Laser therapy for twin-to-twin transfusion syndrome (TTTS)

Recurrent twin-twin transfusion syndrome after selective fetoscopic laser photocoagulation: a systematic review of the literature

OBJECTIVES

Selective fetoscopic laser photocoagulation (SFLP) is now the treatment of choice for twin-twin transfusion syndrome (TTTS). The incidence of recurrent TTTS following SFLP has been inconsistently reported across different studies. We performed a systematic review of TTTS recurrence following SFLP.

METHODS

PubMed and MEDLINE online databases were searched for articles published between 2000 and August 2011, using combinations of the terms 'twin-twin transfusion', 'TTTS', 'laser', 'recur' and 'outcome'. Citations identified in the primary search were screened for eligibility. Studies reporting outcomes from selective SFLP for TTTS in twin pregnancies, which addressed specifically the issue of TTTS recurrence, were included. The primary outcome was rate of TTTS recurrence. Secondary outcomes were therapeutic preference and fetal outcomes in cases of recurrent TTTS.

RESULTS

The primary search identified 22 eligible studies that are included in this review (n = 2447 twin pregnancies). Two studies included a minority of non-selective procedures. The published incidence of recurrent TTTS ranged from 0 to 16%. Clinical management was reported in 65.7% (71/108) cases, with repeat SFLP the most commonly performed secondary intervention. Only three studies provided comprehensive outcome data for cases of recurrent TTTS. The overall rate of neurologically-intact survival was 44% (23/52). The data were inadequate to determine the effects of secondary therapeutic approach, placental location or gestational age on perinatal outcome in cases of recurrent TTTS.

CONCLUSIONS

The published rate of TTTS recurrence following SFLP in monochorionic twin pregnancies ranges from 0 to 16%. Although limited follow-up data suggest that recurrence is associated with significant perinatal mortality and morbidity, further study is needed. Currently, there are insufficient data available to guide recommendations for clinical management of TTTS recurrence. Future studies on SFLP for TTTS must include details on recurrence rates and provide outcome data specific to the recurrent subset.

Intrauterine surgery--choices and limitations

BACKGROUND

The past decade has seen much progress in intrauterine surgery. Randomized trials have documented the benefit of some procedures of this type for the unborn child.

METHOD

Selective literature review

RESULTS

Randomized trials have demonstrated the benefit of fetoscopic laser coagulation of placental anastomoses in twin-to-twin transfusion syndrome (TTTS) and of intrauterine surgery via hysterotomy for the repair of spina bifida. Other fetoscopic procedures have yielded promising initial results but are not yet supported by findings from randomized trials. Some intrauterine surgical procedures must still be considered experimental in view of the lack of randomized trials and the rarity of the conditions they are designed to treat. Fetoscopic laser coagulation for TTTS is by far the most common procedure in fetal surgery; TTTS arises in roughly 1 in 2500 pregnancies. The other procedures discussed in this article are performed much less often and for rarer indications. In general, intrauterine surgery is indicated only to treat conditions that would otherwise lead to intrauterine death or irreversible prenatal damage.

CONCLUSION

Intrauterine surgery is a rapidly developing field. Prenatal intervention by laser coagulation is indicated to treat severe TTTS, as its benefit has been shown in a randomized trial. Not enough evidence is yet available for the possible benefit of intrauterine surgery to treat myelomeningocele and congenital diaphragmatic hernia. Other indications are experimental. When an indication for intrauterine surgery exists, the parents should be informed and, depending on their wishes, referred to a center where it can be performed.

Twin-twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) is a serious condition that affects 10% to 15% of twin pregnancies with monochorionic diamniotic placentation. The pathophysiology of TTTS is not completely understood; however, the presence of unbalanced placental vascular communications within a shared circulation has been implicated in its development. The presentation of TTTS is highly variable, and it does not always progress in a predictable manner. Monochorionic twin gestations should, therefore, be monitored for signs of TTTS with serial sonograms starting in the second trimester. Early TTTS can be managed conservatively. However, without intervention, early-onset advanced TTTS is associated with a high perinatal loss rate and risk of severe neurologic impairment among survivors. Limited studies suggest that fetoscopic laser photocoagulation is the best available treatment for advanced TTTS diagnosed in the second trimester. Even with laser therapy, there remains a significant risk of twin demise and neurologic handicap in survivors.