www.elsevier.com/locate/jpedsurg

Journal of Pediatric Surgery (2011) 46, 1182–1185

Tumor volume to fetal weight ratio as an early prognosticclassification for fetal sacrococcygeal teratomaManuel A. Rodriguez a, Darrell L. Cass a,b, David A. Lazar a,b, Christopher I. Cassady b,Kenneth J. Moise b, Anthony Johnsonb, Oren P. Mushin a, Saif F. Hassan a,Bella Belleza-Bascon b, Oluyinka O. Olutoye a,b,⁎

aDivision of Pediatric Surgery, Michael E. DeBakey Department of Surgery, Texas Children's Hospital,Baylor College of Medicine, Houston, TX 77030, USAbTexas Children's Fetal Center, Texas Children's Hospital, Baylor College of Medicine, Houston, TX 77030, USA

Received 15 March 2011; accepted 26 March 2011

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Key words:Sacrococcygeal teratoma;SCT;Fetal surgery;Tumor volume to fetalweight ratio;

TFR;Outcome

AbstractPurpose: This study was designed to develop a prognostic factor for fetuses with sacrococcygealteratoma (SCT) that may be useful to predict outcome and guide counseling early in pregnancy. Wehypothesize that, in fetuses with SCT, the ratio of tumor size to estimated fetal weight in the secondtrimester predicts outcome.Methods: We retrospectively reviewed charts of all patients evaluated at our Fetal Center for SCTbetween 2004 and 2009. Estimated fetal weight and tumor volume were calculated based on prenatalultrasound or fetal magnetic resonance imaging. Patients were stratified based on tumor volume to fetalweight ratio (TFR), and their outcomes were analyzed by Fisher's Exact test.Results: Tumor volume to fetal weight ratio before 24 weeks' gestation was predictive of outcome.Those with a TFR less than or equal to 0.12 (n = 5) had a significantly better outcome than patients witha TFR greater than 0.12 (n = 5, P b .05). All patients with poor outcomes had a TFR greater than 0.12by 24 weeks' gestation. A TFR greater than 0.12 predicted poor outcome with 100% sensitivity and83% specificity. All 4 patients who developed hydrops had a TFR greater than 0.12.Conclusion: In our series of fetuses with SCT, TFR before 24 weeks' gestation correlates with outcome.This novel, prenatal diagnostic tool may be useful in prenatal counseling and for early identification ofhigh-risk fetuses.© 2011 Elsevier Inc. All rights reserved.

Sacrococcygeal teratoma (SCT) is the most common SCT is quite variable. Whereas some fetuses have an

congenital tumor in newborns, with a reported incidence of 1in 27,000 to 40,000 births [1,2]. The outcome of fetuses with

⁎ Corresponding author. Texas Children's Hospital, 6701 Fannin St.,linical Care Center CC650, Houston, TX 77030, USA. Tel.: +1 832 822135(Office); fax: +1 832 825 3141.E-mail address: oolutoye@bcm.edu (O.O. Olutoye).

022-3468/$ – see front matter © 2011 Elsevier Inc. All rights reserved.oi:10.1016/j.jpedsurg.2011.03.051

uncomplicated prenatal course, about one half of thosediagnosed by the second trimester die before birth because ofcomplications of the tumor [3]. As a result, fetuses with SCTrequire close in utero surveillance for rapid tumor growth andsecondary physiologic effects [4]. This variability inoutcome has created a dilemma in family counseling; andseveral prognostic factors have been studied including tumor

1183SCT tumor volume ratio

size, rate of growth, intratumoral calcifications, solid vscystic component, vascularity, presence of hydronephrosis orbladder displacement, and polyhydramnios [5-7].

The objective of this study was to develop a simple andsensitive prognostic factor that may be useful to predictoutcome and guide counseling early in pregnancy. Wehypothesized that in fetuses with SCT, the tumor volumeto fetal weight ratio (TFR) in the second trimester willpredict outcome.

1. Methods

Following approval by the Institutional Review Board ofBaylor College of Medicine (H-26009), the medical recordsof all patients evaluated at the Texas Children's Fetal Centerfor SCT between 2004 and 2009 were retrospectivelyreviewed. Data were collected, including postmenstrual age(PMA) at diagnosis, tumor size on prenatal imaging,estimated fetal weight, and maternal and fetal outcome. All3-dimensional ultrasound and ultrafast magnetic resonanceimaging (MRI) studies were performed and/or interpreted byexperienced Fetal Center radiologists blinded to the fetuses'clinical outcome. Fetal weight was estimated by ultrasoundusing the Hadlock formula; and tumor volume was measuredby ultrasound orMRI using the greatest dimensions of length,width, and depth to calculate a prolate ellipsoid [8-10]. Withthese 2 parameters, the TFR was obtained by dividing thecalculated total tumor volume by the estimated fetal weight.The earliest available TFR was used for analysis.

Two variables were taken into account to analyze thisgroup: TFR and outcome. A good outcome was defined assuccessful tumor resection after delivery and survival togreater than 6 months of age. A poor outcome was defined asthe development of fetal hydrops, fetal demise, or neonataldeath. Fetal hydrops was defined as integumentary edema,presence of effusion in at least 1 body cavity, andechocardiographic evidence of cardiac compromise. Receiv-er operating characteristic analysis was used to select a cutoffvalue for TFR based on optimum sensitivity and specificity.Patients were stratified by TFR, and their outcomes were

Table 1 TFR and outcome of fetuses with SCT

PMA at diagnosis TFR Hydrops PMA at birth

28 0.01 No 3225 0.03 No 3927 0.06 No 3523 0.09 No 3825 0.10 No 3420 0.14 Yes 2724 0.18 No 3623 0.38 Yes 2721 0.44 Yes 2522 1.31 Yes 34

analyzed by Fisher's Exact test. Statistical analysis wasperformed using Prism 4.0 (GraphPad Software, La Jolla,CA). A P value of b .05 was considered significant.

