What is the term given to a woman who has completed one pregnancy with a fetus or fetuses reaching the stage of fetal viability?

Interpretation

The absence of fetal cardiac activity and fetal movement after scanning for a 5-minute interval in a pregnancy of more than 20 weeks’ gestation is said to be 100% reliable for diagnosing a fetal demise. For a first-trimester pregnancy, if uncertainty exists about fetal heart activity, rescanning should be performed in 1 to 2 weeks.

Secondary criteria for fetal demise using POCUS include fetal anomalies such as hydrops, ascites, and pleural or pericardial effusions. Echogenic gas in the fetal heart and vessels may be early findings. Late findings include morphologic changes such as skeletal anomalies and unusual fetal positioning.

Reaction to external stimulation or uterine manipulation should cause brisk reflexes in viable fetuses, as opposed to the passive motions seen with a fetal demise. Avoid misinterpreting the passive motions from uterine contractions around a dead fetus as fetal activity.

Because abruptio placentae cannot always be diagnosed with ultrasound [i.e., it is a clinical diagnosis], ultrasound studies should be used in conjunction with maternal–fetal monitoring in the pregnant patient with significant abdominal trauma. A 4-hour monitoring period should be sufficient to identify fetal distress.

Viability of the Fetus

Fetal viability is a major issue that is dependent on the evolution and progress of modern neonatology [Beauthier, 2007]. It is generally accepted that a 28-week-old fetus that doesn't need resuscitation is viable. However, according to WHO, fetal viability is possible after 20 weeks of fetal life [22 weeks of amenorrhea].Anthropometrical characteristics as well as clinical parameters of fetal age estimation are of high importance.

Determination of Fetal Age

A simple way to calculate fetal age [in lunar months] is to divide the fetal length [in cm] by 4 for fetuses less than 5 months' gestation. If it is less than 5 months' gestation the length [in cm] is divided by 5. Anthropometric measurements collected during examination of the fetus are used to estimate its age more accurately [Beauthier, 2011b]. Three types of data can be gathered from radiologic investigations [Scheuer et al., 1980]:

direct fetal age estimation from measurement of the length of long bones [Scheuer et al., 1980];

fetal age estimation from measurement of the long bones and calculation of fetal stature [crown–heel or crown–rump length] [O'Rahilly and Müller, 2001; Scheuer and Black, 2004]; and

a more difficult method involving the degree of deciduous teeth calcification; this method requires the conservation of dental crowns and is not particularly suitable for this type of investigation.

Scheuer reports the following values from her study on full-term fetuses in the UK [Scheuer et al., 1980]:

crown–rump length: from 28 to 32 cm; and

crown–heel length: from 48 to 52 cm.

Various authors have highlighted the importance of long bones radiography, in particular the fetal femoral diaphysis [Odita et al., 1982; Piercecchi-Marti et al., 2002]. A study was carried out to investigate the fidelity and reproducibility of the radiographic methods used for measuring the femoral diaphysis [Adalian et al., 2001]. The regression equation obtained was as follows:

Fetalage[inweeks]=6.93+0.434×femurlength[inmm]

The lower limb centers of ossification [distal epiphysis of the femur, proximal epiphysis of the tibia, posterior tarsus] are of great practical interest.

Echographic examination can provide useful information in the living subject.

Many studies have been carried out using ultrasonography, with a focus on the length of fetal long bones [Jeanty et al., 1984], the length of the femur, the relationship between the length of the femur and fetal weight [Honarvar et al., 2001], biparietal diameter, and cephalic and abdominal perimeters [Davis et al., 1993; Nasrat and Bondagji, 2005; Yagel et al., 1986]. Using ultrasonography other authors have examined the relationship between fetal weight, abdominal perimeter, and femur length, and a mathematical model was proposed [Ferrero et al., 1994].

Table 2 shows some useful anthropometric and visceral parameters in the full-term fetus.

Table 2. Anthropometric and visceral parameters of the full-term fetus

Source: Beauthier, J-P., 2011a. La problématique du foetus et du nouveau-né en médecine légale. In: Beauthier, J-P. [Ed.], Traité de Médecine Légale. Bruxelles: De Boeck Université, pp. 389–402.

Signs Observed in the Stillborn Baby

Differentiating between the stillborn baby and the child who has not lived is not easy. The phenomena of maceration [aseptic autolysis which occurs when the fetus dies in utero] and putrefaction [postmortem ex utero deterioration] can notably complicate the medicolegal approach.

Descriptions of the criteria of extrauterine life are based on the existence of respiratory events and an effective circulatory system after birth. Cardiovascular function is evident in children who are victims of physical violence in particular [bruising, vital tegumentary lesions, associated fractures, and hemorrhage]. Ventilatory function is assessed by histological study of the lung, and the presence or absence of territorial atelectasis is established. Multiple samples are required to clarify the matter.

Introduction

Assessments of the fetal well-being and cardiac function and identification of a likely disease mechanism are important diagnostic steps in the clinical evaluation of the fetus with cardiac compromise. Table 28.1 summarizes the echocardiographic features of the main conditions associated with in-utero HF. The prenatal diagnosis of HF primarily relies on the ultrasound-based documentation of systolic and/or diastolic cardiac dysfunction and the circulatory consequences [31].

Table 28.1. Echocardiographic Features of Conditions Associated With Fetal Heart Failure

CCAM, congenital cystic adenomatoid malformations of the lung; CHB, complete heart block; CM, cardiomyopathy; DA, ductus arteriosus; DV, ductus venosus; EFE, endocardial fibroelastosis; MCA, middle cerebral artery; N, normal; NC, ventricular noncompaction; RV > LV, right ventricle more severely affected than the left ventricle; TRAP, twin reversed arterial perfusion sequence; TTTS, twin–twin transfusion syndrome; ↑, increased; ↓, decreased; –, absent.

Measures of the Cardiovascular Status

In early stages of HF, disease manifestations that are readily detectable by echocardiography may be subtle. At more advanced stages [Fig. 28.1], findings include ascites, pleural effusion, pericardial effusion, or a combination of these findings, in addition to cardiomegaly, valvar regurgitation, poly- or oligohydramnios, preferential shunting of blood flow to the brain and heart, absence or reversal of the end-diastolic umbilical artery [UA] flow, and reduced or absent fetal movements. In end-stage HF, generalized skin edema is seen easily over the scalp and abdominal wall.

Measures of Cardiac Function

M-mode is useful to quantify the fetal systolic ventricular function by measurements of the changes in ventricular dimensions at the end of diastole [EDD] and of systole [ESD], respectively. Ventricular shortening fraction is calculated as SF [%] = [EDD-ESD]/EDD × 100. An LV or RV SF