A 30 year old woman (G1P0), from a non-consanguineous couple and with noncontributive history was sent to our unit at 12 weeks, 2 days gestational age (GA). She was negative for TORCH infections. Our ultrasound revealed a huge cystic structure within the fetal abdomen, with normal nasal bone and thickness of the nuchal translucency. Initially we considered the cystic structure as a distended urinary bladder due to an outlet obstruction, but a few days later the small bladder with umbilical arteries passing around its walls was recognized lying below the cystic structure.
The patient was scanned again at 15 weeks, 6 days GA and the structure had slightly decreased in size and was placed predominantly in the right side of the abdomen.
Following repeated scans were performed between 19 weeks, 6 days GA and 25 weeks, 0 days GA and the structure had decreased in size dramatically leaving just multiple calcifications among fetal bowels and within the liver. A small cyst was found within upper dome of the right hepatic lobe.
Later in pregnancy the cystic structure was no longer visible, but multiple bowel and hepatic calcifications were present.
The baby was delivered at 38 weeks (male, 2750 g, and 48 cm) with normal postnatal adaptation. Only a small hepatic cyst was found during the postnatal ultrasound. The baby was also diagnosed to have cryptorchidism. In a few weeks the abdominal findings were negative and the infant is doing well.
Cystic abdominal structures represent frequent findings during prenatal ultrasound. They may originate from various organs and structures of the fetal abdomen (renal, gastro-intestinal, ovarian, hepatic, biliary, adrenal, splenic, or pancreatic origin, meconium pseudocysts, hydrometrocolpos, urachal cysts, varices of the umbilical vein, etc.). Due to this variability it is sometime difficult to classify them correctly and several diagnoses are often considered in our differential diagnostic contemplation. Even more difficult is to estimate prognosis of such findings.
The big size of the structure and our incipient false presumption of the bladder obstruction even led us to think of termination of the pregnancy initially. Later course and development of the pregnancy was a bit astonishing. Taking into consideration the gradual resolution of the structure leaving just multiple liver and bowel calcifications, we presume that a meconium pseudocyst
could be the cause of the cystic structure in our case.
The favorable course of the pregnancy presented in our case leads us to recommendation of expectation management of abdominal cystic fetal structures seeing in the first trimester if the accurate diagnosis is not obvious.
This assertion is supported by other similar cases. In Moshe Bronshtein' practice (Haifa, Israel) they had 15 cases of transient abdominal cysts seen during first trimester scans. All of them had disappeared and had good outcome.
Here are some images that we obtained:
Images 1, 2, 3, and 4
: 12 weeks, 2 days GA; 2D sagittal scans of the fetus showing huge cystic structure within the fetal abdomen.
Images 5, 6
: 12 weeks, 2 days GA; 3D scans of the fetus showing huge cystic structure within the fetal abdomen.
Images 7, 8, 9, and 10
: 15 weeks, 6 days GA; 2D scans of the fetus showing the huge cystic structure within the fetal abdomen (images 8 and 10 represent a fusion of the images 7 and 9 with a drawings showing approximate position of the fetus).
: 15 weeks, 6 days GA; 2D transverse scan of the fetus showing relation of the cystic structure and urinary bladder (bypassed by the umbilical arteries).
: 19 weeks, 6 days GA and 25 weeks, 0 days GA; several scans of the fetal abdomen - the originally huge cystic structure had disappeared leaving just multiple calcifications among bowels and within the liver (purple arrows). A small cyst of the upper pole of the right hepatic lobe could be seen (green arrow on the image 13).
Image 20, and videos 1, 2
: Some similar examples of abdominal cysts in first trimester followed by spontaneous resolution and good outcome (Moshe Bronshtein).