Keywords fetal adnexal cyst - ultrasound-guided aspiration - fetal intervention - individualized
prenatal care - prenatal diagnosis
Advancements in ultrasound (US) technology have notably broadened the scope of fetal
interventions, transforming diagnostic and therapeutic approaches for conditions identified
throughout pregnancy. Among these conditions, the prenatal management of large fetal
ovarian cysts remains controversial, as no controlled trials have been performed,
and the prognostic implications of cyst US characteristics—such as size, septations,
and wall thickness—are not yet fully understood.[1 ]
[2 ] Most fetal ovarian cysts are diagnosed by US in the third trimester,[3 ] with a reported false-positive rate of 7.5% (95% confidence interval [CI]: 4.4–11.4%).[3 ]
[4 ] Although nearly always benign, these cysts carry an increased risk of complications,
such as ovarian torsion or hemorrhage, which rises as their diameter increase.[4 ]
[5 ] Higher rates of complications have been reported in cysts measuring ≥4.0 cm.[4 ] These risks highlight the potential role of prenatal treatment in reducing cyst
size and averting complications. The criteria for in-utero US-guided aspiration remain
debatable, with suggested interventions centering on cyst characteristics such as
echogenicity, size, progression, fetal positioning, and gestational age at the time
of consideration.[6 ]
In this context, we present a case of a large fetal adnexal cyst prenatally treated
with cyst aspiration and review the related literature. We discuss relevant clinical
aspects, including the importance of multidisciplinary evaluation and shared decision-making.
Case Report
A 35-year-old healthy Caucasian female, G4P2, with a spontaneous singleton pregnancy,
was referred to our fetal care center at 33 weeks of gestation due to a fetal adnexal
cyst in a female fetus. The US at 331/7 weeks revealed an enlarged fetal abdominal circumference (>99th percentile), a central
anechoic and avascular cyst in the fetal pelvis measuring 7.0 cm × 6.4 cm × 5.5 cm,
and polyhydramnios with a maximum vertical pocket (MVP) of 10 cm.
At 345/7 weeks, MRI confirmed a cyst measuring 7.0 cm × 6.9 cm × 8.1 cm, suggestive of an
ovarian origin ([Fig. 1A ]). The US-calculated transverse abdominal diameter (TAD) was 11.2 cm. Management
and delivery options, including in utero US-guided aspiration followed by vaginal
delivery (VD), expectant management with VD, or elective cesarean delivery (CD), was
thoroughly discussed with the maternal–fetal medicine specialists.
Fig. 1 (A ) MRI at 345/7 weeks showing a cyst suspected to be of ovarian origin, measuring 7.0 cm × 6.9 cm × 8.1 cm
(arrow). (B, C ) Follow-up ultrasound at 356/7 weeks showed cyst enlargement (calculated volume > 210 mL; arrow) and associated
polyhydramnios (AFI 27.8 cm, MVP 11.9 cm). (D ) Limited transabdominal follow-up ultrasound at 360/7 weeks revealing a small volume of free fluid in the fetal left lower quadrant (arrow)
and absence of the cyst, with a high normal AFI of 21.1 cm and MVP of 6.7 cm. (E ) Follow-up ultrasound at 14 days old showing a large, amorphous, anechoic cystic
structure in the right pelvis, extending to the inferior hepatic margin (5.9 cm × 3.8 cm × 3.3 cm)
with a single daughter cyst noted along the periphery of the lesion. No vascularity
was observed. (F ) Ultrasound at 3 months old showing normal appearance of the left ovary, containing
a small follicle, with symmetric arterial flow and good arterial flow.
