Diagnosis and management of mirror syndrome: a case series with emphasis on the potential role of the sFLT-1/PlGF ratio in clinical practice

Behenck, Gabrielle Soares; Curtois, Fernanda; El Beitune, Patrícia; Jimenez, Mirela Foresti; Vettorazzi, Janete; Silva, Marcelo Brandão da; Muller, Betania; Teixeira, Lucas; Longo, Carolina; Callado, Gustavo Yano; Araujo Júnior, Edward; Micheletti, Talita

doi:10.61622/rbgo/2026rbgo6

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Original Article • Rev Bras Ginecol Obstet 48 • 2026 • https://doi.org/10.61622/rbgo/2026rbgo6 linkcopy

Diagnosis and management of mirror syndrome: a case series with emphasis on the potential role of the sFLT-1/PlGF ratio in clinical practice

Authorship SCIMAGO INSTITUTIONS RANKINGS

Objective: To characterize the maternal clinical, ultrasound, and laboratory parameters, maternal and perinatal outcomes of mirror syndrome, and to discuss the role of sFlt-1/PlGF biomarkers in diagnosis and management.

Methods: We conducted a case series including all cases of mirror syndrome diagnosed at a tertiary reference center in Brazil. Clinical, laboratory, ultrasound, and biomarker data were collected, along with maternal and perinatal outcomes.

Results: Nine cases of mirror syndrome were identified, with a mean gestational age at diagnosis of 27+6 weeks. The most frequent maternal findings were lower limb edema (n=7), hypertension (n=8), and proteinuria (n=8). Ultrasound demonstrated fetal hydrops (n=7), polyhydramnios (n=6), and placentomegaly (n=7). Laboratory abnormalities included abnormal proteinuria/creatinuria ratio in 5/8 women tested, elevated 24-hour proteinuria in all 5, anemia in 7, thrombocytopenia in 3, and elevated creatinine in 1. The sFlt-1/PlGF ratio was measured in 5 women; 4 had abnormal results, with 3 above 85, all of whom developed maternal complications or fetal death. Resolution occurred after a mean of 3.4±3.6 days, due to fetal death (n=3), delivery (n=5), or fetal surgery (n=1). In one monochorionic twin pregnancy complicated by twin–anemia–polycythemia sequence, biomarker normalization after intrauterine death of the hydropic twin allowed safe prolongation of the pregnancy and term delivery of the co-twin.

Conclusion: Mirror syndrome should be suspected in pregnancies presenting with preeclampsia-like features in the setting of fetal hydrops or polyhydramnios. The sFlt-1/PlGF ratio may assist in differentiating mirror syndrome from preeclampsia and in identifying women at risk for adverse outcomes.

Keywords
Mirror syndrome; sFlt-1/PlGF; Biomarkers; Perinatal outcomes

Case	Underlying condition	Diagnosis	Gestational age at diagnosis	Maternal signals/symptoms	Ultrasound findings	P/C and/or 24h PTU (g) at diagnosis	sFLT-1/PlGF ratio at diagnosis	Other laboratory parameters at diagnosis
1	Fetal heart anomalies	Supraventricular tachycardia	29w4d	Lower limb edema High arterial pressure	Hydrops Polyhydramnios Placentomegaly	PTU 0.40g	16.3	Hb 10,1g/dl Ht 29.5% Plat 149000/mm³ Uric acid 8.4mg/dl
2	Anemia	Non-immune refractory anemia (uncertain etiology)	24w6d	Lower limb edema High arterial pressure	Hydrops Placentomegaly	P/C 0.18 PTU 0.47g	149.0	Hb 8.9g/dl Ht 26.6% Plat 142000/mm³ Uric acid 7.0mg/dl
3	Twin pregnancy	TTTS	23w1d	Lower limb edema High arterial pressure	Hydrops Polyhydramnios Placentomegaly	P/C 0.35 PTU 0.33g	Not collected	Hb 8.9g/dl Ht 26.5% Plat 197000/mm³ Uric acid 4.9mg/dl
4	Twin pregnancy	TAPS	26w5d	Lower limb edema High arterial pressure Gestational cholestasis	Hydrops Placentomegaly	P/C 6.57 PTU 7.77g	235.4	Hb 10,1g/dl Ht 30.8% Plat 198000/mm³ Uric acid 8.0mg/dl
5	Fetal tumor	Sacrococcygeal teratoma	26w6d	Lower limb edema	Polyhydramnios	P/C 0.14	Not collected	Hb 9.7g/dl Ht 29.9% Plat 340000/mm³ Uric acid 5.2mg/dl
6	Fetal heart anomalies	Pulmonary atresia	32w1d	Lower limb edema High arterial pressure	Hydrops Polyhydramnios Placentomegaly	P/C 0.95	370.7	Hb 10.5g/dl Ht 28.7% Plat 125000/mm³ Uric acid 10mg/dl Creatinine 1.1mg/dl
7	Fetal heart anomalies	Aortic atresia	24w1d	High arterial pressure	Hydrops Placentomegaly	P/C 0.27 PTU 0.3g	Not collected	Hb 12.4g/dl Ht 35.5% Plat 270000/mm³ GOT 93U/l, GPT 249U/l
8	Fetal heart anomalies	Isomerism, atrioventricular septal defect, pulmonary stenosis, atrioventricular block	32w3d	Lower limb edema High arterial pressure	No hydrops criteria (only subcutaneous edema) Polyhydramnios	P/C 0.66	Not collected	Hb 12.5g/dl Ht 35.5% Plat 350000/mm³ Uric acid 7.6mg/dl
9	Fetal heart anomalies	Aortic stenosis	30w4d	High arterial pressure	Hydrops Polyhydramnios Placentomegaly	P/C 1.2	47	Hb 9.3g/dl Ht 27.8% Plat 178000/mm³ GPT 72U/l Uric acid 3.9mg/dl

Outcome	Number of cases/total cases (%) or mean ± standard deviation	Comments
Presence of severe maternal complication	3/9 (33%)	Case 4: nephrotic syndrome Case 5: pleural effusion Case 6: acute renal insufficiency
Time interval from diagnosis to resolution (days)	3.4 ± 3.6	Resolution by delivery (n=7) or fetal death (1) or fetal surgery (n=1, twin pregnancy with TAPS)
Neonatal outcomes
At least 1 fetus alive	1/9 (11%)	Case 4: twin pregnancy with TAPS
Fetal death	1/9 (11%)	Case 2: death due to underlying fetal condition
Neonatal death	7/9 (78%)	Due to prematurity or underlying fetal condition Case 3: no time for mirror syndrome improvement confirmation due to preterm labor following fetal surgery

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[TFN1] P/C: proteinuria/creatininuria ratio (normal < 0.3); 24h PTU: 24h urinary protein (normal < 300mg/24h); Hb: hemoglobin (normal 12-16 g/dL); Ht: hematocrit (normal 34-47%); Plat: platelets (normal 150.000-450.000/m³); UA: uric acid (normal 2.4-5.7 mg/dL); LDH: lactate dehydrogenase (normal 100-190 U/L); sFLT-1/PlGF ratio: soluble fms-like tyrosine kinase-1/placental growth factor (< 38 low risk of preeclampsia; 38-84 elevated risk of preeclampsia; > 85 preeclampsia or imminent adverse outcome); GPT: glutamic pyruvic transaminase (normal < 33 U/L); GOT: glutamic-oxalacetic transaminase (normal < 40 U/L). TAPS: twin-twin polycythemia sequence. TTTS: twin-twin transfusion syndrome