¹ Ultrasound Division, ASL Roma B, Rome, Italy;
² Ultrasound Division, Ceprano Hospital, Ceprano, Italy;


(Edited by F. G.)

 

Ovarian cysts are the most frequent, prenatally diagnosed intra-abdominal cysts. The etiology of fetal ovarian cysts is still unknown, but hormonal stimulation is generally considered to be responsible for the disorder. The association of fetal ovarian cysts with maternal diabetes or fetal hypothyroidism has been described. When a cystic abdominal mass is diagnosed in the female fetus, differential diagnoses should include mesenteric and urachal cysts, intestinal duplication anomalies, cystic teratoma, and intestinal obstruction. A differential diagnosis between ovarian cysts and one of these conditions cannot always be made with intrauterine sonography.

Once the prenatal diagnosis of a probable ovarian cyst has been made, it is important to perform serial ultrasound examinations to detect any change (size, appearance) in the mass or other complications (hydramnios, ascites, torsion). If there is intracystic bleeding or torsion, the cyst acquires a heterogeneous structure, in part with internal septa. Postnatal surgery for all fetal ovarian cysts which are complex, irrespective of their size, has been recommended. Aspiration of the cysts is recommended if they are huge enough to impair spontaneous delivery or cause distension of the fetal abdomen and impair fetal lung expansion..

In summary, the most appropriate clinical approach in the management of benign fetal-neonatal ovarian cysts is to adopt a wait-and-see policy. Asymptomatic fetal ovarian cysts smaller than 5 cm in diameter with tendency to regress should be monitored by serial ultrasonographic exams pre- and postnatally until spontaneous resolution. If they regress spontaneously, no surgical intervention is necessary independent of their sonographic appearance.

These are some images and videos of a cystic mass in the left pelvic area of a fetus at 32 weeks. This mass was well distinguishable from the kidney, the stomach and the bladder. The patient was scanned again at 36 weeks and the cyst had disappeared.

Cyst location and its spontaneous regression in utero together with the female sex of the fetus made us consider it an ovarian cyst.

Images 1, 2, 3, 4, 5, and 6: The images show a few third trimester scans of the fetal pelvis and abdomen with a cystic structure representing an ovarian cyst. The image 1 shows female gender of the fetus. The image 2, 3, and 4 shows relation of the ovarian cyst to the other structures (Image 2 distinguishes the ovarian cyst and urinary bladder; the image 3 shows relation of the ovarian cyst, marked with asterisk, to the stomach; the image 4 shows relation of the cyst to the fetal kidneys).  The images 5 and 6 shows the size of the ovarian cyst (40 x 34 mm) and its poor vascularization.

Videos 1, 2: The videos represent transverse sweeps via the fetal abdomen and pelvis showing the cystic structure representing ovarian cyst.

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