By 356/7 weeks, the cyst had enlarged, with a calculated volume above 210 mL ([Fig. 1B ] and [C ]) and persistent polyhydramnios with an amniotic-fluid index (AFI) of 27.8 cm and
an MVP of 11.9 cm. The patient emphasized her desire to maximize her chances of a
vaginal birth and minimize neonatal interventions. Following multidisciplinary consultations,
which included input from the neonatologist and the social worker, in utero US-guided
aspiration was performed. Under local anesthesia, after fetal immobilization using
fentanyl (35 mcg), atropine (70 mcg), and rocuronium (6.8 mg), a 20-gauge needle was
used to aspirate 230 mL from the cyst and 800 mL of amniotic fluid, completely reducing
the cyst's volume with no postoperative complications. A 12 mL sample of straw-colored,
translucent fluid from the cyst was sent for cytological analysis, which showed a
sparsely cellular specimen with no epithelial elements. A limited follow-up US the
next day showed the cyst was no longer visible ([Fig. 1D ]). The AFI decreased from 27.8 to 21.1 cm, and MVP from 11.9 to 6.7 cm.
Uncomplicated spontaneous VD occurred at 372/7 weeks at an outside hospital, with a birth weight of 3,960 g. The neonate was discharged
in excellent condition. At the 2-week visit with the pediatric surgeon, the mother
reported the infant's increased fussiness postfeeding but no signs of gastrointestinal
obstructive symptoms and normal weight gain. A mildly rounded abdomen was observed
but the cyst was not palpable. A pelvic US revealed a large anechoic cyst (5.9 cm × 3.8 cm × 3.3 cm)
in the pelvis extending to the level of the inferior hepatic margin, without evidence
of torsion ([Fig. 1E ]). A normal right ovary was seen. Given the cyst's size, both serial US surveillance
and diagnostic laparoscopy with ovarian cystectomy (if the ovary was viable) versus
oophorectomy (if not viable) were offered. The parents opted for surgery to maximize
ovarian preservation.
At 20 days old, the infant underwent diagnostic laparoscopy, which confirmed a torsed
but viable left ovary containing a large cyst consistent with the dimensions observed
in US. A very small cyst was also identified on the normal right ovary. The left ovarian
cyst was laparoscopically aspirated to facilitate exteriorization, followed by an
ovarian cystectomy with preservation of the ovary. Pathological analysis revealed
nonspecific findings, suggesting the cyst could represent an atretic cystic follicle,
a pseudocyst, or a benign inclusion cyst. The infant's postoperative course was uneventful,
and she was discharged the following day. A follow-up pelvic US performed at 3 months
of age demonstrated two normal ovaries in a healthy, normally developing infant ([Fig. 1F ]).
Discussion and Review of the Literature
Discussion and Review of the Literature
This case demonstrates the importance of individualized care in perinatal medicine,
with decisions guided by a combination of parental preferences and clinical risk factors.
The parents' strong desire for VD and preservation of ovarian function played central
roles in shaping the management plan. Following a collaborative decision-making process,
in utero US-guided aspiration allowed for a safe and uncomplicated VD, as the patient
desired. Postnatally, diagnostic laparoscopy was chosen over serial monitoring to
resolve the ovarian cyst definitively, with successful ovarian preservation.
