Normal fetal lips and nose are shown in Figure 10-19. A fetal profile is not a required component of standard examination but may be helpful in identiying cases of micrognathia-an abnormally small jaw (Fig. 10-20). Micrognathia should be considered in the evaluation of hydramnios (Chap. 11, p. 227). Use of the ex-utero intrapartum treatment (EI) procedure for severe micrognathia is discussed in Chapter 16 (p. 327).
here are three main types of clefts. he irst type, clt lip and palate, always involves the lip, may also involve the hard palate, can be unilateral or bilateral, and has a birth prevalence that approximates 1 in 1000 (Cragan, 2009; Dolk, 2010). If isolated, the inheritance is multifactorial-with a recurrence risk of 3 to 5 percent for one prior afected child. If a cleft is visible in the upper lip, a transverse image at the level of the alveolar ridge may demonstrate that the defect also involves the primary palate (Fig. 10-21).
In one systematic review of low-risk pregnancies, cleft lip was identiied so no graphically in only about half of cases
FIGURE 10-20 Fetal profile. A. This image depicts a normal fetal profile. B. This fetus has severe micrognathia, which creates a severely recessed chin.
(Maarse, 2010). Approximately 40 percent of those detected in prenatal series are associated with other anomalies or syndromes, and aneuploidy is common (Maarse, 2011; Oferdal, 2008). The rate of associated anomalies is highest for bilateral defects that involve the palate. Using data from the Utah Birth Defect Network, Walker and associates (2001) identified aneuploidy in 1 percent with cleft lip alone, 5 percent with unilateral cleft lip and palate, and 13 percent with bilateral cleft lip and palate. It is reasonable to ofer fetal chromosomal microarray analysis when a cleft is identiied.
he second type of cleft is isolated clt palate. I t begins at the uvula, may involve the soft palate, and occasionally involves the hard palate-but does not involve the lip. The birth prevalence approximates 1 in 2000 (Dolk, 2010). Identiication of isolated cleft palate has been described using specialized 2-and 3-dimensional sonography (Ramos, 2010; Wilhelm, 2010). However, it is not expected to be visualized during a standard sonographic examination (Maarse, 2011; Oferdal, 2008).
A third type of cleft is median clt lp, which is found in association with several conditions. hese include agenesis of the primary palate, hypotelorism, and holoprosencephaly.
FIGURE 10-21 Cleft lip/palate. A. This fetus has a prominent unilateral (left-sided) cleft lip. B. Transverse view of the palate in the same fetus demonstrates a defect in the alveolar ridge (arrow), The tongue ) is also visible.
Median clefts may also be associated with hypertelorism and frontonasal hyperplasia, formerly called the median clt ace syndrome.
This venolymphatic malformation is characterized by luidilled sacs that extend from the posterior neck (Fig. 10-22). Cystic hygromas may be diagnosed as early as the irst trimester and vary widely in size. They are believed to develop when lymph from the head fails to drain into the jugular vein and accumulates instead in jugular lymphatic sacs. Their birth prevalence approximates 1 in 5000. But, reflecting the high in-utero lethality of the condition, the first-trimester incidence exceeds 1 in 300 (Malone, 2005).