Umbilical cord cysts were usually detected incidentally on routine obstetric ultrasongraphy with the reported occurrence rate 0.4-3.4%[1, 6]. Our department was one of the largest top three specialized hospitals in China and the total number of birth was about two million per year,while only twenty-eight pregnancy women were diagnosed with umbilical cord cysts during the past six years. This, to some extent, explained umbilical cord cysts were really rare.As being detected accidently and no large scale reports, proper prenatal management was difficult to be established.The existing literature had reported that the gestational week of beening diagnosed, number,type and location of umbilical cord cysts were associated with poor fetal outcome.Umbilical cord cysts which occurred in first trimester and completely resolved before 20 weeks usually had a good outcome[7, 8]. However, the percentage of fetal structural defects might increased remarkably to 50% when they persisted to or were diagnosed in second and third trimester[9]. The association of umbilical cord cysts with abdominal wall defect[10] and urinary tract such as omphalocele[11-13] had been well documented previously and rare ones including cardiac malformation[14] and single umbilical artery[15] were also reported. Of our case series, six fetus had structural defects and the ratio was about 21%. Besides the above defects,other complicated abnormalities such as lobular whole forebrain,kidney absence or kidney cyst had yet not been reported. we suggested that women diagnosed with umbilical cord cysts should be given a systematic and comprehensive ultrasound assessment to exclude potential structural defects[16].
Literature also reported that it was the umbilical cord pseudocysts,rather than true cysts that had a higher risk of fetal trisomy 13 and 18[12].Though classied into true cysts and pseudocysts, it was difficult to distinguish them by prenatal ultrasound and it was very important to choose a relialbe prenatal method to screen fetal chromosomal abnormality for these women.There were three screening methods including maternal serum screening,NIPT and karyotype analysis of amniocentesis at present.The results of serum biochemical markers(AFP,free β-HCG ,PAPP-A) could just be used in general population to screen trisomy 21and 18. Meantime,the maternal serum AFP and free β-HCG levels tended to be significantly low in pregnant women with trisomy 18 fetus[17, 18] while fetus with abdominal defects,the two levels tend to be significantly high[19],then when the two coincidenced,the two levels might be in the normal range. NIPT had been widely used in prenatal screening for trisomy 21,18 and 13 both in high risk and general pupulation[20].In our present series,twenty had maternal serum screening and/or NIPT and three had karyotype analysis while five cases had no record (showed in Table 3).Of the twenty cases, eight had only maternal serum screening, six had NIPT directly and six had both tests.With maternal serum screening,one had high risk and the other one had middle risk while they both further had NIPT low risk.Still another one had a HCG MoM up to 2.9 whose fetal had left kidney cyst. One fetal had abnormal karyotype of our three karyotype analysis, and fetal mosaic tetrasomy 10p was also reported[21], thus karyotype analysis or NIPT at least was more recommended in these high risk population though half of our cases had low risk of serum screening.
Poor fetal outcomes were also reported to be related with larger ,multiple cysts or cysts located near to the placenta and fetus because of the compression of umbilical vessels or umbilical cord rupture. Limited cases reminded that umbilical cord cystic masses such as hematoma lead to intrauterine fetal death at any stage of pregnancy[22, 23], and some authors recommended cesarean section to prevent intrauterine vascular compression of umbilical cord during labor[13]. But so far there was no general consensus whether these women should choose vaginial delivery or elective cesarean section. In the present case series, the majority cases were located to near either placenta or fetus, twelve had the cycst diameter more than 5cm at delivery with the largest up to15cm, five had multiple cysts. However, all had a relative good outcome.The mean delivery week was 39+W, six women had successful vaginal delivery without fetal distress including the one with cycst diameter up to 15cm. Seven had emergency cesarean section duo to high S/D, fetal distress or breech position while the other twelve also had selective cesarean section for scarred uterus,intrauterine infection, or IVF. So experience from our case series was that more attention should be paid to fetal distress during pregnancy and vaginal delivery could be a choose unless they had other contraindication which was in accordance with Leyre Ruiz Campo’s view[24].We also paid close attention to the fetal birth weight and sex,only one fetal’s birth weight was lower than the 10 percentage and the femail:mail was 17:11, we still agreed to the view that umbilical cord cysts did not influence fetal growth while we did not note a male dominance[24].As prenatal ultrasound could not distinguish true cysts from pseudocysts, the pathological examination should be performed after delivery in each case. Unfortunately,only five cases had pathological examination, among whom 1 was pseudocysts and the remaining 23 cases could not be distinguished.So a limitation of our study was that the low rate of pathological examination.