© 2004 by the American Institute of Ultrasound in Medicine
J Ultrasound Med 23:1663-1666 • 0278-4297
Successful Sonographically Guided Laser Ablation of a Large Acardiac Twin at 26 Weeks’ Gestation
Waldo Sepulveda, MD,
Jorge Hasbun, MD,
Victor Dezerega, MD,
Juan C. Devoto, MD and
Juan L. Alcalde, MD
Fetal Surgery Program, Department of Obstetrics and Gynecology, Clinica Las Condes, Santiago, Chile (W.S., V.D., J.C.D., J.L.A.); and Department of Obstetrics and Gynecology, Hospital Clinico, University of Chile, Santiago, Chile (J.H.).
Address correspondence and reprint requests to Waldo Sepulveda, MD, Fetal Medicine Center, Clinica Las Condes, Casilla 208, Santiago 20, Chile. E-mail: waldosep{at}hotmail.com.
 |
Introduction
|
|---|
A cardiac twinning, also known as the reversed arterial perfusion sequence, is a unique complication of monochorionic placentation occurring in 1% of monozygotic twins and 1 per every 35,000 pregnancies.1 In this condition, the structurally normal "pump" twin provides blood supply to the parasitic acardiac twin in a retrograde, paradoxical fashion through a single superficial artery-to-artery anastomosis.2 In many cases, the continuous growth of the acardiac twin and the associated "vascular steal" phenomenon may lead to cardiac insufficiency and polyhydramnios in the pump twin.3 In such cases, intrauterine treatment to interrupt blood flow to the acardiac twin could be the only way to prevent perinatal death of the pump twin.4,5
Percutaneous sonographically guided laser coagulation of the intra-abdominal vessels (ie, the intra-abdominal segment of the single umbilical artery, the intrapelvic vessels, and the abdominal aorta) has been reported as an effective, minimally invasive method to ablate acardiac twins, but the few reported cases to date have been carried out in early pregnancy, during which the size of the acardiac twins is relatively small.6,7 In this report, we describe the use of this technique in the management of a twin pregnancy complicated by a large acardiac twin at 26 weeks’ gestation.
|
Case Report
|
|---|
A 26-year-old primigravida was referred to our tertiary referral center at 26 weeks’ gestation because of a twin pregnancy complicated with a rapidly growing acardiac twin and polyhydramnios. The diagnosis of a monochorionic-diamniotic twin pregnancy was established at 12 weeks’ gestation, at which time a fetus with no abnormalities, a crown-rump length of 66 mm, and nuchal translucency of 1.7 mm was seen in 1 sac, and a 44-mm edematous, acardiac, acephalic fetus with gross abnormalities was seen in the other sac. Color Doppler sonography confirmed the reversed arterial perfusion sequence. Follow-up sonograms at 17 and 22 weeks’ gestation revealed continuous growth of the acardiac twin but no congenital anomalies, cardiac impairment, or polyhydramnios in the pump twin. At 25 weeks, however, the patient had rapid increase in uterine height, mild uterine contractions, and positional discomfort. At referral, sonography confirmed cardiomegaly and polyhydramnios in the pump twin. The acardiac twin was much larger than the pump twin because of the presence of massive subcutaneous edema and large cystic hygromas (Figure 1 ). Cervical assessment revealed a short cervix with funneling.
View larger version (122K):
[in this window]
[in a new window]
|
Figure 1. Sonographic view of the acardiac acephalic twin (left) and the abdominal circumference of the pump twin (right) at 26 weeks’ gestation. Note that the acardiac twin is much larger than the pump twin.
