel B. Tulipan, Mary E. Bartoo, Carole. Begley, Sharon.
Belluck, Pam. Couzin, Jennifer. Harrison, Michael R. Filly, Julian T. Parer, Michael J. Faer, Jerome B. Jacobson, Alfred A. Scott Adzick, Alan W.
Flake, Russell W. Jennings, James M. Estes, Thomas E. MacGillivray, Jane T. Chueh, James D. She should be thoroughly informed that any subsequent pregnancy will require cesarean section at 37 weeks to avoid the risk of uterine rupture 38 , Once maternal risks have been established, attention can turn to fetal risks.
The most common fetal risks are preterm premature rupture of membranes and preterm labor. Research is being conducted on additional ways to decrease the incidence of preterm premature rupture of membranes and preterm labor see Research and Future directions below. After informed consent is obtained, the surgical intervention may proceed. The mother is placed on the operating room table with a left tilt, sequential compression devices in place and invasive blood pressure monitoring.
General anesthesia is induced with high concentrations of inhaled anesthetic to maintain uterine relaxation with the goal of minimizing fetal cardiac dysfunction during surgery 41 , Supplementing desflurane with intravenous anesthesia has been shown to reduce fetal cardiac dysfunction during open fetal surgery.
High doses of inhalational anesthesia can decrease maternal cardiac output with associated significant decreases in uterine blood flow. Diminished uterine blood flow results in decreased oxygen delivery to the placenta leading to subsequent fetal hypoxia. Supplemental intravenous anesthesia with desflurane may cause less acute fetal cardiac dysfunction compared to traditional high-dose inhalation anesthesia during fetal surgery. The fetus is continuously monitored intraoperatively.
This allows prompt detection of bradycardia which often precedes hypoxemic events. Once monitoring devices are in place, a Pfannensteiel, Maylard or lower midline maternal laparotomy is made followed by a hysterotomy.
The hysterotomy is made as far from the placental edge as possible at least 4cm , in order to minimize bleeding This may require exteriorizing the uterus to perform a posterior hysterotomy, if the placenta is anterior The fetus is positioned such that the tumor, defect, head and neck, or chest is delivered through the hysterotomy.
Tocolytic therapy is initiated as the hysterotomy is being closed. Next, the maternal laparotomy is approximated in layers. Finally, a plan is established for postoperative multimodal analgesia, as maternal pain can also initiate uterine contractions Figure 1. Exposure for Open Fetal Surgery for Myelomeningocele. Intravenous tocolysiis, which is begun in the operating room with a magnesium bolus and infusion, is continued for 24 hours.
Oral or rectal indomethacin is also often administered for hours following surgery. After this point, the mother is maintained on oral nifedipine until delivery. The fetus is sonographically monitored on a daily basis while the mother is recovering in the hospital and on a weekly basis once discharged. The fetus is then delivered at 37 weeks via cesarean section or at which time preterm premature rupture of membranes or preterm labor ensues.
Ex-utero intrapartum therapy EXIT serves as a modification of cesarean delivery to allow a near term fetal intervention before the neonate is delivered.
The main anesthetic goals are preservation of placental blood flow until other means of gas exchange can be established for the neonate, uterine relaxation, and fetal anesthesia The EXIT to airway procedure is further classified into extrinsic, intrinsic and iatrogenic Table 3 EXIT procedures are most commonly used to treat lymphatic malformations An EXIT procedure may be considered if the fetus has undergone prenatal imaging indicating the potential for severe airway obstruction or hypoxia.
A multidisciplinary team, composed of a pediatric surgeon trained in fetal surgery, maternal-fetal medicine obstetrician, pediatric otolarynologist, fetal cardiologist, social worker, radiologist, neonatologist, and anesthesiologist must then determine whether the mother and fetus are appropriate candidates Contraindications for the procedure include excessive risk such as instances with minimal tracheal involvement, or when little benefit is expected from the procedure, such as when there is complete tracheal agenesis or concomitant anomalies that make survival unlikely Placenta previa and subchorionic hemorrhage pose an increased maternal risk of complications and are therefore relative contraindications for the procedure The final decision to utilize an EXIT procedure requires consensus from the multidisciplinary team that a normal delivery would result in a tenuous airway that would be difficult to secure emergently.
Once the decision is made that it is appropriate to proceed with the EXIT procedure, informed consent should address the potential risks to the both the mother and fetus. It is crucial to emphasize that the health and safety of the mother will take precedence for all treatment considerations. Maternal complications to be discussed should include endometriosis and impact on subsequent pregnancies uterine rupture.
