OBJECTIVE: To examine the incidence of preterm premature rupture of membranes 
(PPROM) in pregnancies affected by twin-twin transfusion syndrome (TTTS) treated 
with laser photocoagulation where an absorbable gelatin sponge was used as a 
chorioamnion sealant of the fetoscopic access port.
METHOD: A retrospective review was undertaken of consecutive cases undergoing 
fetoscopic directed laser surgery for TTTS between October 2006 and November 
2008 at Texas Children's Fetal Center, in which an absorbable gelatin sponge, 
used as a chorioamnion 'plug', was placed at the conclusion of the intervention 
as a possible prophylactic measure to prevent PPROM. We excluded cases that had 
a failure of plug placement and those in which it was not attempted. PPROM was 
defined as rupture of membranes before 34 weeks' gestation. A comparison was 
performed between the PPROM group and a no-PPROM group to determine risk factors 
and outcomes.
RESULTS: Successful plug placement occurred in 79 of 84 cases (94%) in which it 
was attempted after laser surgery, with a rate of PPROM of 34% in these 
patients. PPROM occurred at an average gestational age of 26.5 +/- 3.6 weeks, 
with an average procedure-to-PPROM interval of 5.2 +/- 3.5 weeks. There were no 
statistically significant differences between the PPROM group and the no-PPROM 
group in maternal demographics or preoperative parameters including: amniotic 
fluid volumes in the recipient twin's gestational sac, volume of amnioreduction, 
and location of the placenta. The procedure-to-delivery interval for the total 
cohort (n = 79) was 9.2 +/- 4.7 weeks, without a significant difference between 
the two groups (P = 0.08). However, after exclusion of one PPROM outlier, the 
PPROM group had an average procedure-to-delivery time 2 weeks shorter than the 
group with no PPROM (P = 0.03). The live birth rates were similar in the PPROM 
and no-PPROM groups, at 77 and 73%, respectively. However, the average 
recipient's weight in the PPROM group was significantly lower than in the 
no-PPROM group (1321 +/- 493 vs. 1705 +/- 576 g; P = 0.02).
CONCLUSION: The rate of PPROM and the mean gestational age at delivery in 
pregnancies in which an absorbable gelatin sponge was used as a sealant of the 
fetoscopic port following laser photocoagulation for TTTS were comparable to 
those that have been reported by other laser centers where membrane sealants 
were not used. A randomized controlled trial should be considered to evaluate 
the effect of chorioamnion plugging.