*3.2.1. Diagnostic criteria and staging*

could be due to the increased experience with fetoscopic laser in general and not to the use of the Solomon technique. In the only randomized trial, the single twin and both twins' survival rates after 1 month in the SFLP were 87% and 60%, while in the Solomon group these rate

The neurologic outcomes in the neonatal period following laser procedures, such as intraventricular hemorrhage, periventricular leukomalacia, cerebral white matter cysts, ventricular dilatation, and cerebral atrophy, range from 8 to 18% [51, 72, 73]. The long-term neurodevelopmental outcomes vary between 3 and 12% for cerebral palsy and 4 and 18% for neurodevelopmental impairment [73]. In one study, the neurodevelopmental scores in preterm-born children treated with laser therapy for TTTS were similar in preterm-born DC children, suggesting that prematurity has the main role in the neurologic impairment in fetus treated with laser photocoagulation [74]. Other authors have suggested risk factors for poorer neurodevelopmental outcomes [75, 76]. Lopriore et al. analyzed 212 pregnancies treated with fetoscopic laser surgery and found that advanced gestational age at laser surgery, low gestational age at birth, low birthweight, and high Quintero stage are risk factors of poor neurological develop-

Several studies report a rapid cardiac function recovery in the recipient and in the donor twin [36, 38, 77–80]. The coagulation of vascular anastomoses stops the volume exchange, as well as the vasoactive mediators, allowing cardiac output, cardiac size, valvular regurgitation, and ventricular inflow to normalize in the recipient twin in about half of the cases [38, 77]. The donor twin shows an increase in left ventricular filling pressure and cardiac output, which can temporarily cause a relative volume overload. It can worsen the cardiac function and cause ductus venosus alterations and even hydrops; however, these changes tend to disappear by 2 to 4 weeks

There are other types of treatment, such as septostomy. This procedure increases the risk of severe complications like cord entanglement and disruption of the membrane. This procedure has generally been abandoned [64, 83]. The selective reduction is another therapeutic option that tries to improve the outcome of the surviving twin whenever there is an imminent risk of spontaneous intrauterine death of one fetus. It can be performed either by ultrasound-guided vascular embolization or cord clamping through fetoscopy. A maximum of 50% survival is

The fetoscopic laser coagulation is the gold standard treatment in stage II to stage IV TTTS affected pregnancies; the SFLP and Solomon technique are the best options for lowering the mortality and morbidity in theses fetuses. For Quintero stage I, there is not enough data that favors laser surgery, and more powered studies should be done comparing it to other kinds

Selective intrauterine growth restriction happens in 10–25% of MC gestations and it considerably increases perinatal morbidity and mortality [84–86]. The diagnostic criteria for sFGR differ among clinicians; therefore, it is hard to compare the findings of existing studies, to

reached and most services have not supported this technique [68].

of treatment; therefore, the treatment for this stage has to be individualized.

were 85% and 64%, respectively [66].

134 Multiple Pregnancy - New Challenges

ment at 2 years of age [76].

after the laser procedure [79, 81, 82].

**3.2. Selective intrauterine growth restriction**

Since many authors have proposed different diagnostic criteria, in 2017, the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) published a guideline for the sFGR diagnostic. It is defined as a condition in which one fetus has estimated fetal weight (EFW) < 10th centile and the intertwin EFW discordance is >25%. EFW discordance is calculated by the following formula: (weight of larger twin – weight of smaller twin) × 100)/weight of larger twin [45]. This weight discordance was proposed by an expert consensus, mainly based on data that show that an 18% EFW discordance reflects poorer outcomes both in DC and MC pregnancies [88]. Curiously, the charts used to monitor the fetal growth should be the same as those used in singleton pregnancies [45, 89], although specific multiple pregnancy charts are available [90]. However, there is a reduction in fetal growth in twin compared with singleton pregnancy, particularly in the third trimester. The key question for clinicians is whether this difference in growth represents adaptation or restriction [91]. Once the diagnosis is made, a detailed anomaly scan and screening for viral infections (cytomegalovirus, rubella, and toxoplasmosis) should be made. Amniocentesis may also be required to exclude chromosomal abnormalities as a cause of FGR [45, 92].

**Figure 6.** Macroscopic photograph demonstrates the measurement of the vascular anastomoses. There is a 2-mm arterioarterial anastomosis (dashed arrow) and 5 AV anastomoses (arrows). A macroscopic placental surface discordance is also visible (green dashed line: Vascular equator). Adapted from Am J Obstet Gynecol. Lewi et al. [86].

In order to follow up the sFGR pregnancies, as well as in singleton pregnancies, umbilical artery Doppler waveforms and UA-PI are accessed. In pregnancies complicated with sFGR, there are particularities in the umbilical artery Doppler probably because of the variability in the intertwin vascular anastomoses resistance [93, 94]. Three patterns are observed in the umbilical artery Doppler: positive end-diastolic flow, absent or reversed end-diastolic flow (AREDF), and intermittent absent or reversed end-diastolic flow (iAREDF) [95]. The latter pattern though is to result from the presence of transmitted waveforms from the larger into the smaller twin's cord due to the existence of placental large AA anastomoses (**Figure 6**) [93–95]. Based on these three Doppler types, Gratacós et al. proposed a three-stage classification system of the sFGR fetuses. In stage I, the umbilical artery in the smaller twin has a positive end-diastolic flow; in stage II, there is an AREDF; and stage III is characterized by iAREDF (**Figure 7**) [95].