To date, no maternal deaths have been reported during an EXIT procedure The mother should also be consented for transfusion and a preoperative type and cross should be performed as maternal blood loss tends to ranging from ml during these procedures Fetal outcomes have been highly variable depending on the indication for EXIT procedure. This makes the consent more difficult. The discussion of fetal risks must be tailored to the specific patient and caution should be used when comparing outcomes of a particular study to a presenting patient as the selection criteria for each study is highly specific.
One of the most common indications for EXIT to airway is congenital high airway obstruction syndrome CHAOS , which is caused by several different etiologies including laryngeal atresia, subglottic stenosis or laryngeal. Fetuses with CHAOS must be monitored for the development of hydrops and degree of airway obstruction preoperatively. It is essential to determine the degree and location of the occlusion prior to the procedure.
The case by Vaikunth et al illustrates this point well. The fetus involved had complete tracheal agenesis which required neck and mediastinal exploration to secure an airway Without careful preoperative planning, the patient may have died in the operating room despite the EXIT procedure because a tracheostomy would have been unsuccessful in securing the airway. EXIT to resection is beneficial for thoracic, pulmonary or mediastinal Cass et al studied this group of patients and who also had persistent mediastinal compression near birth.
All patients who underwent EXIT procedures had favorable outcomes and survived to discharge All patients in the standard delivery group developed respiratory distress requiring urgent operations and two did not survive to discharge.
Stoffan et al performed a study on patients with severe congenital diaphragmatic hernia. EXIT to separation has been reported in the literature. Bouchard et al described a case of thoracoomphalopagus conjoined twins wherein Twin B had a rudimentary heart and was receiving blood flow from Twin A. Since cases of conjoined twins which would share the particular anatomy that would benefit from the EXIT procedure is exceedingly rare, it is uncertain whether this procedure will remain.
Typically, EXIT procedures are recommended at weeks gestational age, however certain considerations are made for individuals that would benefit from earlier deliveries Maternal conditions such as a history of preterm delivery, short cervix or fetal conditions polyhydramnios , may indicate the need for earlier delivery In all cases, the timing of delivery requires careful consideration and discussion. The team will include a maternal anesthesiologist, fetal anesthesiologist, scrub nurses, circulators, anesthesia technician, maternal-fetal medicine specialist, fetal cardiologist, pediatric surgeons, and the ECMO team at minimum.
This team of people is required for a successful EXIT procedure Attention to detail and thoroughness are essential. Each individual must know their assigned roles and each task needs to be assigned to a specific individual On the day of operation, two adjacent operating rooms are prepared and the team assembles to review key details of the procedure. As for open fetal surgery, the mother is positioned appropriately and monitoring devices for both the mother and fetus are applied. Prior to making a low transverse abdominal skin incision, ultrasonography is used to determine placental and fetal position, followed by increased anesthetic inhalation.
The abdomen is then entered via a muscle dividing or midline fascial incision to expose the uterus. A sterile ultrasound is repeated to verify the position of the fetus and placenta and place full-thickness stay sutures in the uterine wall at the location of the planned hysterotomy at least 4 cm away from the placental edge.
A bloodless hysterotomy, which involves isolating and clamping off all blood vessels to temporarily stop blood flow to the area, is established using a uterine stapler. The fetus is partially delivered and given intramuscular analgesics, paralytics and atropine. Fetal monitoring continues throughout the case with pulse oximetry and intermittent echocardiograms.
A catheter is placed within the uterus and warmed Ringer lactate or normal saline is infused to maintain amniotic fluid volume. Fetal interventions then typically begin with direct laryngoscopy followed by rigid bronchoscopy. If an airway is unable to be established, a tracheostomy may be necessary These steps may be altered depending on the indication for surgery and in some situations the initial intervention may be tracheostomy as anatomy would not permit the preceding steps, such as in congenital high airway obstruction syndrome.
In other cases associated severe congenital heart disease ECMO cannulation may be the first intervention required. Reports have indicated that the fetus can be maintained on placental circulation for up to 59 minutes, given that the uterus remains quiescent It is crucial to note that if the mother begins to hemorrhage, the fetus must be delivered at this time, regardless of if a definitive airway has been secured Prior to clamping the cord, all members of the team should be alerted.
