Fetal Surgery

Background

EarlyStages keyFetal Surgery is a term used to describe a wide array of procedures used in the treatment of birth defects while the fetus is still in the womb. Both open and minimally invasive surgical techniques have been used to correct various pathologies from cardiac abnormalities to limb defects. As with any surgical procedure, there are inherent risks, although in these cases, two patients (mother and fetus) are vulnerable instead of one. Most birth defects discovered during the pregnancy are amenable to treatment after birth, however, improved outcomes have been demonstrated for some defects corrected in utero. Therefore, the risk of fetal surgery to both the mother and fetus always has to be weighed against the potential benefit of the treatment to the fetus.

Congenital Heart defects (CHDs) are the most common type of birth defect. They affect almost 1% or about 40,000 births per year in the U.S. and are the leading cause of infant illness and death. Currently, there are about 2 million children and adults living with CHDs.

Current Treatment

Minimally invasive fetal surgery has gained popularity in recent years due to advancements in surgical techniques and imaging. Treatments can be performed through tiny openings in the abdomen that limit the risk to the mother and reduce the chance of provoking pre-term labor. Common defects that can now be treated with minimally invasive surgery include:

  • Twin-twin Transfusion syndrome (laser ablation of blood vessels)
  • Fetal Bladder Obstructions
  • Aortic or Pulmonary Valvuloplasty (opening of the aortic or pulmonary valves to allow blood to flow)
  • Atrial Septostomy (opening the inter-atrial septum to allow blood flow between the right and left atrium)
  • Spina Bifida

Focused Ultrasound Research

Focused Ultrasound is not currently an approved treatment for fetal birth defects but has been proposed as a potential non-invasive alternative to open surgery. Focused ultrasound has the ability to use acoustic energy to destroy target tissue through cavitation (histotripsy) or thermal ablation. This could help treat defects like Twin-twin transfusion syndrome (ablation of vessels), fetal bladder obstructions and a range of CHDs (atrial-septal defects, valvuloplasty, tetralogy of fallot).

Some pre-clinical feasibility studies have yielded promising results for procedures including cardiac valve ablation, vascular occlusion and fetal tissue ablation. However, for research to progress past the pre-clinical and anecdotal stages, more studies are needed to further explore safety and efficacy.

Notable Papers

Shaw CJ, ter Haar GR, Rivens IH, Giussani DA, Lees CC. Pathophysiological mechanisms of high-intensity focused ultrasound-mediated vascular occlusion and relevance to non-invasive fetal surgery. J R Soc Interface. 2014 Mar 26;11(95):20140029.

Okai T, Ichizuka K, Hasegawa J, Matsuoka R, Nakamura M, Shimodaira K, Sekizawa A, Kushima M, Umemura S. First successful case of non-invasive in-utero treatment of twin reversed arterial perfusion sequence by high-intensity focused ultrasound. Ultrasound Obstet Gynecol. 2013 Jul;42(1):112-4.

Griffiths A, terHaar G, Rivens I, Giussani D, Lees C. High-intensity focused ultrasound in obstetrics and gynecology: the birth of a new era of noninvasive surgery? Ultraschall Med. 2012 Dec;33(7):E8-15.

Ichizuka K, Hasegawa J, Nakamura M, Matsuoka R, Sekizawa A, Okai T, Umemura S. High-intensity focused ultrasound treatment for twin reversed arterial perfusion sequence. Ultrasound Obstet Gynecol. 2012 Oct;40(4):476-8.

Kim Y, Gelehrter SK, Fifer CG, Lu JC, Owens GE, Berman DR, Williams J, Wilkinson JE, Ives KA, Xu Z. Non-invasive pulsed cavitational ultrasound for fetal tissue ablation: feasibility study in a fetal sheep model. Ultrasound Obstet Gynecol. 2011 Apr;37(4):450-7.

Paek B, Foley J, Zderic V, Starr F, Shields LE, Vaezy S. Selective reduction of multifetal pregnancy using high-intensity focused ultrasound in the rabbit model.
Ultrasound Obstet Gynecol. 2005 Sep;26(3):267-70.

Otsuka R1, Fujikura K, Hirata K, Pulerwitz T, Oe Y, Suzuki T, Sciacca R, Marboe C, Wang J, Burkhoff D, Muratore R, Lizzi FL, Homma S. In vitro ablation of cardiac valves using high-intensity focused ultrasound. Ultrasound Med Biol. 2005 Jan;31(1):109-14.

Paek BW, Vaezy S, Fujimoto V, Bailey M, Albanese CT, Harrison MR, Farmer DL. Tissue ablation using high-intensity focused ultrasound in the fetal sheep model: potential for fetal treatment. Am J Obstet Gynecol. 2003 Sep;189(3):702-5.

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