Lower urinary tract obstruction is defined as partial or complete obstruction of the urinary tract at the level of the urethra and the bladder. The posterior urethral valves are the most common cause, 9 percent of the fetal uropathies. The incidence range is wide, because of different databases show different populations. The most severe obstructive uropathy is in patients with kidney damage, oligohydramnios and pulmonary insufficiency. If no prenatal intervention is performed, 45 percent of these patients die in the first 3 weeks of life and 25 percent have renal failure. In utero therapy is indicated to prevent renal damage and pulmonary hypoplasia in cases associated with progressive development of oligohydramnios. The treatment is usually limited to male fetuses with bladder outlet obstruction. The selection criteria (contraindications of fetal intervention) are: normal amniotic fluid volume, suggestion of nonobstructive dilatation of the urinary tract, sonographic evidence of renal cystic dysplasia, abnormal fetal urinary parameters, abnormal karyotype, presence of associated major congenital anomalies, fetal urinary parameters are above threshold. At the follow up after a prenatal intervention showed an apparent statistically significant improvement in perinatal survival with prenatal intervention relative to no intervention. Furthermore, there was no significant difference between the proportions of survivors with normal renal function who underwent bladder drainage and those who did not. Improved perinatal survival was also suggested in those fetuses with a poor prognosis. A nonsignificant improvement in perinatal survival for those fetuses with a good prognosis was also seen.

Maternal, fetal or placental pathologies may result in an excessive amount of amniotic fluid (AF) volume. Therefore, the surveillance of the AF volume, predominantly by ultrasound, has become an important instrument for the assessment of fetal well-being. An excessive accumulation of amniotic fluid, as a consequence of a disturbed balance between production, fetal resorption and secretion, is defined as polyhydramnios. Its degree correlates significantly with fetal morbidity and mortality. Therefore, polyhydramnios is an important clinical pattern in perinatal medicine. Approximately 20 percent of the fetuses with severe polyhydramnios show a congenital anomaly, whereas 50 percent of all cases are considered to be idiopathic, mostly with mild patterns. Furthermore, the likelihood of aneuploidy varies from 0.4 to 10 percent. Early detection, provides a correct diagnosis and allows a individual therapy. A referral to a tertiary center is advised in case of severe polyhydramnios and unknown etiology.

In this review, current diagnostic as well as therapeutical aspects are discussed.

Conjoined twins have an estimated incidence of one in 50,000 to one in 100,000 births. The first cases of prenatal diagnosis of conjoined twins using B-mode ultrasound were reported in the 1970s, followed by prenatal real-time ultrasonographic diagnosis shortly thereafter. Since then, real-time ultrasound has been the most reliable method in establishing prenatal diagnosis of conjoined twins and in detecting associated anomalies. Moreover, recent improvements in real-time ultrasound technology - in some cases coupled with use of Magnetic Resonance Imaging (MRI) - have made early diagnosis of conjoined fetuses in the first trimester possible. Prenatal diagnosis of conjoined fetuses is considered essential for further management. Parents need detailed counseling in order to decide among various management options, which include the following: (a) pregnancy continuation and scheduled neonatal surgery, (b) termination of pregnancy, and (c) multifetal pregnancy reduction or selective fetocide in cases of high-order multifetal pregnancies with a component of conjoined fetuses. An interdisciplinary medical team, involving obstetricians, neonatologists, pediatric surgeons and anesthetists, should carefully approach and assist parents in their decisions. In special cases, additional consultation may be given by other specialists, even from specialized centers in other countries, depending on the area of conjunction, the involvement of other organ systems, and the presence of associated anomalies.

Although three-dimensional ultrasound (3DUS) has been available for more than 10 years in Indonesia, there was no publishing article from our region which systematically evaluates our experiences in this most recent ultrasound technologies and its application to obstetric. 3DUS is revolving into a technology with various range of applications in numerous fields because it helps overcome some of the key limitations related to two-dimensional imaging. It is through this review that we attempt to develop a continuous line of understanding the current diagnostic benefits of 3D and 4DUS in diagnosis of fetal abnormalities and consider the utility and role of this type of imaging in the routine clinical practice.