Inhaled anesthetics should be reduced, oxytocin bolus administered and the uterus massaged to allow the uterus to contract and avoid maternal hemorrhage. The cord is then clamped and the fetus and placenta delivered. If the uterus remains atonic, methylergonovine and carboprost or mistoprostol can be administered to support uterine contraction and decrease maternal blood loss. A B-Lynch procedure can be utilized if there is continued maternal blood loss and uterine atony The B-Lynch procedure is performed by compressing the uterus with a large absorbable suture to control uterine hemorrhage or atony without hysterectomy.
In rare and very severe cases, hysterectomy may be required to control uterine hemorrhage. After control of uterine bleeding has been established, the hysterotomy and laparotomy are closed In this event, the mother requires transfusions as clinically indicated Other possible postoperative complications include endometritis and wound infections 57 , both of these conditions can be treated with antibiotic therapy.
As with open fetal surgery, if the hysterotomy must be extended onto the muscular, active portion of the uterus, there is a risk of uterine rupture in following pregnancies In these scenarios, the mother should be counseled to have a scheduled cesarean section in any subsequent pregnancies, prior to the onset of labor Several fetal procedures can be performed without the need for a hysterotomy and these are collectively referred to as closed fetal surgery This class of fetal interventions includes a wide array of procedures ranging from those that are entirely percutaneous technique to fetoscopic surgery requiring multiple trocars.
Twin-twin transfusion syndrome TTTS , twin reversed arterial perfusion TRAP sequence, multifetal reduction, and discordant structural anomalies are common indications for closed fetal surgery. Ultrasonic indications of monochorionicity include a single placenta, concordant sex by external genitalia and the shape of the intertwin membrane All pregnancies complicated by TTTS have placental vascular anastomoses and it is theorized that there is unbalanced flow between the twins which causes TTTS Prenatal ultrasound diagnostic criteria for TTTS includes monochorionicity; polyhydramnios and enlarged bladder in the recipient twin; oligohydramnios and small bladder in the donor twin, and weight discordance These pregnancies are at risk for the development of mirror syndrome which is potentially left-threatening to both the mother and fetus.
Symptoms of mirror syndrome include edema, hypertension, proteinuria, mild transaminases, headache or visual changes These symptoms closely resemble those of preeclampsia and are best distinguished by anemia in mirror syndrome but slight polycythemia in preeclampic patients Mothers affected by mirror syndrome may experience postpartum hemorrhage, pulmonary edema, congestive heart failure, DIC and acute renal failure They are also at increased risk of severe complications after undergoing interventions that increase blood flow across the hydropic placenta Therefore, closed fetal surgical interventions for TTTS should not be performed in cases of mirror syndrome as it may increase maternal morbidity and mortality.
TRAP sequence is a rare phenomenon occurring in monozygotic pregnancies TRAP sequence can be identified in monochorionic twins via prenatal ultrasound by identification of acardia in one twin, placental vascular anastomosis on Doppler with reverse flow on artery-artery anastomosis If TTTS or TRAP sequence develops, preoperative planning must include consideration of maternal and fetal factors related to the type of procedure and location of the intervention.
There are a variety of fetal interventions that can be used to treat TTTS. There are unique risks and benefits to each type of procedure and fetoscopes are only approved to treat TTTS between weeks of gestation limiting some indications Serial amnioreduction and serial amnioreduction with micorseptostomy are perhaps the least invasive of the fetal procedures to treat TTTS.
These are palliative measures which simply reduced the amount of amniotic fluid around the recipient twin to a normal amniotic fluid volume The goal of these procedures is merely to decrease the risk of preterm labor and premature rupture of membranes This goal must be tempered with the knowledge that removal of more than 5 liters at once increases the risk of placental abruption and fetal bradycardia Adding microseptostomy to amnioreduction allows equilibration of intra-amniotic pressure between the two gestational sacs.
Moise et al performed a randomized control trial of amnioreduction versus amnioreduction with microseptostomy. They did note that the amnioreduction group did require statistically more interventions than the amnioreduction with microseptostomy group The risks of microseptostomy include amniotic bands and disruption of the intertwin membrane creating a monoamniotic pregnancy with risk of cord entanglement and double demise.
Microseptostomy is similarly performed under ultrasound guidance but a single passage of the needle is made through the amniotic sac of the donor twin. It is important to note, that only a single passage should be performed through the donor sac as multiple punctures can result in monoamnionicity, cord entanglement and fetal demise Like serial amnioreduction, with laser ablation, there is the potential for survival of both twins As mentioned above, monochorionic twin pregnancies complicated by TTTS have abnormal placental vascular anastomoses.
