Choroid Plexus Cysts

What , as an obstetrician we should know about Sonological featurss of C P Cyst? Any rare association  with Trisomy 18?? What is meant by CP cysts ??  Basics of C Plexus Cysts ?    Ans:- What is normal or Physiological?? The cranial lateral ventricles contain sonolucent cerebrospinal fluid. We know that. We also know that within the lateral ventricles lies the 3 brightly echogenic choroid plexus that normally fills the atrium and may contain cysts .

CPCs(choroid plexus cysts) are a relatively common finding during the second trimester  especially with current  improved sonographic technology and resolution. The reported   prevalence of echogenic CP Cysts are  among normal fetuses is variable and ranges anywhere from 0.3%  to 3.65 . This variability  can be accounted for by various    factors such as  indications for referral  completeness of the scan size criteria for diagnosing cysts and gestational age. CPCs themselves have no known effect on fetal development and  are essentially benign.

Good news on  CPCs(choroid plexus cysts              :--  In addition unlike other aneuploidy   markers   there is no known association with other adverse outcomes if the karyotype is normal.

When sonologically  CPC may be visible?? Ans:-CPCs are seen   almost exclusively in fetuses between 16 to 21 weeks of gestational age  and appear to be transient . By  the 23^rd   week of gestation they are   usually undergoing regression and it is uncommon to see them sonographically after 25 to 26 weeks cysts may be unilateral or bilateral single or multiple and small or large . commonly they are  multilocular in appearance and th cysts typically  range  from between 0.5 cm and 2 cm in size Occasionally they may be so large as to fill almost the entire lateral  ventricle  and expand its walls giving the false appearance  of ventriculomegaly.

Doubt 1: Can  association of  CP cyst gives an signal that foetus may have Trisomy 18??  Should we insist on invasive tets to exclude aneuploidy,  if one such soft marker is visible in  genetic sonogram?  No, that it not done for isolated marker. Reasonig:-CPSs can be a significant finding because there have been reports in the literature over the years describing the association of CPS with fetal aneuploidy specifically with trisomy  18 .  CPCs appear to be present in approximately one third of trisomy 18 fetuses. Because of this association there is much debate to whether fetuses having CPCs  on ultrasound should undergo karyotyping.  

Consensus :-It is clearly recommended that when  fetuses with CPCs  have  other sonographic finding invasive testing should be  offered. However  when  prenatal   sonography   by experienced personnel reveals that   the CPCs are isolated management  should be conservative.

Caveat!!!!! However  some investigators believe that fetuses having isolated CPCs  and no other  anomalies may still carry a risk  of aneuploidy  high enough  to justify amniocentesis. However  the critical component lies in whether an isolated CPC is in fact truly  isolated. This can  only be presumed once a detailed  fetal survey by experienced examiners has failed to reveal other structural abnormalities /markers .Therefore it is  imperative   that all fetuses with CPCs  undergo  a detailed fetal sonographic  anatomic survey    by someone who is skilled and expe4rienced in prenatal diagnosis.