We read with interest the paper by Stirnemann et al.1 evaluating the utility of the CHOP (Children's Hospital of Philadelphia) cardiovascular score for twin–twin transfusion syndrome (TTTS) as a predictor of outcome following laser photocoagulation of placental vessels. They found the CHOP score not to be predictive of survival. In an accompanying Opinion, Quintero, amongst a number of other points, questioned the role of fetal echocardiography in the evaluation of TTTS patients2.

In developing the CHOP score, our intent was not to develop a tool to predict survival after laser therapy, nor to replace the Quintero staging system, but rather to add an additional layer of understanding to the evaluation, utilizing an analysis scheme specific to the cardiovascular system3. Cardiovascular abnormalities are prevalent in TTTS and contribute to the origins and foundation of the disease. Some of these abnormalities are subtle, and some are not so subtle, but they are readily evident to those who look. The CHOP score provides a means of characterizing and quantifying the degree of cardiovascular disease burden present in a systematic and logical manner, tailored to our current understanding of the mechanisms of the disease. It provides a sense of scale to the physiological aberration present that is not adequately provided by the Quintero staging system.

We have learned much since our initial description of the CHOP score in 2007. We find it is most helpful when utilized as a continuous variable with points ranging from 0 to 20, and not as a categorical variable divided into quartiles or ‘cardiac stages’ as evaluated in part by Stirnemann et al.1. We have found it to be a tool that provides the capacity to improve our understanding of the physiological impact of laser photocoagulation therapy. At the 2010 ISUOG World Congress we present data in an abstract4 looking at the CHOP score in a serial manner, before and after therapy. We found no change in CHOP score at 24 hours, but noted a significant reduction at 1 week after laser photocoagulation. Furthermore, assessment of change in the individual elements of the CHOP score provides insight into the physiological effects of therapy, as diastolic elements such as filling properties of the ventricle improve well in advance of systolic elements such as atrioventricular valve regurgitation.

Is there value in assessment of the cardiovascular system in TTTS? Stirnemann et al.1 did not find the CHOP score to be predictive of outcome as defined by survival; however, as most fetuses are now expected to survive, it has become more important to look at other outcome variables, such as cardiovascular morbidity. Such morbidity, if present, also demands scrutiny and serial follow-up during the course of gestation. Development of right-sided outflow tract obstruction continues to plague 10–20% of recipient fetuses3. Persistent ventricular dysfunction or valvular regurgitation in laser treatment survivors may require intervention in the neonatal period. Furthermore, ongoing gestation and development within the inhospitable physiological storm of TTTS may impact negatively on postnatal cardiovascular health in childhood and later adult life5. The means to measure this degree of cardiovascular derangement by utilization of the CHOP score at initial diagnosis, after therapy and in a serial manner throughout gestation provides a way with which to assess continued disease manifestations and correlate these findings with long-term outcome—a role not fulfilled by the Quintero staging system.

TTTS is a multidimensional disease and as such it demands a multidimensional approach to evaluation. Both the Quintero staging system and the CHOP score are tools to be wielded in the battle against TTTS. But perhaps the perspective needs to be broadened beyond simple fetal survival. The objective in the current era should be to optimize outcome and provide the best quality of life, free of residual disease. This, undoubtedly, is the goal.


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  • 1
    Stirnemann JJ, Nasr B, Proulx F, Essaoui M, Ville Y. Evaluation of the CHOP cardiovascular score as a prognostic predictor of outcome in twin–twin transfusion syndrome after laser coagulation of placental vessels in a prospective cohort. Ultrasound Obstet Gynecol 1010; 36: 5257.
  • 2
    Quintero R. Chop, chop. Ultrasound Obstet Gynecol 2010; 36: 69.
  • 3
    Rychik J, Tian Z, Bebbington M, Xu F, McCann M, Mann S, Wilson RD, Johnson MP. The twin–twin transfusion syndrome: spectrum of cardiovascular abnormality and development of a cardiovascular score to assess severity of disease. Am J Obstet Gynecol 2007; 197: 392. e1e8.
  • 4
    Rychik J, Bebbington M, Johnson M, Zeng S, Tian Z. OC07.04. Pattern of cardiovascular disease regression following fetoscopic selective laser photocoagulation for twin–twin transfusion syndrome. Ultrasound Obstet Gynecol 2010; 36 (Suppl.1): 14.
  • 5
    Gardiner HM, Taylor MJ, Karatza A, Circulation 2003; 107: 1906–1911. Twin-twin transfusion syndrome: the influence of intrauterine laser photocoagulation on arterial distensibility in childhood. Circulation 2003; 107: 19061911.

J. Rychik*, Z. Tian*, M. Bebbington†, J. Moldenhauer†, N. Khalek†, M. Johnson†, * Fetal Heart Program, The Children's Hospital of Philadelphia, Philadelphia, PA, USA, † Center for Fetal Diagnosis and Treatment, The Children's Hospital of Philadelphia, Philadelphia, PA, USA