Correction of the TTTS has been shown to have superior outcomes to amnioreduction in randomized control trials. Furthermore, the procedure has been modified over the years to improve outcomes. The most recent variation on this procedure, the Solomon technique described below , has been shown to have improved outcomes in a randomized control trial Recurrent TTTS and large intertwin anastomoses are also more likely to occur if the cord is short.
Also like serial amnioreduction, laser ablation is generally performed under local anesthesia The dividing membrane is identified and each vessel inspected to determine its endpoint If there is no endpoint, it is determined to be an intertwin anastomosis and W from a diode or Yttrium Aluminum Garnet YAG laser is delivered to the aberrant vessel with a um laser fiber This portion of the procedure is referred to as selective fetoscopic laser photocoagulation.
The Solomon technique involves the addition of laser photocoagulation in a line from one edge of the placenta to the other This supplementary portion of the procedure effectively dichorionizes the placenta. Prior to completion of the procedure, amnioreduction is also performed Unlike serial amnioreduction and laser ablation where there is the possibility of dual twin survival, other treatments of TTTS, such as radiofrequency ablation RFA and bipolar cord occlusion, involve selective fetal reduction.
Both of these procedures require complete ablation of blood flow in the umbilical cord If complete cord occlusion is not achieved, there can be a shift in the blood flow from the healthy to the dying twin which results in demise of both fetuses As a result, ultrasounds are often performed on postoperative day one to look for increased middle cerebral artery pressures in the surviving twin which are indicative of fetal anemia Radiofrequency ablation is generally performed on fetuses ranging in age from weeks estimated gestational age EGA and outcomes do not seem to be related to the gestational age at which the procedure is performed 61 , Radiofrequency ablation also includes complications specific to the procedure itself.
The procedure can cause thermal injury to the surviving twin 61 , 68 , Kumar et al reported their experience with cases of RFA. In their cohort there were two cases of presumed thermal injury to the surviving twin.
Both cases resulted in significant injury, as one resulted in a severe limb abnormality and the other required skin grafting As with most fetal procedures, RFA is performed under ultrasound guidance. The cord insertion site of the target twin is identified and a trajectory for the RFA needle identified to avoid the placenta.
The RFA needle is only 8cm in length, therefore maternal obesity or a posterior placenta may be a may pose a challenge for accessibility or be an absolute contraindication Local anesthetic is instilled followed by a 3 mm incision in the maternal abdominal wall The RFA gauge needle is inserted, positioned at the cord insertion of the fetal abdominal wall, and the tines are extended.
One cycle is often adequate but if further cycles are required, the tines are allowed to cool for minutes between cycles 61 , 68 , Cycles are continued until there is cessation of flow in the umbilical cord by pulsed wave and color Doppler and cardiac asystole is confirmed To date, there has not been a randomized control trial comparing RFA with BCO but there has been a recent metaanalysis reported This study revealed that there was no statistical difference between RFA and BCO with regards to live birth rate, neonatal death rate or overall survival.
RFA was associated with a significantly lower rate of preterm premature rupture of membranes Thus, the authors appropriately concluded that one procedure is not clearly superior. To perform this procedure, a free cord loop of the umbilical cord is identified near its abdominal or placental insertion site A cannula is inserted into the uterine cavity perpendicular to the cord such that a cross-sectional view of all three vessels is visible A 5mm endoscopic bipolar coagulation forceps is inserted, the cord grasped and bipolar coagulation initiated at 20 Watts If needed, the power can slowly be increased until Doppler flow demonstrates complete occlusion of the vessels This is repeated at two additional cord segments Occasionally there are indications for fetoscopic surgery wherein multiple trocars are required in the uterus.
For example, fetoscopic surgery with multiple trocars has been used for tracheal occlusion in severe congenital diaphragmatic hernias, to release amniotic bands if the fetus or limb is threatened 71 and in patients with myelomeningocele MMC Preoperative counseling and imaging are similar to other forms of fetal surgery.
A multidisciplinary team should meet with the mother to discuss risks, benefits, expected outcomes, and perinatal care. The fetus should undergo thorough imaging with a complete sonographic anatomic survey, echocardiogram, amniocentesis and fetal MRI to rule out other anatomic and chromosomal anomalies. Complications of fetoscopic surgery are also similar to other forms of fetal surgery including premature labor and premature rupture of membranes.
Currently, fetoscopic repair of MMC is controversial. It has been reported to require longer operative times in comparison to open fetal surgical repair and presents technical difficulty as the result of the layered closure of the defect. These findings are unexpected and be indicative of the need for multiple trocars and longer operative times for fetoscopic repair.