The stage I prognosis is better, with an overall intrauterine mortality rate of 3–4% and a 97% rate of intact survival-free from neurological complications according to two recent meta-analyses. The neonatal morbidity, defined as abnormal brain imaging, respiratory distress syndrome (RDS), admission to the neonatal intensive care unit (NICU), or retinopathy of prematurity (ROP), was reported in about 9% of newborns. The neurologic outcome in this stage seems to be better when compared to the others as well as the gestational age at delivery [84, 93–95, 97]. Stage II sFGR has a poorer prognostic. It is reported that these fetuses tend to have a high risk of hypoxic deterioration and consequently overall, single, and double intrauterine death rates of 16.6%, 8.2%, and 10.4% of cases managed expectantly [97] and a 21% perinatal mortality [84]. The double survival rate in this stage is about 25% [98]. The iAREDF pattern has an intrauterine mortality rate similar to stage II. The overall, single, and double intrauterine death occurred in 13.2%, 7.2%, and 5.5% of cases managed expectantly although this stage is more unpredictable than the others [86, 93, 95, 97, 98]. Some ultrasound markers can be used as adverse predictors such as ductus venosus Z score [98], velamentous cord insertion (**Figure 8**) [99, 100], and weight discordance. A recent meta-analysis found that, in MC twin pregnancies, excluding cases affected by twin to twin transfusion syndrome, twins with birthweight discordance ≥25% were at higher risk of intrauterine death (OR 3.2, 95%CI, 1.5–6.7) and neonatal

death (OR 4.66, 95% CI, 1.8–12.4) compared with controls [101]. Gratacós et al. [93] found a 15% unexpected intrauterine death rate in the smaller twin on stage III sFGR compared with 2.6% and 0 in stages I and II, respectively. On the other hand, other authors show a better prognosis. Rustico et al. [102] showed a 0% rate in double fetal death at stage III as well as better rates in overall survival and lower neonatal death in the smaller twin (8% and 62%, respectively).

**Figure 8.** Monochorionic placenta with velamentous cord insertion in the smaller twin side. AV and VA anastomoses are

Complications in Monochorionic Pregnancies http://dx.doi.org/10.5772/intechopen.83390 137

seen and on big AA anastomoses. Adapted from Am J Obstet Gynecol. Lewi et al. [96].

When sFGR presents with an umbilical artery positive end-diastolic flow, the prognosis is good, and therefore it is a consensus that the expectant management based on a weekly fetal growth and UA-PI evaluation should be done to look for progression to more severe stages which can occur in up to 25% of cases. For stages II and III, several studies compared SFLP with cord occlusion or expectant management, but there are not powered studies to support a gold standard treatment. In a retrospective study with 142 stage II sFGR fetuses treated with SFLP, there was survival rate of the smaller, larger, and both twins of 38.7, 67.6, and 34.5%, respectively. The survival rate of at least one twin was 71.8% [103]. When compared to expectant management, SFLP for stage III sFGR showed a higher overall intrauterine death (14.5 vs. 36%, respectively) as well as a higher death rate in the smaller twin which is 19% for the expectant group and 66% for the SFLP group [104]. Other prospective trial with ten pregnant women with sFGR stages II or III and oligohydramnios treated with SFLP showed that only three newborns of the restricted group survived and all of the newborns in the larger twin

Cord occlusion of the smaller twin is an option for early diagnosed sFGR, when the spontaneous death of the restricted fetus is most likely to happen, but it is the most difficult decision for the parents to make since they give up the life of one child to protect the other. Chalouhi et al.

*3.2.2. Management of sFGR*

group were well and alive at 28 days of age [105].

**Figure 7.** Classification of selective fetal growth restriction in monochorionic twin pregnancy. In type I, the umbilical artery Doppler waveform has positive end-diastolic flow, while in type II there is absent or reversed end-diastolic flow (AREDF). In type III there is a cyclical/intermittent pattern of AREDF. Extracted from ISUOG. https://www.isuog.org/ uploads/assets/uploaded/b4ce0129-a7e8-40a9-8543c4243fb7638f.pdf [45].

**Figure 8.** Monochorionic placenta with velamentous cord insertion in the smaller twin side. AV and VA anastomoses are seen and on big AA anastomoses. Adapted from Am J Obstet Gynecol. Lewi et al. [96].

death (OR 4.66, 95% CI, 1.8–12.4) compared with controls [101]. Gratacós et al. [93] found a 15% unexpected intrauterine death rate in the smaller twin on stage III sFGR compared with 2.6% and 0 in stages I and II, respectively. On the other hand, other authors show a better prognosis. Rustico et al. [102] showed a 0% rate in double fetal death at stage III as well as better rates in overall survival and lower neonatal death in the smaller twin (8% and 62%, respectively).