Managing large or complex cysts remains a challenging area of prenatal care. In utero
US-guided aspiration of fetal cysts can reduce cyst size, thereby potentially preventing
torsion and its complications, such as necrosis, adhesion formation, and potential
loss of the ovary with impaired ovarian reserve.[2 ] Current indications for fetal intervention are evolving, particularly for larger
simple cysts. While complex cysts and simple cysts <4.0 cm are generally managed with
observation,[7 ] there remains controversy regarding the optimal management of larger simple cysts
due to the risks associated with in-utero intervention.[8 ]
[9 ] Although the specific risks associated with US-guided aspiration of fetal cysts
have not been extensively documented, they are likely comparable to those of other
in-utero needle procedures, such as amniocentesis. These risks include miscarriage,
estimated at 0.1 to 0.3%, as well as preterm premature rupture of membranes, occurring
in 1 to 2% of cases.[10 ]
A recent retrospective cohort published by Bloomfield et al found that, among 52 patients
with antenatally diagnosed ovarian cysts, 10 (19%) had no cyst at their first postnatal
US.[11 ] Resolution rates were significantly higher and faster for simple cysts compared
to complex cysts (84% vs. 52%, p < 0.05).[11 ] Similarly, a 2017 meta-analysis and a 2020 retrospective cohort study both highlighted
that complex cysts (those containing blood or a solid component on imaging) and simple
cysts ≥4.0 cm in diameter are less likely to resolve spontaneously either during pregnancy
or after birth compared to simpler or smaller cysts, respectively.[3 ]
[4 ] Despite these findings, neither cyst size nor complexity was found to predict ovarian
torsion in the retrospective cohort,[3 ] while the meta-analysis identified an increased risk of ovarian torsion and postnatal
surgery in cysts ≥4.0 cm.[4 ]
A 2017 review of 92 case reports and series reported on 380 cysts (324 observed and
56 aspirated in utero) in 365 fetuses.[12 ] The authors found that prenatal torsion rates were lower in aspirated cysts (4%,
2/56) compared to cysts managed conservatively sized 3.0 to 3.9 cm (15%, p = 0.02), 4.0 to 4.9 cm (27%, p < 0.001), 5.0 to 5.9 cm (34%, p < 0.001) and 7.0 to 7.9 cm (21%, p = 0.02).[12 ] Aspirated cysts had also lower postnatal surgery rates (7% vs. 49%, p < 0.001).[12 ] In 2018, a multicenter, prospective, randomized trial showed that aspiration of
cysts >3.0 cm increases in-utero involution and reduces oophorectomy rates due to
torsion.[13 ] However, recurrence rates after in-utero aspiration are notable (37.9%; 95% CI:
14.8–64.3%), with postnatal diagnoses of ovarian torsion and intracystic hemorrhage
in 10.8% (95% CI: 4.4–19.7%) and 12.8% (95% CI: 3.8–26.0%), respectively.[4 ]
An important concern with large pelvic cysts is the potential for abdominal dystocia,
which may necessitate CD to prioritize maternal and fetal safety. Several case reports
document dystocia arising from abdominal masses, though these cases differ from ours.
Examples include a fetal cystic hygroma (14 cm ×11 cm) that caused difficult extraction,[14 ] as well as a fetus with enlarged kidneys where a TAD of approximately 12 cm led
to dystocia requiring continued expulsive efforts and gentle fetal traction.[15 ] Even in a recent case of bowel dilation, dystocia was reported despite factors typically
favoring a VD, such as prior successful VD, the preterm status of the fetus, and the
expected compressibility of the abdomen.[16 ] While dystocia has not been reported with fetal ovarian cysts, our case illustrates
the importance of anticipating potential risks. The cyst measured 7.0 cm × 6.9 cm × 8.1 cm,
with an estimated TAD of 11.2 cm at 355/7 weeks, presenting only a potential risk of dystocia. The strong maternal preference
for a safe VD was carefully balanced against this risk. Ultimately, our intervention
minimized the possibility of abdominal dystocia, facilitating a successful VD.
Further research is essential to improve standards of care for fetal abdominal cysts.
Establishing a registry for these cases could help develop standardized protocols
and improve outcomes. Comparing fetal and neonatal outcomes between in-utero aspiration
and expectant management, stratified by US cyst characteristics and size, is essential
to establish standardized protocols. Additionally, advancements in diagnostic criteria
and imaging modalities would enhance prenatal diagnostic accuracy, facilitating better
clinical decision-making.
Conclusion
The successful in-utero US-guided aspiration of a large fetal ovarian cyst, in this
case, highlights the importance of personalized care in achieving optimal maternal
and neonatal outcomes. By effectively reducing cyst size, in-utero aspiration may
play a role in facilitating spontaneous vaginal birth, aligning with the priorities
of this family. This highlights the need for future research to confirm whether such
interventions consistently contribute to favorable delivery outcomes. This case underscores
the advancements in fetal intervention, where a nuanced understanding of cyst characteristics,
gestational timing, and parental preferences guides shared decision-making. Ongoing
studies are essential to refine the indications for and enhance the efficacy of prenatal
interventions for fetal abdominal cysts, ultimately improving care for affected families.
