Special thank to Moshe Bronshtein (Haifa, Israel) for his review of the findings and valuable opinion.

*    Ultrasound Division, ASL Roma B, Rome, Italy;
**   Reparto di ostetricia e ginecologia, Ospedale Fatebenefratelli San Pietro Rome, Italy.
*** Ultrasound Division, Ceprano Hospital, Ceprano, Italy.

Introduction

Triploidy can be classified into two phenotypes based on placental and ultrasound findings:

• In Type I the placenta is enlarged and partially multicystic (molar) whereas the fetus is relatively well-grown with either proportionate head size or slight microcephaly.
• Type II, which is the most common, is characterized by a small normal looking placenta and severely
  growth restricted fetus with pronounced wasting of the body and sparing of the head.

The deficit in triploidy 1st trimester trunk and head volume is 45%, in contrast to a 15% reduction in the crown-rump length. Hence, the trunk and head are decreased even after correcting for the crown-rump length. Congenital anomalies have been detected on 1st trimester ultrasound examinations of triploidy fetuses.

Case report

This is a case of a 33 years G1P0 pregnant with a history of severe pelvic endometriosis. Pregnancy arrived unexpectedly because a recent hysterosalpingography had shown no tubal patency bilaterally.

First ultrasound examination was performed at 8 weeks of amenorrhea and biometry was consistent with dates (CRL 15 mm).

At 11⁺⁶ days of amenorrhea our findings were:

• Biometry not consistent with dates (CRL 43 mm) as for early growth restriction;
• Disproportionate fetal body with marked cephalo-abdominal biometry discrepancy (big head, smaller abdomen);
• Reverse flow in ductus venosus;
• Failure to identify the "butterfly" sign of choroid plexus, partial absence of falx cerebri in some brain sections both cranially and caudally. Although mimicking holoprosencephaly, the diagnosis of hydrocephaly was made because of remnant falx was present;
• Large cisterna magna;
• Fetal legs astride as for bilateral hip dislocation

A chorionic villous sampling was scheduled for the week after (12⁺⁶ weeks) and US findings were:

• CRL 50 mm and disproportionate fetal body (AC/HC = 34%);
• Normal NT (1.6 mm);
• Present nasal bone;
• Hydrocephaly;
• Hypertelorism;
• No fetal tachycardia, no megacystis, no pyelectasia, three vessel cord, apparently normal heart;
• Placenta looked thin and large as for placenta membranacea.

Chromosomal analysis revealed triploidy 69,XXY. The couple opted for pregnancy interruption.

Images 1-7; 11⁺⁶ weeks of pregnancy;

Images 1, 2: Image 1 - CRL below normal range, disproportionately larger size of fetal head in comparison with its body; Image 2 -  fetal head with remnant of falx cerebri and hydrocephaly.

Videos 1, 2: Transverse scans of fetal head with hydrocephaly and remnant of falx cerebri.

References

Falcon O, Peralta CFA, Cavoretto P, Auer M, Nicolaides KH. Fetal trunk and head volumes in chromosomally abnormal fetuses at 11 + 0 to 13 + 6 weeks of gestation. Ultrasound Obstet Gynecol 2005;26:517-520.

Kagan KO, Anderson JM, Anwandter G, Neksasova K. Nicolaides KH. Screening for triploidy by the risk algorithms for trisomies 21, 18 and 13 at 11 weeks to 13 weeks and 6 days of gestation. Prenat Diagn 2008;28:1209-1213.

Sepulveda W, MD, Dezerega V, Be C. Value of the "Butterfly" Sign, JUM 2004;23(6):761-765

Sepulveda W, Lutz I, Be C. Holoprosencephaly at 9 weeks 6 days in a triploid fetus. Two-and 3-dimensional findings. J Ultrasound Med 2007;26:411-414.

Spencer K, Liao AWJ, Skentou H, Cicero S, Nicolaides KH Screening for triploidy by fetal nuchal translucency and maternal serum free b-hCG and PAPP-A at 10±14 weeks of  gestation. Prenat Diagn 2000;20:495-499.