2. Results

Twelve fetuses presented with SCT during the studyperiod. One patient with a history of Ebstein anomaly andanother who underwent elective termination of pregnancyowing to psychosocial issues were excluded from thisanalysis (Table 1).

Twenty-one ultrasounds and 10 MRI studies wereavailable to obtain measurements of tumor size and estimatedfetal weight. Nine pregnancies were singletons, and one was atwin pregnancy. Serial evaluations were not possible for allpatients because of individual differences in the timing of thereferral, fetal intervention, delivery, or termination ofpregnancy secondary to fetal hydrops or mirror syndrome.The PMA at the time of initial imaging ranged from 16and 6/7 weeks to 32 weeks (median, 23 weeks). In 6 cases,serial evaluations were available; in 4 cases, only the initialevaluation was obtained. The calculated tumor volumeranged from 21 to 1136 mL (median, 221 mL), and theestimated fetal weight ranged from 400 to 2444 g (median,850 g). The TFR ranged from 0.01 to 1.31 (median, 0.58).In all cases with multiple measurements, both tumorvolume and TFR increased with PMA.

The TFR before 24 weeks PMA was predictive ofoutcome. Using receiver operating characteristic analysis(Fig. 1), a cutoff of the TFR greater than 0.12 predicted pooroutcome with a sensitivity of 100%, a specificity of 83%, anegative predictive value of 100%, and a positive predictivevalue of 80%. All fetuses with a TFR less than or equal to0.12 (n = 5) had a good outcome compared with only 20% ofthose with a TFR greater than 0.12 (n = 5, P b .05). Thosepatients with TFR less than or equal to 0.12 before 24weeks PMA that subsequently increased to greater than0.12 with advancing age and tumor size still had a goodoutcome. In those patients whose initial evaluation wasafter 24 weeks PMA and had TFR less than or equal to

Outcome Comments

Survival Postnatal resectionSurvival Postnatal resectionSurvival Postnatal resectionSurvival Postnatal resectionSurvival Postnatal resectionNeonatal death Emergent C-section for mirror syndromeSurvival Twin gestation, postnatal resectionNeonatal death Emergent C-section for hydropsNeonatal death Emergent C-section for mirror syndromeSurvival Fetal tumor debulking

Fig. 1 Receiver operating characteristic curve illustratingsensitivities and specificities of TFR. A cutoff value of TFR greaterthan 0.12 predicted poor outcome with 100% sensitivity and 83%specificity. Area under the curve = 0.958.

1184 M.A. Rodriguez et al.

0.12, we estimated that the TFR before 24 weeks wouldhave been less than the value at initial evaluation; and theyall had a good outcome. The fetus with the greatest TFR(1.31) developed hydrops at 25 weeks PMA and subse-quently underwent fetal surgical resection of the extrapelvictumor. The remaining intrapelvic component was resectedafter birth; and at 2-year follow-up, the child is neurode-velopmentally normal but yet to be potty trained.

Four fetuses in our series developed hydrops, althoughonly one developed hydrops before 24 weeks PMA. Allfetuses who eventually went on to develop hydrops had aTFR greater than 0.12 by 24 weeks PMA. Without fetalsurgical resection, those with hydrops died. There was nosignificant difference in the Altman classification type [11]between patients with good and poor outcome (Table 2).

3. Discussion

Advances in prenatal care and obstetric ultrasound overthe past 2 decades have allowed for early detection of fetalmalformations, among them SCT. Once diagnosed, fetuseswith these anomalies can be further evaluated with ultrafastMRI and fetal echocardiogram [12-16]. This study focusedon the development of a prognostic factor with high

Table 2 Distribution of patient outcome by Altmanclassification

Type I Type II Type III Type IV

Good outcome 1 4 1 0Poor outcome 0 3 1 0

sensitivity and negative predictive value that would besimple to calculate and useful for counseling as early as thesecond trimester.

In our series of fetuses with SCT, a TFR less than or equalto 0.12 predicted an uncomplicated perinatal course with100% survival. Patients with a TFR greater than 0.12 before24 weeks PMA had an increased risk of complicatedpregnancy and perinatal demise. Fetal demise in cases ofSCT has been explained through several mechanisms.Massive hemorrhage into the tumor with fetal exsanguina-tion may occur spontaneously in utero or be precipitated bylabor and delivery. Alternatively, high output cardiac failuremay develop owing to a vascular steal phenomenonsecondary to either high flow requirements of the tumor orarteriovenous fistulization [3,7]. This cardiac failure is oftenfollowed by mirror syndrome and/or fetal demise.

Attempted fetal interventions for the treatment of SCThave encountered varying degrees of success and haveranged from in utero resection to percutaneous laser orradiofrequency ablation of the tumor or drainage of cysticSCTs [17-20]. Postnatal adjuncts to surgical tumor resectioninclude laparoscopic ligation of the median sacral artery orpreoperative angiography with embolization of the tumorvessels [18-25]. The TFRmay help identify fetuses at risk forpoor outcome that may benefit from close monitoring for theonset of hydrops. Furthermore, this modality provides anobjective comparison of the size of the mass to the fetus. Wepropose that the term giant SCT be reserved for patients withTFR greater than 0.12 who are more likely to require in uterointervention or advanced perinatal management.

Our study is limited by the small number of patients withthis rare anomaly. A large multicenter study to furtherevaluate and validate the TFR in other patient populations isalready in progress. We propose TFR as a novel diagnostictool that, once validated, may be useful in prenatalcounseling and for identifying high-risk fetuses with SCTsin the second trimester who may benefit from advancedperinatal management.

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