Macerated Fetus: Causes and Medical Insights

A macerated fetus is one that has died inside the uterus and remained there for a period, undergoing specific post-mortem changes. This physical state indicates that fetal demise occurred some time before delivery or diagnosis. It is a sign of intrauterine fetal death (IUFD).

Understanding Fetal Maceration

Maceration is a destructive process involving aseptic autolysis, the self-digestion of cells by their own enzymes. This process begins shortly after fetal death when the fetus is retained within the uterus.

Physical changes become observable within hours of death. Early signs, often seen 4 to 6 hours after intrauterine death, include reddened skin that easily separates from the underlying dermis upon pressure, known as skin slippage. As maceration progresses, the skin may peel extensively, exposing a red and moist dermal surface. Fluid accumulation, or anasarca, can make the fetus appear edematous. Internal organs, especially the liver, spleen, adrenals, and brain, soften significantly, and overlapping of the skull bones, known as Spalding’s sign, also occurs.

Reasons for Fetal Demise

Fetal maceration is a consequence of intrauterine fetal demise (IUFD). The causes of IUFD are varied and can stem from issues related to the placenta, maternal health, or the fetus itself. Placental problems are a common category, encompassing conditions like placental insufficiency, where the placenta fails to provide adequate nutrients and oxygen to the fetus. Placental abruption, the premature separation of the placenta from the uterine wall, or umbilical cord accidents such as cord compression, knots, or entanglement, can also lead to fetal death.

Maternal health conditions can also contribute to fetal demise. Severe infections contracted during pregnancy, such as listeriosis, rubella, or toxoplasmosis, can affect the fetus. Uncontrolled chronic diseases in the mother, including severe hypertension, diabetes, or autoimmune disorders like lupus, can lead to IUFD. Preeclampsia, a pregnancy complication characterized by high blood pressure, is another maternal factor associated with fetal demise.

Fetal factors represent another group of causes. Severe genetic abnormalities or chromosomal alterations can prevent proper development, leading to non-viability. Structural malformations, or congenital defects, can also be incompatible with life. Additionally, severe infections originating within the fetus itself can cause demise. Despite thorough investigation, a notable percentage of IUFD cases, ranging from 25% to 60%, remain without a clear, identifiable cause.

Identifying Maceration and Its Medical Insights

Prenatal ultrasound is a primary diagnostic tool, revealing signs such as the absence of fetal heart activity. Overlapping skull bones, known as Spalding’s sign, and fluid accumulation within fetal tissues (anasarca) are also visible on ultrasound, indicating that death occurred days to weeks prior to the examination. Fetal maceration may be visible on ultrasound between 12 to 24 hours after fetal death.

Post-mortem examination confirms maceration and aids in investigating the cause of death. During this examination, the characteristic changes like skin slippage, tissue discoloration, and softening of internal organs are observed. The degree of maceration helps differentiate a macerated stillbirth from a fresh stillbirth, where no signs of maceration are present, implying death occurred much closer to delivery, typically within hours. This distinction is important for medical professionals in determining potential underlying causes and guiding future pregnancy management.

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