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ORIGINAL RESEARCH |
From the Fetal Medicine Center, Department of Obstetrics and Gynecology, and the Cytogenetics Laboratory, Clinica Las Condes, Santiago; and the Ultrasound Unit, Department of Obstetrics and Gynecology, San Jose Hospital, Santiago, Chile.
Address reprint requests to: Waldo Sepulveda, MD, Fetal Medicine Center, Clinica Las Condes, Casilla 268, Santiago 34, Chile, E-mail: waldosep{at}chilesat.net
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Abstract |
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Methods: The prenatal sonographic findings, karyotype, and perinatal outcome in 13 fetuses with umbilical cord pseudocysts were reviewed retrospectively.
Results: Umbilical cord pseudocysts were diagnosed at a median gestation of 27 weeks (range 15–37). Pseudocysts were single in eight cases with cyst diameters ranging from 20 to 50 mm, and double in one case. In the remaining four cases, multiple small cystic masses measuring less than 8 mm were identified. Additional sonographic findings were noted in 11 cases; ten of these fetuses had prenatal karyotyping, which showed trisomy 18 in five cases, trisomy 13 in one case, and a 46,XX, inv ins(18;21) complement in one case. Among the seven chromosomally abnormal fetuses, umbilical cord pseudocysts were multiple in four fetuses and single in three. All chromosomally abnormal fetuses and two euploid fetuses with associated structural defects died in utero or in the neonatal period. There were no perinatal complications in either of the fetuses with isolated pseudocysts.
Conclusion: The prenatal sonographic appearance of umbilical cord pseudocysts varied widely. These umbilical cord cystic masses were associated strongly with chromosomal disorders and structural defects, regardless of their sonographic appearance in utero.
With the widespread use of sonography in prenatal care, anomalies involving the umbilical cord are being diagnosed in utero more often.1,2 Umbilical cord cystic masses are detected the most commonly. These might be true cysts or pseudocysts. True cysts are lined by epithelium and originate from embryonic remnants, such as the allantois or omphalomesenteric duct, whereas pseudocysts are due to local degeneration or focal edema of Wharton’s jelly and lack an epithelial lining.3–6
Umbilical cord pseudocysts are by far more common than true cysts.1,7 Prenatal identification is important because they are associated with fetal trisomy5–7 and other congenital anomalies, including omphalocele; vertebral defects, imperforate anus, tracheoesophageal fistula, and radial and renal dysplasia association; and angiomyxoma of the cord.7–10 A recent review7 of umbilical cord cystic masses detected prenatally by sonography showed that among 13 histologically proven cases of pseudocysts, eight were associated with aneuploidy and two with other anomalies. Most reports involve small numbers of cases, precluding overall evaluation and supplying limited information for counseling.
In this report we present a series of 13 fetuses with umbilical cord pseudocysts detected in the second or third trimester, with emphasis on prenatal sonographic appearance and their association with aneuploidy.
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Materials and Methods |
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shows the clinical and sonographic findings. Median maternal age was 32 years (range 22–43), and median gestational age at diagnosis was 27 weeks (range 15–37). Women were referred for sonographic examination for a variety of clinical indications, including fetal abnormalities found by examinations at referring institutions in ten cases, cystic anomalies of the umbilical cord in two cases, and dating in one case. Detailed examination of umbilical cords at referral revealed that the pseudocysts were single in eight cases, double in one case, and multiple in four cases. Additional umbilical cord anomalies were found in three cases, including single umbilical artery (UA) in two cases and allantoic cyst in one case. In those fetuses in which a single pseudocyst was identified, the diameter ranged between 20 and 50 mm and the cyst was near the fetal insertion in five cases, near the placental insertion in one case and in a free loop in two cases (Figure 1A, B, C). In the fetus in which double cystic masses were found, the pseudocysts measured 30 and 45 mm in diameter and were close to each other near the fetal insertion. In all four cases of multiple pseudocysts, sonographic appearances were similar: masses were small, measuring less than 8 mm, and were near the fetal insertions and in relation to areas of localized thickening of the Wharton’s jelly (Figure 1D).
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). In three of those cases, prenatal karyotyping revealed trisomy 18.
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Discussion |
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Sonographic appearance of umbilical cord pseudocysts in utero varies widely. In our series, pseudocysts most frequently presented as large, cyst-like masses close to the fetal insertion or in a free loop of the cord. However, four fetuses had small multiple cysts near a localized thickening of Wharton’s jelly. All these cases were associated with aneuploidy: trisomy 18 in three cases and trisomy 13 in one case. A computerized search of the English-language medical literature on MEDLINE, encompassing the years 1988–1997, using the search terms "umbilical cord," "pseudocysts," and "aneuploidy" identified no previous reports describing the relationship between this prenatal sonographic appearance of umbilical cord pseudocysts and aneuploidy. Sonographic examination of chromosomally abnormal fetuses in previous reports probabaly did not include detailed examination of the umbilical cord, and therefore, small cystic masses were overlooked. In all our chromosomally normal fetuses, including the three that developed into phenotypically normal infants at birth, the cystic masses were large. However, umbilical cord pseudocysts in chromosomally abnormal fetuses comprised both large and small cysts; therefore, prenatal karyotyping always should be considered, regardless of sonographic appearance of the cysts.