|
|
Due to the risk of prematurity, polyhydramnios, and the substantial growth of the acardiac mass over the last 3 weeks, a wide range of minimally invasive treatment options were discussed at length.5 The parents opted for percutaneous sonographically guided laser coagulation of the intra-abdominal vessels, which was performed under epidural anesthesia at 26 weeks 4 days. The protocol was approved by the Institutional Review Board, and, after informed consent was obtained, the main vessel supplying the acardiac twin was identified with color Doppler sonography, and the segment where both the artery and vein were simultaneously identified within the fetal abdomen was selected as the target. An 18-gauge needle was then passed under continuous sonographic control until the tip of the needle was located near the targeted vessels (Figures 2 and 3). The stylet was then retrieved, and a 400-µm neodymium:yttrium-aluminum-garnate laser fiber (Surgical Laser Technologies, Montgomeryville, PA) was passed and advanced 1 cm away from the tip of the needle to reach the vessels. Intermittent pulses of 30 to 40 W were used to coagulate the vessels until complete absence of blood flow signals was documented by color Doppler sonography. The ablation procedure lasted 10 minutes and was complemented with aspiration of 200 mL of clear fluid from the largest cystic hygroma and amniodrainage of 2200 mL, restoring the amniotic fluid volume to normal. The patient received steroids intramuscularly to enhance fetal lung maturity and was discharged home in good condition the following day with an indication of bed rest for the remainder of the pregnancy. Follow-up scans showed progressive shrinkage of the acardiac mass and normal fetal growth of the pump twin.
View larger version (132K):
[in this window]
[in a new window]
|
Figure 2. Sonographically guided laser ablation of the acardiac twin. The laser fiber has been passed through an 18-gauge needle.
|
|
At 36 weeks, reduced amniotic fluid volume and decreased fetal movements prompted induction of labor. The pump twin was delivered vaginally, weighed 2820 g, and had Apgar scores of 9 and 9 at 1 and 5 minutes, respectively. The acardiac twin was delivered with the placenta and weighed 324 g. Pathologic examination confirmed the prenatal diagnosis of an acardiac twin with single artery-to-artery and vein-to-vein anastomoses in the surface of the placenta.
|
Discussion
|
|---|
Management of a twin pregnancy complicated by an acardiac twin is a major perinatal challenge because the continuous growth of the acardiac fetus is potentially deleterious to the healthy pump twin by leading to cardiac insufficiency, polyhydramnios, prematurity, and even perinatal death of the structurally intact twin in up to 50% of cases.3 Several case studies have shown that when growth of the acardiac twin continues and the pump twin decompensates in a previable gestation, perinatal death or severe prematurity of the pump twin may be prevented with prenatal intervention.4,5 However, ablation of the acardiac twin can be technically challenging. Initial attempts aimed at interrupting the blood supply at the level of the acardiac twin’s umbilical cord.4 However, difficulties in accessing the abnormally short, friable, and thin umbilical cord, in addition to the close juxtaposition of the single umbilical artery and vein, were frequently associated with death of the pump twin due to cord accidents and passage of ablative material into the pump twin’s circulation. Lately, more effective methods for cord occlusion have been reported, such as ligation and laser coagulation of the umbilical cord under fetoscopic control.5 Endoscopic techniques, however, are more invasive, lengthy, and cumbersome than sonographically guided needle techniques and require surgical skills and equipment only available in a few centers in the world. In addition, they frequently require additional procedures such as a second port for amnioinfusion and septostomy in cases in which the access is through the sac of the pump twin.8
Targeting the intrafetal rather than the umbilical cord vessels is an alternative option.9 Currently, 4 methods for sonographically guided intrafetal ablation are available: intravascular chemosclerosis with absolute alcohol,9,10 monopolar diathermy,11 interstitial laser ablation,6,7 and radio frequency ablation.12 This approach has been greatly facilitated with the use of color Doppler sonography, which allows clear identification of the feeding vessel and its intra-abdominal branches, making these vessels easier targets to reach than the umbilical cord when using sonographically guided needle techniques. The most important advantage of intrafetal ablation over endoscopic techniques is the fact that it can be carried out in any fetal medicine unit with facilities to perform fetal blood sampling using needles commonly used for standard cytogenetic diagnostic procedures. In addition, a recent systematic review of the literature on acardiac twins treated with minimally invasive techniques showed that intrafetal ablation is indeed simpler, safer, and more effective than cord occlusion techniques.5
In the case we report here, laser energy was used to ablate a large acardiac twin successfully at 26 weeks’ gestation. To our knowledge, on the basis of a MEDLINE search, this very same technique has been reported in 4 previous cases of acardiac twinning, although during the early second trimester, with all 4 pump twins being delivered at term with no neonatal complications.6,7 We think that the main reason for the high success rate of this technique is the ease of identification of the intra-abdominal vessels on color Doppler sonography and a good technique to reach the targeted vessels when the operator is familiar with intrauterine invasive procedures. However, further experience in this area would be desirable to more specifically address the definitive value of sonographically guided intra-abdominal laser ablation in the treatment of acardiac twinning.
