Twin anemia-polycythemia sequence
Twin anemia-polycythemia sequence | |
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Other names | TAPS |
Photo of twins legs with twin anemia-polycythemia sequence color difference | |
Specialty | Obstetrics |
Twin anemia-polycythemia sequence (TAPS) is a chronic type of unbalanced fetal transfusion in monochorionic twins that results in polycythemia in the TAPS recipient and anemia in the TAPS donor due to tiny placental anastomoses.[1] Post-laser TAPS and spontaneous TAPS are the two forms of TAPS. Unlike twin-twin transfusion syndrome, which arises when twin oligohydramnios polyhydramnios sequence (TOPS) is absent, TAPS develops in its absence.[2]
Signs and symptoms
A pale, anemic donor and a plethoric, polycythemic recipient make up the traditional clinical picture of TAPS.[3]
In 29% of spontaneous TAPS twins and 23% of post-laser TAPS twins, severe
Causes
The cause of TAPS is slow and persistent unbalanced feto-fetal transfusion through tiny placental anastomoses, which progressively results in highly discordant hemoglobin levels. This causes the recipient twin to become polycythemic and the donor twin to become anemic.[1]
Mechanism
There are very few, tiny arteriovenous vascular anastomoses present in TAPS placentas. This distinct angiography is the foundation of the pathogenesis of TAPS. A slow transfusion of blood from the donor to the recipient is made possible by the few tiny anastomoses, which eventually cause very disparate hemoglobin levels. It's unclear if hormonal dysfunction may also contribute to the onset of TAPS.[6]
Diagnosis
Classification
Antenatal stage | Results of a Doppler ultrasound scan |
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Stage 1 | MCA-PSV donor >1.5 MoM and MCA-PSV recipient <1.0 MoM, without other signs of fetal compromise |
Stage 2 | MCA-PSV donor >1.7 MoM and MCA-PSV recipient <0.8 MoM, without other signs of fetal compromise |
Stage 3 | As stage 1 or 2, with cardiac compromise of donor, defined as critically abnormal flow.[note 1] |
Stage 4 | Hydrops of donor. |
Stage 5 | Intrauterine demise of one or both fetuses preceded by TAPS |
Postnatal stage | Intertwin hemoglobin difference, g/dl |
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Stage 1 | >8.0 |
Stage 2 | >11.0 |
Stage 3 | >14.0 |
Stage 4 | >17.0 |
Stage 5 | >20.0 |
Prevention
The rate of residual anastomoses can be decreased to prevent postlaser TAPS. The "Solomon technique," an alternate method of laser surgery, may help lower the possibility of omitting a tiny anastomosis during the procedure.[6]
Treatment
Weekly ultrasound monitoring, which includes a full staging Doppler examination with the MCA-PSV, is part of the expectant management protocol. The recent onset of ultrasound abnormalities may require an increase in the surveillance frequency. When TAPS patients present in the first or early second trimester, this approach is preferred because many of these patients may resolve or remain clinically stable. Expectant care can be continued with the aim of achieving a late preterm delivery in stable cases that do not advance past stage 2. It is necessary to take into account alternate management options if TAPS is accelerating.[7]
Treatments that are temporary include
Treating TAPS with fetal laser coagulation of vascular anastomoses is the only potentially effective modality.[9]
Outlook
In the TAPS Registry cohort, 11% of post-laser TAPS twins and 5% of spontaneous TAPS twins experienced spontaneous fetal death.[5][4]
Epidemiology
Postlaser TAPS can occur in 2–13% of cases, depending on the definitions and criteria applied.[10][11] The range of incidence for spontaneous TAPS is 3–5%.[6]
See also
Notes
References
Further reading
- Khalil, A.; Gordijn, S.; Ganzevoort, W.; Thilaganathan, B.; Johnson, A.; Baschat, A. A.; Hecher, K.; Reed, K.; Lewi, L.; Deprest, J.; Oepkes, D.; Lopriore, E. (2020). "Consensus diagnostic criteria and monitoring of twin anemia–polycythemia sequence: Delphi procedure". Ultrasound in Obstetrics & Gynecology. 56 (3): 388–394. PMID 31605505.
- Tollenaar, Lisanne S.A.; Prins, Sandra A.; Beuger, Sabine; Slaghekke, Femke; Oepkes, Dick; Lopriore, Enrico (2021). "Twin Anemia Polycythemia Sequence in a Dichorionic Twin Pregnancy Leading to Severe Cerebral Injury in the Recipient". Fetal Diagnosis and Therapy. 48 (4). S. Karger AG: 321–326. PMID 33774643.