In our series, associated structural anomalies were invariably present in fetuses with chromosomal abnormalities. However, in early second-trimester pregnancies, umbilical cord pseudocysts might be the only anomaly indicating chromosomally abnormal fetuses. At least three second-trimester trisomic fetuses in which pseudocysts were isolated findings have been reported: two fetuses with trisomy 185,6 and one fetus with trisomy 13.14 In these fetuses, subsequent scans showed several abnormalities not seen on initial scan. These cases add strong support to our recommendation of prenatal karyotyping even when isolated umbilical cord cystic masses are found before 24 weeks.6
The cause of umbilical cord pseudocysts and their strong association with chromosomal abnormalities is unknown. Because a substantial proportion of chromosomally abnormal fetuses in our series showed signs of fetal growth restriction or hydrops fetalis, increased vascular pressure in the umbilical-placental circulation, causing increased hydrostatic umbilical cord pressure, could be blamed. This might transfer fluid into the Wharton’s jelly, causing localized edema and formation of pseudocysts.5 This also could happen when an umbilical cord pseudocyst is associated with anterior abdominal wall defects, which was the case in five of our fetuses. A mass at the fetal cord insertion might increase umbilical venous pressure by obstructing the return of blood to the fetus, with subsequent cyst formation in the Wharton’s jelly. Another explanation could be focal degeneration, either cystic or mucoid, of Wharton’s jelly, associated with a local pathologic process of the umbilical cord.15,16
Umbilical cord pseudocysts were late findings in our series, cystic masses being detected after 24 weeks’ gestation in eight of the 13 fetuses. Further evidence supporting the late appearance of pseudocysts is that in three of the fetuses in our series, we did not see umbilical cord cystic masses in earlier second-trimester scans, despite detailed examination of the cord, which suggests that the pseudocysts developed later. That might explain why umbilical cord pseudocysts have not been considered sonographic markers of aneuploidy in the second trimester and were mentioned only anecdotally as being present in fetuses with aneuploidy.17 In two large series of fetuses with trisomies 18 and 13, umbilical cord cystic masses were found in only two of 47 fetuses with trisomy 18, both in the third trimester,18 and in none of 33 fetuses with trisomy 13.19 In Chile, because the current law does not permit abortion under any circumstances, there is the opportunity to examine and follow pregnancies complicated by aneuploidy beyond 24 weeks, when the prevalence of umbilical cord pseudocysts seems to be higher, which might explain the high number of cases in our series.
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Footnotes |
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Received April 3, 1998. Received in revised form August 3, 1998. Accepted August 13, 1998.
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References |
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2. Sherer DM, Anyaegbunam A. Prenatal ultrasonographic morphologic assessment of the umbilical cord: A review. Part II. Obstet Gynecol Surv 1997;52:515–23.[Medline]
3. Fox H. Pathology of the placenta. Philadelphia: WB Saunders, 1978:426.
4. Benirschke K, Kaufmann P. Pathology of the human placenta. 2nd ed. New York: Springer-Verlag, 1990:208.
5. Jauniaux E, Donner C, Thomas C, Francotte J, Rodesch F, Avni FE. Umbilical cord pseudocyst in trisomy 18. Prenat Diagn 1988;8:557–63.[Medline]
6. Sepulveda W, Pryde PG, Greb AE, Romero R, Evans MI. Prenatal diagnosis of umbilical cord pseudocyst. Ultrasound Obstet Gynecol 1994;4:147–50.[Medline]
7. Smith GN, Walker M, Johnston S, Ash K. The sonographic finding of persistent umbilical cord cystic masses is associated with lethal aneuploidy and/or congenital anomalies. Prenat Diagn 1996;16: 1141–7.[Medline]
8. Jauniaux E, Jurkovic D, Campbell S. Sonographic features of an umbilical cord abnormality combining a cord pseudocyst and a small omphalocele: A case report. Eur J Obstet Gynecol Reprod Biol 1991;40:245–8.[Medline]
9. Kalter CS, Williams MC, Vaughn V, Spellacy WN. Sonographic diagnosis of a large umbilical cord pseudocyst. J Ultrasound Med 1994;13:487–9.[Medline]
10. Jauniaux E, Moscoso G, Chitty L, Gibb D, Driver M, Campbell S. An angiomyxoma involving the whole length of the umbilical cord. Prenatal diagnosis by ultrasonography. J Ultrasound Med 1990;9:419–22.[Medline]
11. Sepulveda W, Bower S, Dhillon HK, Fisk NM. Prenatal diagnosis of congenital patent urachus and allantoic cyst: The value of color flow imaging. J Ultrasound Med 1995;14:47–51.[Medline]
12. Benirschke K. Obstetrically important lesions of the umbilical cord. J Reprod Med 1994;39:262–8.[Medline]
13. Heifetz SA. The umbilical cord: Obstetrically important lesions. Clin Obstet Gynecol 1996;39:571–87.[Medline]
14. Bromley B, Benacerraf BR. Transient omphalocele. J Ultrasound Med 1993;12:688–9.[Medline]
15. Iaccarino M, Baldi F, Persico O, Palagiano A. Ultrasonographic and pathologic study of mucoid degeneration of umbilical cord. J Clin Ultrasound 1986;14:127–9.[Medline]
16. Yavner DL, Redline RW. Angiomyxoma of the umbilical cord with massive cystic degeneration of Wharton’s jelly. Arch Pathol Lab Med 1989;113:935–7.[Medline]
17. Hill LM. The sonographic detection of trisomies 13, 18, and 21. Clin Obstet Gynecol 1996;39:831–50.[Medline]
18. Nyberg DA, Kramer D, Resta RG, Kapur R, Mahony BS, Luthy DA, et al. Prenatal sonographic findings of trisomy 18: Review of 47 cases. J Ultrasound Med 1993;12:103–13.[Abstract]
19. Lehman CD, Nyberg DA, Winter TC, Kapur RP, Resta RG, Luthy DA. Trisomy 13 syndrome: Prenatal US findings in a review of 33 cases. Radiology 1995;194:217–22.
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