In spite of this, Pedreira et al recently completed a Phase I trial suggesting that fetoscopic repair can be safe and effective using the technique described below Further research will be necessary to directly compare the outcomes of these two interventions.
Maternal antibiotics are administered within one hour prior to incision. Next the mother is administered local, epidural, or general anesthesia. The gravid abdomen is imaged through ultrasound to determine the position of the fetus and placenta. To avoid injury to the fetus, bleeding, or inducting PPROM; an anterior placenta may require maternal laparotomy with exteriorization of the uterus, but laparoscopic-assisted fetoscopy or the use of curved trocars can be utilized to avoid maternal laparotomy.
Once proper positioning is established to triangulate the fetal pathology, Seldinger technique is used to insert a camera port. Additional trocars are placed. Amnioinfusion or partial amniotic Carbon Dioxide CO 2 insufflation can improve visibility 72 , The fetus is monitored by sonography throughout the procedure. For MMC repair, the fetus is positioned and the neural placode is released circumferentially at the transition zone The placode can be covered with a patch and then skin is closed over the defect.
A two-layer closure is performed. A skin substitute may be used if the defect does not allow midline approximation Although not required, uterine closure devices may be used to seal the puncture sites if the patient is believed to benefit from their use Fetoscopic tracheal occlusion FETO has been shown to improve outcomes in severe congenital diaphragmatic hernias in multiple studies. Since the most profound influence on outcomes in congenital diaphragmatic hernia is due to pulmonary hypoplasia and the resulting pulmonary hypertension, Dr.
Harrison theorized that tracheal occlusion would stimulate lung growth. After developing an ovine model and proving this theory in sheep, it was translated to humans. With careful selection of the patient population, randomized control trials have demonstrated increased survival in isolated congenital diaphragmatic hernias treated with FETO However, studies have also shown that the mortality for is greater for a subset of this population who deliver prior to 35 weeks gestation and that these patients require significantly longer duration of mechanical ventilation, supplementary oxygen and have longer hospital stays Once trocars are placed and the fetoscope inserted, the fetus is given an intramuscular injection of anesthetic and paralytic.
The cannula containing the fetoscope is advanced into the fetal mouth and down through the vocal cords into the trachea. A catheter is inserted along the scope containing a detachable balloon and positioned just above the carina.
The balloon is inflated with 0. The position of the balloon just above the carina is confirmed by ultrasound. The procedure is concluded as above. Little can be said regarding the long-term outcomes for children whom have undergone fetal surgery.
Many have theorized that neonatal exposure to anesthetics could lead to neurocognitive deficits. Thus, similar concerns are held for survivors of fetal surgery but studies are lacking. Tosello et al have looked at short and medium-term outcomes for survivors of fetoscopic laser therapy for TTTS 79 , 8.
They found increased survival for their cohort but demonstrated a 5. Van Klink et al also published a meta-analysis on long-term neurodevelopmental outcomes in twins after fetal therapy Not surprisingly, they found decreased gestational age to be an independent risk factor for neurodevelopmental impairment Their data also suggested an overall rate of cerebral palsy of 7. More information is available for outcomes on mothers involved in fetal surgery. As mentioned above, fetal surgery offers the mother no benefits and has long term implications.
There is a risk of maternal death during or shortly after surgery. Likewise, there is a risk of postoperative pulmonary edema that may require intensive care and intubation Perhaps the most extensively studied aspect of maternal outcomes is the impact on her future reproductive health.
In order to decrease these risks, it is recommended that mothers wait two years after open fetal surgery to attempt a subsequent pregnancy to allow the uterus to heal. Likewise, she is not allowed to labor during subsequent pregnancies and thus requires a cesarean section prior to the onset of labor at 37 weeks. Subsequent pregnancies are also at risk of placental accreta.
The incidence of placental accreta is rare and the incidence after fetal surgery has not been calculated at this point, but when the placental vasculature invades the wall of the uterus too deeply, the effects can be life threatening Identifying potential modifications of the procedures to decrease these risks could greatly expand the indications for these procedures by decreasing the associated risks.
Cervical length shortening is an identified risk factor for preterm labor. Cervical pessary and cervical cerclage have been proposed to minimize the risk of preterm delivery after fetal surgery. In a retrospective study of 16 patients, delivery at greater gestational ages was achieved through the use of the Arabin cervical pessary Further research is required to verify these data given the modest sample size and retrospective nature of this study.
Inconsistent findings have been reported with cervical cerclage.
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