It is well established that chorionicity rather than zygosity determines the outcome in multifetal pregnancies. Chorionicity can be determined antenatally by conventional twodimensional ultrasonography in cases of multiple pregnancies. However, in high-order pregnancies it is difficult to obtain an accurate sonographic view of the junction of the interfetal membranes. We present a case of a quadruplet pregnancy where the chorionicity was successfully determined antenatally using three-dimensional scanning technology.
Case reportA 32-year-old pregnant patient was referred to our unit for her first trimester ultrasound scan. She was 12 weeks and 3 days, according to her last menstrual period, into her second pregnancy, having had a vaginal delivery at term in 1996. The current pregnancy was the result of spontaneous conception.The transabdominal ultrasound examination revealed four live fetuses in utero within four separate sacs and one placental mass at the anterior uterine wall. The gestation was redated by the largest crown-rump length to 13 weeks and 3 days. The nuchal translucency measurement of all fetuses was within normal limits for gestation. All fetuses appeared to have a normal anatomy for this gestation.Detailed examination of all possible combinations of pairs of fetuses at the junction of the interfetal membranes with the placental mass showed the presence of a 'lambda sign' in all cases, and therefore the impression was of a quadrochorionic pregnancy (Fig. 1).Furthermore, an examination with a 3D ultrasound scanner (Voluson 530D, Kretztechnik AG, Zipf, Austria) was carried out which revealed a thick junction of the four membranes, confirming the presence of chorion at this junction and therefore the chorionicity (Fig. 2).The couple were offered extensive counselling regarding the management options in this pregnancy, namely expectant management or multifetal pregnancy reduction. The parents decided against reduction.At 18 weeks of gestation the mother had her second ultrasound scan, which also showed one placental mass lying high at the anterior uterine wall. Interestingly the 'lambda signs' were still present. All fetuses had normal midtrimester anatomies.The mother had an uneventful antenatal period and finally delivered at 32 weeks and 6 days by elective Caesarean section. The infants were three males and one female, weighing 1744, 1837, 1738 and 1510 g, respectively, and were in good health.The placenta and the membranes were sent for histology, and the report confirmed a quadrochorionic pregnancy.
DiscussionSpontaneous quadruplet pregnancy is rare with an estimated incidence of 1 : 512 000. We present a case of a quadruplet Fig. 1. 'Lambda sign' between a pair of the quadruplets.
DiscussionSpontaneous quadruplet pregnancy is rare with an estimated incidence of 1 : 512 000. We present a case of a quadruplet Fig. 1. 'Lambda sign' between a pair of the quadruplets.
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