Current indications for prenatal intervention in pregnancies complicated with acardiac twinning include evidence of cardiac failure in the pump twin, severe polyhydramnios, and overgrowth of the acardiac twin. Although several investigators have recently recommended prenatal intervention in early stages of pregnancies to prevent, rather than to treat, these complications,6 we think that close sonographic surveillance could confidently select those pregnancies destined to have a poor outcome. Therefore, treatment can be offered only to those pregnancies that will benefit from therapy. In these cases, laser coagulation of the acardiac twin’s abdominal vessels may have potential value for improving the perinatal outcome of the pump twin, even in pregnancies at advanced gestational ages.
|
Footnotes
|
|---|
Received July 24, 2004, from the Fetal Surgery Program, Department of Obstetrics and Gynecology, Clinica Las Condes, Santiago, Chile (W.S., V.D., J.C.D., J.L.A.); and Department of Obstetrics and Gynecology, Hospital Clinico, University of Chile, Santiago, Chile (J.H.). Revision requested July 29, 2004. Revised manuscript accepted for publication August 2, 2004.
This work was supported by Sociedad Profesional de Medicina Fetal "Fetalmed" Limitada and a grant from the Direccion Academica, Clinica Las Condes, Santiago, Chile.
|
References
|
|---|
- Sebire NJ, Sepulveda W, Jeanty P, Nyberg DA, Nicolaides KH. Multiple gestations. In: Nyberg DA, McGahan JP, Pretorius DH, Pilu G (eds). Diagnostic Imaging of Fetal Anomalies. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:777–813.
- Van Allen MI, Smith DW, Shepard TH. Twin reversed arterial perfusion (TRAP) sequence: a study of 14 twin pregnancies with acardius. Semin Perinatol 1983; 7:285–293.[Medline]
- Moore TR, Gale S, Benirschke K. Perinatal outcome of forty-nine pregnancies complicated by acardiac twinning. Am J Obstet Gynecol 1990; 163:907–912.[Medline]
- Arias F, Sunderji S, Gimpelson R, Colton E. Treatment of acardiac twinning. Obstet Gynecol 1998; 91:818–821.[Abstract]
- Tan TYT, Sepulveda W. Acardiac twin: a systematic review of minimally invasive treatment modalities. Ultrasound Obstet Gynecol 2003; 22:409–419.[Medline]
- Jolly M, Taylor M, Rose G, Govender L, Fisk NM. Interstitial laser: a new surgical technique for twin reversed arterial perfusion sequence in early pregnancy. BJOG 2001; 108:1098–1102.[Medline]
- Soothill P, Sohan K, Carroll S, Kyle P. Ultrasound-guided, intra-abdominal laser to treat acardiac pregnancies. BJOG 2002; 109:352–354.[Medline]
- Quintero RA. Sonography-guided invasive procedures in the management of abnormalities involving multifetal monochorionic pregnancies. In: Monteagudo A, Timor-Tritsch IE (eds). Ultrasound and Multifetal Pregnancy. New York, NY: Parthenon Publishing Group; 1998:165–178.
- Sepulveda W, Bower S, Hassan J, Fisk NM. Ablation of acardiac twin by alcohol injection into the intra-abdominal umbilical artery. Obstet Gynecol 1995; 86:680–681.[Abstract]
- Sepulveda W, Corral E, Aiello H, et al. Intrafetal alcohol chemosclerosis of acardiac twins: a multicenter experience. Fetal Diagn Ther 2004; 19:448–452.[Medline]
- Rodeck C, Deans A, Jauniaux E. Thermocoagulation for the early treatment of pregnancy with an acardiac twin. N Engl J Med 1998; 339:1293–1295.[Free Full Text]
- Tsao K, Feldstein VA, Albanese CT, et al. Selective reduction of acardiac twin by radiofrequency ablation. Am J Obstet Gynecol 2002; 187:635–640.[Medline]
|
|
Top
Introduction
Case Report
